SOLAR HEAT PUMP

BACKGROUND TO THE INVENTION

This invention relates to a system for and method of providing hot water using a soiar heat pump. In particular, but not exclusively, this invention concerns a system for and method of increasing the efficiency of a solar heat pump which is, for example, used in domestic water heating applications. More particularly, the invention relates to a system for and method of increasing the efficiency of a soiar heat pump by controlling water and energy usage as well as peak power demand on-site and sending measurement data over the Internet to provide centralized control while also providing relevant information to assist end-users in managing water usage habits to reduce consumption.

The applicant is aware of traditional solar water heaters comprising a solar thermal collector and hot water storage tank that are used to replace traditional electric water heaters in an attempt to reduce energy consumption. These known heaters typically have a back-up electric heating element to supplement solar water heating and achieve energy savings of around 65%. Low pressure solar water heaters are inexpensive however, in modern households with high pressure water supply from the utility, more expensive high pressure solar water heaters are required. In the high pressure heaters both the solar collector and hot water storage tank are manufactured to withstand high pressure. This often restricts the size of the hot water storage tank due to cost implications.

The latest air to water solar heat pumps extract energy from the air using an integrated solar collector to heat up the refrigerant directly using sun rays and are used to replace traditional electric water heaters. These systems are able to achieve energy savings of up to 80% when operating at in high ambient temperatures at midday and the hot water storage tank is manufactured for high pressure water heating with the size of the hot water storage tank restricted due to cost implications.

In these known systems the solar water heaters and solar heat pumps are normally installed as independent appliances with timers set to switch off power supply during peak electricity demand hours. These systems are also applied to single households and larger installations involving apartment complexes with partially centralized water heating. This often leads to dissatisfaction by the end-users due to heated water being supplied at lower than acceptable temperatures with timers disabled to ensure sufficient hot water is available at all times. It is also not the practice to measure the energy use, water consumption or hot water temperature for water heating appliances and make this information readily available to end-users. End-users mostly have no informed means to improve habits to reduce consumption and it also does not cater for improved efficiency by means of optimized and automated control methods.

It is an object of this invention to alleviate at least some of the problems experienced with the use of existing solar water heaters and heat pumps. It is a further object of this invention to provide a system and method that will be useful alternatives to existing systems and method being used.

It is yet a further object of the invention to provide a more efficient way of generating hot water by means of a smart, grid enabled, hybrid solar water heating system with reduced energy consumption, reduced peak power demand and reduced water consumption by end-users on a community scale.

SUMMARY OF THE INVENTION

In accordance with a first aspect of the invention there is provided a hot water supply system including:

a solar heat pump;

a high pressure water heater comprising a high pressure hot water storage tank and a high pressure hot water heat exchanger which is in fluid communication with the solar heat pump;

a iow pressure water heater comprising a low pressure hot water storage tank and a iow pressure solar water heat exchanger which is operable to heat water in the low pressure hot water storage tank;

a circulation pump to circulate hot water between the low pressure solar water heat exchanger and the high pressure hot water storage tank; and

a controller, which is operable to control operation of the circulation pump and solar heat pump in a hybrid solar configuration, thereby to increase solar hot water storage capacity, heat water fed to end-user supply piping and control the water flow rate within the system in order to reduce water and energy consumption.

The controller and circulation pump are preferably operable to adjust the flow rate of hot water delivered by the high pressure water heater. The low pressure solar water heat exchanger may be integrated in the low pressure hot water storage tank and may be operable to heat up cold water from a mains water supply.

In one embodiment of the invention the low pressure solar water heat exchanger is in fluid communication with the high pressure hot water storage tank so that, in use, the circulation pump feeds water heated by the low pressure solar water heat exchanger to the high pressure hot water storage tank.

The solar heat pump may be operable to regulate the temperature of hot water delivered by the high pressure hot water heater.

It is envisaged that the electrical supply to the system may be provided by either grid electricity, or off-grid by means of solar PV, or in combination to reduce peak power demand on the electricity supply grid.

The controller is preferably operable to take data measurements at various point in the system in order to switch control relays controlling the electrical supply to the solar heat pump and/or circulation pump on or off automatically.

The measured data may include temperature, energy consumption, water consumption and/or the availability of grid electricity and/or solar PV electricity supply.

Preferably, the controller is a smart-grid controller capable of communicating the measured data over a communications network, in one embodiment the smart-grad controller may be operable to communicate the measured data to a main controller over the Internet.

The smart-grid controller may be controlled by the main controller automatically, thereby overriding local control by switching control relays for electrical supply to the solar heat pump and circulation pump based on the measured data. The main controller may receive measured data from multiple smart-grid controllers. The smart-grid controllers may be located at different end-user locations.

The smart-grid controller is preferably in communication with at ieast one user terminal such that operational information is communicated to end- users. The user terminals may be in the form of smart phones, tablets, laptops and PCs for receiving the operational information over the Internet.

In accordance with a second aspect of the invention there is provided a method of supplying hot water, said method including the following steps: heating water by means of a low pressure solar water heater including a low pressure hot water storage tank and a low pressure hot water heat exchanger;

heating water by means of a high pressure solar water heater including a high pressure hot water storage tank and a high pressure hot water heat exchanger, wherein the high pressure solar water heater is heated by a solar heat pump;

heating up cold water from a mains water supply by means of the low pressure hot water heat exchanger;

circulating the heated water between the low pressure hot water heat exchanger and the high pressure hot water storage tank;

controlling operation of the low and high pressure solar water heaters and the circulation of water though the system in a hybrid solar configuration, thereby to increase solar hot water storage capacity, regulate the supply of heated water to end-user supply piping and control the water flow rate within the system in order to reduce water and energy consumption.

The method may include feeding the heated water from the low pressure hot water heat exchanger to the high pressure hot water storage tank using the pressurised mains water supply when an end-user draws water. The method may further include regulating the temperature of the hot water delivered to the end-user, through the combination of the high pressure water heater and low pressure water heater in a hybrid configuration, by way of controlling operation of the solar heat pump.

Preferably, the method includes measuring data at various points in the system and using the data for automated control of the solar heat pump and circulation pump.

In one embodiment of the invention the solar heat pump and circulation pump are controlled using a controller. The controller may control power supply relays to the solar heat pump and circulation pump.

The data that is measured may include temperature, energy consumption and/or water consumption.

In the preferred embodiment the controller is a smart-grad controller capable of communicating the measured data over a communications network.

The measured data may be communicated from the smart-grid controller to a main controller via the Internet.

In one embodiment the method includes controlling the solar heat pump and circulation pump based on measured data received from multiple smart-grid controllers, which could be located at different end-user locations.

The method may further include bypassing the smart-grid controllers when controlling the solar heat pump and circulation pump from the main controller.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described in more detail, by way of example only, with reference to the accompanying drawings in which:

Figure 1 shows a system for increasing the efficiency of a solar heat pump in accordance with a first embodiment of the invention;

Figure 2 shows a method of increasing the efficiency of a soiar heat pump in accordance with the first embodiment of the invention;

Figure 3 shows a system for increasing the efficiency of a solar heat pump in accordance with a second embodiment of the invention; and

Figure 4 shows a method of increasing the efficiency of a solar heat pump in accordance with the second embodiment of the invention.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENT

Referring to the drawings, in which like numerals indicate like features, a non-limiting example of a system for increasing the efficiency of a solar heat pump in accordance with a first embodiment of the invention is generally indicated by reference numeral 100.

The system 100 includes a soiar heat pump 1 with integrated solar collectors 2 that directly heat up the refrigerant (working fluid), as known in the art. The system 100 further includes a high pressure hot water storage tank 3, including a heat exchanger 4 for the working fluid located in the high pressure hot water storage tank 3. The system 100 further includes a low pressure solar hot water storage tank 5 located in the proximity of the heat pump, including a solar pre-feed heat exchanger 6 feeding high pressure municipal fresh water 16 through a pressure regulator 17 to the low pressure hot water storage tank 5 for heat transfer to the heat pump and high pressure hot water storage tank 3.

According to an aspect of the invention a metallic, the system 100 includes a manifold 7 integrated into the low pressure hot water storage tank 5, accommodating solar collector tubes 8 that circulate solar heated water through the hot water storage tank 5 by thermos-syphon effect. This allows for the use of the low pressure hot water storage tank 5 with low cost material such as mild steel with anti-rust treatment, thin stainless steei plate or food grade or high temperature grade plastic. The low pressure hot water storage tank 5 includes an air vent 9 to relieve any pressure.

A high temperature water pump 10 is installed with a one-way valve and pressure regulator as well as an inlet port 11 and outlet port 12. The hot water storage tank further is circulated through a one-way valve 13 and ball valve 14 and 15 from the heat pump 1 high pressure hot water storage tank 3 to the low pressure hot water storage tank 5 therefore creating a larger solar hot water store to improve efficiency. The solar heat pump 1 may also be used to regulate the temperature of the combined hot water storage tanks.

According to an aspect of the invention, the system 100 further comprises a smart-grid controller 19 for controlling the high temperature water pump 10, by means of temperature measurement of the hot water supplied by the heat pump high pressure hot water storage tank 3 and the low pressure hot water storage tank 5 and possibly the solar pre-feed heat exchanger 6. Energy measurement 23 is also included for performance verification and to monitor energy consumption and activate circulation and control heat pump operation in the most energy efficient way while using the increased hot water storage as a thermal battery in peak electricity demand times. The system 100 further includes a flow meter 20 to measure pre-heating water supply and a second flow meter 21 to measure hot water usage, to further assist with performance verification and teak detection.

It is to be appreciated that the hybrid solar system 100 may be integrated into a chassis enclosure 24 to allow for structural support of components and weather-proofing and makes possible pre-assembly to simplify installation of the system, in use.

It is further to be appreciated that the system 100 enhances water heating performance and increases hot water storage for high pressure hot water supply by using cost effective low pressure solar water heating.

In Figure 2, in accordance with embodiments of the invention, a method of increasing the efficiency of a solar heat pump, is exemplified with reference to reference numeral 200.

At block 202, a solar heat pump directly heats up the refrigerant (working fluid). At block 206, the working fluid is circulated through a heat exchanger located in the heat pump high pressure hot water storage tank.

At block 204, a solar pre-feed heat exchanger located in the proximity of a low pressure solar hot water storage tank feeds high pressure municipal fresh water through a pressure regulator to the low pressure hot water storage tank for heat transfer to the heat pump high pressure hot water storage tank.

At block 206, solar collector tubes in the low pressure hot water storage tank circulate solar heated water through the hot water storage tank by thermo-syphon effect.

At block 208, a high temperature water pump pumps water from the tow pressure hot water storage tank into the heat pump high pressure hot water storage tank through an inlet port and outlet port. At block 210, the hot water is circulated through a one-way valve and bail valve from the heat pump high pressure hot water storage tank to the low pressure hot water storage tank therefore creating a larger solar hot water store to improve efficiency.

At block 212, high pressure municipal fresh water is also fed through a pressure regulator and one-way valve to replenish the water in the low pressure hot water storage tank that is withdrawn through the outlet port of the heat pump high pressure hot water storage tank for use.

At block 214, a high pressure water pump is controlled by means of temperature measurement of the heat pump high pressure hot water storage tank and the low pressure hot water storage tank and possibly the solar pre-feed heat exchanger.

At block 216, performance verification is provided including monitoring energy consumption and activating circulation and controlling heat pump operation in the most energy efficient way while using the increased hot water storage as a thermal battery in peak electricity demand times.

It will be appreciated that the above method 200 reduces the duty cycle of the heat pump which leads to a reduction in energy consumption and increases the operational life of the heat pump.

It will be appreciated by those known in the art that through use of a smart controller, energy consumption can be monitored and circulation activated. In addition, a heat pump may be operation In the most energy efficient way while using the increased hot water storage as a thermal battery in peak electricity demand times and shutting down heat pump operation during peak electricity demand times, as indicated by the utility provider.

Referring now to Figures 3 and 4 a non-limiting example of a hot water supply system and a method of supplying hot water in accordance with a second embodiment of the invention are generally indicated by reference numeral 300 and 400 respectively. The system 300 provides a system for increasing the efficiency of a soiar heat pump which is, for example, used in domestic water heating applications. Similarly, the method 400 provides a method for increasing the efficiency of a solar heat pump which is, for example, used in domestic water heating applications.

Referring now to Figure 3, the system 300 includes a solar heat pump 301 with integrated solar collectors 302 that directly heat up the refrigerant, also referred to as the working fiuid. The system 300 further includes a high pressure water heater having a high pressure hot water storage tank 303 and a high pressure hot water heat exchanger 304. In use, the working fluid is circulated between the solar heat pump 301 and the high pressure hot water heat exchanger 304 via conduits 324. It should be understood that heat is transferred between the working fluid inside the heat exchanger 304 and the water in the high pressure water storage tank 303.

The system 300 further includes a low pressure water heater having a low pressure solar hot water storage tank 305 and a low pressure hot water heat exchanger. The low pressure water heater is in use located in close proximity to the heat pump 301. In use, high pressure municipal fresh water 307 is fed to the low pressure hot water heat exchanger 306 located inside the low pressure hot water storage tank 305. As shown in Figure 3, the heat exchanger 306 is in fluid communication with the high pressure hot water storage tank 303 so that water heated by the heat exchanger 306 is fed into the storage tank 303.

Referring still to Figure 3, the low pressure water heater of the system 300 includes a manifold 308 integrated into the low pressure hot water storage tank 305. The manifold 308 accommodates solar collector tubes 309 that circulate solar heated water through the hot water storage tank 305 by thermo-syphon effect. This allows for the use of a low pressure hot water storage tank 305 with low cost material, such as mild steel with anti-rust treatment, thin stainless steel plate or high temperature grade plastic for example. The low pressure hot water storage tank 305 includes an air vent 310 to relieve any pressure.

A circulation pump 311 is installed at the outlet of the high pressure hot water storage tank 303 together with a one-way valve 312 and a high pressure release valve 313. The hot water produced at the outlet of the high pressure hot water storage tank 304 is circulated through hot water supply piping servicing end-user locations. In Figure 3, the end-user locations are shown as six dwellings which are typically in the form of apartments 322. From this figure it should be dear that the hot water is circulated from the high pressure hot water storage tank 303, to the apartments 322, to the low pressure hot water storage tank 305 where it passes through the heat exchanger 306 to heat up the hot water supply pipes and to create a larger solar hot water store to improve efficiency. The solar heat pump 301 is used to regulate the temperature of the hot water supplied through the piping by the combined hot water storage tanks 304 and 305. Still referring to Figure 3, it can be seen that the hot water returning from the apartments 322 and the municipal fresh water line 307 feed into the inlet of the low pressure hot water heat exchanger 306. In this illustrated embodiment these two lines join prior to entering the heat exchanger 306.

The system 300 further comprises a controller 314, preferably a smart-grid controller, capable of taking data measurements at various locations in the system. In the illustrated system 300 the smart-grid controller 314 controls the circulation pump 311 by means of temperature measurement 315 of hot water supplied by the high pressure hot water storage tank 303. Energy measurement 316 and water flow measurement 317 is also included for performance verification, to monitor energy consumption and to activate the circulation pump 311 and control the solar heat pump 301 operation in the most energy and water efficient way while using the increased hot water storage as a thermal battery in peak electricity demand times. The flow meter 317 is used to measure cold and hot water usage to further assist with water consumption management and leak detection.

It is further envisaged that electrical supply can be provided by either grid electricity 318 or off-grid by means of sofar PV 319 or in combination to reduce peak power demand on the electricity supply grid

The smart-grid controller 314 is operable to measure temperature 315 at various positions, energy 16, water consumption 317 and the availability of either grid electricity 318 or electricity from solar PV 319 and automatically switch control relays for electrical supply to the solar heat pump 301 and circulation pump 311.

The smart-grid controller 314 is also operable to communicate the measured data over a communications network 320. It is envisaged that the measured data could be communicated over the Internet 320 to a main controller. In this embodiment the measured data such as temperature 315, energy 316 and water consumption 317 and the availability of either grid electricity 318 or electricity from solar PV 319, are communicated to the main controller for automatic control over the Internet. It should be understood that where the system 300 is controlled automatically over the Internet from the main controller, local control is overridden. It is envisaged that the system 300 could be controlled by the main controller by switching control relays controlling electrical supply to the solar heat pump 301 and circulation pump 311 based on measurement data from multiple smart-grid controllers 321. Although only two smart-grid controllers are shown in Figure 3, the system 300 is not limited to any number of controllers. It is further envisaged that the controllers 321 could be located at multiple end- user sites.

It is further to be appreciated that the system 300 enhances water heating performance and increases hot water storage for high pressure hot water supply by using cost effective low pressure solar water heating. in Figure 4, in accordance with embodiments of the invention, a method of increasing the efficiency of a soiar heat pump, is exemplified with reference to reference numeral 400.

Turning now to Figure 4, the method 400 as represented in the flow diagram will be described in greater detailed.

At block 401 , the solar heat pump 301 uses the rays of the sun to heat up directly the refrigerant or working fluid that is circulated through the heat exchanger 304 located in the high pressure hot water storage tank 303 and reduces the electrical energy requirement of the solar heat pump 301.

At block 402, the low pressure solar water heater uses the sun to heat up directly the water inside the low pressure solar hot water storage tank 305 with soiar collector tubes by means of thermo-syphon effect.

At block 403, the pump 311 circulates water through the low pressure hot water heat exchanger 306 in the low pressure hot water storage tank 305 to the high pressure hot water storage tank 303 in order to increase the temperature of the water inside solar heat pump high pressure hot water storage tank 303 according to an optimized algorithm using temperature data creating a larger solar hot water store to improve efficiency

At block 404, the heat exchanger 306 located within the low pressure solar hot water storage tank 305 heats up high pressure municipal fresh water 307 passing through the low pressure hot water storage tank 305 to heat up the high pressure hot water storage tank 303 when end-users draw hot water.

At block 405, the pump 311 circulates water through the heat exchanger 306 in the low pressure hot water storage tank 305 to the high pressure hot water storage tank 303 heating the hot water supply pipes to the end-users according to an optimized algorithm. At block 406, the circulation pump 311 is controlled by means of temperature and water flow measurement between the high pressure hot water storage tank 303 and the low pressure hot water storage tank 305 through the hot water supply pipes.

At block 407, efficiency optimization is provided by monitoring and controlling energy and water consumption of the circulation pump 311 and controlling heat pump 301 operation in the most energy efficient way while using the increased hot water storage as a thermal battery in peak electricity demand times.

At block 408, performance optimization is provided over the Internet of the circulation pump 311 and solar heat pump 301 operation in the most energy efficient way taking operating data at multiple sites within a community into consideration while using the increased hot water storage as a thermal battery in peak electricity demand times.

It will be appreciated that the above method 400 reduces the duty cycle of the solar heat pump 301 and circulation pump 311 which leads to a reduction in energy consumption and increase in operational life.

It will be appreciated by those known in the art that through use of a smart- grid controller 314, energy and water consumption can be monitored and circulation pump 311 speed controlled. In addition, the solar heat pump 301 may be operated in the most energy efficient way while reducing peak electricity demand using the increased hot water storage as a thermal battery in peak electricity demand times and shutting down heat pump 311 operation during peak electricity times, as indicated by the utility.