CONTROLLING THERMAL ENERGY STORAGE

RELATED APPLICATION/S

The present application claims priority from U.S. Provisional Patent Application number 62/824,541 filed on 27 March 2019, which is related to International Patent Application Number PCT/IB2018/001091 filed on 25 September 2018, which claims priority from U.S. Provisional Patent Application number 62/685,147 titled CONFIGURABLE THERMAL ENERGY STORAGE ARRAY, filed on 14 lune 2018, and from U.S. Provisional Patent Application number 62/562,562 titled CONFIGURABLE THERMAL ENERGY STORAGE ARRAY, filed on 25 September 2017.

This filing also claims priority from U.S. Provisional Patent Application number 62/824,914 filed on 27 March 2019, and U.S. Provisional Patent Application number 62/824,575 filed on 27 March 2019, the disclosures of which are incorporated herein by reference.

The contents of all of the above applications are incorporated by reference as if fully set forth herein.

FIELD AND BACKGROUND OF THE INVENTION

The present invention, in some embodiments thereof, relates to a system and method for thermal energy storage and particularly but not exclusively to controlling use of and applications for thermal energy storage, and even more particularly but not exclusively to software and components for controlling efficiency of thermal energy storage.

The controlling use of and applications for thermal energy storage, and the software and components for controlling efficiency of thermal energy storage are applicable to various types of systems for thermal energy storage, including Thermal Energy Systems (TES) systems as described in above-mentioned International Patent Application Number PCT/IB 2018/001091, various“ice-on-coil” storage systems,“encapsulated ice” systems, and other TES systems.

Many studies of energy consumption in the developed world have pointed to peak energy (electricity) consumption occurring during less than 400-300 hours annually (5% of the time). A substantial amount of this peak energy demand may be attributed to structural cooling systems such as chillers, air conditioning or space heating systems relying on heat pumps. There is therefore a growing need to provide efficient and cost effective cooling systems that can counter balance the grid’s fluctuation.

One response to this need has been the development of thermal energy storage systems, especially ice storage systems, which store cold or hot energy by running grid electricity consuming chillers or heat pumps during off-peak hours and then discharging the stored energy during peak or other hours. Some disadvantages of some current systems are their incompatibility with a commercial building, lack of modularity, and their significant footprint - often requiring the usage of expensive real estate assets of a building in order to provide sufficient thermal energy storage; as a result, this method of storing energy is almost totally absent from the commercial sector (office buildings, shopping malls, hotels, hospitals and so on), which is a great contributor to the peak demand phenomena.

The most common type of such a conventional system for storing thermal energy is known as an“ice-on-coil” storage system. These systems comprise a tank filled with water/ice as a phase change medium (PCM) for storing heat, especially by utilizing the phase change of liquid water into ice. These systems further comprise a coil that is placed inside the tank in the water in order to exchange heat with the water/ice. While charging this type of system, ice is built up around the coil in order to form a massive block. These systems suffer from a significant loss of efficiency, since the freezing of the water starts regularly at or on the coil, and frozen water is quite a good thermal insulator. Hence, a layer of ice on the coil increases its thickness when the tank is cooled to below around zero degrees Celsius with the coil in order to store latent heat energy. Consequently, an increasing insulation layer makes it increasingly difficult to freeze the whole volume of the storage tank. This is known as the“ice-build-up” problem. Conventional systems thus have to use very low temperatures for cooling the coil, which is inefficient. Furthermore, working at too low temperatures hurts the chiller’s COP (coefficient of performance).

Furthermore, a different type of conventional thermal energy storage systems is known as “encapsulated ice” storage systems, wherein a plurality of containers that contain water as PCM for storing energy is placed inside a tank. A further medium, for example a water-glycol mixture, for exchanging heat with the water/ice inside the containers is pumped through the tank on demand. However, until now this type of a thermal energy storage system also lacks efficiency and reliability.

One of the inefficiencies of some current systems, especially of“encapsulated ice” and“ice on coil” systems that use water/ice, is slow or inconsistent ice nucleation that results in inefficient thermal energy storage and discharge. The inconsistent ice nucleation and generation is generally caused by super-cooled water that is not freezing at the desired temperature.

A still further limitation of some current systems is a limited ratio between storage fluid (water) volume and total system volume and/or the limited contact between the storage fluid (water) and the heat transfer fluid (such as glycol) either due to the growing water barrier between the two inside the capsules as the discharge cycle advances, to a low packing factor of the storage fluid containers, or poor design of the storage fluid containers such that they do not expose a great enough surface area to the heat transfer fluid or block the flow of the heat transfer fluid, thus greatly reducing the efficiency of the thermal storage. A further limitation in some systems is the inefficient discharge process that does not result in melting of all of the ice stored in the system. Furthermore, conventional systems provide an insufficient and especially dropping discharge rate, which is not sufficient to support load demands. In other words, conventional ice storage systems have usually the problem of an unstable and a degrading discharge behavior / discharge curve.

A further problem of some thermal energy storage systems that use water/ice as energy storage medium is that they suffer from a degradation of system performance over their lifetime, for example due to material fatigue or changes of the flow properties of the system. Especially with current“encapsulated ice systems”, the repeated expansion and contraction of the volume of water while freezing can create such problems. One further problem with some conventional thermal energy storage systems that use water as PCM is a power rate drop in the second half of the discharge cycle. This phenomenon is caused by the melted water within capsules that act as barrier to the thermal heat exchange/conduction, wherein this thermal barrier gets constantly larger as the ice melts.

The disclosures of all references mentioned above and throughout the present specification, as well as the disclosures of all references mentioned in those references, are hereby incorporated herein by reference.

SUMMARY OF THE INVENTION

The present invention, in some embodiments thereof, relates to a system and method for thermal energy storage and particularly but not exclusively to controlling use of and applications for thermal energy storage, and even more particularly but not exclusively to software and components for controlling efficiency of thermal energy storage.

The controlling use of and applications for thermal energy storage, and the software and components for controlling efficiency of thermal energy storage are applicable to various types of systems for thermal energy storage, including Thermal Energy Systems (TES) systems as described in above-mentioned International Patent Application Number PCT/IB 2018/001091, various“ice-on-coil” storage systems,“encapsulated ice” systems, and other TES systems.

Methods and devices for controlling use of and applications for thermal energy storage are described herein in addition to descriptions taken from International Patent Application Number PCT/IB2018/001091 for a thermal energy storage system which are suitable for being used with the above-mentioned methods, devices and applications. It is pointed out that a person skilled in the art will learn from the present application how to implement such methods, devices and applications for other, additional thermal energy storage systems.

According to an aspect of some embodiments of the present invention there is provided a method of flattening electric energy demand from an electric grid including, during less-than-peak electricity demand periods, freezing Phase Change Material (PCM) in a Thermal Energy Storage (TES) system, and during peak electricity demand periods, using the TES to cool air conditioning refrigerant fluid and/or to pre-cool returning water or heat transfer fluid of a building before it returns into an existing cooling system.

According to some embodiments of the invention, the method is used by an establishment selected from a group consisting of a server farm, a residential building, a shopping center, an office building, a hotel, a hospital, a small scale energy center, a medium scale energy center, a large scale energy center, a small scale cooling system, a medium scale cooling system, and a large scale cooling system.

According to an aspect of some embodiments of the present invention there is provided a method of flattening electric energy demand of a cooling system and/or an air-conditioner from an electric grid including receiving a control signal, and instmcting a fluid distribution system to direct heat exchange fluid of an air-conditioner from flowing through a condensing coil to flowing through a Thermal Energy Storage (TES) system.

According to some embodiments of the invention, the control signal is a radio signal or any other method of sending a signal from an electric power supply company transmitter.

According to some embodiments of the invention, the control signal is a signal pushed over the Internet, or from an electric power supply company transmitter.

According to an aspect of some embodiments of the present invention there is provided a system of flattening electric energy demand of a cooling system and/or an air-conditioner from an electric grid including an air conditioner, a Thermal Energy Storage system, and a controller, wherein the controller is programmed to implement any one of the above methods.

According to some embodiments of the invention, the system is configured to control flow of refrigerant fluid from the air conditioner through the TES.

According to some embodiments of the invention, the system is configured to exchange heat, optionally via a heat exchanger, using a heat transfer fluid, to a building’s return water.

According to an aspect of some embodiments of the present invention there is provided a method of charging a Thermal Energy Storage (TES) system by freezing Phase Change Material (PCM) in the TES system including setting a temperature of heat exchange fluid at a temperature higher than -10 degrees Celsius when directed to ice bricks containing water and an ice nucleation agent.

According to some embodiments of the invention, the setting includes setting at a temperature of -5 degrees Celsius. According to some embodiments of the invention, the setting includes setting at a temperature of -2.7 degrees Celsius.

According to an aspect of some embodiments of the present invention there is provided a Thermal Energy Storage (TES) system capable of discharging more than 50% of a heat capacity of the TES.

According to some embodiments of the invention, the TES system is capable of discharging more than 80% of a heat capacity of the TES.

According to some embodiments of the invention, the TES system is capable of discharging more than 90% of a heat capacity of the TES.

According to some embodiments of the invention, the TES system is capable of discharging more than 80% of a heat capacity of the TES within a period of 4 hours or less.

According to some embodiments of the invention, the TES system is capable of discharging more than 90% of a heat capacity of the TES within a period of 4 hours or less.

According to an aspect of some embodiments of the present invention there is provided a Thermal Energy Storage (TES) system controller programmed to discharge more than 50% of a heat capacity of the TES .

According to some embodiments of the invention, the TES system controller is programmed to discharge more than 80% of a heat capacity of the TES.

According to some embodiments of the invention, the TES system controller is programmed to discharge more than 90% of a heat capacity of the TES.

According to some embodiments of the invention, the TES system controller is programmed to discharge more than 80% of a heat capacity of the TES within a period of 4 hours or less.

According to some embodiments of the invention, the TES system controller is programmed to discharge more than 90% of a heat capacity of the TES within a period of 4 hours or less.

According to an aspect of some embodiments of the present disclosure there is provided a method for flattening electric energy demand from an electric grid including during less-than-peak electricity demand periods, freezing Phase Change Material (PCM) in a Thermal Energy Storage (TES) system, and during peak electricity demand periods, using the TES to cool air conditioning refrigerant fluid. According to some embodiments of the disclosure, the method is used by an establishment selected from a group consisting of a server farm, a residential building, a shopping center, an office building, a hotel, a hospital, a small scale energy center, a medium scale energy center, a large scale energy center, a small scale cooling system, a medium scale cooling system, and a large scale cooling system.

According to an aspect of some embodiments of the present disclosure there is provided a method for flattening electric energy demand of an air-conditioner from an electric grid including receiving a control signal, and instructing a fluid distribution system to direct heat exchange fluid of an air-conditioner from flowing through a condensing coil to flowing through a Thermal Energy Storage (TES) system.

According to some embodiments of the disclosure, the control signal is a radio signal from an electric power supply company transmitter.

According to some embodiments of the disclosure, the control signal is a signal pushed over the Internet from an electric power supply company transmitter.

According to an aspect of some embodiments of the present disclosure there is provided a method for flattening electric energy demand of an air-conditioner from an electric grid including an air conditioner, a Thermal Energy Storage system, and a controller, wherein the controller is programmed to implement the method described herein.

According to some embodiments of the disclosure, the system is configured to control flow of refrigerant fluid from the air conditioner through the TES.

According to an aspect of some embodiments of the present disclosure there is provided a method for freezing Phase Change Material (PCM) in a Thermal Energy Storage (TES) system including setting a temperature of heat exchange fluid at a temperature higher than -10 degrees Celsius when directed to ice bricks containing water and an ice nucleation agent.

According to some embodiments of the disclosure, the setting includes setting at a temperature of -5 degrees Celsius.

According to some embodiments of the disclosure, the setting includes setting at a temperature of -2.7 degrees Celsius.

According to an aspect of some embodiments of the present disclosure there is provided a Thermal Energy Storage (TES) system capable of discharging more than 50% of a heat capacity of the TES.

According to some embodiments of the disclosure, capable of discharging more than 80% of a heat capacity of the TES. According to an aspect of some embodiments of the present disclosure there is provided a Thermal Energy Storage (TES) system controller programmed to discharge more than 50% of a heat capacity of the TES .

According to some embodiments of the disclosure, programmed to discharge more than 80% of a heat capacity of the TES.

According to an aspect of some embodiments of the present disclosure there is provided a method for mitigating frequency drift in an electric circuit, the method including using a compressor in a refrigerant flow of an air conditioner, monitoring electric circuit frequency, when the frequency declines by more than a threshold value, then using a TES system to cool the refrigerant of the air conditioner, else continuing to use the compressor of the air conditioner.

According to an aspect of some embodiments of the present disclosure there is provided a method of mitigating frequency drift in a three phase electricity circuit, the method including using a compressor in a refrigerant flow of an air conditioner, monitoring phase angle between conductors in a three phase electric system providing electricity to the air conditioner, when phase angle is different from a nominal phase angle by more than a threshold value, then using a TES system to cool the refrigerant of the air conditioner, else continuing to use the compressor of the air conditioner.

According to an aspect of some embodiments of the present disclosure there is provided a method for mitigating imbalance in a three phase electric circuit, the method including using a compressor in a refrigerant flow of an air conditioner, monitoring phase imbalance between conductors in a three phase electric system providing electricity to the air conditioner, when phase imbalance is greater than a threshold value, then using a TES system to cool the refrigerant of the air conditioner, else continuing to use the compressor of the air conditioner.

According to an aspect of some embodiments of the present disclosure there is provided a method for mitigating electricity costs caused by imbalance in a three phase electric circuit the method including using a compressor in a refrigerant flow of an air conditioner, monitoring cost of electricity from power company, and when cost of electricity rises due to phase drift, then using a TES system to cool the refrigerant of the air conditioner, else continuing to use the compressor of the air conditioner.

According to an aspect of some embodiments of the present disclosure there is provided a method for controlling an interrupted mode of operation of a compressor in an air conditioning system, the method including using a compressor in a refrigerant flow of an air conditioner, detecting when the air conditioner turns on or turns off, estimating chum based on the detecting, when churn estimate indicates the compressor is churning, then using a TES system to cool the refrigerant of the air conditioner, else continuing to use the compressor of the air conditioner.

According to an aspect of some embodiments of the present disclosure there is provided a method for mitigating electricity costs caused by charging electric vehicles at a facility, the method including using a compressor in a refrigerant flow of an air conditioner, monitoring cost of electricity from power company, and when cost of electricity rises, then using a TES system to cool the refrigerant of the air conditioner, thereby lowering electric consumption, else continuing to use the compressor of the air conditioner.

According to some embodiments of the disclosure, further including lowering the rate of charging of the electric vehicle when cost of electricity rises.

According to some embodiments of the disclosure, further including stopping the charging of the electric vehicle when cost of electricity rises.

According to some embodiments of the disclosure, further including taking electricity charged in the electric vehicle for use at the facility when cost of electricity rises.

According to an aspect of some embodiments of the present disclosure there is provided a method for mitigating electricity costs caused by peak electric demand charges, the method including using a compressor in a refrigerant flow of an air conditioner, monitoring use of electricity at a facility, predicting when peak electric demand charges are anticipated, and when peak electric demand charges are anticipated, then using a TES system to cool the refrigerant of the air conditioner, thereby lowering electric consumption, else continuing to use the compressor of the air conditioner.

According to an aspect of some embodiments of the present disclosure there is provided a method for preventing reaching an upper limit of electric consumption at a facility, the method including using a compressor in a refrigerant flow of an air conditioner, monitoring use of electricity at a facility, and when reaching an upper limit of electric consumption is anticipated, then using a TES system to cool the refrigerant of the air conditioner, thereby lowering electric consumption, else continuing to use the compressor of the air conditioner.

According to an aspect of some embodiments of the present disclosure there is provided a method for mitigating CO ₂ emissions caused by electric consumption, the method including using a compressor in a refrigerant flow of an air conditioner, monitoring CO ₂ emissions corresponding to use of electricity at a facility, and using a TES system to cool the refrigerant of the air conditioner at high- CO ₂ emission periods, thereby lowering CO ₂ emissions. According to an aspect of some embodiments of the present invention there is provided a method of mitigating frequency drift in a three phase electricity circuit, the method including using a compressor in a refrigerant flow of an air conditioner, monitoring phase angle between conductors in a three phase electric system providing electricity to the air conditioner, when phase angle is different from a nominal phase angle by more than a threshold value, then using a TES system to cool the refrigerant of the air conditioner, else continuing to use the compressor of the air conditioner.

According to an aspect of some embodiments of the present invention there is provided a method for mitigating imbalance in a three phase electric circuit, the method including using a compressor in a refrigerant flow of an air conditioner, monitoring phase imbalance between conductors in a three phase electric system providing electricity to the air conditioner, when phase imbalance is greater than a threshold value, then using a TES system to cool the refrigerant of the air conditioner, else continuing to use the compressor of the air conditioner.

According to an aspect of some embodiments of the present invention there is provided a method for mitigating electricity costs caused by imbalance in a three phase electric circuit the method including using a compressor in a refrigerant flow of an air conditioner, monitoring cost of electricity from power company, and when cost of electricity rises due to phase drift, then using a TES system to cool the refrigerant of the air conditioner, else continuing to use the compressor of the air conditioner.

According to an aspect of some embodiments of the present invention there is provided a method for controlling an interrupted mode of operation of a compressor in an air conditioning system, the method including using a compressor in a refrigerant flow of an air conditioner, detecting when the air conditioner turns on or turns off, estimating chum based on the detecting, when churn estimate indicates the compressor is churning, then using a TES system to cool the refrigerant of the air conditioner, else continuing to use the compressor of the air conditioner.

According to some embodiments of the present invention a thermal energy storage array comprises a plurality of ice bricks wherein each of said ice bricks comprises a plurality of capsules; wherein said ice bricks are interconnected for fluid communication of a first fluid flowing through said ice bricks and wherein said ice bricks are configured in a modular structural arrangement comprising one or more of: said bricks are stacked on top of one another; said bricks are laid end to end; or said bricks are laid next to one another.

Optionally, the array further comprises insulation panels surrounding the outer surface of said modular structural arrangement of said bricks. On one hand, these insulation panels are provided for surrounding the outside surfaces of the module. On the other hand, insulation panels are avoided for non-external surfaces. The insulation panels are designed to be attached over one or more bricks according to a planned modular arrangement of bricks. This results in a homogenous ice-brick structure, an easy installation, which is also easy to disassemble. This configuration saves on the total insulation needed as only the outer surface of the complete array needs to be insulated and not every surface of every brick.

Optionally, said capsules comprise a second fluid. Optionally, said second fluid comprises water. Optionally, the array further comprises a fluid distribution system. Optionally, said first fluid has a lower freezing point than said second fluid. Optionally, said second fluid comprises an ice nucleation agent. Optionally, said ice nucleation agent is quartz. Optionally, said brick comprises between 65% and 85% of said second fluid contained inside said capsules. Optionally, the array further comprises a TES chiller for cooling said first fluid.

Optionally, the condensation part of said TES chiller is cooled by a third fluid which also cools the load in the structure serviced by said array. Optionally, the array further comprises an air compressor. Optionally, said capsule comprises a filling nozzle placed on an upper comer of said capsule to enable filling of said capsule to a maximum with said second fluid. Optionally, said capsule comprise one or more of narrow-side spacers and broad-side spacers and wherein said spacers create a gap between said capsules when these are packed together inside said brick. Optionally, said capsule surface comprises protmsions adapted to increase the turbulent flow of said first fluid around said capsules. Optionally, said brick is rectangular. Optionally, said brick has a size of 50X50X400 cm. Optionally, said brick has a size of 25X25X400 cm. Optionally, said brick has a volume of 750 - 1200L. Optionally, said brick has an energy storage capacity of 15 - 23 TRH. Optionally, said capsule comprises a cyclohexane shape. Optionally, said cyclohexane shaped capsules are placed inside said brick to freely settle inside brick.

Optionally, said brick is adapted to be positioned underground. Optionally, said brick is cylindrical and comprises a pipe comprising a spiral metal reinforcement than runs along the outside of said brick to enable placement of said brick underground. Optionally, said capsules are arranged in a fixed position inside said brick. Optionally, said bricks further comprise a plurality of spacers inserted between said capsules, wherein said spacers ensure fluid flow of said first fluid through said brick and said spacers maximize turbulent flow when the gap between said capsules increases due to said second fluid melting.

According to some embodiments of the present invention a method for discharging a thermal energy storage (TES) system for cooling of a load comprises: providing a TES system wherein said TES system comprises an array of ice bricks, a controller, and a fluid distribution system and wherein said array is divided by said fluid distribution system into a plurality of subsets of ice bricks; wherein said controller is a computing device; activating by said controller of a first subset of said plurality of subsets such that a first fluid flows through said first subset for cooling of said load; monitoring by said controller of the temperature of said first fluid; when the temperature of said first fluid exceeds a threshold, activating by said controller of a further subset of said plurality of subsets such that a first fluid flows through said further subset for cooling of said load, wherein said further subset is a subset that has not been activated during the active discharging process; and repeating the previous two steps.

Optionally, said further subsets are activated in addition to said first subset such that said first fluid flows through all activated subsets. Optionally, the method further comprises: determining by said controller whether all of said plurality of said subsets have been activated and when all of said plurality of said subsets have been activated, terminating by said controller of said discharging. Optionally, said fluid distribution system comprises at least one pump and at least one flow control mechanism and wherein said activating a subset comprises activating said at least one pump and said at least one flow control mechanism such that said first fluid flows through said subset. Optionally, said ice bricks each comprise a container comprising capsules and comprising inlet and outlet piping for enabling fluid communication of said first fluid within said array. Optionally, said capsules comprise a second fluid that has a temperature lower than that of said first fluid prior to discharging and wherein said capsules cool said first fluid as said first fluid flows through said ice brick.

According to some embodiments of the present invention a thermal energy storage unit is provided comprising: a tube having at least one inlet and at least one outlet for a first fluid; a plurality of capsules having a second fluid therein, wherein the plurality of capsules is arranged inside the tube; wherein the first fluid is a heat transfer fluid for exchanging heat with the second fluid; the second fluid is a phase-change medium; wherein the average length of an actual flow path of the first fluid from inlet to outlet is larger than a length of the tube.

According to some embodiments of the present invention a thermal energy storage unit is provided comprising: a tube having at least one inlet and at least one outlet for a first fluid; a plurality of plate-shaped capsules having a second fluid therein, wherein the plurality of capsules is stacked inside the tube or wherein the plurality of capsules is arranged inside the tube to form a plurality of stacks of capsules; wherein the first fluid is a heat transfer fluid for exchanging heat with the second fluid; the second fluid is a phase-change medium; wherein a plurality of defined narrow or shallow flow paths for the first fluid is provided between the capsules.

Optionally, said thermal energy storage unit has capsules that are adapted such that the flow path is provided in a meander pattern in at least a part of the flow path. Optionally, said thermal energy storage unit is configured such that the tube is rectangular; and a ratio of the length of the tube to its width is in a range of about 4 to 50; and/or a ratio of a width of the tube to its height is in a range of about 0.5 to 2.

Optionally, said thermal energy storage unit is configured such that the shape of the tube is rectangular; and a ratio of the length of the tube to its width is in a range from 12 to 20, optionally, about 16; and/or a ratio of a width of the tube to its height is about 1.

Optionally, said thermal energy storage unit is configured such that a total volume of the second fluid of the plurality of capsules is 50% to 90%, optionally, 65% to 85%, of the total volume of the tube. This has proven to be to optimal or near to optimal ratio of the volumes of second fluid to the total volume of the tube. On one hand, there has to be sufficient space for the first fluid in order to be able to exchange heat with the fluid, and on the other hand there should be as much available capacity for storing heat as possible.

Optionally, said thermal energy storage unit is configured such that the thermal energy storage is provided such that: a) the inlet and the outlet are provided at the same end of the tube; and that b) a flow of the first fluid from the inlet to the outlet over each capsule is essentially bi directional. For example, a rubber sealing element which is placed approximately at the middle of the capsule can act as a flow divider for the flow of the first fluid inside the tube. Hence, two generally bi-directional flows of the first fluid can pass by the capsule which can have different temperatures. Consequently, the capsule is affected by two different flows of the first fluid and heated or cooled with two different temperatures such that a temperature gradient is provided inside the capsule. This temperature gradient results in an advantageous circulation of the second fluid (water) inside the capsule, which provides a heat transport effect in the interior of the capsule and which additional acts against the buildup of an isolative barrier of melted water inside the capsule.

Optionally, said thermal energy storage unit is configured such that he broad- sides of the box or plate shaped capsules are concave (shaped). Such capsules having concave walls provide a certain flexibility of the walls at least at the center. Hence, the wall of the capsule can flex in order to allow an increase of the volume of the second fluid in its phase change without getting damaged. Moreover, the concave shape of the broad-sides provides narrow-shaped and defined flow paths between capsules that are stacked side by side. Due to the concave shape of the broad-sides of the walls of the capsules, a flow channel for the first fluid is created between neighboring capsules of a stack that is narrow (or shallow). Consequently, the surface-to-volume ratio of this channel as compared to a cylindrical channel is improved, and the surface of the first fluid touching the broad side of the capsule is increased. Hence, by providing corresponding (narrow) shapes of the flow channel (and the flow path) for the first fluid and the capsules, the heat exchange through the contact surface between capsule and first fluid is improved, wherein this is additionally a space saving solution. In other words, by providing flat capsules with corresponding flat flow channels between, the heat exchange rate between the capsule and the first fluid can be significantly improved.

Optionally, said thermal energy storage unit is configured such that at least one surface of the capsules comprises protrusions adapted to create or increase a turbulence of the flow of the first fluid through the tube. This potentially increases the efficiency of the system.

Optionally, said thermal energy storage unit is configured such that each capsule of the plurality of capsules is of the same type, or each capsule of the plurality of capsules has the same volume for the second fluid. This potentially lowers manufacturing costs and makes it easier to create stacks of capsules with defined flow paths.

Optionally, said thermal energy storage unit further comprises rigid spacers placed between the capsules. Accordingly, rigid, e.g. grid-type, spacers made from metal or plastic are placed between the capsules’ flat walls, wherein the grid may have many shapes: rectangular, rhombus or square holes grid-welded or chain-lock type. The spacers are optionally sized in such a manner that there is sufficient free space for the capsule wall to expand into, the free space should be greater than 15% of capsule volume but less than 30% of the hypothetical free flow area between the capsules without the spacers. A metal grid could be made of stainless steel rods with a diameter of approximately 2.8 mm, which are welded in square mash configuration sized 310x140 mm with 8 longitudinal rods and 6 transversal rods.

Optionally, said thermal energy storage unit further comprises flexible spacers placed between the capsules, wherein the flexible spacers comprise flaps. These flexible flaps potentially provide a flexible flow control that adjusts itself according to the charging status of the capsules.

Optionally, said thermal energy storage unit is configured such that the capsules are generally box or plate shaped; and the spacers are sized such that a free flow area between the broad-sides of two capsules is in a range of 15% to 30% of the free flow area between the capsules without the spacers.

Optionally, said thermal energy storage unit is configured such that at least one capsule comprises a nucleating agent, optionally, quartz. Consequently, the cooling temperature for the capsule can potentially be higher as compared to conventional ice storage systems.

Optionally, said thermal energy storage unit is configured such that the capsules comprise heat transfer strips, which are optionally, arranged such that they conduct heat to the interior of the capsule. A problem with some conventional capsules containing water is that the heat transfer coefficient of water is very low. Hence, the heat transfer from the very interior of the capsule to its outside is blocked by the water/ice located closer to the wall. Using heat transfer strips potentially solves this problem since they provide an efficient heat transfer also to the interior of the capsule.

Optionally, said thermal energy storage unit is configured such that the heat transfer strips are made of aluminum. This material provides a good heat transfer rate. Alternatively, the heat transfer strips can be made of another material with a good thermal conductivity, for example stainless steel. Optionally, said thermal energy storage unit is configured such that the heat transfer strips are made of a material that has a thermal conductivity k of more than 10 W/(m*K) under standard conditions. Optionally, the thermal conductivity k of the strips is larger than 75 W/(m*K) under standard conditions. This potentially further improves the ice generation process inside the capsule.

Optionally, said thermal energy storage unit is configured such that the heat transfer strips have a thickness of 0.4 to 4 mm, a length of 35 to 350 mm and a width of 5 to 10 mm. These dimensions potentially provide a good heat transfer rate to the interior of the capsule. Furthermore, these strips can be easily placed inside a capsule through a small opening.

Optionally, said thermal energy storage unit is configured such that the capsules are generally box or plate-shaped; and the capsules comprise a single filling port at a corner of the capsule. This shape has a high surface-to-volume ratio. This potentially improves the heat exchange rate between first and second fluid.

Optionally, said thermal energy storage unit is configured such that the capsules are generally box or plate shaped; and the capsules comprise ridges such that the capsules are arranged to be spaced to each other. The ridges enable the creation of free spaces for a defined flow path of the first fluid between the capsules.

Since the capsules have flat or not in generally flat broad-sides, narrow (or shallow) spaces between two stacked capsules are created. Consequently an improved and defined flow path for the first fluid is created that enables a high heat exchange rate.

Optionally, said thermal energy storage unit is configured such that the outer shape of the tube is prismatic; and a length of the prismatic tube is four times greater that its maximum diameter.

Optionally, said thermal energy storage unit is configured such that the capsules have a base body and protrusions, the protrusions protruding from the base body; the base body is generally a sphere with a first radius; the protrusions have generally the shape of semi-spheres with a second radius; the second radius is at least 50% smaller than the first radius. This preferred embodiment relates to the cyclohexane-shaped capsules, which are discussed later.

Optionally, said thermal energy storage unit is configured such that the protrusions are evenly distributed on the surface of the base body.

Optionally, said thermal energy storage unit is configured such that the capsule has 12 protrusions, and hence is cyclohexane shaped.

According to some embodiments of the present invention, a thermal energy storage system is provided, the system comprising a plurality of thermal energy storage units as mentioned above, the system characterized in that the thermal energy storage units are part of a structural arrangement of a building; wherein the structural arrangement is a wall, a floor or a roof, or a combination of a wall, a floor or a roof.

According to some embodiments of the present invention, a thermal energy storage system is provided, the system comprising a plurality of thermal energy storage units as mentioned above, the system characterized in that a ratio of a combined length of the plurality of tubes to a flow-cut- area is in a range of about 40 to 200, optionally, of about 60 and 150; wherein the flow-cut-area is defined as cross sectional free flow area for the first fluid in the tube per capsule.

Optionally, said thermal energy storage system is configured such that the number of tubes is 3 to 5, optionally, 4.

Optionally, said thermal energy storage system is configured such that the combined length of the plurality of tubes is from 10 to 20 meters, optionally, 16 meters. This did prove to create the optimal heat exchange rate for the system.

According to some embodiments of the present invention, a capsule for a thermal energy storage system or thermal energy storage unit as explained above is provided, wherein the capsule contains an ice nucleation agent, which optionally, comprises quartz.

According to some embodiments of the present invention, a capsule for a thermal energy storage system or thermal energy storage unit as explained above is provided, wherein the capsule contains at least one heat conducting element, Optionally, a metal stripe.

The technical effects of the above mentioned embodiments are explained below in more detail. One of the key performance criteria of thermal storage systems is the average discharge rate relative to the stored capacity which can be maintained through the whole discharge effective period within the required temperature limits. A typical system holding a certain capacity should be able to discharge as much as possible of its stored capacity during, for example, a 4 hour period and maintain a final exit temperature of the first fluid lower than or equal to 5 degrees Celsius. As a result of the requirements described above the effective heat transfer rate of a given capsule should be as high as possible. In detail, the heat transfer rate of a capsule is governed by:

1. Areas of transfer of the heat, comprising:

1. active transfer areas of the ice material (e.g., chunk) inside the capsule 715 (the heat transfer starts with the entire internal surface area of the capsule envelope and decreases while the ice material starts to melt and vice versa during ice formation)

ii. internal areas of the capsule envelope (i.e., the ice/water heat transfer area to the material of the capsule)

iii. external areas of the capsule’s envelope (i.e., the outer heat transfer area to the first fluid)

2. Heat transfer coefficients (HTC), comprising:

i. the second fluid, i.e., ice to water (melting) or water to ice (freezing).

ii. further effects of water inside the capsule (i.e., the heat conduction from the inside of the capsule through the water itself)

iii. the second fluid to the capsule material (the so-called film HTC; i.e., border effects that are e.g. dependent the circulation of the second fluid inside the capsule)

iv. the capsule material itself, e.g., a polymer (i.e., the heat conduction of the capsule’s material itself)

v. capsule material to first fluid (i.e., border effects that are e.g. dependent on the velocity and turbulence of the first fluid flowing outside the capsule)

3. Temperature differential, comprising:

i. total temperature differential between the interior of the capsule and the first fluid ii. individual differentials per stages 2i to 2v.

Several variables can be considered to be approximately constant: Iii, liii, 2i, 2ii, 2iii, 2iv, 3i. The rest of the variables change during the process of discharging. In detail:

li The ice material (chunk) surface area significantly decreases during the discharging process. The rate of decreasing is not necessarily in a linear relationship with the percentage of melted ice.

2v The heat transfer coefficient of the capsule material to the second fluid 120 is highly dependent on the flow characteristic of the second fluid 120. The fact that the space of the flow path keeps on growing due to the melting of ice (the capsules contract to their“as filled by water size”) results in a decline of the HTF velocity and the plastic to HTF surface HTC declines with it (not necessarily in linear proportion to the percentage of melted ice, depending on the flow Reynolds number) The above mentioned embodiments consider several of the above mentioned items 1 to 3. For example, plate or box-shaped capsules provide an increased capsule area relative to its volume. By reducing thickness of the capsules’ material by using a rigid polymer, the FITC through the capsules envelope is improved. Providing metal transfer strips inside the capsule improves the ice to water HTC and water FITC. Causing internal circulation of the second fluid inside the capsule by exposing each capsule to bi-directional passes of the first fluid at different temperatures results in an advantageous exchange of volume of the second fluid inside the capsule, which improves the internal HTC of the capsule, since the conduction of heat is facilitated by the circulation. Providing a turbulent flow profile for the flow paths of the first fluid by adding protrusions on the capsule’s surface results in a more efficient heat transfer between the capsule’s envelope and the first fluid, since again the heat conduction is facilitated by the transport of the first fluid itself. In contrast, a purely laminar flow profile would negatively influence the heat transfer rate, since the velocity of the first fluid at the border of the capsule tends to zero (this is due to a border phenomenon) and hence in the case of a purely laminar flow no or just a small heat transport is provided by the movement of the first fluid itself. Using metal or other materials for spacers or a grid between the capsules results in a turbulent flow profile and defined flow paths. Using variable/flexible spacers which maintain tight flow paths between the spacer and the capsule also increases the heat transfer rate.

To summarize the above, some of the presented embodiments and aspects of the invention potentially enable water to become a usable capacitor for energy in a safe, clean, efficient and affordable fashion.

Unless otherwise defined, all technical and/or scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention pertains. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of embodiments of the invention, exemplary methods and/or materials are described below. In case of conflict, the patent specification, including definitions, will control. In addition, the materials, methods, and examples are illustrative only and are not intended to be necessarily limiting.

The term“ice brick” can be understood as a thermal energy storage unit that is especially adapted to enclosing a heat transfer fluid (i.e., the first fluid) and a plurality of capsules containing the PCM (i.e. the second fluid).

The term“tube” can be understood as an elongated hollow body that has a length that is at least two times, preferable 6 times, larger than its diameter. The cross-section of said tube can be circular-, oval-, square-, rectangular- or polygonal-shaped. Optionally, the cross-section of said tube is rectangular-shaped and essentially constant over its entire length.

The term“capsule” can be understood as an enclosed volume for permanently storing a PCM, such as water or a mixture of water. Additionally, several further components or ingredients can be stored inside this enclosed volume.

The term“heat” refers to thermal energy that can be stored and exchanged.

The efficiency or effectiveness of a heat exchanger is the ratio of the rate of the actual heat transfer in the heat exchanger to the maximum possible heat transfer rate.

A cross-section shows a sectional view in a width direction of the tube.

Implementation of the method and system of the present invention involves performing or completing certain selected tasks or steps manually, automatically, or a combination thereof. Moreover, according to actual instrumentation and equipment of preferred embodiments of the method and system of the present invention, several selected steps could be implemented by hardware or by software on any operating system of any firmware or a combination thereof. For example, as hardware, selected steps of the invention could be implemented as a chip or a circuit. As software, selected steps of the invention could be implemented as a plurality of software instructions being executed by a computer using any suitable operating system. In any case, selected steps of the method and system of the invention could be described as being performed by a data processor, such as a computing platform for executing a plurality of instructions.

Although the present invention is described with regard to a“controller”,“computing device”, a "computer", or“mobile device”, it should be noted that optionally any device featuring a data processor and the ability to execute one or more instructions may be described as a computer, including but not limited to any type of personal computer (PC), PLC (programmable logic controller), a server, a distributed server, a virtual server, a cloud computing platform, a cellular telephone, an IP telephone, a smartphone, or a PDA (personal digital assistant). Any two or more of such devices in communication with each other may optionally comprise a "network" or a "computer network".

As will be appreciated by one skilled in the art, some embodiments of the present invention may be embodied as a system, method or computer program product. Accordingly, some embodiments of the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, micro-code, etc.) or an embodiment combining software and hardware aspects that may all generally be referred to herein as a“circuit,”“module” or“system.” Furthermore, some embodiments of the present invention may take the form of a computer program product embodied in one or more computer readable medium(s) having computer readable program code embodied thereon. Implementation of the method and/or system of some embodiments of the invention can involve performing and/or completing selected tasks manually, automatically, or a combination thereof. Moreover, according to actual instrumentation and equipment of some embodiments of the method and/or system of the invention, several selected tasks could be implemented by hardware, by software or by firmware and/or by a combination thereof, e.g., using an operating system.

For example, hardware for performing selected tasks according to some embodiments of the invention could be implemented as a chip or a circuit. As software, selected tasks according to some embodiments of the invention could be implemented as a plurality of software instructions being executed by a computer using any suitable operating system. In an exemplary embodiment of the invention, one or more tasks according to some exemplary embodiments of method and/or system as described herein are performed by a data processor, such as a computing platform for executing a plurality of instructions. Optionally, the data processor includes a volatile memory for storing instructions and/or data and/or a non-volatile storage, for example, a magnetic hard-disk and/or removable media, for storing instructions and/or data. Optionally, a network connection is provided as well. A display and/or a user input device such as a keyboard or mouse are optionally provided as well.

Any combination of one or more computer readable medium(s) may be utilized for some embodiments of the invention. The computer readable medium may be a computer readable signal medium or a computer readable storage medium. A computer readable storage medium may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples (a non-exhaustive list) of the computer readable storage medium would include the following: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the context of this document, a computer readable storage medium may be any tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device.

A computer readable signal medium may include a propagated data signal with computer readable program code embodied therein, for example, in baseband or as part of a carrier wave. Such a propagated signal may take any of a variety of forms, including, but not limited to, electro magnetic, optical, or any suitable combination thereof. A computer readable signal medium may be any computer readable medium that is not a computer readable storage medium and that can communicate, propagate, or transport a program for use by or in connection with an instruction execution system, apparatus, or device.

Program code embodied on a computer readable medium and/or data used thereby may be transmitted using any appropriate medium, including but not limited to wireless, wireline, optical fiber cable, RF, etc., or any suitable combination of the foregoing.

Computer program code for carrying out operations for some embodiments of the present invention may be written in any combination of one or more programming languages, including an object oriented programming language such as Java, Smalltalk, C++ or the like and conventional procedural programming languages, such as the "C" programming language or similar programming languages. The program code may execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer may be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet Service Provider).

Some embodiments of the present invention may be described below with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and/or block diagrams, and combinations of blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instmctions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks.

These computer program instructions may also be stored in a computer readable medium that can direct a computer, other programmable data processing apparatus, or other devices to function in a particular manner, such that the instmctions stored in the computer readable medium produce an article of manufacture including instmctions which implement the function/act specified in the flowchart and/or block diagram block or blocks.

The computer program instmctions may also be loaded onto a computer, other programmable data processing apparatus, or other devices to cause a series of operational steps to be performed on the computer, other programmable apparatus or other devices to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide processes for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks.

Some of the methods described herein are generally designed only for use by a computer, and may not be feasible or practical for performing purely manually, by a human expert. A human expert who wanted to manually perform similar tasks, such as controlling thermal energy storage, might be expected to use completely different methods, e.g., making use of expert knowledge and/or the pattern recognition capabilities of the human brain, which would be vastly more efficient than manually going through the steps of the methods described herein.

The term ton of refrigeration (TR), also called a refrigeration ton (RT), is a unit of power used in some countries (especially in North America) to describe heat-extraction capacity of refrigeration and air conditioning equipment. The TR is defined as a rate of heat transfer that results in freezing or melting of 1 short ton, 2,000 lb or 907 kg, of pure ice at 0°C in 24 hours.

A refrigeration ton is approximately equivalent to 12,000 BTU/h or 3.5 kW.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

The invention is herein described, by way of example only, with reference to the accompanying drawings. With specific reference now to the drawings in detail, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion of the preferred embodiments of the present invention only, and are presented in order to provide what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the invention. In this regard, no attempt is made to show structural details of the invention in more detail than is necessary for a fundamental understanding of the invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the invention may be embodied in practice.

Some embodiments of the invention are herein described, by way of example only, with reference to the accompanying drawings. With specific reference now to the drawings in detail, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion of embodiments of the invention. In this regard, the description taken with the drawings makes apparent to those skilled in the art how embodiments of the invention may be practiced.

In the drawings:

Figures 1A-1E are schematic diagrams of a thermal energy storage system according to at least some embodiments of the present invention; Figures 2A-2Y are illustrations of ice bricks, ice capsules and thermal storage arrays according to at least some embodiments of the present invention;

Figure 3 shows an ice capsule according to at least some embodiments of the present invention;

Figure 4 shows a cylindrical ice brick according to at least some embodiments of the present invention;

Figure 5A shows a TES system capable of activating separate subsets of ice bricks by a controller.

Figure 5B shows a flow diagram for operation of a TES system.

Figure 5C shows experimental data from operation of a TES system according to at least some embodiments of the present invention;

Figures 6A-6G show spacers for use in an ice brick according to at least some embodiments of the present invention;

Figures 7 A to 7D show a thermal energy storage unit and cross-sectional views of a thermal energy storage unit including the tube and capsules according to at least some embodiments of the present invention;

Figures 8A and 8B show capsules containing metal strips according to at least some embodiments of the present invention;

Figures 9A and 9B show spacers between capsules according to at least some embodiments of the present invention;

Figure 10A is a simplified flow chart illustration of a method for controlling use of higher heat discharge rate bricks and lower heat discharge rate bricks according to an example embodiment of the invention;

Figure 10B is a simplified flow chart illustration of a method for controlling use of higher heat discharge rate bricks and lower heat discharge rate bricks according to an example embodiment of the invention;

Figure IOC is a simplified flow chart illustration of a method for controlling rate of freezing or cooling heat transfer fluid according to an example embodiment of the invention;

Figure 11 A is a simplified flow chart illustration of a method for flattening electric energy demand from an electric grid according to an example embodiment of the invention;

Figure 1 IB is a simplified block diagram illustration of a system for flattening electric energy demand from an electric grid according to an example embodiment of the invention; Figure 12A is a simplified flow chart illustration of a method for controlling an interrupted mode of operation of a compressor in an air conditioning system according to an example embodiment of the invention;

Figure 12B is a simplified flow chart illustration of a method for mitigating imbalance in a three phase electric circuit according to an example embodiment of the invention; and

Figure 12C is a simplified flow chart illustration of a method for mitigating electricity costs caused by imbalance in a three phase electric circuit according to an example embodiment of the invention;

Figure 12D is a simplified flow chart illustration of a method for mitigating electricity costs caused by charging electric vehicles at a facility according to an example embodiment of the invention;

Figure 12E is a simplified flow chart illustration of a method for mitigating electricity costs caused by peak electric demand charges according to an example embodiment of the invention;

Figure 12F is a simplified flow chart illustration of a method for mitigating CO2 emissions caused by electric consumption according to an example embodiment of the invention;

Figure 12G is a simplified flow chart illustration of a method for preventing reaching an upper limit of electric consumption at a facility according to an example embodiment of the invention; and

Figure 12H is a simplified flow chart illustration of a method for mitigating frequency drift in an electric circuit according to an example embodiment of the invention.

DESCRIPTION OF SOME SPECIFIC EMBODIMENTS OF THE INVENTION

The present invention, in some embodiments thereof, relates to a system and method for thermal energy storage and particularly but not exclusively to controlling use of and applications for thermal energy storage, and even more particularly but not exclusively to software and components for controlling efficiency of thermal energy storage.

The controlling use of and applications for thermal energy storage, and the software and components for controlling efficiency of thermal energy storage are applicable to various types of systems for thermal energy storage, including Thermal Energy Systems (TES) systems as described in above-mentioned International Patent Application Number PCT/IB 2018/001091, various“ice-on-coil” storage systems,“encapsulated ice” systems, and other TES systems.

Methods and devices for controlling use of and applications for thermal energy storage are described herein in addition to descriptions taken from International Patent Application Number PCT/IB2018/001091 for thermal energy storage systems which are suitable for being used with the above-mentioned methods, devices and applications. The present application describes how to implement some methods, devices and applications for other, additional thermal energy storage systems such as ice-on-coil systems, and even energy storage systems such as battery storage.

Before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not necessarily limited in its application to the details of construction and the arrangement of the components and/or methods set forth in the following description and/or illustrated in the drawings and/or the Examples. The invention is capable of other embodiments or of being practiced or carried out in various ways.

Various exemplary control methods of Thermal Energy Storage (TES) systems will be described below, which apply to: (a) TES systems as described herein with reference to FIGs 1A- 9B ; (b) TES systems which include a mix of TES systems as described herein with reference to FIGs 1A-9B and TES systems which do not share inventive aspects with the TES systems as described herein with reference to FIGs 1A-9B; and (c) TES systems which do not share inventive aspects with the TES systems as described herein with reference to FIGs 1A-9B.

Where TES systems are mentioned herein, additional systems can also be used, or combined, and in some cases a tradeoff between systems is optionally made based on cost, capacity, etc.

TES systems as described herein with reference to FIGs 1A-9B can potentially provide a high rate of discharge, potentially maintain the high rate of discharge stable over a relatively long period of time, and potentially achieve a high percentage of depth of discharge, relative to similarly sized other systems.

In some embodiments, TES systems as described herein, by using multiple capsules, and/or by providing a high heat transfer area to stored volume ratio, and/or by maintaining turbulent flow patterns, can potentially achieve the high rate of discharge even when 80% or more of the stored energy is already consumed.

For example, in some embodiments, TES systems as described herein can potentially discharge up to ~ 90-92% of the stored energy within a 4 hour period.

Controlling Systems Having Mixed higher heat discharge rate and lower heat discharge rates

In some embodiments, some ice bricks or TES units in a TES system are ice bricks have a relatively higher heat discharge rate and some ice bricks have a relatively lower heat discharge rate.

Some example values: The term low rate of heat discharge is used herein to mean less than 90% discharge depth during 6 or more hours of discharge.

The term medium rate of heat discharge is used herein to mean more than 90% discharge depth during 4 hours of discharge.

The term high rate of heat discharge is used herein to mean more than 85% discharge depth during 2 hours of discharge.

The term very-high rate of heat discharge is used herein to mean more than 75% discharge depth during 1 hours of discharge.

In various embodiments, TES systems as described herein achieve all of the above- mentioned low, medium, high and very-high rates of heat discharge.

In some embodiments, a mix of higher heat discharge rate bricks and lower heat discharge rate bricks potentially enable producing TES systems with improved capabilities over previous such systems.

In some embodiments, a controller is optionally used to control when and how much energy is drawn from the higher heat discharge rate bricks and when and how much energy is drawn from the relatively lower heat discharge rate bricks.

It is noted that combining higher heat discharge rate bricks and lower heat discharge rate bricks potentially enables providing an immediate cooling effect, optionally followed by a long term continuing cooling effect.

It is noted that if higher heat discharge rate bricks are more expensive than lower heat discharge rate bricks, combining the two types potentially enables providing a lower-total-cost system which can potentially provide both immediate cooling and longer term cooling.

In some embodiments, installation space may forces or allows to use a specific mix.

It is noted that if higher heat discharge rate bricks are more (or less) efficient in volume/space consumption than lower heat discharge rate bricks, combining the two types potentially enables providing a lower-total-cost system which can potentially answer a specific volume/space consumption while potentially keeping system costs down.

Some configurations which potentially produce higher-heat- discharge-rate ice bricks include:

Increasing a heat transfer area to stored heat ratio by making the capsules narrower.

Making the capsules of superior heat transfer material such as metal and/or Heat Transfer

Plastic.

Including turbulence inducers between the capsules, optionally adjustable turbulence inducers. Including heat transfer fins in the capsules.

In some embodiments several groups of containers with different discharge characteristics potentially provide heat capacity for at least two heat demand regimes - by way of a non-limiting example a first regime providing X refrigeration tons (RTH) suitable for a regime of load shift (for example for 4 hours) and providing Y refrigeration tons (RTH) suitable for grid demand or other high discharge requirements, for example 1 to 2 hours of high discharge rate, and optionally 10- 15 minutes of Z refrigeration tons during specific hours and/or as a response to a request, optionally from a power grid manager.

In some embodiments several groups of containers with different discharge characteristics are optionally used at a same time.

In some embodiments, a controller is optionally used to control when and how much energy is stored into the higher heat discharge rate bricks and when and how much energy is stored into the relatively lower heat discharge rate bricks.

In some embodiments, a controller, or a control program, optionally uses a greedy algorithm which matches which ice brick to charge based on a capacity, rate, fill level, expected size of charge, etc. of the ice brick.

In some embodiments, a controller, or a control program, optionally uses an economic optimization algorithm which matches which ice brick to charge based on a capacity, rate, fill level, expected size of charge, etc. of the ice brick.

In some embodiments, the control program includes data such as an efficiency curve and/or a rate curve per ice brick type of even per specific ice brick, and the control program uses the data to make decisions (while taking into account predictions of when the stored energy will be needed, and optionally actual cost of electricity and energetic cost to make/use ice).

Reference is now made to Figure 10A, which is a simplified flow chart illustration of a method for controlling use of higher heat discharge rate bricks and lower heat discharge rate bricks according to an example embodiment of the invention.

In some embodiments a combination of higher heat discharge rate bricks and lower heat discharge rate bricks is controlled as shown in Figure 10A:

a controller determines what heat discharge schedule is desired (1002);

at a beginning of the schedule a first rate of heat discharge rate bricks are optionally used (1004); and

later on in the schedule a second rate of heat discharge rate bricks are optionally used

(1006). In some embodiments, the controller determines what heat discharge schedule is desired based on recording a historic heat discharge schedule for previous days, for a weekly cycle, and so on.

In some embodiments, a control program is fed with a desired heat discharge schedule.

In some embodiments, the controller determines what heat discharge schedule is desired based on taking into account a weather forecast.

In some embodiments, the controller determines what heat discharge schedule is desired based on taking into account known variances in a length of sunshine over a yearly schedule.

Reference is now made to Figure 10B, which is a simplified flow chart illustration of a method for controlling use of higher heat discharge rate bricks and lower heat discharge rate bricks according to an example embodiment of the invention.

In some embodiments a combination of higher heat discharge rate bricks and lower heat discharge rate bricks is controlled as shown in Figure 10B:

A controller determines what heat discharge rate is desired (1012);

If a requirement is for a higher heat discharge rate, higher heat discharge rate bricks are optionally used (1014); and

If a requirement is for a lower heat discharge rate, lower heat discharge rate bricks are optionally used (1016).

In some embodiments the controller provides a heat discharge rate based on a schedule stored in the controller. In some embodiments the controller provides a heat discharge rate based on a schedule received by the controller, by way of a non-limiting example received by electronic means, wired or wireless, by way of a non-limiting example received from a power supply company, from an air-conditioning client, and so on.

In some embodiments the controller compares a desired schedule with predicted capacity, and controls storing energy to provide for the capacity.

In some embodiments the controller compares a desired schedule with predicted capacity, and optionally communicates a warning that capacity is not up to the predicted load, potentially hours or even days (based on weather forecast for example) before the predicted lack of capacity.

In some embodiments, during an early period of operation, fully charged bricks, both high discharge rate bricks and low discharge rate bricks, can support a high discharge rate, since most of the capsules are frozen. The high heat discharge rate capsules are optionally“saved” in a standby mode until a last portion of the discharge period, thus allowing fast response even if a big portion of the total installed heat capacity has been used. In some embodiments a controller or control software optionally takes into account a contractual status of heat provision of an installation in deciding which mode to use first high heat- discharge-rate or low heat-discharge-rate. By way of a non-limiting example, once the heat provision system fails, for example once in a month, to support a specific fast demand requirement, the heat provision system or company is penalized just this once a month and the control software optionally decides to use stored energy for load shifting only.

In some embodiments the controller of control software is optionally updated with monthly, weekly, daily, hourly, or even minute-by-minute contractual obligations and in some cases, optionally, the commercial value of the contractual obligations.

In some embodiments a client facility meter is optionally used as an input to support control decisions regarding peak demand energy saving.

In some embodiments instead of a simple pre-determined load shifting profile control software is optionally used to inject cooling capacity and/or reduce chillers power consumption when the client facility electrical demand approaches a contractual obligation of the client. In some embodiments, an energy demand above the contractual obligation may be followed by high demand charges. In some cases the commercial value of the high demand charges is higher than the commercial value of shifted kWhrs (KiloWatt-Hours).

In some embodiments control software optionally monitors an operating point of facility chiller(s) which supply cooling requirements of a facility. Based on predefined data related to Best Efficiency Point(s) [BEP] of the chillers and the commercial value of electricity during a specific period, a controller optionally instructs the energy or heat storage system to increase or decrease cooling capacity injected into a cooling consumer, in order to potentially shift a chiller’s operating point to the BEP of the chiller.

In some embodiments control software optionally monitors a temperature of heat transfer fluid required by facility chiller(s) which supply cooling requirements of a facility. Based on the required temperature, a controller optionally instructs the energy or heat storage system to increase or decrease heat transfer fluid temperature injected into a cooling consumer.

Some non-limiting examples of measured values or status values are: chiller(s)’ electrical load; chiller(s)’ cooling load; client facility actual load; ambient temperature; and remaining cooling capacity in the TES .

In some embodiments, a difference between each chiller’ s actual operation point and power consumption (in kW) and a related efficiency (data available from a chiller’ s supplier) is optionally calculated. The calculation results are optionally compared to an expected efficiency and power consumption which can be achieved if the load on the chiller is changed to BEP by increasing or decreasing the load using TES energy, such calculation optionally based on Chiller supplier data, the controller potentially identifies economic gain, and optionally switches to use TES energy.

A TES system with high discharge capability

In some embodiments, for example such as described herein and such as described in above-mentioned International Patent Application Number PCT/IB2018/001091, a TES system can potentially discharge a high percentage of the heat stored therein.

In some embodiments, a Thermal Energy Storage (TES) system is provided which is capable of discharging more than, for example, 50-70% of a heat capacity of the TES during 1 hour, or 80% during 2 hours. In some embodiments, a Thermal Energy Storage (TES) system is provided which is capable of discharging more than 92% of a heat capacity of the TES during 4 hours of discharge. In some embodiments, a Thermal Energy Storage (TES) system is provided which is capable of discharging any desired percentage value in a range between 0% and 100% of a heat capacity of the TES, optionally at a desired discharge rate. The controller potentially uses one or more inputs such as desired percentage of discharge, desired rate of discharge, desired duration of discharge, to determine at what temperature to provide and/or at what flow rate to provide HTF.

In some embodiments, a Thermal Energy Storage (TES) system is provided which includes a controller set to discharge more than 50% of a heat capacity of the TES. In some embodiments, the controller is set to discharge more than 80% of a heat capacity of the TES. In some embodiments, the controller is set to discharge a percentage value in a range between 0% and 80% of a heat capacity of the TES. In some embodiments, the controller is set to discharge a percentage value in a range between 60% and 95% of a heat capacity of the TES.

The controller or a control program optionally includes storage memory for storing parameter such as required discharge percentage, required discharge rate, and so on.

Controlling rate of freezing or cooling heat transfer fluid

In some embodiments one or more sensors are optionally used to sense a state of an ice brick or a thermal storage array - a state such as whether the ice brick has started to freeze; is completely frozen; has reached a specific temperature difference between incoming fluid and outgoing fluid.

In some embodiments the sensor is an ultrasound sensor, potentially sensing a difference between frozen matter and liquid matter. In some embodiments the sensor measures impedance or resistivity, potentially sensing a difference between frozen matter and liquid matter.

In some embodiments sensors measure temperature of various locations of an ice brick, e.g. fluid entrance and/or exit into ice brick and/or within the ice brick.

In some embodiments the sensor is built into an ice brick array. In some embodiments the sensor is built into an ice brick.

In some embodiments sensor(s) measurement(s) is/are optionally used to control a rate of freezing ice bricks or using the ice bricks for cooling, by controlling various control parameters applicable to freezing the ice bricks or using the ice bricks for cooling. Such control parameters potentially include, by way of some non-limiting examples, temperature of heat transfer fluid, rate of flow of heat transfer fluid, pressure of heat transfer fluid.

In some embodiments heat transfer fluid is controlled to be provided at a lower temperature, for example in a range between -12 and -8 degrees Celsius, to reach a beginning of freezing of an ice brick, and subsequently controls heat transfer fluid to be provided at a relatively higher temperature, optionally at higher temperature as enabled by the more efficient ice bricks described herein, for example in a range of temperature between -8 degrees Celsius and -2.7 degrees Celsius.

In some embodiments heat transfer fluid is controlled to be provided at a higher flow rate to reach a beginning of freezing of an ice brick, and subsequently controlled to be provided at a relatively lower flow rate, as enabled by the more efficient ice bricks described herein.

In some embodiments, by way of a non-limiting example, a TES system as described herein is requested to provide a nominal 0.6 m ³ per hour per Refrigeration Ton. In some embodiments, the flow rate of the HTF may be may be 0.6 m ³ per hour at the nominal temperature. In some embodiments, the flow rate of the HTF may be may be proportionally higher than 0.6 m ³ per hour, at a higher-than-nominal temperature or load demand. In some embodiments, the flow rate of the HTF may be proportionally lower than 0.6 m ³ per hour, at a lower-than-nominal temperature or load demand.

Reference is now made to Figure IOC, which is a simplified flow chart illustration of a method for controlling rate of freezing or cooling heat transfer fluid according to an example embodiment of the invention.

The method of Figure IOC includes:

cooling an ice brick at with heat transfer fluid at a first cooling temperature (1022);

receiving sensor measurements from the ice brick (1024);

estimating the state of the ice brick (1026); and if the ice brick is estimated to be frozen, then cooling the ice brick with heat transfer fluid at a second, higher cooling temperature (1028),

else continuing to cool the ice brick with heat transfer fluid at the first cooling temperature

(1029).

Flattening Electric Energy Demand

In some embodiments energy provided during less-than-peak electricity demand periods is optionally used to freeze Phase Change Material (PCM) in a Thermal Energy Storage (TES) system, and optionally used to cool air conditioning refrigerant fluid during peak electricity demand periods.

Reference is now made to Figure 11 A, which is a simplified flow chart illustration of a method for flattening electric energy demand from an electric grid according to an example embodiment of the invention.

The method of Figure 11 A includes:

during less-than-peak electricity demand periods, freezing Phase Change Material (PCM) in a Thermal Energy Storage (TES) system (1102);

during peak electricity demand periods, using the TES to cool air conditioning refrigerant fluid (1104).

In some embodiments the above method is optionally used by a server farm, a residential building, shopping centers, offices, hotels, hospitals, and additional commercial small, medium and large scale energy centers and/or cooling systems

In some embodiments the TES system includes a radio receiver, and optionally receives a radio signal from an electric power supply company transmitter indicating a peak electricity demand period.

In some embodiments the TES system includes an Internet connection, and optionally receives an internet message from the electric power supply company transmitter indicating a peak electricity demand period.

In some embodiments the TES system is configured as an Internet-of-Things device, and optionally receives an instruction from the electric power supply company transmitter indicating a peak electricity demand period.

Reference is now made to Figure 1 IB, which is a simplified block diagram illustration of a system for flattening electric energy demand from an electric grid according to an example embodiment of the invention. Figure 11B shows a power company 1122, and a system 1120 which includes an air conditioner 1124, a TES unit or system 1128 and a controller 1126.

Various example embodiments of the system are described below, of potential scenarios of using the system 1120 in a manner which flattens electric energy demand from an electric grid.

The power company 1122 provides electric power 1121 to the air conditioner 1124.

In some embodiments, by way of a non-limiting example during peak electric power demand, the power company 1122 optionally sends a message 1123 to the controller 1126.

The message 1123 may be an instruction to enter an electric-power saving mode, as described below. In some embodiments, the message 1123 may be a schedule for when the system 1120 should enter the electric-power saving mode.

In some embodiments, the controller 1126 controls the system 1120 to enter (or leave) electric-power saving mode.

To enter electric -power saving mode, the controller 1126 may instruct 1125 1127 the TES system 1128 and the air conditioner 1124 to use cooling fluid 1129 from the TES system 1128 rather than use the air conditioner’s compressor, thereby lowering energy demand by the air conditioner 1124.

To leave electric-power saving mode, the controller 1126 may instruct 1125 1127 the TES system 1128 and the air conditioner 1124 to stop using cooling fluid 1129 from the TES system 1128, and use the air conditioner’s compressor.

In some embodiments the power company 1122 is potentially connected to several/many such systems 1120, and optionally flattens or lowers total electricity demand by instructing some systems 1120 to use their TES 1128 for cooling and some to use electricity 1121, optionally rotating electric-energy-saving mode among the different systems 1120.

In some embodiments, the signal 1123 is optionally a radio signal, as is used in some localities by power companies to stop air-conditioners equipped with compatible receivers.

In some embodiments, the signal 1123 is optionally conveyed over the Internet.

In some embodiments, the controller 1126 and/or the air conditioner 1124 and/or the TES 1128 and/or system 1120 use the Internet of Things protocol for communicating or receiving instmctions from the power company 1122.

In some embodiments, such as described in Figures 11 A and 1 IB above, an air conditioner optionally turns its compressor OFF and/or ON based on a power company sending a message or a schedule.

In some embodiments, such as described in Figures 11 A and 1 IB above, an air conditioner 1124 or a TES system 1128 or a controller 1126 optionally controls a flow path of cooling fluid 1129, so that the cooling fluid 1129 is cooled either by flowing through a compressor or by flowing through the TES system 1128.

In some embodiments, potentially based on grid electricity demand and/or a signal from an electric power supply company, the system 1120 optionally turn off a compressor of the air conditioner 1124 even for short periods, such as 2, 3, 5, 10 minutes, and use the TES system 1128 for cooling instead.

In some embodiments such short periods are potentially made possible based on a rapid response to cooling by high-heat-discharge rate ice bricks as described herein.

It is noted that such a load balancing can potentially occur within seconds, and potentially last for a period of seconds, minutes and even hours.

In some embodiments the controller 1126 optionally takes into account a cost of starting and stopping the compressor, in terms of wear-and-tear on the compressor, and compares the compressor wear-and-tear cost to a cost of not switching the compressor off and not taking advantage of cooling stored at lower electricity costs. The controller 1126 is optionally programmed to NOT switch the compressor off if the savings in electricity costs are lower than the cost of wear-and-tear on the compressor.

Controlling an interrupted mode of operation of a compressor

In some cases a compressor of an air conditioner turns on and off frequently, for example when its cooling load is not equal to its cooling power. In some case a compressor of an air conditioner turns on and off frequently, for example when its cooling power quickly overcomes the cooling load, and a thermostat turns the compressor off. Such a frequent turning on and off of a compressor is sometimes called an interrupted mode of operation, or“churn”. In some embodiments, the controller 1126 optionally controls the system 1120 to chum less, by turning the compressor off for longer periods, using the TES 1128 instead.

Reference is now made to Figure 12 A, which is a simplified flow chart illustration of a method for controlling an interrupted mode of operation of a compressor in an air conditioning system according to an example embodiment of the invention.

The method of Figure 12 A includes:

using a compressor in a refrigerant flow of an air conditioner (1201);

detecting when the air conditioner turns on or turns off (1202);

estimating chum based on the detecting (1204);

if churn estimate indicates the compressor is churning (1206), then using a TES system to cool the refrigerant of the air conditioner (1208), else continuing to use the compressor of the air conditioner (1210).

In some embodiments indication of chum is optionally produced by comparing a value of a chum estimate or measure to a chum threshold value.

In some embodiments indication of chum is optionally produced by using“fuzzy logic” to categorize a value of a chum estimate as likely or not likely to indicate chum.

It is noted that such a response to detecting churn can potentially occur within seconds, and potentially last for a period of seconds, minutes and even hours.

In some embodiments a method is provided to control an interrupted mode of operation of a compressor in an air conditioning system and/or some other cooling system, the method including using a compressor in a refrigerant cooling system, detecting when the air conditioner turns on or turns off, estimating chum based on the detecting, when churn estimate indicates the compressor is churning, then using a TES system to cool the refrigerant of the air conditioner, else continuing to use the compressor of the air conditioner.

Phase balancing and/or frequency stabilization.

In some cases, an air conditioner works off one phase or one conductor in a three-phase electric supply. However, when the three-phase electric supply is not balanced, by one conductor drawing significantly more electricity than the other two conductors, the phase difference between the three conductors of the three phase electric supply may change. Such an altered phase is called an imbalanced phase.

In some cases the imbalance causes a change in frequency of the alternating electricity. Such a change of frequency has a potential to undermine circuits or device which depend on the grid frequency.

Electricity from an imbalanced three phase circuit may provide less power and/or be less efficient, in terms of power and/or cost-to-operate, than electricity from a balanced three phase circuit.

In some cases, electricity from an imbalanced circuit is more expensive.

In some cases, when an air conditioning unit, for example such as the air conditioner 1124 of the system 1120 described with reference to Figure 11B, draws a large load of electricity, the air conditioning unit may cause a phase imbalance.

A non-limiting example of such imbalance may be caused in a system where an air conditioner compressor receives electricity from one phase conductor of a three phase electrical system, for example a small air conditioning system in a private home. In some embodiments a controller optionally monitors the phase difference between phases in three phase electricity supply, and optionally causes the air conditioning unit to switch from using a compressor to using a TES system for cooling the air conditioning refrigerant.

Reference is now made to Figure 12B, which is a simplified flow chart illustration of a method for mitigating imbalance in a three phase electric circuit according to an example embodiment of the invention.

The method of Figure 12B includes:

using a compressor in a refrigerant flow of an air conditioner (1222);

monitoring phase imbalance between conductors in a three phase electric system providing electricity to the air conditioner (1224);

if phase imbalance is greater than a threshold value (1226), then using a TES system to cool the refrigerant of the air conditioner (1228),

else continuing to use the compressor of the air conditioner (1230).

In some embodiments a method is provided to mitigate frequency change, such as frequency drop, when the electricity grid becomes unstable. In some embodiments the method includes monitoring the grid’s frequency, and ordering chillers and or compressors used by a Thermal Energy System (TES) to turn off when the electric grid frequency changes, for example drops below a certain threshold. In such a case the electric load potentially drops, by removing the electric load of a compressor of the chillers of the TES. In some embodiments, a signal coming from a grid operator is optionally used to trigger removing the electric load of the compressor of the chillers of the TES. Such services are called ancillaries and are not performed by current ice storage systems due to their slow rate discharge limitations.

Reference is now made to Figure 12H, which is a simplified flow chart illustration of a method for mitigating frequency drift in an electric circuit according to an example embodiment of the invention.

The method of Figure 12H includes:

using a compressor in a refrigerant flow of an air conditioner (1292);

monitoring electric circuit frequency (1293);

when the frequency declines by more than a threshold value (1294),

then using a TES system to cool the refrigerant of the air conditioner (1295),

else (1296) continuing to use the compressor of the air conditioner.

Mitigating electricity costs

In some cases phase drift causes a power company to increase electricity cost. In some embodiments, if price of electricity spikes, for example due to frequency drift or phase imbalance, the controller optionally turn off the compressor, and optionally uses cooling by a TES system.

Reference is now made to Figure 12C, which is a simplified flow chart illustration of a method for mitigating electricity costs caused by imbalance in a three phase electric circuit according to an example embodiment of the invention.

The method of Figure 12C includes:

using a compressor in a refrigerant flow of an air conditioner (1242);

monitoring cost of electricity from power company (1244);

if cost of electricity rises (1246), then using a TES system to cool the refrigerant of the air conditioner (1248),

else continuing to use the compressor of the air conditioner (1250).

In some embodiments the determination whether the cost of electricity rises specifically determines of if cost of electricity rises due to phase drift.

It is noted that such a response to frequency drift or phase imbalance can potentially occur within seconds, and potentially last for a period of seconds, minutes and even hours.

In some embodiments a method is provided to mitigate electricity costs caused by load imbalance of the electric grid and/or by available supply capacity relative to load demand. In some embodiments the method includes monitoring cost of electricity from a power company, and ordering chillers and or compressors used by a Thermal Energy System (TES) to turn off at times when cost of electricity rises, optionally using a TES system to replace a chiller’s compressor can reduce electrical power consumption, and avoid paying for electricity at high-electricity-cost times. In some embodiments, a signal coming from a grid operator is optionally used to trigger removing the electric load of the compressor of the chillers of the TES and/or by removing other chillers in the system and replacing the chillers with the TES stored energy.

Smart balancing of energy storage and consumption

In some embodiments a controller is used to plan a smart balance of energy storage and energy consumption.

There is a cost involved in consuming energy from an electric grid. Electricity consumption from a grid involves varying parameters, such as, by way of a non-limiting example, cost of the electricity consumption from the grid as a function of time. Such cost may vary over a daily cycle and be different on a weekend or even holidays. Such cost may be retrieved by receiving a transmission of the cost from a power supply company, or by receiving a transmission of a schedule of the cost from the power supply company.

There is a cost involved in storing energy. By way of a non-limiting example there is a cost to freeze an ice brick.

By monitoring total power demand of a facility, a control system can identify events when the facility’s profile of electric consumption are experiencing spikes and might penalize a customer with high electricity demand costs. In some embodiments the control system optionally identifies the increased demand as a demand that will last only for a short time and the control system calculates or monitors that there is enough available energy storage to mitigate the spikes. In some embodiments, detecting and monitoring the spikes is optionally done by monitoring a building’s electricity meter.

In some embodiments a control system monitors a rate of change in electric demand in a facility and optionally determines predicted electricity demand and/or predicted electricity cost. The control system optionally controls using energy from the electric power supply company or using energy from a TES based on the electricity demand and/or predicted electricity cost. In some embodiments the prediction is optionally based on using a prediction algorithm. In some embodiments the prediction algorithm is optionally based on past load behavior of the facility.

In some embodiments the control system optionally predicts when electric power consumption will reach or exceed what threshold and/or for what period of time the electric power consumption will reach or exceed what threshold.

In some embodiments, the control systems monitor an electric meter which measures electric power usage of a facility or building, including power usage of a TES system and power usage of other system at the facility. Electric cost at such a facility may be based on total electric cost, including both the TES system and the other, non-TES systems at the facility. Methods for saving electric cost, saving C02 emissions, and controlling peak electric demand which are described herein optionally apply to total cost, to cost of operating the TES system by itself, and to various combination including TES and just some of a facility’s electric power consuming systems.

By monitoring total power demand of the facility, the control system potentially identifies events when the facility is approaching an electrical consumption level which will trigger load demand charges which can be very high due to a short peak period. The control system optionally calculates an anticipated gain of cutting an anticipated peak demand value. In some embodiments, a quick reaction to anticipated short peak periods is enabled by a system as described herein. Such a quick reaction may optionally be in addition to, and may be different than, a scheduled load shifting which is typically bases on a difference in energy costs which are optionally used to determine to charge a TES at low energy cost periods and discharge the TES at high energy cost periods.

Some example system limitations can be distribution limitation of a local grid and load limitation of a facility itself (leads, control and safety breakers and metering devices)

In some embodiments such a cost is known and/or estimated, and entered into a control program for smart balancing of energy storage and energy consumption.

In some embodiments a controller measures electric consumption, and calculates an energy cost to freeze a specific amount of ice bricks.

In some embodiments the controller measures environmental parameters, such as temperature of the environment during freezing, humidity, time-of-day, sun or shade, precipitation, and so on.

In some embodiments a control program optionally calculates a dependency of cost of storing energy based on the capacity of ice bricks and/or stored energy left from previous days and/or one or more environmental variables. In some embodiments a control program optionally produces a Look Up Table illustrating a dependency of cost of storing energy based on the capacity of ice bricks and optionally based on values of one or more of the measured environmental parameters.

In some embodiments a control program gathers information and signals from various energy and electricity storage systems in a facility, optionally in addition to information related to the TES system’s cold thermal energy storage, and optionally triggers a charging or discharging process of the TES system based on a calculated savings or on a total electricity consumption load shifting, optionally used to support business operations.

Some of the cost involved with storing energy is related to energy loss over time. Energy stored in ice bricks may be lost, at a rate based on insulation of the ice bricks or the TES system, or on the ice bricks or TES system being in shade or in sunlight.

There is a cost involved in retrieving stored energy. By way of a non-limiting example there is a cost to circulate fluid through a TES.

In some embodiments such a cost is known and/or estimated, and entered into a control program for smart balancing of energy storage and energy consumption.

In some embodiments a controller measures electric consumption, and calculates an energy cost to retrieve a specific amount of energy. In some embodiments the controller measures and/or receive from a public or a dedicated data center, environmental parameters, such as temperature of the environment during energy retrieval, humidity, time-of-day, sun or shade, precipitation, and so on.

In some embodiments a control program optionally calculates a dependency of cost of retrieving energy based on the capacity of ice bricks and one or more environmental variables. In some embodiments a control program optionally produces a Look Up Table illustrating a dependency of cost of retrieving energy based on the capacity of ice bricks and optionally based on values of one or more of the measured environmental parameters.

In some embodiments a control program optionally calculates a cost of storing energy, compares the cost of storing energy to the cost of energy from the electric grid, and optionally initiates storing energy when the cost of storing energy is less than the cost of the grid energy.

In some embodiments a control program optionally calculates a cost of storing energy plus a cost of retrieving the energy, compares the cost of storing-and-retrieving energy to the cost of energy from the electric grid, and optionally initiates storing energy when the cost of storing-and- retrieving energy is less than the cost of the grid energy.

In some embodiments a control program optionally calculates a cost of retrieving energy, compares the cost of retrieving energy to the cost of energy from the electric grid, and optionally initiates retrieving energy when the cost of retrieving energy is less than the cost of the grid energy.

Some example embodiments of smart balancing of energy storage and consumption are described below.

In an example embodiment, a control program determines that a cost of energy at noon is lower than in the afternoon or evening, for example, at noon solar electricity is at a peak, and in the afternoon air conditioning demand is still high. In such an embodiment the control program optionally controls storing energy at noon, for example by freezing ice bricks, and retrieving energy during the afternoon or evening, for example by using the frozen ice bricks to cool air conditioning system(s).

In an example embodiment, a control program determines that a cost of energy at night is lower than during the day. In such an embodiment the control program optionally controls storing energy at night, for example by freezing ice bricks, and retrieving energy during the day, for example by using the frozen ice bricks to cool air conditioning system(s).

The above description is a description of an embodiment of the control program using a prediction of energy demands or energy costs to perform smart balancing of energy storage and consumption. In some embodiments the control program uses various types of data to predict required energy demands. Some non-limiting examples of such data include: a weather forecast; cost-of- energy data from a power company, optionally based on a daily or weekly schedule; historical energy costs, optionally associated with time-of-day and/or day-of-week and/or holiday/weekday/weekend.

It is noted that TES systems as described herein provide relatively lower costs of storing and/or retrieving energy, potentially enabling a control program as described herein to operate when more expensive systems for storing and/or retrieving energy cannot work, or would not save energy or cost.

In some embodiments the control program predicts future energy requirements, and/or predicts future opportunities for load balancing and/or predicts future opportunities for consuming lower-cost electricity from the grid. The prediction(s) is optionally used to cause storing heat energy in a TES, in preparation for subsequent heat energy retrieval.

Supporting electric vehicles on an electric grid

In some embodiments a load balance of a facility is supported in order to allow charging of electrical vehicles at a rate and during a periods or periods of time. The charging periods may optionally be pre-defined and/or as required in order to limit the facility electrical demand from the grid to a specific system limitation.

By monitoring the total power demand of a facility, the control system potentially identifies events when the facility is approaching its limitation either in internal or local distribution, and optionally compares cost of electricity for continuing to charge electric cars relative to cost of discharging a TES system. The control system optionally identifies when to charge electric vehicles, when to discharge a TES system, when to charge a TES system, based on total power demand of a facility and on electricity cost according to an electric supplier’s cost, which may be linked to time-of-day and/or spikes in electric demand. In some embodiments, the control system calculates a gain of cutting an anticipated peak demand value relative to a saving based on a scheduled load shifting, where the scheduled load shifting is typically based on a difference in energy charge values between the two periods of charging and discharging. In some embodiments, the control system optionally supplies cooling energy to the facility to allow switching off of chillers to reduce electrical load.

In some embodiments a load balance of a facility is supported in order to enable optionally using electricity stored in electrical vehicles during a periods or periods. The periods when the electric charge of the vehicles is used may optionally be pre-defined and/or as required in order to limit the facility electrical demand from the grid to a specific system limitation.

Reference is now made to Figure 12D, which is a simplified flow chart illustration of a method for mitigating electricity costs caused by charging electric vehicles at a facility according to an example embodiment of the invention.

The method of Figure 12D includes:

using a compressor in a refrigerant or heat transfer fluid flow of an air conditioner (1252); monitoring cost of electricity from power company (1254); and

when cost of electricity rises (1256),

then using a TES system to cool the refrigerant or heat transfer fluid of the air conditioner, thereby lowering electric consumption (1258),

else (1260) continuing to use the compressor of the air conditioner.

Reference is now made to Figure 12E, which is a simplified flow chart illustration of a method for mitigating electricity costs caused by peak electric demand charges according to an example embodiment of the invention.

The method of Figure 12E includes:

using a compressor in a refrigerant flow of an air conditioner (1262);

monitoring use of electricity at a facility (1264);

predicting when peak electric demand charges are anticipated (1266); and

when peak electric demand charges are anticipated,

then using a TES system to cool the refrigerant of the air conditioner, thereby lowering electric consumption (1268,

else (1270) continuing to use the compressor of the air conditioner.

Controlling CO2 emissions

In some embodiments a control program takes into account an amount of CO2 emissions corresponding to an amount of electric power usage and additional parameters such as time of day and source of the electric power. In some cases cost of electricity is linked to amount of corresponding CO2 emissions. However, in some cases CO2 emissions may not correlate directly to cost or may not correlate to cost at all. In some embodiments the control system optionally controls using TES system to lower an energy consumption load of a facility in order to reduce CO2 emissions. In some embodiments the control system optionally controls using TES system to lower an energy consumption load of a facility taking into account both CO2 emissions and electric energy cost. In some embodiments the control program measures Co2 emissions as amount of CO2 consumed per kWh.

Reference is now made to Figure 12F, which is a simplified flow chart illustration of a method for mitigating CO2 emissions caused by electric consumption according to an example embodiment of the invention.

The method of Figure 12F includes:

using a compressor in a refrigerant flow of an air conditioner (1272);

monitoring CO2 emissions corresponding to use of electricity at a facility (1274); and using a TES system to cool the refrigerant of the air conditioner at high- CO2 emission periods (1276), thereby lowering CO2 emissions.

Controlling maximum power demand

In some embodiments a control program takes into account a top limit of electric power usage which may be imposed on a facility. The control program optionally measures electric power usage of a facility, and when the facility reaches a top limit value, or reaches a threshold value, when the control program calculates and predicts reaching any of the above-mentioned values, the control program optionally uses energy stored in TES system to take on some of the electric load used for cooling, thereby freeing up some electric load.

By way of a non-limiting example, in some cases a facility has a top limit of Q (kW or MW) electric power consumption, and provides X electric power for air conditioning, X electric power for various systems, and Z electric power for charging electric vehicles. It is noted that charging electric vehicles takes up a large amount of power. Even a large building may be able to provide charging for 10 electric vehicles, but not for 20. When the control program senses that the top limit is close to being reached, the control program may initiate using the TES system to provide cooling for air conditioning, thereby freeing up electric power consumption of the air conditioning for charging additional electric vehicles.

Reference is now made to Figure 12G, which is a simplified flow chart illustration of a method for preventing reaching an upper limit of electric consumption at a facility according to an example embodiment of the invention.

The method of Figure 12G includes:

using a compressor in a refrigerant flow of an air conditioner (1282);

monitoring use of electricity at a facility (1284); and

when reaching an upper limit of electric consumption is anticipated (1286), then using a TES system to cool the refrigerant of the air conditioner (1288), thereby lowering electric consumption,

else (1290) continuing to use the compressor of the air conditioner.

Settings

In some embodiments, a controller such as the controller described herein is set to provide heat exchange fluid at a temperature higher than -10 degrees Celsius to ice bricks containing water and an ice nucleation agent.

Providing water at higher temperatures is potentially more efficient. For example, potentially less heat is lost to the environment by providing heat exchange fluid at a temperature closer to the environmental temperature.

It is noted that ice nucleation agents such as mentioned herein, by way of a non-limiting example such as quartz, enable phase change materials, by way of a non- limiting example, water, to freeze at a temperature higher than conventional systems, for example at a temperature higher than freezing coil systems.

In some embodiments a structure of an ice brick or array or TES system as described herein together with phase change materials to which ice nucleation agents are added, potentially provides a synergistic effect, of storing energy by phase change more efficiently, and/or at higher temperatures, than conventional systems.

In some embodiments a structure of an ice brick or array or TES system as described herein together with phase change materials to which ice nucleation agents are added, potentially provides a synergistic effect, of using chiller fluid set to higher temperatures than conventional systems, potentially saving energy and energy costs.

In some embodiments, the controller is set to provide heat exchange fluid at a temperature of -5 degrees Celsius, and even a temperature of -2.7 degrees Celsius to the ice bricks containing water and the ice nucleation agent.

In some embodiments, the controller is set to provide heat exchange fluid at a temperature of in a range between -10 degrees Celsius and -2.5 Degrees Celsius, inclusive, to the ice bricks containing water and an ice nucleation agent.

Above-mentioned International Patent Application Number PCT/IB2018/001091 describes, at least in some embodiments, a system and method for thermal energy storage using configurable ice bricks or thermal energy storage units.

Reference is now made to figures 1A-1E which are schematic diagrams of a thermal energy storage system according to at least some embodiments of the present invention. As shown, thermal energy storage (TES) system 100 uses the HVAC chiller 102 of an air-conditioning (HVAC) system in an installation. Non- limiting examples of an installation include an office building, residential building, shopping mall, airport terminal, factory, server room or similar. When operating without the system 100 of the present invention, HVAC chiller 102 cools a third fluid 124 which is then circulated throughout the installation for cooling load 130. Third fluid 124 is optionally, water.

As described above one aim of some embodiments of the present invention is to“store cooling” using the TES 100. Alternatively the same system 100 may be used to store heat. The TES 100 comprises a fluid distribution system 104 which comprises those components necessary for distributing the first fluid 120, second fluid 122 and third fluid 124 throughout system 100. Therefore distribution system 104 comprises one or more pumps 106, piping 108, flow control mechanisms 107 such as valves, and monitoring components 109 for monitoring, for example, temperatures and flow rates inside system 100. Monitoring 109 optionally feeds data to a controller 105 for controlling the freezing and/or cooling process via control of chillers 102 and 150, HE 170, load 130, array 110, and the components of fluid distribution system 104 as described further below. In normal use HVAC chiller 102 cools third fluid 124 which is directed by fluid distribution system 104 from HVAC chiller 102 via pipes 108C to pipes 108L for flow through load 130.

TES 100 further comprises a thermal storage array 110. Array 110 comprises multiple ice bricks 112. Each ice brick 112 comprises multiple ice capsules 114 surrounded by first fluid 120. Embodiments of ice bricks 112 and ice capsules 114 are described further below with reference to figures 2A-2U and 3. Ice capsules 114 are closed or sealed capsules containing second fluid 122. Second fluid 122 is optionally, water such that exposure of capsules 114 to a low temperature first fluid 120 surrounding capsules 114 results in capsules 114 cooling and in turn second fluid 122 cooling and changing phase into ice.

First fluid 120 optionally has a lower freezing point than second fluid 122. Non-limiting examples of a first fluid 120 include ethylene glycol, ethylene glycol mixed with water, salt water, or similar fluids. TES 100 further comprises a TES chiller 150 for cooling first fluid 120 to a temperature lower than the freezing point of second fluid 122. TES chiller 150 is one of air-cooled or water-cooled.

Second fluid 122 is optionally water mixed with an ice nucleation agent. The ice nucleation agent is optionally quartz. The type of quartz used may be any one of but is not limited to: Herkimer Diamond, Rock crystal, Amethyst, Ametrine, Rose quartz, Chalcedony, Cryptocrystalline quartz, Carnelian, chalcedony, Aventurine, Agate, Onyx, Jasper, Milky quartz, Smoky quartz, Tiger's eye, Citrine, Prasiolite, Rutilated quartz, or Dumortierite quartz. Quartz is cheap and easily available and resistant to repeated freezing cycles of the second fluid. Furthermore it raises the required starting temperature of freezing the ice by several degrees. Hence, a nucleation agent improves the efficiency and responsiveness of the thermal energy storage system 100.

Optionally second fluid 122 comprises strips of a metal floating in second fluid 122 inside capsules 114 and causing even distribution of ice formation inside capsules 114. Optionally, the metal is aluminum. Optionally, the strips are up to 0.5mm thick. Optionally, the strips are up to 30 cm long, optionally the strips are up to 1cm wide. This optional aspect is explained in more detail with reference to Figure 8.

Each ice brick 112 optionally has a long and narrow form factor as shown in figures 2E to 2H to enable efficient heat transfer between capsules 114 and first fluid 120. An ice brick 112 with a long form factor has optionally a length L that is at least three or four times greater than its maximum width W and/or height H. Bricks 112 can optionally be connected end to end creating long linear modules comprising multiple bricks 112. The modular structure and number of bricks 112 used enables control of the rate of energy being discharged to provide for the exact thermal energy storage needs per installation and also provides for flexible installation options as array 110 can be shaped as required. This optional aspect is explained in more detail with reference to Figures 8A and 8B .

Capsules 114 are optionally spaced slightly apart within bricks 112 to increase the overall ratio between surface area and volume of the second fluid 122 that is to be frozen. Optionally, brick 112 contains between 65% and 85% of second fluid 122. Optionally, brick 112 contains 75% of second fluid 122. Capsules 114 optionally comprise polymers such as polyvinyl chloride or other suitable durable and low cost materials. Capsules 114 optionally comprise protrusions or ridges on their outer surface to provide spacing between capsules 114 for flow of first fluid 120 and for increasing turbulence of first fluid 120.

In use of system 100 shown in Figure 1A, TES chiller 150 cools first fluid 120, optionally to a temperature below the freezing point of second fluid 122. First fluid 120 is pumped from TES chiller 150 via pipes 108G and directed by fluid distribution system 104 via pipes 108T through array 110 to freeze second fluid 122 (also referred to herein as a“charging process”). First fluid 120, which has increased in temperature then exits array 110 via pipes 108T and is directed by fluid distribution system 104 back to the pipes 108G to chiller 150 to be cooled again. During the charging process the provision of first fluid 120 may be continuous or non-continuous. The charging process is optionally stopped when a desired temperature of first fluid 120 is reached within one or more bricks 112, or when a predefined time period has lapsed, or when a predefined amount of energy is stored in array 110. A (fully) charged array 110 usually comprises a plurality of capsules 114 with a second fluid 122 in a frozen state.

Once array 110 has been charged, a cooling process (also referred to herein as a discharge process), is used to cool load 130 using array 110. First fluid 120 inside array 110 is directed via piping 108T to distribution system 104 and through pipes 108S into heat exchanger 170 where first fluid 120 cools third fluid 124. Distribution system 104 then directs cooled third fluid 124 through pipes 108H into pipes 108C to flow through HVAC chiller 102 and then load 130 (via pipes 108L).

Alternatively third fluid 124 is directed through pipes 108H in parallel to HVAC chiller 102 directly to load 130 via fluid distribution system 104 to piping 108L. Since third fluid 124 has been cooled by first fluid 120 in HE 170, HVAC chiller 102 optionally does not need to be activated, thus producing energy savings. As first fluid 120 circulates between HE 170 and array 110, capsules 114 containing frozen second fluid 122 cool first fluid 120 which then directly or indirectly cools third fluid 124 and load 130. Optionally, the temperature of first fluid 120 entering heat exchanger 170 is between 5 degrees Celsius at the inlet and 10 degrees Celsius at the outlet. As capsules 114 cool first fluid 120, frozen second fluid 122 gradually undergoes a phase change and melts until a point where array 110 is no longer sufficiently cooling first fluid 120 and array 110 is said to be discharged. A (fully) discharged array 110 usually comprises capsules 114 with a second fluid 122 in a liquid state.

The charging process optionally takes place during off-peak hours (hours in which the load on the electrical grid is low) while the discharge process optionally occurs according to the demands of load 130 - even during peak hours. The discharge process is optionally stopped when a cutoff temperature of first fluid 120 is reached, or when a predefined time period has elapsed, or when a predefined amount of energy is output from array 110, or under control of load 130 or when the demand for cooling at load 130 has lowered to a desired level. The direction of flow of first fluid 120 within array 110 during the charging process may be the same, or may differ from the direction of flow of first fluid 120 during the discharge process.

Alternatively, system 100 is used for heating. For heating TES chiller 150 optionally operates as a heat pump. TES Chiller 150 heats first fluid 120, optionally in off peak hours. First fluid 120 is pumped from TES chiller 150 via pipes 108G and directed by fluid distribution system 104 via piping 108T and through array 110 to warm second fluid 122 (also referred to herein as a charging process). First fluid 120, which has decreased in temperature then exits array 110 and is directed by fluid distribution system 104 through pipes 108T and piping 108G to TES chiller 150 to be warmed again. During the warming process the provision of first fluid 120 may be continuous or non-continuous. The wanning process is optionally stopped when a desired temperature of first fluid 120 is reached within one or more of bricks 112, or when a predefined time period has lapsed, or when a predefined amount of energy is stored in array 110, and the like. No phase change takes place in the array.

Once array 110 has been charged, a warming process (also referred to herein as a discharge process), is used to warm load 130 using array 110. First fluid 120 inside array 110 is directed via distribution system 104 through pipes 108T and 108S into heat exchanger 170 where first fluid 120 warms third fluid 124. Distribution system 104 then directs warmed third fluid 124 from pipes 108H through pipes 108C to flow through HVAC chiller 102 and then load 130 (via pipes 108L). Alternatively third fluid 124 is directed through pipes 108H in parallel to HVAC chiller 102 directly to load 130 via fluid distribution system 104 to piping 108L. Since third fluid 124 has been warmed by first fluid 120 in HE 170, HVAC chiller 102 (functioning as a heat pump) optionally does not need to be activated as third fluid 124 has been warmed thus producing energy savings. As first fluid 120 circulates between heat exchanger 170 and array 110, capsules 114 containing warmed second fluid 122 warm first fluid 120 which then directly or indirectly warms third fluid 124 and load 130.

The charging process optionally takes place during off-peak hours (hours in which the load on the electrical grid is low) while the discharge process optionally occurs according to the demands of load 130 - even during peak hours.

Monitoring 109 of fluid distribution system 104 optionally comprises one or more temperature monitors for monitoring at least one of: The temperature of first fluid 120 before entering array 110; The temperature of first fluid 120 in any location within array 110; The temperature of first fluid 120 after exiting array 110; The temperature of second fluid 122 within one or more capsules 114; The temperature of one or more ice bricks 112; The temperature of first fluid 120 before entering HE 170; and the temperature of first fluid 120 when leaving HE 170. Additionally or alternatively, monitoring 109 comprises one or more flow monitors (not shown) for monitoring at least one of: The flow of the first fluid 120 before, inside and after array 110; and the flow of first fluid 120 before, inside and after HE 170.

While figures 1A-1E show single instances of chillers 102 and 150, HE 170, load 130, array 110, and the components of fluid distribution system 104 it should be understood that TES 100 may comprise any suitable number of these components.

The system 100 of figure IB functions in the same manner as that of figure 1A, but the illustrated embodiment comprises an air compressor 140. Compressor 140 draws air 126 from the top of the each of bricks 112. This air 126 is optionally compressed to between 10 and 20 bar resulting in the air 126 heating up as a result of compression. This compressed air 126 is then pumped into the bottom of each of bricks 112 through an air to air heat exchanger 142 and/or an expansion valve (not shown) - dropping to a temperature of between -20 to -30 degrees Celsius. This air 126 is bubbled through each of bricks 112 to further cool the contents before exiting through the top of the bricks 112 at between -5 to +5 degrees Celsius. This cold air 126 is then fed once again into the compressor 140 creating a cooling closed loop 108P. Cooling loop 108P is shown for simplicity as connected directly to thermal storage array 110 but cooling loop 108P is optionally part of fluid distribution system 104 and is controlled as are other piping systems as described herein. In this embodiment second fluid 122 is optionally combined with salt or other suitable material to lower the freezing point of second fluid 122.

The system of figure 1C functions in the same manner as that of figure 1A, but where the condensation cycle of TES chiller 150 is water cooled comprises a heat exchanger 152 fed from third fluid 124. In this embodiment load piping 108K is adapted to connect to HE 152 in TES chiller 150. Load piping 108K carries third fluid 124 which has been chilled by HVAC chiller 102 - typically to a temperature between but not limited to 7 to 12 °C.

TES chiller 150 then cools first fluid 120 via HE 154 to a temperature below the freezing point of second fluid 122 such that first fluid 120 may be pumped through array 110 to freeze second fluid 122 inside capsules 114. The discharging process then takes place in HE 170 as for other embodiments. This arrangement increases the energy efficiency of TES chiller 150 which can utilize the abundant supply of cooled third fluid 124 available when load 130 is partially or entirely not being used for example but not limited to nighttime usage in an office complex. HVAC chiller 102 optionally, cools third fluid 124 at night when the outside temperature is lower and electricity costs are lower for more effective and cheaper energy usage. Since water cooled TES chiller 150 is more efficient it can also be smaller than in other embodiments where an air-cooled chiller is used.

The system of figure ID combines the functionality of figures IB and 1C to provide for a TES chiller 150 connected to third fluid via HE 152 that is supplemented by compressive cooling from air compressor 140.

The system of figure IE functions in the same manner as that of figure 1A, but in the illustrated embodiment some or all of ice bricks 112 do not comprise capsules 114. In the embodiment of figure IE TES 100 is used to store first fluid 120 in ice bricks 112. Thus first fluid 120 is cooled by chiller 150 and this cooled first fluid 120 is then pumped into ice bricks 112 for storage and use for cooling third fluid (via HE 170) at other times. As above, non-limiting examples of a first fluid 120 include ethylene glycol, ethylene glycol mixed with water, salt mixed with water, or other combinations of these or other fluid to form“slushes” or similar fluids.

Reference is now made to figures 2A-2U which are illustrations of ice bricks, ice capsules and thermal storage arrays according to at least some embodiments of the present invention. Figures 2A-2D show preferred embodiments of capsules 114. Capsule 114 comprises a filling nozzle 202 placed on an upper comer of capsule 114 to enable filling of capsule 114 to a maximum with second fluid 122 while still enabling efficient packing of capsules 114. Capsules 114 optionally comprise narrow-side spacers 204 and broad-side spacers 206. When provided, spacers 204 and 206 create a gap between capsules 114 when these are packed together inside brick 112. This gap is required to allow flow of first fluid 120 between capsules 114 for freezing of second fluid 122 inside capsules 114. Capsules 114 comprise a high ratio of depth D vs. length L and height H to create a greater surface area around a thinner piece of ice for a more efficient heat transfer of second fluid 122).

Figures 2E-2H show preferred embodiments of ice bricks 112 comprising capsule 114. Ice brick 112 comprises a rectangular enclosure 220 for enclosing multiple capsules 114. Capsules 114 are packed together to maximize the amount of second fluid 122 that is contained inside brick 112. Brick is equipped on each end with alignment or support panels 227 for aligning capsules 114 and sealing brick end panels 226 such that brick 112 is watertight when sealed. Brick 112 is connected to array 110 via inlet/outlet pipes 224. Mounting brackets 222 are provided for mounting brick 112 in a fixed position in the array 110 as further described below. Aside from inlet/outlet pipes 224 and interconnecting piping 228 used to connect bricks, brick 112 is completely sealed to fully contain first fluid 120 that flows through brick 112.

Optionally, brick 112 has a size of 50X50X400 cm. Optionally, brick 112 has a volume of 1000L comprising 75% (750L) of second fluid 122. Optionally, brick 112 has an energy storage capacity of 19.8 trhl69 kWh. Alternatively, brick 112 has a size of 25X25X400 cm. The size of brick 112 is selected to provide a balance between sufficient energy storage and construction modularity of the array.

Figures 2I-2N show preferred embodiments of bricks 112 in flexible configurations of thermal storage arrays 110. Brick 112 is used as a building block for configuration of an array 110 that is of any desired layout and also capacity. As shown in figure 21 and 2J, bricks 112 are stacked on top of one another, laid end to end and also laid next to one another. Inlet/outlet pipes 224 and interconnecting piping 228 are then used to provide fluid connection between the bricks 112 in the array for first fluid 120. Bricks 112 are fluidly connected in parallel or alternatively in series or alternatively a combination of parallel and series connections. As shown in figures 2K-2N, once the array 110 has been built with a desired capacity (number of bricks 112), and form (arrangement of bricks 112), insulation panels 230 are attached to the outer surface of the array 110 to fully insulate the array and preserve the thermal storage within the bricks 112. This configuration saves on the total insulation needed as only the outer surface of the complete array 110 needs to be insulated, and not every surface of every brick 112. Array 110 is optionally assembled on top of base frame 232 which is optionally insulated on its underside.

Once array 110 has been arranged into the desired form such as the rectangular box of figure 2M or the planar platform of figure 2N or any combination of these to create any structural arrangement required for the specific installation, this form can be integrated into the structure served by the thermal storage system 100. As a non-limiting example, the platform of figure 2N could function as a floor or could be erected vertically to function as a wall or could function as both floor and wall or could function as a raised platform inside, next to, or on the building/structure serviced by the TES system 100.

Figures 20-2R show additional preferred embodiments of ice bricks 112 comprising capsules 114, wherein capsules 114 are narrower in a middle section thus creating gaps between capsules 114 for flow of first fluid 120.

Figures 2S-2U show additional preferred embodiments of capsules 114, wherein capsules 114 comprise a widened middle with a supporting ridge 250 so that upper part 256 and lower part 254 do not collapse when ice forms inside capsule 114. Ridge 250 and ridges 252 create a gap between capsules 114 when these are packed together inside brick 112. This gap is required to allow flow of first fluid 120 between capsules 114 for freezing of second fluid 122 inside capsules 114. Capsules 114 also comprise protmsions 260. Protmsions 260 increase the Reynolds number for first fluid 120 outside capsules 114 thus resulting in a more turbulent flow of first fluid 120 and therefore better distribution of ice formation inside capsule 114.

Figure 2V shows a side view of a capsule 114 with protrusions 260, a ridge 252 and a filing nozzle 202. The filling nozzle is placed such that it does not increase beyond the general outer shape of the rectangular shaped capsule 114. Figure 2W shows the capsule of Figure 2V in another side view, perpendicular to the view of Figure 2V. Figure 2X shows the capsule of Figures 2V and 2W in a front view, wherein the broad-side of the capsule 114 and the general flow direction 290 of the first fluid 120 is shown. The capsule 114 has protmsions 260 that are arranged such that the flow path of the first fluid 260, which passes by the capsule 114, is provided in a meander pattern 291 (or a serpentine pattern). A meander pattern 291 in the sense of the invention is characterized in that the direction of the flow is repeatedly changed. Optionally, the meander pattern 291 is characterized in that the direction of the flow is regularly changed. Even more preferred is that the meander pattern is approximately symmetrical around a center line at least in a part of the meander pattern. The reference numeral 292 refer to flat areas of the capsules 114 between the protrusions 260. Figure 2Y shows a perspective view of the capsule 114, which is shown in figures 2v, 2W and 2X.

Reference is now made to figure 3 which shows an ice capsule according to at least some embodiments of the present invention. As shown in figure 3, capsule 114Cy is optionally provided in a cyclohexane shape. In use, multiple cyclohexane shaped capsules 114Cy are placed inside brick 112 to freely settle inside brick 112. Thus capsules 114Cy are not fixed inside brick 112. The irregular shape of cyclohexane shaped capsules 114Cy enables a high packing factor within brick 112 while allowing gaps for flow of first fluid 120 around capsules 114Cy for freezing the second fluid 122 inside them. Moreover, also a plurality of cyclohexane-shaped capsules 114Cy provides defined flow paths inside the brick 112C, since such defined cyclohexane-shaped capsules 114C will create a defined geometric pattern of these capsules 114c when placing a plurality of them inside an enclosed volume.

Reference is now made to figure 4 which shows a cylindrical Ice brick according to at least some embodiments of the present invention. In the optional embodiment as shown in figure 4, ice brick 112C is cylindrical and comprises capsules 114C arranged in one or more arrays. Optionally there are multiple arrays placed at different heights within brick 112C. Optionally, the cylindrical brick 112C is adapted to be positioned underground. Brick 112C is manufactured from a pipe comprising a spiral metal reinforcement (not shown) than runs along the outside of brick 112C to enable placement of brick 112C underground. The volume of ice brick 112C is optionally between 100-10,000 cubic meters.

Reference is now made to figure 5A which shows a TES system capable of activating separate subsets of ice bricks by a controller, figure 5B which shows a flow diagram for operation of a TES system, and figure 5C which shows experimental data from operation of a TES system according to at least some embodiments of the present invention. As shown in figure 5A, TES system 100 is structured and operates as per TES system 100 of figure 1A. Optionally any of the embodiments of figures 1A-1E may be used as described with reference to figure 5B. In the embodiment of figure 5A, system 100 comprises N ice bricks 112 where N is an integer greater than 2. It should be appreciated that, as described above, array 110 optionally comprises as many ice bricks 112 as are needed to provide sufficient thermal energy storage. Ice bricks 112 are interconnected using inlet/outlet pipes 224 and interconnecting piping 228 and further are interconnected using components of fluid distribution system 104. Flow control 107 of fluid distribution system 104 enables segmentation of array 110 into subsets 520 of ice bricks 112 that can be activated individually as described below.

As above first fluid 120 flows through ice bricks 112 for charging and discharging. In the discharging process 500 of figure 5B, in step 501, the discharging process is initiated. The steps of process 500 are optionally controlled by controller 105 that controls the components of system 100 as described above. Activation of the discharging process may involve several steps such as but not limited to activating pumps 106, opening or closing valves in flow control 107, and monitoring temperatures and flow rates of fluids 120, 122, and 124 using monitoring 109.

In step 502 as part of the activation process, controller 105 activates a first subset 520A of ice bricks 112 and first fluid 120 is pumped only through this first subset 520A and not through any other ice bricks 112. As shown in figure 5A first subset 520A includes ice bricks 112A and 112B, however any number of ice bricks 112, and even a single ice brick 112, may be included in a subset and the example of two ice bricks 112 in a subset 520 should not be considered limiting. Optionally more than one subset 520 is activated in step 502. As first fluid 120 passes through first subset 520A, first fluid 120 is cooled while second fluid 122 is warmed. In step 503, the temperature of first fluid 120 is monitored such as by monitoring 109 as it exits array 110. Optionally temperatures of other fluids in system 100 are also measured in step 503.

In decision step 504, monitoring 109 indicates whether the monitored temperature has risen above a defined threshold. If the monitored temperature does not exceed the threshold then no action is taken by controller 105 and step 503 of monitoring is continued. When monitoring 109 indicates that the temperature has risen above the defined threshold (which is optionally defined in controller 105) the implication is that second fluid 122 passing through subset 520A is no longer being sufficiently cooled by subset 520A since second fluid 122 of subset 520A has risen in temperature. In a non-limiting example, where the temperature of first fluid 120 has risen above 5 degrees Celsius at the outlet of array 110, subset 520A is no longer sufficiently cooling first fluid 120.

In decision step 505 controller 105 checks whether all subsets of ice bricks 112 have been activated. When it is determined that not all subsets of ice bricks 112 have been activated, controller 105 activates a next subset 520B of ice bricks 112 in step 506. As above while figure 5A shows subset 520B including only ice bricks 112C and 112D, this should not be considered limiting and subset 520B could comprise any number of ice bricks 112. Subset 520B is optionally activated in addition to subset 520. Alternatively subset 520 is deactivated when subset 520B is activated. Optionally more than one subset is activated in step 506. The activation of subset 520B results in a decreased temperature as monitored by monitoring 109 in step 503. Steps 503, 504 and 505 are repeated as shown in figure 5B until it is determined in step 505 that all available subsets, up to subset 520N, of ice bricks 112 have been utilized and in step 507 the discharge process 500 is stopped.

Figure 5C shows experimental data from operation of a TES system. As shown in the graph of figure 5C, the temperature of first fluid 120 is monitored at the outlet of array 110 and plotted as line 532 as a function of time elapsed since activation of a discharging process. In the experimental system, three ice bricks 112 were activated at time = 0 and as shown, the temperature increased from -5 degrees Celsius to around 5 degrees Celsius at the time indicated at point 530. At time 530, another ice brick was activated in addition to the initial three ice bricks and this immediately lowered the outlet temperature as in graph 532 to around 0 degrees Celsius. The temperature then gradually rose once more to around 5 degrees Celsius as the fourth ice brick also discharged. As can be seen from the experimental graph 532, the gradual activation of ice bricks 112 or subsets of ice bricks 520 results in more balanced discharging of TES system 100, longer discharging time resulting in longer periods of TES cooling of a load 130, and better utilization of each ice brick 112 which is more fully discharged.

Reference is now made to figures 6A-6G which show spacers for use in an ice brick according to at least some embodiments of the present invention. Spacers 600 and 620 are inserted between capsules 114 inside ice bricks 112. An ice brick 112 optionally comprises multiple spacers 600 or alternatively spacers 620.

Alternatively an ice brick 112 comprise a combination of spacers 600 and 620.

Figure 6D and 6E show two capsules 114 without any spacer 600 or 620 in a discharged (figure 6D) and charged (figure 6E) state. Figure 6F and 6G show two capsules 114 with spacer 620 in a discharged (figure 6F) and charged (figure 6G) state. Two capsules 114 are shown for purposes of simplicity and it should be apparent that any number of capsules and spacers may be provided as required inside brick 112. The purpose of spacers 600 and 620 is to maintain a minimum flow area 630 around capsules 114. Flow area 630 is required since capsules 114 expand (figure 6E) when capsules 114 are fully charged (second fluid 122 such as water has changed into ice). This expansion by capsules 114 can block the flow of first fluid 120 by constricting flow area 630 (figure 6E) preventing first fluid 120 from passing through ice brick and 112 and thereby preventing efficiently cooling of first fluid 120. Further, when second fluid 122 (such as water) is in a discharged state (figure 6D) capsules 114 shrink and the flow area 630 between capsules 114 grows causing a significant decrease in first fluid flow velocity which effects heat transfer for both charging and discharging. In the embodiment of figure 6A spacer 600 ensures a sufficient flow area 630 by fitting between capsules 114 such that capsules 114 cannot expand to fill the flow area. Holes 604 in spacer 600 allow for flow of first fluid 120. When capsules 114 discharge, flexible flaps 602 open away from spacer 600 in order to occupy flow area 630 and thereby increase first fluid flow velocity.

In the embodiment of figures 6B, 6C, 6F and 6G, spacer 620 ensures a sufficient flow area 630 by fitting between capsules 114 such that capsules 114 cannot expand while freezing to fill flow area 630. Figure 6C shows cross section A'-A' of spacer 620. Gaps 624 between the vertical bars 621 and horizontal bars 622 in spacer 620 allow for flow of first fluid 120. As shown in figure 6F spacer 620 fits between capsules 114 and vertical bars 621 and horizontal bars 622 increase the flow velocity of first fluid through flow area 630. As shown in figure 6G, when capsules 114 are charged and expand, spacer 620 prevent capsule 114 from blocking flow area 630 thus ensuring continued flow of first fluid 120 around capsules 114.

Reference is now made to figures 7A to 7D, which show an ice brick 112, i.e., a thermal energy storage unit 711.

The thermal energy storage unit 711 of Figure 7A comprises a tube 712, which has the shape of an elongated, hollow body. The tube 712 is optionally made of metal, e.g., carbon steel or stainless steel. A front end element 713 A and a back end element 713B are arranged to close the tube at both ends such that a rectangular- shaped enclosure is provided. Both elements 713 A and 713B are also optionally made of metal, e.g., stainless steel or carbon steel and provide means for mounting the thermal energy storage unit 711 e.g. to supporting means (not shown). The front end element 713A and the back end element 713B have an inlet 714A and an outlet 714B, respectively. The inlet 714A and the outlet 714B can be connected to further thermal energy storage units 112, the piping 10 and/or to the fluid distribution system 104. Inside the tube 712, a plurality of capsules 715 is arranged. The capsules 115 have the shape of plates or bricks. Furthermore, the capsules 715 have a concave or recessed shape of their main surfaces (i.e. of their broad-sides). The arrangement of the capsules 715 inside the tube is optionally configured by a plurality of horizontally arranged stacks 717 of capsules 715 (i.e., the stacks are stacked in a width direction of the tube 712). For example, 16 or 8 capsules 715 can form one stack 717of capsules 715. A plurality of stacks 717 is arranged one after another along the length of the tube 712. The capsules contain a phase-change material as second fluid 122 such as water, and preferable a nucleation agent, such as quartz. Between the capsules 715, as well as between the capsules and the tube 712, a space 716 is provided, in which the first fluid 120, e.g., a water/glycol mixture, can flow inside the tube 712 from inlet 714A to outlet 714B. This arrangement allows an efficient exchange of heat between the first fluid 120 and the second fluid 122 via the wall of the capsule 715. The actual heat exchange rate between the capsule 715 and the first fluid 120 is dependent on several factors including the speed of the flow, the effective area of the contact surface between the flow of the first fluid 120 and the capsule 715, and the type of the flow (e.g., turbulent or laminar). The embodiment of Figure 7 A improves all of these factors. This is explained in more detail below:

The elongated shape of the tube in combination with the stacked arrangement of the capsules 715 defines residual free spaces 716, which result in a plurality of predefined flow paths 718 of the first fluid next to the capsules. The overall flow of the first fluid 120 at the inlet 714A is divided into the plurality of predefined flow paths 718, wherein each of the flow paths 718 passes by a plurality of capsules along the length of the tube 712. Moreover, the capsules 715 are configured such that the flow paths 718 are defined in a frozen (expanded) state of the capsules 715 as well as in a non-frozen (non-expanded) state of the capsules 715. In other words, a plurality of predefined or fixed flow channels for the first fluid 120 is provided between the capsules 715 while considering the changing volume of the capsules due to the volume change of the second fluid, especially while changing phase. Consequently and in contrast to conventional tank-based thermal energy storage units, a predefined system of a plurality of flow paths 718 for the first fluid 120 for exchanging heat is provided. The flow of the heat transfer fluid in conventional tank based thermal energy storage units has a high degree of randomness, wherein for example it is hard for the first fluid to reach edges of the tank.

Moreover, the plate shape of the capsules 715 geometrically increases the surface of the capsules 715 (i.e., its surface-to-volume ratio), wherein the largest surfaces (i.e. the broad-sides) of the capsules 715 advantageously define its main surfaces for exchanging heat.

Correspondingly, each flow path 715 of Figure 7A has a narrow shape that is aligned parallel to said main surfaces of the capsules 715. The narrow shape of defined flow paths 718 utilizes the main surfaces of the capsules 715 such that the heat transfer rate is increased. In other words, the above explained arrangement of the thermal energy storage unit 711 significantly increases the effective area of the contact surface for exchanging heat while keeping the pressure drop at an acceptable level (e.g., below 1 bar).

The elongated shape of the tube 712 provides defined flow paths of the first fluid 120 that are significantly longer than with conventional systems. Hence, the exchange of heat of the first fluid 120 with the plurality of stacks 717 is optimized, since a gradual activation of the stacks 717 while frosting or defrosting the capsules 715 takes place. Additionally, the average length of the flow paths is increased to be longer than the length L of the tube 712. This additionally increases the heat transfer rate.

Figure 7B shows a cross-section of an empty tube 712. Figure 7C shows a cross-section of a tube 712 including a stack 717 of capsules 715 with water in a liquid (non-frozen) state. Hence, the thermal energy storage unit 711 of Figure 7C is fully discharged. Figure 7D shows a cross- section of a tube 712 including a stack 717 of capsules 715 with water in a frozen/solid state. Hence, the thermal energy storage unit 711 of Figure 7D is fully charged. The tube 712 of Figure 7B has ideally an overall cross-section (i.e. cross-sectional area) of the tube 712A for the first fluid 120, if considered without any capsule 715. If a stack 717 of capsules 715 is placed inside the tube 712, narrow-shaped flow paths are provided between capsules 715; in Figure 7C one of these narrow flow paths 718 is indicated by a plurality of circles, which indicate the flow direction of the first fluid 120. The flow paths 718 are provided in a cross-sectional area between each of two capsules 120 (one of these free-flow cross-sectional areas for the flow paths is indicated with the reference numeral 718A in Figure 7C) for the first fluid 120 and, at the left and right side of Figure 7C, between the wall of the tube 120 and the outmost left and right capsule 715, respectively. One of these cross-sectional areas that define the flow paths 718 is indicated with the reference numeral 718A in Figure 7C. Figure 7D shows almost the same configuration as Figure 7C with the key difference that the residual cross-sectional areas for the flow of the first fluid 120 between the capsules 715 are smaller, since the capsules 715 are expanded by the frozen second fluid 122 inside them. One of these free-flow cross-sectional areas that define the flow paths 718 for the first fluid 120 is indicated in Figure 7D by the reference numeral 718B. The plurality of stacks 717 is arranged such that continuous flow paths 718 are provided along the length of the tube in general from the front end to the back end to the tube. The average length of these flow paths 718 is longer than the length of the tube 712 itself. Optionally, the stacks 717 of the capsules 715 have the same number of capsules 715. Optionally, the stacks 717 are consecutively arranged next to each other such that the flow paths 718 are provided by the plurality of stacks 717 itself.

Since water expands its volume while charging/freezing, the capsules 715 of Figure 7C require more space than the capsules of Figure 7B. This effect is also called“breathing-effect” of the capsules 715. Due to this breathing effect, the residual space for the first fluid 120 changes according to the state of the second fluid 122 inside the capsules 715. The breathing-effect of the capsules 715 has to be considered while defining the flow paths 718. First, the stacks 717 have to be adapted such that the flow paths 718 are not blocked in the charged and in the discharged state. Second, the stacks 717 have to be adapted such that the flow paths 718 provide an acceptable pressure drop in the case of frozen capsules 715 as well as in the case of non-frozen capsules 715. Third, the overall thermodynamic configuration of the thermal energy storage unit 711 has to be optimized. This includes especially the flow dynamics of the first fluid 120 in the flow path 718 that should be configured such that an efficient heat transfer between the capsules 715 and the first fluid 120 can take place.

The first item mentioned above is for ensuring that a flow of the first fluid 120 can be provided at all times.

The second item mentioned above is explained more in detail as follows. The longer the flow path and smaller the flow path’ s cross-sectional area, the greater is the increase of the pressure drop. An increased pressure drop has the disadvantage of a higher pumping power consumption (i.e., higher system losses and less total efficiency of the system) and the disadvantage of increasing mechanical requirements for the whole system. Consequently, the pressure drop from inlet 714A to outlet 714B has to be below 1 bar (atmosphere). Optionally, thermal energy storage unit is configured such that the pressure drop is less than 0.5 bar in its fully- charged as well as in its fully-discharged state.

With respect to the third item mentioned above, a ratio of a combined length of a plurality of tubes (or one very long tube) to a flow-cut-area is in a range of about 40 to 200, optionally of about 60 and 150. These ratios of a flow-cut-area to a combined length of a plurality of tubes (i.e., the total length of several tubes 712 connected together in series) provide an efficient heat transfer rate with an acceptable pressure drop.

This allows on one hand more time for the capsules placed closest to the inlet (which suffer from reduced heat transfer rate due to ice melting inside the capsules) to continue their heat transfer into the first fluid 120 at a lower heat transfer rate and a lower exchange temperature, while the capsules 715 located more downstream of the flow of the first fluid 120 continue their heat transfer at a higher heat transfer rate.

The term“flow-cut- area” is a number which is calculated as follows:

AFFCAp = (TCSA - (CCSA-LS + CCSA-FS)/2 x CPS)/CPS

wherein the above stated variables are defined as follows:

AFFCAp = Average free flow-cut-area per capsule

TCSA = overall available cross-sectional area 712A of the tube (see Figure 7B);

CCSA-LS = capsule cross-sectional area 715 in the liquid state of the second fluid (i.e. in a discharged state, see Figure 7C);

CCSA-FS = capsule cross-sectional area 715 in the frozen state of the second fluid (i.e. in a charged state, see Figure 7D);

CPS = number of capsules 715 installed in parallel. With the above stated formula, an average free flow cross-sectional area (i.e., (AFFCAp) per capsule 715 is used to calculate the available total flow area in a tube’s cross-section. The result is then used to calculate the average cross-sectional flow area per capsule, i.e., the flow-cut- area.

The calculated flow-cut-area can be used to calculate a ratio gamma that is a good indicator for the efficiency of the heat transfer between capsule and first fluid as follows:

Ratio gamma = combined length of the plurality of tubes / flow-cut-area (cm/cm ² )

A gamma ratio of the combined length of the plurality of tubes to the said flow-cut-area of approximately 150 is an optimal value. A system which has been configured according to the above explained requirement demonstrated a yield value (a percentage of second fluid melted during a 4 hours period discharge rate) higher than 80% with an acceptable exit temperature of the first fluid below 5 degrees Celsius and an acceptable pressure drop (-0.5 bar). Increasing the ratio to 200 (with a shape of the capsule according to the above explained embodiments) will increase the pressure drop beyond the desired limit. Decreasing the ratio below 40 will decrease the yield percentage while discharging to 50%. A ratio in the range of 60 to 90 will also result in a reasonable efficiency of the unit 711. Moreover, the embodiment provides, in contrast to conventional “encapsulated ice” systems, a flat and stable discharge curve (behavior).

It is to be noted that the above stated rages and optimal values for the ratio gamma are the result of theoretical and practical experiments with the above embodiments.

Figure 8A shows a capsule 114 with a filling nozzle 202 that has a predefined diameter. Flat metal strips 801 are provided such that they are arranged inside the capsule 114. The width of the strips is adapted to the diameter of the filling nozzle 202 such that the strips can be inserted into the capsule 114. It is to be noted that the strip 801 that is placed in the filling nozzle 202 in Figure 8A is only shown for demonstration purposes. The capsule 114 as finally used for the heat storage unit is only provided with strips 801 that are completely located in the interior of the capsule 114. The length of the strips 801 is preferable dimensioned such that they fit well inside the length of the capsule 114. In this way, the strips 801 will stay in place in the interior of the capsule 114 and will effect a large part of the internal volume of the capsule 114. Optionally, a plurality of metal strips is used in order to increase the overall heat transfer efficiency of the capsule 114. These strips 801 act as heat transfer elements, which improve the transfer of heat inside the capsule 114 and improve the total heat transfer efficiency of the individual capsule.

Figure 8B shows a capsule 114 with a filling nozzle 202 that has a predefined diameter. Flelical flat metal strips 802 are provided such that they are arranged inside the capsule 114. The width of strips is adapted to the diameter of the filling nozzle 202 such that the strips can be inserted into the capsule 114. It is to be noted that the strip 802 that is placed in the filling nozzle 202 in Figure 8A is only shown for demonstration purposes. Helical flat metal strips 802 provide an even better distribution of heat in the interior of the capsule 114.

Figure 9A shows a rigid spacer 620 having vertical bars 621, horizontal bars 622 and gaps 624 between the bars. The rigid spacer 600 is provided between two neighboring capsules 114. Reference is made to Figures 6B and 6C and the corresponding explanation. This rigid spacer could, for example, be used in combination with the embodiment described in context with Figures 7.

When the capsule’s wall deflects towards the neighboring capsule wall while charging (i.e., while freezing of the second fluid 122), the horizontal bars 622 maintain a free flow path near them, which will allow parallel flows 650 of the first fluid 120, which will cause melting of the ice across the whole capsule width. The perpendicular vertical bars will create turbulent flow which will improve the heat transfer coefficient between the wall of the capsule and the flow of the first fluid 120, as depicted by the curved arrows 640.

Figure 9B shows a flexible spacer 600 having flaps 602. The flexible spacer 600 is provided between two neighboring capsules 114. Reference is made to Figure 6A and the corresponding explanations. Furthermore, protrusions 603 are provided in order to create a more turbulent flow. This flexible spacer 600 could, for example, be used in combination with the embodiment described in context with Figures 7.

The placement of flexible spacers 600 equipped with flaps 602, which are preloaded to press against the neighboring capsule’s 114 flat walls, will force the first fluid to flow through the narrow gap between the capsules’ 114 walls. This increases the heat transfer rate of the first fluid 120 with the capsule 114. Additionally the turbulence of the flow is increased. This is depicted by the lines 900 in Figure 9B. The minimum clearance in the charged stage (i.e., the minimal size of the gap) should be approximately 1 mm on each side.

Furthermore, the flexible spacer 600 can be configured such that the gap will grow (due to ice melting) to approximately 3 to 5 mm on each side. This which will advantageously cause a reduction of the velocity of the fluid flow of the first fluid 120 to one fourth (¼) of its maximum velocity in the tube.

The flaps (wings) which are pre-set to expand away from the straight sheet and to move toward the capsule wall and to maintain narrow flow gap for the first fluid 120 near the capsule 114 and will prevent the degradation of performance as described above. It is expected that during the life of a patent maturing from this application many relevant air conditioners, chillers and TES systems will be developed and the scope of the terms air conditioners, chillers and TES systems is intended to include all such new technologies a priori.

As used herein with reference to quantity or value, the term“about” means“within + 20

% of’.

The terms“comprising”,“including”,“having” and their conjugates mean“including but not limited to”.

The term“consisting of’ is intended to mean“including and limited to”.

The term“consisting essentially of’ means that the composition, method or structure may include additional ingredients, steps and/or parts, but only if the additional ingredients, steps and/or parts do not materially alter the basic and novel characteristics of the claimed composition, method or structure.

As used herein, the singular form“a”,“an” and“the” include plural references unless the context clearly dictates otherwise. For example, the term“a unit” or“at least one unit” may include a plurality of units, including combinations thereof.

The words“example” and“exemplary” are used herein to mean“serving as an example, instance or illustration”. Any embodiment described as an“example or“exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments and/or to exclude the incorporation of features from other embodiments.

The word“optionally” is used herein to mean“is provided in some embodiments and not provided in other embodiments”. Any particular embodiment of the invention may include a plurality of“optional” features unless such features conflict.

Throughout this application, various embodiments of this invention may be presented in a range format. It should be understood that the description in range format is merely for convenience and brevity and should not be construed as an inflexible limitation on the scope of the invention. Accordingly, the description of a range should be considered to have specifically disclosed all the possible sub-ranges as well as individual numerical values within that range. For example, description of a range such as from 1 to 6 should be considered to have specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6 etc., as well as individual numbers within that range, for example, 1, 2, 3, 4, 5, and 6. This applies regardless of the breadth of the range.

Whenever a numerical range is indicated herein (for example“10-15”,“10 to 15”, or any pair of numbers linked by these another such range indication), it is meant to include any number (fractional or integral) within the indicated range limits, including the range limits, unless the context clearly dictates otherwise. The phrases“range/ranging/ranges between” a first indicate number and a second indicate number and“range/ranging/ranges from” a first indicate number “to”,“up to”,“until” or“through” (or another such range-indicating term) a second indicate number are used herein interchangeably and are meant to include the first and second indicated numbers and all the fractional and integral numbers therebetween.

Unless otherwise indicated, numbers used herein and any number ranges based thereon are approximations within the accuracy of reasonable measurement and rounding errors as understood by persons skilled in the art

It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub combination or as suitable in any other described embodiment of the invention. Certain features described in the context of various embodiments are not to be considered essential features of those embodiments, unless the embodiment is inoperative without those elements.

Although the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, it is intended to embrace all such alternatives, modifications and variations that fall within the spirit and broad scope of the appended claims. All publications, patents and patent applications mentioned in this specification are herein incorporated in their entirety by reference into the specification, to the same extent as if each individual publication, patent or patent application was specifically and individually indicated to be incorporated herein by reference. In addition, citation or identification of any reference in this application shall not be construed as an admission that such reference is available as prior art to the present invention.

All publications, patents and patent applications mentioned in this specification are herein incorporated in their entirety by reference into the specification, to the same extent as if each individual publication, patent or patent application was specifically and individually indicated to be incorporated herein by reference. In addition, citation or identification of any reference in this application shall not be constmed as an admission that such reference is available as prior art to the present invention. To the extent that section headings are used, they should not be construed as necessarily limiting. In addition, any priority document(s) of this application is/are hereby incorporated herein by reference in its/their entirety. List of reference signs: energy storage (TES) system 100 chiller 102/150 fluid distribution system 104 controller 105 pumps 106 flow control mechanisms 107 piping 108 to 108T monitoring components 109 array 110 ice bricks 112, 112B, 112C, 112D ice capsules 114, 114C, 114Cy first fluid 120 second fluid 122 third fluid 124 air 126 cooling load 130 air compressor 140 Heat exchanger (HE) 142, 152, 170 filling nozzle 202 narrow-side spacers 204 broad-side spacers 206 rectangular enclosure 220 Mounting brackets 222 inlet/outlet pipes 224 end panels 226 support panels 227 interconnecting piping 228 base frame 232 ridge 250, 252 lower part 254 upper part 256 protrusions 260 general flow direction 290 meander p attem 291 discharging process 500 subsets 520, 520A, 520B 520, 520A, 520B spacers 600, 620 flaps 602 protrusions 603 vertical bars 621 horizontal bars 622 gaps 624 flow area 630 curved arrows 640 flows 650 tube 712 overall cross-section of the tube 712A front end element 713 A back end element 713 B inlet 714A outlet 714B capsule 715 spaces 716 stacks of capsules 717 flow paths 718 free flow cross-sectional area in the liquid

state of the second fluid 718 A free flow cross-sectional area in the frozen

state of the second fluid 718B