FIELD

The present disclosed subject matter relates to energy storage and usages. More particularly, the present disclosed subject matter relates to energy storage container and its use as a heater.

BACKGROUND

Water heaters for household uses or boilers are based on heat transfer process that uses an energy source in order to heat the water to a relatively high temperature; a temperature that is above the initial temperature of the water. The typical water heaters are of tank type or storage water heaters. The water tank is a cylindrical vessel or container that is configured to keep the water relatively hot and ready to use. The water tank may be heated using various energy sources such as electricity, natural gas, propane, heating oil, solar, a combination of the energy sources or by any other source.

Tankless water heaters have gained popularity in recent years. These high-power heaters are based on continuous flow of the water while the water is instantly heated as it flows through the device while it is heated through a heat exchanger coil. The main advantage of tankless water heaters in comparison to batch type boilers is the continuous flow of hot water. In batch type boilers, the amount of hot water is limited to the amount of water in the tank.

None of the present water tanks solutions does not provide the possibility to store the energy in order to use it for heating water in an on-demand need. BRIEF SUMMARY

It is an object of the present subject matter to provide a container capable of accumulating energy so as to use it to heat fluid upon demand. The liquid is heated using the energy that is stored within the container or more particularly, the medium within the container.

According to a first aspect of the present disclosed subject matter, a heat accumulator is provided that comprises: a container; a medium contained within the container wherein the medium is capable of storing thermal energy; a heating source configured to heat the medium.

According to another aspect of the present disclosed subject matter, the medium is a material having a phase transition.

According to another aspect of the present disclosed subject matter, the material having phase transition has a phase transition below 100°C.

According to another aspect of the present disclosed subject matter, the medium is releasing the thermal energy upon demand. According to another aspect of the present disclosed subject matter, the phase transition is from solid state to liquid state.

According to another aspect of the present disclosed subject matter, the medium is selected from a group of materials consisting of inorganic materials (salt and salt hydrates), organic compounds such as paraffins or fatty acids, and polymeric materials such as poly(ethylene glycol).

According to another aspect of the present disclosed subject matter, the heating source is a heater having a heating body that is immersed within the medium.

According to another aspect of the present disclosed subject matter, the heating source receives electricity from energy sources selected from a group consisting of electricity grid or mains, solar energy, natural gas, propane, heating oil, a combination thereof or the like.

According to another aspect of the present disclosed subject matter, the heat accumulator is further comprising a tube that passes through walls of the container in an inlet side and an outlet side, wherein the tube is immersed within the medium.

According to another aspect of the present disclosed subject matter, the tube is a coiled tube. According to another aspect of the present disclosed subject matter, liquid that passes from the inlet side to the outlet side is heated from accumulated thermal energy of the medium.

According to another aspect of the present disclosed subject matter, heat is exchanged between the liquid in the tube and the medium. According to another aspect of the present disclosed subject matter, the liquid is water for domestic usage.

According to yet another aspect of the present disclosed subject matter, a boiler is provided for heating water comprising: a container; a medium contained within the container wherein the medium is capable of storing thermal energy; at least one heating source wherein one of the heating sources is a solar panel configured to heat the medium during day time; a tube having an inlet and an outlet, both passing through walls of the container, wherein the tube is immersed within the medium and is configured to receive cold water from the inlet, heat the water by exchanging heat with the medium and discharging them from the outlet in a hotter state.

According to another aspect of the present disclosed subject matter, the medium is a material having a phase transition that is below 100°C.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosed subject matter belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present disclosed subject matter, suitable methods and materials are described below. In case of conflict, the specification, including definitions, will control. In addition, the materials, methods, and examples are illustrative only and not intended to be limiting. BRIEF DESCRIPTION OF THE DRAWINGS

Some embodiments of the disclosed subject matter 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 disclosed subject matter only, and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the disclosed subject matter. In this regard, no attempt is made to show structural details of the disclosed subject matter in more detail than is necessary for a fundamental understanding of the disclosed subject matter, the description taken with the drawings making apparent to those skilled in the art how the several forms of the disclosed subject matter may be embodied in practice.

In the drawings:

Figure 1 illustrates a cross sectional view of an energy accumulator, in accordance with some exemplary embodiments of the disclosed subject matter;

Figure 2 schematically illustrates a typical solid-liquid PCM system, as known in the art; and

Figure 3A illustrates a heat exchange process in the day time of a cross sectional view of a heat accumulator in accordance with another preferred embodiment of the disclosed subject matter.

Figure 3B illustrates a heat exchange process in the night time of a cross sectional view of a heat accumulator in accordance with another preferred embodiment of the disclosed subject matter. DETAILED DESCRIPTION

Before explaining at least one embodiment of the disclosed subject matter in detail, it is to be understood that the disclosed subject matter is not limited in its application to the details of construction and the arrangement of the components set forth in the following description or illustrated in the drawings. The disclosed subject matter is capable of other embodiments or of being practiced or carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein is for the purpose of description and should not be regarded as limiting. The drawings are generally not to scale. For clarity, non-essential elements were omitted from some of the drawings.

The terms "comprises", "comprising", "includes", "including", and "having" together with their conjugates mean "including but not limited to". The term "consisting of" has the same meaning as "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 compound" or "at least one compound" may include a plurality of compounds, including mixtures thereof.

Throughout this application, various embodiments of this disclosed subject matter 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 constmed as an inflexible limitation on the scope of the disclosed subject matter. 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. It is appreciated that certain features of the disclosed subject matter, 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 disclosed subject matter, 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 disclosed subject matter. 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.

According to one aspect of the present subject matter, it is provided an energy accumulator comprising a container; medium contained within the container wherein the medium is a material having a phase transition below 100°C; a heating source configured to heat the medium. The phase transition is preferably from solid state to liquid state.

Referring now to Figure 1 illustrating a cross sectional view of an energy accumulator, in accordance with some exemplary embodiments of the disclosed subject matter.

In accordance with a preferred embodiment of the present subject matter, an energy accumulator 10 is provided that accumulates energy within a contained medium 12 that is received within a container 14. The medium is capable of accumulating thermal energy it receives and release it upon demand. A preferable medium to be used is a material having a phase change. Phase change materials (PCM) can accumulate and release large amounts of thermal energy during the phase change transition. The energy storage capacity is determined by the value of the phase transition enthalpy. PCMs are selected from a group of materials as inorganic materials (salt and salt hydrates), organic compounds such as paraffins or fatty acids, and polymeric materials such as poly(ethylene glycol).

Referring now to Figure 2 schematically illustrating a typical solid-liquid PCM system, as known in the art. The X axis is the temperature while the Y axis is the energy stored or contained within the PCM. Starting from the left-hand side of the diagram, the PCM is in solid state. As the temperature rises, it absorbs energy. When the ambient temperature reaches the melting point of the PCM, it absorbs large amounts of heat while the temperature remains almost constant. This continues until all the material is transformed to the liquid phase. Energy in the form of heat is stored in the PCM while the temperature is maintained at a known value. Upon further heat transfer to the PCM, the medium is in the form of liquid and the temperature further rises. When the temperature of the liquid PCM falls, it crystallizes again, releasing the latent heat that was stored when heat is transferred to the material and while the temperature remains substantially constant. This latent heat can be used in the energy accumulator of the present subject matter.

It should be mentioned that a phase transition from liquid to gas can be employed as well and the usage of the phase transition from solid to liquid is provided herein as an example.

Coming back to Figure 1, as mentioned herein before, it is preferable that a medium 12 of PCM is contained within the container 14 and heat is accumulated within the PCM.

In accordance with a preferred embodiment of the present subject matter, heat is transferred to the medium 12 by a heater 16 having a heating body 17 that is immersed within the medium 12 and capable of heating the medium.

Energy for heating the heater 16 can be selected from various sources of energy that can be from the electricity grid or mains 18, from solar panels 20 that uses solar energy, natural gas, propane, heating oil (not all the sources are shown in Figure 1), a combination thereof or the like. Optionally or alternatively, the heating source can be placed in a position that is distant from the container.

One of the uses of the thermal energy that is stored within the container 14 is for heating water for domestic use. In order to be able to heat water, a tube, preferably coiled tube 22, is passing through the walls of the container 14 in an inlet side 22A and an outlet side 22B, while the coil is being also immersed within medium 12. The water passing within the tube is heated from the heat that is expelled from the medium, and not directly from the heaters body as in prior art water heaters. The coiled tube 22 has a length and width that correspond the temperature exchange process between the medium 12 and the water that passes through the coiled tube. The properties of the tube 22 is designed so that the length of the tube is determined so that the water in the tube will be enough time in the environment of the medium while passing through the immersed tube and its width is determined by the heat exchange temperature profile within the tube.

It is preferable that the phase change temperature of the medium is below 100°C so that water can be heated during the crystallization phase of the medium. According to yet another aspect of the present disclosed subject matter, a boiler is provided for heating water comprising: a container; a medium contained within the container wherein the medium is capable of storing thermal energy; at least one heating source wherein one of the heating sources is a solar panel configured to heat the medium during day time; a tube having an inlet and an outlet, both passing through walls of the container, wherein the tube is immersed within the medium and is configured to receive cold water from the inlet, heat the water by exchanging heat with the medium and discharging them from the outlet in a hotter state.

According to another aspect of the present disclosed subject matter, the medium is a material having a phase transition that is below 100°C.

Reference is now made to Figure 3 illustrating a heat exchange process in the day time of a cross sectional view of a heat accumulator in accordance with another preferred embodiment of the present subject matter.

The heat accumulator system 100 is provided with a container 102 with a PCM medium 104 received within the container 102. It is important to note that the container can be of any shape or form, such as a cylindrical container as shown in Figure 1 , a flat shaped rectangular container as shown in Figure 3 or any other shape that assures the correct positioning of the container on a roof or otherwise. A heater 106 is provided and immersed within the PCM medium 104. The source of the electricity for the heater 106 is solar energy generated in the solar panels 108 that are electrically connected to the heater 106.

The temperature of the PCM medium 104 is determined by the solar panels 108, at least in the hours that sun energy can be utilized by the solar panels. The utilization of the solar panels is similar to its usage in prior art systems, however, in the preferred embodiment of the present subject matter, the PCM medium 104 in its solid state is heated so that its temperature rises and is maintained while in transition state, after melting temperature is achieved. In this state - the energy from the solar panels 108 is being stored within the PCM medium lOtube for 4.

Optionally, the container is isolated by a thermal isolation material 110 that assures that the heat loss from the PCM medium to the outer environment is minimized and the PCM is maintained in melted state, while accumulating as much energy as possible.

A tube 112 having an input and an output is configured to receive water through the input, passing it through the tube 112 that is immersed in the PCM medium 104, and outputting the water through the output. The water is getting into the tube in the cool state, getting hotter while passing through the portion of the tube that is immersed in the medium 104, the getting out of the output in a hot state. The tube 112 can be coiled or zigzagged, or in any other configuration that will keep the water within the tube so as to allow it to absorb the heat that is accumulated within the PCM medium. The heat is exchanged while the temperature of the PCM medium is maintained substantially constant.

It should be emphasized that during the day time, heat is continuously transferred to the heat accumulated system 100 so the PCM medium is kept in liquid state.

Optionally and alternatively, other heat sources can be used in order to heat the water in the night time or in times when the solar panel is not activated in an effective way and cannot heat the medium to the desired extent.

Referring now to Figure 3B illustrating a heat exchange process in the night time of a cross sectional view of a heat accumulator in accordance with another preferred embodiment of the disclosed subject matter.

When the system is not exposed to daylight or sun light and the solar system 108 is not operable, the PCM medium 104 state is in a state in which the accumulated energy is being maintained and there is no electricity to heat the medium. When cold water is being transferred through the tube 112 that is immersed within the medium, the heat from the medium is being transferred to the cold water while heating them. In exchange, the state of the PCM medium is transferred to be solidified. The thermal energy stored within the medium is being transferred to the water. In oppose to prior art systems, the water is being heated from the medium while the medium's phase is changed rather than be heated directly from the heater.

In accordance with another embodiment of the present subject matter, the usage of the accumulator can be for industrial, agricultural, as well as other fields without limiting the scope of the present subject matter.

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.