Photovoltaic heat pump energy storage system and control method

Abstract

The invention discloses a photovoltaic heat pump energy storage system and a control method. The photovoltaic heat pump energy storage system comprises a heat pump system, an energy storage hot water module and a photovoltaic module. The heat pump system forms a cold and hot dual-supply circulating pipeline through a compressor unit, a four-way reversing valve, a two-medium heat exchanger and a three-medium heat exchanger; the energy storage hot water module uses a single-coil heat exchanger and an energy storage tank to supply heat / cold, and a double-coil heat exchanger supplies hot water; the photovoltaic module heats refrigerant in winter, heats domestic hot water in summer and supplies power to the compressor unit. The system adopts a double-compressor intelligent switching mode and combines photovoltaic and municipal power grid complementary power supply to realize annual efficient operation. The control method comprises multiple heating / cooling modes, and energy utilization is optimized through the reversing valve, temperature threshold adjustment and energy storage management. The system integrates light-electricity-heat coordination, energy storage buffering and intelligent temperature control, is high in comprehensive energy efficiency ratio, is suitable for the field of building energy supply, and has the advantages of energy conservation, stability and multiple functions.

Description

Technical Field

[0001] This invention relates to the field of solar heat pump applications, specifically to a photovoltaic heat pump energy storage system and control method. Background Art

[0002] Traditional building energy supply methods, such as using coal / gas boilers, are inefficient (<90%), energy-intensive, and polluting. Electric heat pump systems, on the other hand, result in high electricity costs, are highly susceptible to electricity price fluctuations, and face the risk of power outages due to grid overload caused by extreme weather events (such as cold waves). While photovoltaic panels can be installed on building exteriors, the limited surface area and the intermittent nature of photovoltaic power generation mean that electricity generation does not perfectly match electricity consumption.

[0003] This system employs a photovoltaic (PV) and heat pump energy storage coupling approach. PV power directly drives the heat pump system, enabling off-grid self-consumption of PV energy. The energy storage system stores some of the cooling / heating energy, improving daytime PV utilization and reducing nighttime electricity consumption, effectively lowering building energy costs and carbon emissions. By rationally designing the PV-heat pump combination, the combined electrothermal efficiency is enhanced, maximizing the use of PV power to meet cooling and heating load demands. Summary of the Invention

[0004] In view of the problems and shortcomings of the existing technology, the present invention provides a photovoltaic heat pump energy storage system and control method.

[0005] The technical solution of this invention is as follows: A photovoltaic heat pump energy storage system includes a heat pump system. The heat pump system includes a compressor unit, a gas-liquid separator, a four-way reversing valve, a two-medium heat exchanger, a liquid storage tank, and a three-medium heat exchanger connected in sequence to form a cold and hot dual-supply circulation pipeline. The three-medium heat exchanger is equipped with a fan and two heat exchange channels. The photovoltaic heat pump energy storage system also includes an energy storage hot water module and a photovoltaic module; The energy storage hot water module is used for heating and supplying hot water in winter and for cooling and supplying cold water in summer. It includes a single-coil heat exchanger, a double-coil heat exchanger, and a control valve. The two-medium heat exchanger, the double-coil heat exchanger, and the single-coil heat exchanger are connected in sequence to form a circulation loop. The single-coil heat exchanger is used for heating or cooling and is connected to an energy storage tank, which stores heat or cold. The double-coil heat exchanger is connected to a hot water storage tank to supply hot water, and a parallel pipeline p is set on the pipeline between the double-coil heat exchanger and the two-medium heat exchanger through a reversing valve. Pipeline p is used to switch the connection and disconnection between the double-coil heat exchanger and the two-medium heat exchanger. The photovoltaic module is used to heat the three-medium heat exchanger in winter and to heat or cool the dual-coil heat exchanger in summer, as well as to supply power to the compressor unit. It includes a photovoltaic module and a reversing valve. The photovoltaic module is selectively connected to the three-medium heat exchanger or the dual-coil heat exchanger through the control of the reversing valve. In winter, the photovoltaic module is connected to the three-medium heat exchanger to form a heat exchange circulation pipeline to heat the refrigerant. In summer, the photovoltaic module or the three-medium heat exchanger is connected to the dual-coil heat exchanger to form a heat exchange circulation pipeline to heat the hot water tank; or the photovoltaic module is connected to the three-medium heat exchanger to form a heat exchange circulation pipeline to cool the refrigerant. The compressor unit includes two compressors and has two modes: single compressor and dual compressor. The dual compressor mode is only used for winter heating.

[0006] The dual compressors include a low-pressure compressor and a high-pressure compressor. The low-pressure compressor is installed on the pipeline connecting the suction port of the high-pressure compressor and the outlet of the gas-liquid separator, and an intercooler is also connected between the low-pressure compressor and the high-pressure compressor. Two parallel pipes, e and f, are provided between the intercooler and the two-medium heat exchanger. Pipe e is equipped with an electronic expansion valve and is connected to the intercooler to cool the refrigerant vapor flowing into the low-pressure compressor. Pipe f splits into two parallel branches, g and h, before the inlet of the intercooler. Pipe g is connected to the intercooler and is used to further cool the refrigerant flowing out of the two-medium heat exchanger in dual-compressor mode. Solenoid valves are installed on pipelines e, g, and h.

[0007] A water pump is installed on the outlet pipe of the two-medium heat exchanger. Downstream of the water pump, it is connected to pipe p and the inlet pipe of the double-coil heat exchanger through a first three-way reversing valve. The outlet of pipe p is connected to the outlet pipe of the double-coil heat exchanger and the inlet pipe of the single-coil heat exchanger through a second three-way reversing valve.

[0008] A water pump is installed on the outlet pipe of the photovoltaic module. Downstream of the water pump, the inlet pipe of the three-medium heat exchanger and the inlet pipe of the dual-coil heat exchanger are connected through a fourth three-way reversing valve. The return pipe of the three-medium heat exchanger and the return pipe of the dual-coil heat exchanger are connected to the return pipe of the photovoltaic module through a third three-way reversing valve. The photovoltaic module heats or cools the three-medium heat exchanger or the dual-coil heat exchanger by circulating heat exchange through the fourth three-way reversing valve and the third three-way reversing valve.

[0009] The two-medium heat exchanger and the liquid storage tank are connected by a main pipe to two parallel branch pipes, a and b. The liquid storage tank and the three-medium heat exchanger are connected by a main pipe to two parallel branch pipes, c and d. Branch pipes a and c are used for heating circulation, while branch pipes b and d are used for cooling circulation. Electronic expansion valves are installed on branch pipes b and c.

[0010] A photovoltaic heat pump energy storage control method, used in the photovoltaic heat pump energy storage system of claim 1, includes the following control modes: Heating Mode 1: When the sunshine conditions are good, the photovoltaic modules supply power to the compressor unit, start the compressor unit and switch to the heating mode; at the same time, the reversing valve connects the circulation pipeline between the photovoltaic modules and the three-medium heat exchanger to heat the refrigerant; in the energy storage heating module, a single coil provides heat to the user and the energy storage tank stores heat, while a dual coil heats the hot water storage tank to supply hot water. Heating Mode 2: When sunlight conditions are poor, the compressor unit is powered by the photovoltaic modules and the municipal power grid, the compressor unit is started and switched to heating mode; at the same time, the reversing valve connects the circulation pipeline of the photovoltaic modules and the three-medium heat exchanger to heat the refrigerant, and the fan is started to heat the refrigerant together; in the energy storage heating module, a single coil provides heat to the user and the energy storage tank stores heat, while a dual coil heats the hot water storage tank to supply hot water; Heating Mode 3: When there is no sunshine, the compressor unit is powered by the municipal power grid, the compressor unit is started and switched to heating mode; the reversing valve first disconnects the circulation pipeline between the photovoltaic module and the three-medium heat exchanger, and then the fan starts and heats the refrigerant; in the energy storage heating module, the single coil provides heat to the user and the energy storage tank stores heat, and the dual coil heats the hot water storage tank to supply hot water. Cooling Mode 1: When there is sufficient sunshine, the photovoltaic modules supply power and switch to cooling mode; the hot water in the photovoltaic modules enters the dual-coil heat exchanger to exchange heat and supply hot water to the hot water storage tank; the single coil provides cooling to users, and the energy storage tank stores the cooling capacity. Cooling Mode 2: When there is insufficient sunlight, the photovoltaic modules are connected to the municipal power grid to switch to cooling mode and disconnect the photovoltaic modules from the dual-coil heat exchanger; the three-medium heat exchanger is connected to the dual-coil heat exchanger to heat the water in the hot water storage tank; the single coil provides cooling for users, and the energy storage tank stores the cooling capacity.

[0011] Cooling Mode 3: When there is no sunlight, the compressor is powered by the municipal power grid and switched to cooling mode. The three-medium heat exchanger is connected to the dual-coil heat exchanger to heat the water in the hot water storage tank. When the water temperature in the hot water storage tank reaches the upper limit, the connection between the three-medium heat exchanger and the dual-coil heat exchanger is disconnected, and the photovoltaic module is connected to the three-medium heat exchanger. At the same time, the fan is turned on.

[0012] In heating mode: when the compression ratio of the high-pressure compressor does not exceed the set value, the heat pump system enters single compressor mode and the low-pressure compressor stops running; when the compression ratio of the high-pressure compressor exceeds the set value, the heat pump system automatically enters dual compressor mode and the low-pressure compressor starts.

[0013] In heating mode, the following steps are also performed: When the water temperature in the energy storage tank reaches the first set temperature t1, adjust the speed of the compressor unit to run at low speed. When the water temperature is lower than the second set temperature t2, close the connection valve between the energy storage tank and the user until the temperature is higher than the second set temperature t2, then open the valve again. When the water temperature in the hot water storage tank reaches the third set temperature t3, adjust the reversing valve to connect the two-medium heat exchanger with the single-coil heat exchanger through pipeline p and exchange heat. When the water temperature in the hot water storage tank is lower than the fourth set temperature t4, increase the compressor unit speed to increase the water-side temperature rise of the two-medium heat exchanger.

[0014] In cooling mode, the following steps are also performed: When the water temperature in the energy storage tank reaches the fifth set temperature t5, adjust the compressor unit speed to run at low speed. When the water temperature is higher than the sixth set temperature t6, close the connection valve between the energy storage tank and the user until the temperature is lower than the sixth set temperature t6, then open the valve again.

[0015] When the water temperature in the hot water storage tank is higher than the third set temperature t3, disconnect the three-medium heat exchanger from the dual-coil heat exchanger and open the three-medium heat exchanger from the photovoltaic module. When the water temperature is lower than the fourth set temperature t4, disconnect the three-medium heat exchanger from the photovoltaic module and open the three-medium heat exchanger from the dual-coil heat exchanger.

[0016] The beneficial effects of the present invention are: 1. High-efficiency energy utilization, reducing operating costs Photovoltaic modules not only provide electricity to the compressor unit, but also heat the three-medium heat exchanger in winter (to increase the refrigerant temperature) and the dual-coil heat exchanger in summer (to supply hot water), maximizing the use of solar energy, reducing reliance on the municipal power grid, and lowering energy costs.

[0017] Intelligent switching between dual compressors: In heating mode, the system automatically switches between single and dual compressor modes based on the compression ratio, ensuring efficient heating while avoiding overload and extending equipment life.

[0018] 2. Operates in multiple functions year-round to meet diverse needs. In winter: It can simultaneously provide heating (single coil + energy storage tank) and hot water (dual coil + hot water storage tank), and the waste heat from photovoltaics directly improves the system's heating efficiency.

[0019] In summer: Cooling (single coil + energy storage tank) and hot water supply (photovoltaic or three-medium heat exchanger heating dual coils) run in parallel, solving the problem of waste heat in traditional heat pumps during summer.

[0020] Energy storage modules for peak shaving and valley filling: Energy storage tanks store excess heat / cooling during the day for use at night or when there is insufficient sunlight, balancing load fluctuations and improving system stability.

[0021] 3. Precise temperature control and energy-saving optimization Heating mode: When the water temperature in the storage tank reaches t1, the frequency is reduced and the user-side valve is closed when it is below t2; when the water temperature in the hot water storage tank exceeds t3, it switches to single coil priority heat exchange and increases the frequency and temperature when it is below t4 to ensure supply and demand balance.

[0022] Cooling mode: When the water temperature in the storage tank is below t5, the frequency is reduced; when it is above t6, the valve is closed to avoid excessive cooling. When the water temperature in the hot water storage tank exceeds t3, the heat exchange between the three-medium heat exchanger and the dual-coil heat exchanger is cut off; when it is below t4, the heat exchange between the three-medium heat exchanger and the dual-coil heat exchanger is turned on to ensure supply and demand balance.

[0023] Intelligent pipeline switching: By combining three-way valves, directional valves, and solenoid valves, hot and cold circuits (such as branch pipes p, a / b / c / d) are controlled to reduce ineffective circulation and lower pump consumption.

[0024] 4. Compact structure and high system reliability Modular design: The photovoltaic module, energy storage hot water module and heat pump system are highly integrated, and the function switching is realized through the reversing valve, reducing the dependence on external equipment.

[0025] Redundancy guarantee: When there is insufficient sunlight, the fan will assist in heating (heating mode 2) or the municipal power grid will provide power (cooling mode 2) to ensure continuous operation under extreme weather conditions. Attached Figure Description

[0026] Figure 1 The compressor unit of the voltaic heat pump energy storage system in this embodiment is a system diagram with a single compressor; Figure 2 The system diagram for the voltaic heat pump energy storage system in this embodiment is a dual-compressor system. Figure 3 This is a system diagram for heating mode 1 with a single compressor; Figure 4 This is a system diagram for heating mode two with a single compressor; Figure 5 This is a system diagram for heating mode three with a single compressor; Figure 6 This is a system diagram for heating mode 1 with dual compressors; Figure 7 This is a system diagram for heating mode two with dual compressors; Figure 8 This is a system diagram for heating mode three with dual compressors; Figure 9 This is a system diagram for cooling mode one; Figure 10 This is a system diagram for cooling mode two; Figure 11 This is a system diagram for cooling mode three; 31. First electronic expansion valve; 32. Second electronic expansion valve; 33. Third electronic expansion valve; 61. First solenoid valve; 62. Second solenoid valve; 63. Third solenoid valve; 64. Fourth solenoid valve; 71. First three-way directional valve; 72. Second three-way directional valve; 73. Third three-way directional valve; 74. Fourth three-way directional valve; 75. Fifth three-way directional valve; 76. Sixth three-way directional valve; 81. First water pump; 82. Second water pump. Detailed Implementation

[0027] The technical means adopted to achieve the intended purpose of the present invention will be further described below with reference to the accompanying drawings in the embodiments of the present invention.

[0028] Example 1 See Figure 1 The present invention provides a photovoltaic heat pump energy storage system, including a heat pump system, an energy storage hot water module and a photovoltaic module.

[0029] The heat pump system includes: a compressor unit, a gas-liquid separator, a four-way reversing valve, a two-medium heat exchanger, a liquid receiver, and a three-medium heat exchanger. The compressor unit, gas-liquid separator, four-way reversing valve, two-medium heat exchanger, liquid receiver, and three-medium heat exchanger are connected in sequence to form a dual-supply cooling and heating circulation pipeline.

[0030] The two-medium heat exchanger and the storage tank are connected by a main pipe via two parallel branch pipes, a and b. The storage tank and the three-medium heat exchanger are connected by a main pipe via two parallel branch pipes, c and d. Branch pipe a is equipped with a one-way valve that opens towards the three-medium heat exchanger, branch pipe b is equipped with a one-way valve that opens towards the two-medium heat exchanger, and a second electronic expansion valve 32 is located downstream of the one-way valve on branch b. Branch pipe d is equipped with a one-way valve with the same opening direction as branch b, and branch pipe c is equipped with a one-way valve with the same opening direction as branch a. A first electronic expansion valve 31 is located downstream of the one-way valve.

[0031] The heating cycle process is as follows: compressor unit - gas-liquid separator - four-way reversing valve - two-medium heat exchanger - branch a - liquid receiver - branch c - three-medium heat exchanger - four-way reversing valve - gas-liquid separator - compressor unit. Cooling cycle loop: compressor unit - gas-liquid separator - four-way reversing valve - three-medium heat exchanger - branch d - liquid receiver - branch b - two-medium heat exchanger - four-way reversing valve - gas-liquid separator - compressor unit.

[0032] The energy storage hot water module includes: a second water pump 82, a single-coil heat exchanger, a double-coil heat exchanger, a first three-way reversing valve 71, and a second three-way reversing valve 72. The two-medium heat exchanger stores energy through the single-coil heat exchanger and supplies hot water through the double-coil heat exchanger. The three-medium heat exchanger supplies hot water through the double-coil heat exchanger.

[0033] The inlet of the second water pump 82 is connected to the outlet of the second set of ports of the two-medium heat exchanger, and the outlet is connected to the first port of the first three-way reversing valve 71. The second port of the first three-way reversing valve 71 is connected to the inlet of the first heat exchange tube of the dual-coil heat exchanger, and the outlet of the first heat exchange tube of the dual-coil heat exchanger is connected to the first port of the second three-way reversing valve 72. The second port of the second three-way reversing valve 72 is connected to the inlet of the single-coil heat exchanger, and the outlet of the single-coil heat exchanger is connected to the inlet of the second set of ports of the two-medium heat exchanger. The third port of the first three-way reversing valve 71 is connected to the third port of the second three-way reversing valve 72. The single-coil heat exchanger is circulated with the energy storage tank, and the dual-coil heat exchanger is circulated with the hot water storage tank. By controlling the connection state of the third port of the first three-way reversing valve 71 and the third port of the second three-way reversing valve 72, the connection state of pipeline p is switched, thereby selectively connecting to the energy storage loop or the energy storage heating loop.

[0034] Energy storage loop working fluid circulation path: two-medium heat exchanger - second water pump 82 - first three-way reversing valve 71 - second three-way reversing valve 72 - single coil heat exchanger - two-medium heat exchanger; The working fluid circulation path of the heating circuit is as follows: two-medium heat exchanger - second water pump 82 - first three-way reversing valve 71 - double coil heat exchanger - second three-way reversing valve 72 - single coil heat exchanger - two-medium heat exchanger.

[0035] The photovoltaic module includes photovoltaic modules, a first water pump 81, a third three-way reversing valve 73, and a fourth three-way reversing valve 74. The outlet of the photovoltaic module is connected to the inlet of the first water pump 81, the outlet of the first water pump 81 is connected to the first port of the fourth three-way reversing valve, the second port of the first port of the fourth three-way reversing valve is connected to the inlet of the heat exchange port of the three-medium heat exchanger, the outlet of the heat exchange port of the three-medium heat exchanger is connected to the first port of the third reversing valve, and the second port of the third reversing valve is connected to the inlet of the photovoltaic module. This "photovoltaic module - first water pump 81 - third three-way reversing valve 73 - three-medium heat exchanger - fourth three-way reversing valve 74 - photovoltaic module" connection forms a heating cycle loop, used to heat the three-medium heat exchanger in heating mode (with sunlight), causing the refrigerant to vaporize. The photovoltaic modules of the photovoltaic module can simultaneously power the compressor unit.

[0036] The third port of the fourth three-way reversing valve is connected to the inlet of the second heating tube of the dual-coil heat exchanger, and the outlet of the second heating tube of the dual-coil heat exchanger is connected to the third port of the third reversing valve. The sequence “photovoltaic module - first water pump 81 - fourth three-way reversing valve 74 - dual-coil heat exchanger - third three-way reversing valve 73 - photovoltaic module” forms a heating circulation loop, used to heat the dual-coil heat exchanger in cooling mode (when there is sunlight) to supply hot water to users.

[0037] The compressor unit includes both single-compressor and dual-compressor modes, see [link to relevant documentation]. Figure 1In single-compressor mode, a high-pressure compressor is used, with its exhaust port and suction port connected to the inlet and outlet of the gas-liquid separator, respectively. See also... Figure 2 In dual-compressor mode, there are a low-pressure compressor and a high-pressure compressor. The low-pressure compressor is located on the pipeline connecting the suction port of the high-pressure compressor to the outlet of the gas-liquid separator. An intercooler is also connected between the low-pressure compressor and the high-pressure compressor. The suction port of the low-pressure compressor is connected to the outlet of the gas-liquid separator through a sixth three-way reversing valve 76, and the discharge port is connected to the first inlet of the intercooler. The first outlet of the intercooler is connected to the suction port of the high-pressure compressor through a fifth three-way reversing valve 75. The second inlet of the intercooler is connected to the two-medium heat exchanger through branch e. ​​A first solenoid valve 61 and a third electronic expansion valve 33 are installed on branch e. ​​The high-pressure vapor flowing out of the low-pressure compressor discharge port mixes with the low-temperature liquid refrigerant in branch e, cools down, and then enters the suction port of the high-pressure compressor through the first outlet of the intercooler. After further compression, it is discharged from the discharge port.

[0038] The third inlet of the intercooler is connected to the two-medium heat exchanger via the second solenoid valve 62 downstream of branch f. The second outlet, connected to the third inlet, is connected to the junction of branches a and b via the third solenoid valve 63. The refrigerant passing through the third inlet of the intercooler is further cooled in the intercooler and then flows into branch a from the second outlet via the third solenoid valve 63.

[0039] When two-stage compression is required, both the low-pressure compressor and the high-pressure compressor need to be turned on. The first solenoid valve 61, the second solenoid valve 62, and the third solenoid valve 63 are all turned on, the fourth solenoid valve 64 is turned off, the first port and the second port of the fifth three-way reversing valve 75 are connected, and the second port and the third port of the sixth three-way reversing valve 76 are connected.

[0040] When only single-stage compression is required, the high-pressure compressor starts, the low-pressure compressor stops, the first solenoid valve 61, the second solenoid valve 62, and the third solenoid valve 63 are all disconnected, the fourth solenoid valve 64 is opened, the first and third ports of the fifth three-way reversing valve 75 are connected, and the first and third ports of the sixth three-way reversing valve 76 are connected.

[0041] The single-stage and two-stage processes of the compressor are for the flow of refrigerant. The single-stage process can be used for both cooling and heating, while the two-stage process is only used in heating mode when the ambient temperature is very low, and two-stage compression is forcibly activated when the ambient temperature is below -10°C.

[0042] Single-stage compressor heating process: High-pressure compressor - check valve - gas-liquid separator - four-way reversing valve - two-medium heat exchanger - pipeline h (fourth solenoid valve 64) - pipeline a (check valve) - liquid receiver - pipeline c (check valve - first electronic expansion valve 31) - three-medium heat exchanger - four-way reversing valve - gas-liquid separator - sixth three-way reversing valve 76 - fifth three-way reversing valve 75 - high-pressure compressor.

[0043] High-pressure, high-temperature superheated steam flowing from the high-pressure compressor enters the gas-liquid separator via a one-way valve. Dry, high-temperature, high-pressure refrigerant enters the two-medium heat exchanger via a four-way reversing valve, transforming into a high-pressure, low-temperature liquid. It then enters the liquid receiver via the fourth solenoid valve 64 and branch a. The liquid receiver stores excess refrigerant. The high-pressure, low-temperature liquid refrigerant flowing from the liquid receiver enters the three-medium heat exchanger via the first electronic expansion valve 31 on branch c, where it is throttled and depressurized. It then transforms into a low-temperature, low-pressure gaseous refrigerant, which enters the gas-liquid separator via a four-way reversing valve. The dry gaseous refrigerant flowing from the gas-liquid separator returns to the high-pressure compressor via the sixth three-way reversing valve 76 and the fifth three-way reversing valve 75.

[0044] Two-stage compressor thermal process: low-pressure compressor - intercooler - high-pressure compressor - gas-liquid separator - four-way reversing valve - two-medium heat exchanger - branch and main circuit; Branch: Two-medium heat exchanger - Pipeline e - Intercooler; Main route: Two-medium heat exchanger - Pipeline g - Pipeline a - Liquid receiver - Pipeline c - Three-medium heat exchanger - Four-way reversing valve - Gas-liquid separator - Low-pressure compressor.

[0045] The working cycle is the same as that of a single-stage compressor, except that: when the low-pressure compressor starts, the low-pressure medium-temperature superheated vapor from the low-pressure compressor enters the intercooler. At the same time, the refrigerant from the two-medium heat exchanger is divided into two paths. The first path of refrigerant flows through the first solenoid valve 61 and the third electronic expansion valve 33 on pipeline e into the intercooler, where it mixes and cools with the low-pressure medium-temperature superheated vapor from the low-pressure compressor before entering the high-pressure compressor through the fifth three-way reversing valve 75. The second path of refrigerant flows through the second solenoid valve 62 in the branch pipeline g downstream of pipeline f into the intercooler for further cooling before entering branch a through the third solenoid valve 63.

[0046] Single-stage compressor refrigeration process: High-pressure compressor - one-way valve - gas-liquid separator - four-way reversing valve - three-medium heat exchanger - pipeline d - liquid receiver - pipeline b - pipeline h - two-medium heat exchanger - four-way reversing valve - gas-liquid separator - high-pressure compressor.

[0047] The high-pressure, high-temperature superheated refrigerant from the high-pressure compressor passes sequentially through a check valve, a gas-liquid separator, and a four-way reversing valve into a three-medium heat exchanger, where it is converted into a high-pressure, low-temperature liquid refrigerant. It then enters the receiver tank via branch d, which is used to temporarily store excess refrigerant. After exiting the receiver tank, the refrigerant is throttled and depressurized by the second electronic expansion valve 32 on branch b, and flows through pipeline h, where the fourth solenoid valve 64 is located, into the two-medium heat exchanger, where it is converted into a low-temperature, low-pressure gaseous refrigerant. It then flows back to the high-pressure compressor sequentially through the four-way reversing valve, the gas-liquid separator, the sixth three-way reversing valve 76, and the fifth three-way reversing valve 75.

[0048] Example 2 A photovoltaic heat pump energy storage control method is used in the photovoltaic heat pump energy storage system of Example 1, which includes the following operating modes: three heating modes and three cooling modes.

[0049] Heating Mode 1 (see Figure 3 and Figure 6 ) When sunlight conditions are good, the photovoltaic modules supply power to the compressor unit, start the compressor unit, and control the four-way reversing valve to switch the heat pump system to the heating mode. At the same time, the third three-way reversing valve 73 and the fourth three-way reversing valve 74 are controlled to connect the photovoltaic modules to the heat exchange pipeline of the three-medium heat exchanger, heating the refrigerant in the three-medium heat exchanger.

[0050] Simultaneously, the circulation pipeline of the energy storage heating module is connected, and heat is supplied to users through a single coil. The energy storage tank stores excess heat for nighttime use, and the dual-coil heat exchanger heats the hot water storage tank to supply hot water to users.

[0051] The refrigerant circulation process in this mode is as follows: High-temperature, high-pressure refrigerant vapor is discharged from the compressor, passes through a gas-liquid separator, and then enters a two-medium heat exchanger via a four-way reversing valve. In the two-medium heat exchanger, it condenses and releases heat to become a subcooled liquid. It then enters the liquid receiver tank via branch f and branch a. From the liquid receiver tank, it is throttled and depressurized by the first electronic expansion valve 31 on branch c. The low-temperature, low-pressure refrigerant absorbs heat and evaporates in the three-medium heat exchanger. The gaseous refrigerant returns to the high-pressure compressor via the four-way reversing valve and gas-liquid separator, completing the cycle.

[0052] Two-medium heat exchanger side refrigerant circulation process: The refrigerant absorbs heat from the refrigerant in the two-medium heat exchanger and heats up. After heating, the refrigerant is pumped into the dual-coil heat exchanger by the second water pump 82. In the dual-coil heat exchanger, the refrigerant undergoes two independent heat exchange processes: a) heat exchange with water in the hot water storage tank to heat domestic hot water; b) diversion to the single-coil heat exchanger via the second three-way reversing valve 72. The refrigerant entering the single-coil heat exchanger supplies heat to the user end while storing excess heat in the energy storage tank. The refrigerant that has completed heat exchange returns to the two-medium heat exchanger, forming a closed-loop cycle.

[0053] The refrigerant circulation process in a three-medium heat exchanger: The refrigerant releases heat to the refrigerant in the three-medium heat exchanger and then cools down. The cooled refrigerant enters the backsheet channel of the photovoltaic module through the third three-way reversing valve 73. It absorbs solar heat in the photovoltaic module and heats up. The heated refrigerant is driven by the first water pump 81 and returns to the three-medium heat exchanger through the fourth three-way reversing valve 74. The returned refrigerant exchanges heat with the refrigerant again, completing the cycle.

[0054] Heating mode two, see Figure 4 and Figure 7 When sunlight conditions are poor, the photovoltaic modules supply power to the compressor unit through the municipal power grid, start the compressor unit, and control the four-way reversing valve to switch the heat pump system to the heating mode. At the same time, the third three-way reversing valve 73 and the fourth three-way reversing valve 74 are controlled to connect the heat exchange pipeline of the photovoltaic modules and the three-medium heat exchanger, heat the three-medium heat exchanger, and start the fan to heat the refrigerant in the three-medium heat exchanger.

[0055] Simultaneously, the circulation pipeline of the energy storage heating module is connected, and heat is supplied to users through a single coil. The energy storage tank stores excess heat for nighttime use, and the dual-coil heat exchanger heats the hot water storage tank to supply hot water to users.

[0056] The refrigerant circulation process and the refrigerant circulation process on the two-medium heat exchanger side are the same as in heating mode one. The difference lies in the three-medium heat exchanger, which enhances the heat exchange process and uses a dual heat source of photovoltaic hot water and air convection. Specifically, in the photovoltaic module circulation system, photovoltaic hot water flows through the external channel of the three-medium heat exchanger to perform primary heat exchange with the refrigerant; in the forced convection system, the fan of the three-medium heat exchanger is activated to introduce ambient air for auxiliary heat exchange.

[0057] Heating mode three, see Figure 5 and Figure 8 When there is no sunlight, the compressor unit is powered by the municipal power grid, the compressor unit is started, and the four-way reversing valve is controlled to switch the heat pump system to the heating mode. At the same time, the third three-way reversing valve 73 and the fourth three-way reversing valve 74 are controlled to disconnect the heat exchange pipeline between the photovoltaic module and the three-medium heat exchanger, and the fan is started to heat the refrigerant in the three-medium heat exchanger.

[0058] Simultaneously, the circulation pipeline of the energy storage heating module is connected, and heat is supplied to users through a single coil. The energy storage tank stores excess heat for nighttime use, and the dual-coil heat exchanger heats the hot water storage tank to supply hot water to users.

[0059] The refrigerant circulation process and the refrigerant circulation process on the side of the two-medium heat exchanger are the same as in heating mode one. The difference is that in this mode, the three-medium heat exchanger uses air convection heat exchange or photovoltaic water heat dissipation, and the forced convection system is activated by starting the fan or water pump of the three-medium heat exchanger to introduce ambient air or photovoltaic water for auxiliary heat exchange.

[0060] Cooling mode one, see Figure 9 When sunlight conditions are good, the photovoltaic modules supply power to the compressor unit, starting the compressor unit and controlling the four-way reversing valve to switch the heat pump system to cooling mode. Simultaneously, the third three-way reversing valve 73 and the fourth three-way reversing valve 74 are activated to connect the photovoltaic modules to the heat exchange pipelines of the dual-coil heat exchanger, while disconnecting the heat exchange circulation pipelines of the three-medium heat exchanger and the dual-coil heat exchanger. The heated hot water storage tank then supplies hot water to the user. The fan of the three-medium heat exchanger starts to dissipate heat from the refrigerant.

[0061] Simultaneously, the first three-way reversing valve 71 is activated, and the "two-medium heat exchanger-single coil heat exchanger-two-medium heat exchanger" circulation pipeline of the energy storage heating module is connected. Cooling is provided to users through the single coil, and the energy storage tank stores excess cooling capacity for nighttime use.

[0062] Refrigerant cycle process: High-temperature, high-pressure refrigerant vapor is discharged from the compressor, passes through a gas-liquid separator, and then enters a three-medium heat exchanger via a four-way reversing valve. In the three-medium heat exchanger, it condenses and releases heat to become a subcooled liquid, which enters the liquid receiver tank via pipeline d. From the liquid receiver tank, it is throttled and depressurized by the second electronic expansion valve 32 on branch b. The low-temperature, low-pressure refrigerant absorbs heat and evaporates in the two-medium heat exchanger. The gaseous refrigerant returns to the high-pressure compressor via the four-way reversing valve and gas-liquid separator, completing the cycle.

[0063] Refrigerant circulation process: The refrigerant exchanges heat with the low-temperature refrigerant in the two-medium heat exchanger; after cooling, the refrigerant is pressurized by the second water pump 82; and through the coordinated control of the first three-way reversing valve 71 and the second three-way reversing valve 72, it enters the single-coil heat exchanger, where it performs dual functions: cooling at the user end and cold storage in the energy storage tank; the refrigerant returns to the two-medium heat exchanger to complete the closed-loop cycle.

[0064] Hot water circulation process: The photovoltaic module absorbs solar energy to heat the circulating working fluid, and the first water pump 81 starts to drive the circulation; the high-temperature working fluid flows through the fourth three-way reversing valve 74 into the double coil heat exchanger; in the double coil heat exchanger, it completes the following: heat exchange with the hot water storage tank to heat domestic hot water; the cooled working fluid returns to the photovoltaic module through the third three-way reversing valve 73 for reheating.

[0065] Cooling mode two, see Figure 10 When sunlight conditions are poor, the compressor unit is powered by the photovoltaic modules and the municipal power grid, the compressor unit is started, and the four-way reversing valve is controlled to switch the heat pump system to cooling mode. At the same time, the third three-way reversing valve 73 and the fourth three-way reversing valve 74 are controlled to disconnect the heat exchange circulation pipeline between the photovoltaic modules and the dual-coil heat exchanger, and connect the heat exchange circulation pipeline between the three-medium heat exchanger and the dual-coil heat exchanger, so as to heat the hot water storage tank to supply hot water to users.

[0066] Simultaneously, the circulation pipeline of the energy storage heating module, consisting of "two-medium heat exchanger - single-coil heat exchanger - two-medium heat exchanger", is connected. Cooling is provided to users through the single coil, and the energy storage tank stores excess cooling capacity for nighttime use.

[0067] The refrigerant circulation process and the secondary refrigerant circulation process are the same as in refrigeration mode one. The difference lies in the hot water circulation process: In this mode, the first water pump 81 is turned off, the fourth three-way reversing valve 74 switches to the three-medium heat exchanger passage, and the third three-way reversing valve 73 switches to the return passage; the refrigerant in the three-medium heat exchanger releases heat, and the secondary refrigerant heats up; the high-temperature secondary refrigerant flows through the fourth three-way reversing valve 74 into the dual-coil heat exchanger, where it exchanges heat with the hot water storage tank to heat the domestic hot water; the cooled secondary refrigerant returns to the three-medium heat exchanger via the third three-way reversing valve 73 for reheating.

[0068] Cooling mode three, see Figure 11 When there is no sunlight, the compressor unit is powered by the municipal power grid, starting the compressor unit and controlling the four-way reversing valve to switch the heat pump system to cooling mode. Simultaneously, the third three-way reversing valve 73 and the fourth three-way reversing valve 74 are activated to disconnect the heat exchange circulation lines between the photovoltaic modules and the dual-coil heat exchanger, while connecting the heat exchange circulation lines between the three-medium heat exchanger and the dual-coil heat exchanger, heating the hot water storage tank to supply hot water to users. When the hot water in the dual-coil heat exchanger exceeds the third set temperature t3, the heat exchange circulation lines between the three-medium heat exchanger and the dual-coil heat exchanger disconnect, and the heat exchange circulation lines between the photovoltaic modules and the three-medium heat exchanger open.

[0069] The control of the energy storage heating module is the same as that of the cooling mode two.

[0070] The refrigerant circulation process is the same as in cooling mode one. The difference lies in the hot water circulation process: In this mode, when the water temperature in the hot water storage tank reaches the upper limit of t3, the first water pump 81 is turned on, the fourth three-way reversing valve 74 switches to the three-medium heat exchanger passage, and the third three-way reversing valve 73 switches to the three-medium heat exchanger passage; the refrigerant in the three-medium heat exchanger exchanges heat with the photovoltaic water, and the heat transfer fluid heats up; the high-temperature heat transfer fluid flows through the channel on the back of the photovoltaic panel to dissipate heat from the environment, and after cooling down, it returns to the three-medium heat exchanger through the water pump.

[0071] In heating mode: when the compression ratio of the high-pressure compressor does not exceed the set value (determined according to the compressor, such as 4~5), the heat pump system enters single compressor mode and the low-pressure compressor stops running; when the compression ratio of the high-pressure compressor exceeds the set value (determined according to the compressor, such as 4~5), the heat pump system automatically enters dual compressor mode and the low-pressure compressor starts.

[0072] When the water temperature in the energy storage tank reaches the first set temperature t1, adjust the speed of the compressor unit to run at low speed. When the water temperature is lower than the second set temperature t2, close the connection valve between the energy storage tank and the user until the temperature is higher than the second set temperature t2, then open the valve again. When the water temperature in the hot water storage tank reaches the third set temperature t3, adjust the reversing valve to connect the two-medium heat exchanger with the single-coil heat exchanger through pipeline p and exchange heat. When the water temperature in the hot water storage tank is lower than the fourth set temperature t4, increase the compressor unit speed to increase the water-side temperature rise of the two-medium heat exchanger.

[0073] In cooling mode, the following steps are also performed: When the water temperature in the energy storage tank reaches the fifth set temperature t5, adjust the compressor unit speed to run at low speed. When the water temperature is higher than the sixth set temperature t6, close the connection valve between the energy storage tank and the user until the temperature is lower than the sixth set temperature t6, then open the valve again.

[0074] When the water temperature in the hot water storage tank reaches the third set temperature t3, disconnect the three-medium heat exchanger from the dual-coil heat exchanger and connect the three-medium heat exchanger to the photovoltaic module.

[0075] The above-mentioned set temperatures are preferably, but not limited to, t1 being 55-65℃; t2 being 50-55℃; t3 being 50-55℃; t4 being 40-45℃; t5 being 5-7℃; and t6 being 12-15℃.

[0076] The above description represents a preferred embodiment of the present invention. However, the present invention is not limited to the above embodiments and examples. Within the scope of knowledge possessed by those skilled in the art, all variations, equivalent substitutions, improvements, etc., made without departing from the concept of the present invention should be included within the protection scope of the present invention.

Claims

1. A photovoltaic heat pump energy storage system, comprising a heat pump system, characterized in that, The heat pump system includes a compressor unit, a gas-liquid separator, a four-way reversing valve, a two-medium heat exchanger, a liquid storage tank, and a three-medium heat exchanger connected in sequence to form a cold and hot dual-supply circulation pipeline. The three-medium heat exchanger is equipped with a fan and two heat exchange channels. The photovoltaic heat pump energy storage system also includes an energy storage hot water module and a photovoltaic module; The energy storage hot water module is used for heating and supplying hot water in winter and for cooling and supplying cold water in summer. It includes a single-coil heat exchanger, a double-coil heat exchanger, and a control valve. The two-medium heat exchanger, the double-coil heat exchanger, and the single-coil heat exchanger are connected in sequence to form a circulation loop. The single-coil heat exchanger is used for heating or cooling and is connected to an energy storage tank, which stores heat or cold. The double-coil heat exchanger is connected to a hot water storage tank to supply hot water, and a parallel pipeline p is set on the pipeline between the double-coil heat exchanger and the two-medium heat exchanger through a reversing valve. Pipeline p is used to switch the connection and disconnection between the double-coil heat exchanger and the two-medium heat exchanger. The photovoltaic module is used to heat the three-medium heat exchanger in winter and the dual-coil heat exchanger in summer, as well as to supply power to the compressor unit. It includes a photovoltaic module and a reversing valve. The photovoltaic module is selectively connected to the three-medium heat exchanger or the dual-coil heat exchanger through the control of the reversing valve. In winter, the photovoltaic module is connected to the three-medium heat exchanger to form a heat exchange circulation pipeline to heat the refrigerant. In summer, the photovoltaic module or the three-medium heat exchanger is connected to the dual-coil heat exchanger to form a heat exchange circulation pipeline to heat the hot water tank. The compressor unit includes two compressors and has two modes: single compressor and dual compressor. The dual compressor mode is only used for winter heating.

2. The photovoltaic heat pump energy storage system according to claim 1, characterized in that, The dual compressors include a low-pressure compressor and a high-pressure compressor. The low-pressure compressor is installed on the pipeline connecting the suction port of the high-pressure compressor and the outlet of the gas-liquid separator, and an intercooler is also connected between the low-pressure compressor and the high-pressure compressor. Two parallel pipes, e and f, are provided between the intercooler and the two-medium heat exchanger. Pipe e is equipped with an electronic expansion valve and is connected to the intercooler to cool the refrigerant vapor flowing into the low-pressure compressor. Pipe f splits into two parallel branches, g and h, before the inlet of the intercooler. Pipe g is connected to the intercooler and is used to further cool the refrigerant flowing out of the two-medium heat exchanger in dual-compressor mode. Solenoid valves are installed on pipelines e, g, and h.

3. The photovoltaic heat pump energy storage system according to claim 1, characterized in that, A water pump is installed on the outlet pipe of the two-medium heat exchanger. Downstream of the water pump, it is connected to the pipe p and the inlet pipe of the double-coil heat exchanger through the first three-way reversing valve (71). The outlet of the pipe p is connected to the outlet pipe of the double-coil heat exchanger and the inlet pipe of the single-coil heat exchanger through the second three-way reversing valve (72).

4. The photovoltaic heat pump energy storage system according to claim 1 or 3, characterized in that, A water pump is installed on the outlet pipe of the photovoltaic module. Downstream of the water pump, the inlet pipe of the three-medium heat exchanger and the inlet pipe of the double-coil heat exchanger are connected through the fourth three-way reversing valve (74). The return pipe of the three-medium heat exchanger and the return pipe of the double-coil heat exchanger are connected to the return pipe of the photovoltaic module through the third three-way reversing valve (73). The photovoltaic module heats the three-medium heat exchanger or the double-coil heat exchanger by circulating heat exchange through the fourth three-way reversing valve (74) and the third three-way reversing valve (73).

5. The photovoltaic heat pump energy storage system according to claim 1, characterized in that, The two-medium heat exchanger and the liquid storage tank are connected by a main pipe to two parallel branch pipes, a and b. The liquid storage tank and the three-medium heat exchanger are connected by a main pipe to two parallel branch pipes, c and d. Branch pipes a and c are used for heating circulation, while branch pipes b and d are used for cooling circulation. Electronic expansion valves are installed on branch pipes b and c.

6. A photovoltaic heat pump energy storage control method, characterized in that, The photovoltaic heat pump energy storage system according to claim 1 includes the following control modes: Heating Mode 1: When the sunshine conditions are good, the photovoltaic modules supply power to the compressor unit, start the compressor unit and switch to the heating mode; at the same time, the reversing valve connects the circulation pipeline between the photovoltaic modules and the three-medium heat exchanger to heat the refrigerant; in the energy storage heating module, a single coil provides heat to the user and the energy storage tank stores heat, while a dual coil heats the hot water storage tank to supply hot water. Heating Mode 2: When sunlight conditions are poor, the photovoltaic modules and the municipal power grid jointly supply power to the compressor unit, start the compressor unit and switch to heating mode; at the same time, the reversing valve connects the circulation pipeline of the photovoltaic modules and the three-medium heat exchanger to heat the refrigerant, and the fan starts to heat the refrigerant together; in the energy storage heating module, a single coil provides heat to the user and the energy storage tank stores heat, while a dual coil heats the hot water storage tank to supply hot water; Heating Mode 3: When there is no sunshine, the compressor unit is powered by the municipal power grid, the compressor unit is started and switched to heating mode; the reversing valve first disconnects the circulation pipeline between the photovoltaic module and the three-medium heat exchanger, and then the fan starts and heats the refrigerant; in the energy storage heating module, the single coil provides heat to the user and the energy storage tank stores heat, and the dual coil heats the hot water storage tank to supply hot water. Cooling Mode 1: When there is sufficient sunshine, the system switches to cooling mode by supplying power through photovoltaic modules; the hot water in the photovoltaic modules enters the dual-coil heat exchanger to heat the hot water storage tank; a single coil provides cooling to the user, and the energy storage tank stores the cooling capacity. Cooling Mode 2: When there is insufficient sunlight, the photovoltaic modules and the municipal power grid are used to supply power, switch to cooling mode, and disconnect the photovoltaic modules from the dual-coil heat exchanger; the three-medium heat exchanger is connected to the dual-coil heat exchanger to heat the water in the hot water storage tank. A single coil provides cooling to users, while an energy storage tank stores the cooling capacity.

7. Cooling Mode 3: When there is no sunlight, the compressor is powered by the municipal power grid and switched to cooling mode. The three-medium heat exchanger is connected to the dual-coil heat exchanger to heat the water in the hot water storage tank. When the water temperature in the hot water storage tank reaches the third set temperature, the connection between the three-medium heat exchanger and the dual-coil heat exchanger is disconnected, and the photovoltaic module is connected to the three-medium heat exchanger. At the same time, the fan is turned on.

8. The photovoltaic heat pump energy storage control method according to claim 6, characterized in that, In heating mode: when the compression ratio of the high-pressure compressor does not exceed the set value, the heat pump system enters single compressor mode and the low-pressure compressor stops running; when the compression ratio of the high-pressure compressor exceeds the set value, the heat pump system automatically enters dual compressor mode and the low-pressure compressor starts.

9. The photovoltaic heat pump energy storage control method according to claim 6, characterized in that, In heating mode, the following steps are also performed: When the water temperature in the energy storage tank reaches the first set temperature t1, adjust the speed of the compressor unit to run at low speed. When the water temperature is lower than the second set temperature t2, close the connection valve between the energy storage tank and the user until the temperature is higher than the second set temperature t2, then open the valve again. When the water temperature in the hot water storage tank reaches the third set temperature t3, adjust the reversing valve to connect the two-medium heat exchanger with the single-coil heat exchanger through pipeline p and exchange heat. When the water temperature in the hot water storage tank is lower than the fourth set temperature t4, increase the compressor unit speed to increase the water-side temperature rise of the two-medium heat exchanger.

10. The photovoltaic heat pump energy storage control method according to claim 6, characterized in that, In cooling mode, the following steps are also performed: When the water temperature in the energy storage tank reaches the fifth set temperature t5, adjust the compressor unit speed to run at low speed. When the water temperature is higher than the sixth set temperature t6, close the connection valve between the energy storage tank and the user until the temperature is lower than the sixth set temperature t6, then open the valve again. When the water temperature in the hot water storage tank is higher than the third set temperature t3, disconnect the three-medium heat exchanger from the dual-coil heat exchanger and open the three-medium heat exchanger from the photovoltaic module. When the water temperature is lower than the fourth set temperature t4, disconnect the three-medium heat exchanger from the photovoltaic module and open the three-medium heat exchanger from the dual-coil heat exchanger.

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