Heat storage type heat pump system and cold and heat combined temperature regulation method

Abstract

The application discloses a heat storage type heat pump system and a cold and heat supply temperature regulation method, comprising a three-medium heat accumulator, a heat exchanger, a compressor, a four-way reversing valve, an expansion valve, a solar photovoltaic assembly, a water pump, a three-way valve, an external heat exchange fluid pipeline, a refrigerant pipeline, a cold end and a heat end. The application adopts the solar photovoltaic driving heat pump to work, has lower energy consumption and higher energy efficiency; meanwhile, the three-medium heat accumulator enables the solar photovoltaic resource to be continuously and stably utilized, and has higher energy storage density compared with the sensible heat water tank heat storage; in addition, the proposed system only needs to switch the circulating direction of the heat pump to realize the regulation of the output temperature, is flexible and simple, and has great application potential in the field of building heat management.

Description

Technical Field

[0001] This invention relates to the field of heat pump system technology, and in particular to a heat storage type heat pump system and a method for temperature control in combined cooling and heating systems. Background Technology

[0002] Building energy consumption accounts for more than 30% of my country's total energy consumption, mainly including indoor heating, hot water, cooling, ventilation, and lighting. Among these, cooling and heating energy consumption accounts for more than 60% of the total building energy consumption.

[0003] Solar energy is one of the most abundant renewable energy sources. Currently, as a free and clean energy source, solar energy is widely used in building heating systems, such as solar water heaters providing hot water, solar photovoltaic power generation connected to the grid, and solar photovoltaic-driven heat pumps for building heating. Heat pumps are devices that efficiently convert electrical energy into heat energy, extracting energy from the air for free, resulting in an energy efficiency greater than 1. Using solar photovoltaic power to drive heat pumps allows for zero-energy cooling and heating of buildings. However, solar energy is intermittent, unstable, and discontinuous, which limits the practical application of solar-driven heat pumps. Thermal energy storage technology can provide a low-cost solution to these problems, effectively balancing the issue of discontinuous solar energy resources.

[0004] Buildings typically have different heat demands, such as cooling, medium-temperature, and high-temperature. A search of existing literature on using heat pumps to achieve combined low, medium, and high-temperature energy supply reveals that cooling is achieved through the cooling capacity generated by refrigerant evaporation in an evaporator; medium-temperature heating is achieved through the condensation heat output of a single-stage heat pump; and high-temperature heating is achieved through multi-stage compression or the utilization of the high-temperature sensible heat of the refrigerant. For example, utility model patent application number 202221653702.6 discloses an "air-source water-cooled integrated cooling and heating dual-storage air conditioning system." The entire system consists of a first-stage heat pump circuit, a second-stage heat pump circuit, and a three-medium heat exchanger. During high-temperature heating, the first-stage heat pump circuit operates first, storing the medium-temperature condensation heat in the three-medium heat exchanger. When the second-stage heat pump circuit operates, the three-medium heat exchanger acts as an evaporator, providing heat to the refrigerant, thereby outputting high-temperature heat energy at the condenser end of the second-stage heat pump. For example, invention patent application number 201810898787.6 discloses a "high-temperature, large-temperature-difference heat pump heat storage device and method." This invention stores the high-temperature sensible heat of the compressed refrigerant. After the refrigerant releases its high-temperature sensible heat, it condenses in a condenser to provide medium-temperature heat energy to the heat-consuming end. When there is a high-temperature heat demand, the external heat exchange fluid first passes through the condenser and then through the heat storage device, absorbing the stored high-temperature sensible heat for high-temperature heat output. Although such systems achieve the supply of heat of multiple grades, they cannot achieve sufficient energy saving because they use direct electric heating, and the multi-stage compression leads to system complexity and size. Therefore, how to achieve a low-energy-consumption, high-efficiency, and simple heat pump combined cooling and heating system, and how to regulate the grade of output heat, are currently the challenges in this field. Summary of the Invention

[0005] The purpose of this invention is to provide a thermal storage heat pump system and a method for controlling the temperature of combined cooling and heating, solving the problems of how to achieve a low-energy-consumption, high-efficiency, and simple heat pump combined cooling and heating system and how to control the quality of the output heat.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0007] This invention provides a heat pump system with thermal storage and a method for controlling temperature in a combined cooling and heating system, comprising a heat exchanger, an expansion valve, a three-medium heat accumulator, a four-way reversing valve, and a heat pump compressor connected in sequence through refrigerant pipelines;

[0008] The heat exchanger is provided with a refrigerant channel that connects to the refrigerant pipeline, and an external heat exchange fluid circulates within the heat exchanger. The heat exchanger is provided with an inlet and outlet for the external heat exchange fluid, and a first three-way valve and a second three-way valve are respectively provided at the inlet and outlet. The cold terminal is connected to the first three-way valve and the second three-way valve through a first external heat exchange fluid pipeline, and a first water pump is provided on the first external heat exchange fluid pipeline.

[0009] The three-medium heat accumulator is equipped with a refrigerant coil connected to the refrigerant pipeline, an external heat exchange fluid coil connected to the heat-using terminal, and heat storage material filled in the three-medium heat accumulator; a third three-way valve and a fourth three-way valve are provided outside the three-medium heat accumulator to connect to the inlet and outlet of the external heat exchange fluid coil; the inlet and outlet ports of the heat-using terminal are respectively connected to the third three-way valve and the fourth three-way valve through the third external heat exchange fluid pipeline, and a second water pump is provided on the third external heat exchange fluid pipeline;

[0010] The first three-way valve and the third three-way valve are connected through a second external heat exchange fluid pipeline; the second three-way valve and the fourth three-way valve are connected through a second external heat exchange fluid pipeline.

[0011] Furthermore, multiple fins are respectively provided in the heat exchanger and the three-medium accumulator.

[0012] Furthermore, the heat pump compressor is driven by solar photovoltaic modules or supplied with auxiliary power by the grid.

[0013] Furthermore, the heat storage material is one of phase change heat storage materials, adsorption heat storage materials, or thermochemical heat storage materials.

[0014] Furthermore, the heat pump compressor is one of the following: a piston compressor, a screw compressor, a centrifugal compressor, or a linear compressor.

[0015] This invention provides a method for temperature control of combined cooling and heating, the working modes of which include heat pump heat storage mode, heat pump cooling mode, heat pump medium temperature heating mode, three-medium heat accumulator medium temperature heating mode, and heat pump high temperature heating mode.

[0016] When in the heat pump cooling mode / heat pump thermal storage mode:

[0017] When solar energy is abundant and cooling is required, the electricity provided by the solar photovoltaic modules drives the heat pump compressor. The heat pump system operates in a forward cycle. The three-medium heat accumulator acts as both a condenser and a heat storage tank, while the heat exchanger acts as an evaporator. After being compressed by the compressor, the refrigerant flows into the refrigerant coil of the three-medium heat accumulator to condense. The condensation heat is transferred to the heat storage material through the fins, and the heat is stored. The refrigerant, after releasing heat through condensation, enters the refrigerant channel of the heat exchanger through the expansion valve to evaporate. At this time, by controlling the first three-way valve and the second three-way valve, the cold terminal is connected to the heat exchanger, opening the cold circulation. The heat exchange fluid from the cold terminal enters the heat exchanger to absorb the cooling generated by the refrigerant evaporation. After evaporation, the refrigerant re-enters the compressor through the four-way reversing valve for the next cycle.

[0018] When in heat pump cooling mode / heat pump medium temperature heating mode:

[0019] When there is sufficient solar energy and a demand for both cooling and medium-temperature heating, the solar photovoltaic modules drive the compressor to work, the heat pump system circulates in the forward direction, the three-medium heat storage tank acts as a condenser and heat exchanger, and the heat exchanger acts as an evaporator. By adjusting the first three-way valve and the second three-way valve, the cold terminal is connected to the heat exchanger; by adjusting the third three-way valve and the fourth three-way valve, the heating terminal is connected to the three-medium heat storage tank, and the medium-temperature heating cycle is turned on.

[0020] After being compressed by the compressor, the refrigerant flows into the refrigerant coil of the three-medium heat accumulator and condenses. The heat of condensation is transferred to the external heat exchange fluid coil through the fins, providing medium-temperature heating to the heat-using terminals. After releasing heat through condensation, the refrigerant enters the refrigerant channel of the heat exchanger through the expansion valve to evaporate. The heat exchange fluid of the cold-using terminals enters the heat exchanger to absorb the cooling energy generated by the evaporation of the refrigerant. After evaporation, the refrigerant enters the compressor again through the four-way reversing valve for the next cycle.

[0021] When using a three-medium heat accumulator in medium-temperature heating mode:

[0022] When solar energy is insufficient or there is a demand for medium-temperature heat at night, the heat pump does not work. By adjusting the third and fourth three-way valves, the heat exchange fluid at the heat-using terminal enters the external heat exchange fluid coil of the three-medium heat storage device through the medium-temperature heat-using cycle. The heat stored in the heat storage material is transferred through the fins to supply medium-temperature heat to the heat-using terminal.

[0023] When in heat pump high-temperature heating mode:

[0024] When there is a high-temperature heat demand, the heat pump compressor is driven by solar photovoltaic modules or grid power. The four-way reversing valve is switched, and the heat pump system works in reverse cycle. The three-medium heat accumulator is the evaporator, and the heat exchanger is the condenser. By adjusting the first three-way valve, the second three-way valve, the third three-way valve, and the fourth three-way valve, the heat-using terminal is connected to the heat exchanger, and the high-temperature heat cycle is turned on.

[0025] The refrigerant enters the refrigerant coil of the three-medium heat accumulator, absorbs the heat released by the heat storage material through the fins, evaporates at a medium temperature, and after being compressed by the compressor, enters the refrigerant channel of the heat exchanger to release high-temperature condensation heat. At this time, the heat exchange fluid at the heat-using terminal enters the fin gap of the heat exchanger, absorbs the high-temperature condensation heat of the refrigerant through the fins, and then supplies high-temperature heat to the heat-using terminal.

[0026] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0027] First, the solar photovoltaic-driven heat pump compressor can directly heat or cool or release stored heat when there is a demand for heat or cold during peak grid periods, making full use of solar energy resources, consuming less energy, and achieving greater economic benefits.

[0028] Secondly, the three-medium heat accumulator in this system can be used as a condenser, a heat storage device, and an evaporator. It is integrated, compact in structure, has a small heat exchange temperature difference, high heat storage and release efficiency, and high heat storage density.

[0029] Third, the system can achieve combined cooling and heating by switching between forward and reverse cycles, and can regulate the heat quality to meet different temperature requirements. The system is simple and flexible in regulation. Attached Figure Description

[0030] The present invention will be further described below with reference to the accompanying drawings.

[0031] Figure 1 This is a schematic diagram of the system structure of a specific embodiment of the present invention;

[0032] Figure 2 This is a schematic diagram illustrating the operating principle of the heat pump cooling mode / heat pump heat storage mode of the present invention;

[0033] Figure 3 This is a schematic diagram illustrating the operating principle of the heat pump cooling mode / heat pump medium-temperature heating mode of the present invention.

[0034] Figure 4 This is a schematic diagram illustrating the operating principle of the medium-temperature heating mode of the three-medium heat accumulator of the present invention.

[0035] Figure 5 This is a schematic diagram illustrating the operating principle of the heat pump high-temperature heating mode of the present invention;

[0036] Figure reference numerals:

[0037] 1-1, First three-way valve; 1-2, Second three-way valve; 1-3, Third three-way valve; 1-4, Fourth three-way valve; 2-1, First external heat exchange fluid pipeline; 2-2, Refrigerant pipeline; 2-3, Second external heat exchange fluid pipeline; 2-4, Third external heat exchange fluid pipeline; 3, Cooling terminal; 4, First water pump; 5, Heat exchanger; 5-1, Refrigerant passage; 5-2, Fins; 5-3, External heat exchange fluid; 6, Expansion valve; 7, Solar photovoltaic module; 8, Heat pump compressor; 9, Four-way reversing valve; 10, Three-medium heat accumulator; 10-1, External heat exchange fluid coil; 10-2, Refrigerant coil; 10-3, Heat storage material; 10-4, Fins; 11, Second water pump; 12, Heating terminal. Detailed Implementation

[0038] This embodiment discloses a heat pump system with heat storage, including a heat exchanger 5, an expansion valve 6, a three-medium heat accumulator 10, a four-way reversing valve 9, and a heat pump compressor 8, which are connected in sequence through refrigerant pipeline 2-2.

[0039] The heat exchanger 5 is equipped with a refrigerant channel 5-1 connected to the refrigerant pipeline 2-2, and an external heat exchange fluid 5-3 circulates within the heat exchanger 5. The heat exchanger 5 has inlet and outlet ports for the external heat exchange fluid 5-3, and a first three-way valve 1-1 and a second three-way valve 1-2 are installed at these ports respectively. A cold terminal 3 is connected to the first three-way valve 1-1 and the second three-way valve 1-2 via the first external heat exchange fluid pipeline 2-1, and a first water pump 4 is installed on the first external heat exchange fluid pipeline 2-1. Multiple fins are installed in the heat exchanger 5 to limit the refrigerant channel 5-1, which is a refrigerant circulating coil. The heat exchanger 5 has the dual functions of an evaporator and a condenser, and its specific structure is a tube-fin heat exchanger, including a refrigerant channel 5-1, fins 5-2, and external heat exchange fluid 5-3.

[0040] The three-medium heat accumulator 10 has multiple functions as a condenser / evaporator and a heat storage device. The three-medium heat accumulator 10 contains a refrigerant coil 10-2 connected to the refrigerant pipeline 2-2, an external heat exchange fluid coil 10-1 connected to the heat-using terminal 12, fins 10-4, and heat storage material 10-3 filled in the fin spacing. The fins provide limiting support and enhance heat transfer for the refrigerant coil 10-2 and the external heat exchange fluid coil 10-1 within the three-medium heat accumulator 10. A third three-way valve 1-3 and a fourth three-way valve 1-4 are installed outside the three-medium heat accumulator 10, connecting the inlet and outlet of the external heat exchange fluid coil 10-1. The inlet and outlet ports of the heat-using terminal 12 are respectively connected to the third three-way valve 1-3 and the fourth three-way valve 1-4 via the third external heat exchange fluid pipeline 2-4. A second water pump 11 is installed on the third external heat exchange fluid pipeline 2-4.

[0041] The refrigerant coil 10-2 and the external heat exchange fluid coil 10-1 are in series, parallel, or a combination of series and parallel; the heat storage material 10-3 is one of phase change heat storage material, adsorption heat storage material, or thermochemical heat storage material; the three-medium heat accumulator 10 is completely wrapped with insulation cotton to reduce heat loss.

[0042] In this embodiment, the first three-way valve 1-1 and the third three-way valve 1-3 are connected through the second external heat exchange fluid pipeline 2-3; the second three-way valve 1-2 and the fourth three-way valve 1-4 are connected through the second external heat exchange fluid pipeline 2-3.

[0043] In this embodiment, the heat pump compressor 8 is driven by the solar photovoltaic module 7 or provided with auxiliary power by the grid.

[0044] The heat pump compressor 8 is one of the following: piston compressor, screw compressor, centrifugal compressor, or linear compressor, and it is a single-stage compressor.

[0045] The outlet of heat pump compressor 8 is connected in sequence through refrigerant line 2-2 to four-way reversing valve 9, refrigerant coil 10-2 of three-medium heat accumulator 10, expansion valve 6, refrigerant channel 5-1 of heat exchanger 5, four-way reversing valve 9, and inlet of heat pump compressor 8, forming a forward heat pump cycle. Three-medium heat accumulator 10 is the condenser, and heat exchanger 5 is the evaporator. The outlet of heat pump compressor 8 is connected in sequence through refrigerant line 2-2 to four-way reversing valve 9, refrigerant channel 5-1 of heat exchanger 5, expansion valve 6, refrigerant coil 10-2 of three-medium heat accumulator 10, four-way reversing valve 9, and inlet of heat pump compressor 8, forming a reverse heat pump cycle. Heat exchanger 5 is the condenser, and three-medium heat accumulator 10 is the evaporator.

[0046] In this embodiment, the cold terminal 3 is connected sequentially to the first water pump 4, the first and second ports of the second three-way valve 1-2, the heat exchanger 5, the third and first ports of the first three-way valve 1-1 through the first external heat exchange fluid pipeline 2-1 to form a cooling cycle; the hot terminal 12 is connected sequentially to the second water pump 11, the third and second ports of the third three-way valve 1-3, the external heat exchange fluid coil 10-1 of the three-medium heat accumulator 10, and the fourth heat exchanger 5 through the third external heat exchange fluid pipeline 2-4. The first and third ports of the three-way valves 1-4 constitute a medium-temperature heating cycle; the second water pump 11, the third external heat exchange fluid pipeline 2-4, the third and first ports of the third three-way valves 1-3, the second external heat exchange fluid pipeline 2-3, the second and third ports of the first three-way valves 1-1, the heat exchanger 5, the second and third ports of the second three-way valves 1-2, the second and third ports of the fourth three-way valves 1-4, and the heating terminal 12 are connected in sequence to form a high-temperature heating cycle.

[0047] This embodiment discloses a combined cooling and heating temperature control method, whose working modes include heat pump heat storage mode, heat pump cooling mode, heat pump medium temperature heating mode, three-medium heat accumulator medium temperature heating mode, and heat pump high temperature heating mode.

[0048] like Figure 2 As shown, the heat pump cooling mode / heat pump heat storage mode:

[0049] When solar energy is abundant and cooling is required, the electricity provided by the solar photovoltaic module 7 drives the heat pump compressor 8 to work. The heat pump system operates in a forward cycle. The three-medium heat storage tank 10 serves as a condenser and heat storage tank, and the heat exchanger 5 serves as an evaporator. After being compressed by the compressor 8, the refrigerant flows into the refrigerant coil 10-2 of the three-medium heat storage tank 10 to condense. The condensation heat is transferred to the heat storage material 10-3 through the fins 10-4 for heat storage. The refrigerant, after releasing heat through condensation, enters the refrigerant channel 5-1 of the heat exchanger 5 through the expansion valve 6 to evaporate. At this time, by controlling the first three-way valve 1-1 and the second three-way valve 1-2, the cold terminal 3 is connected to the heat exchanger 5, opening the cold circulation. The heat exchange fluid of the cold terminal 3 enters the heat exchanger 5 to absorb the cooling generated by the evaporation of the refrigerant. After evaporation, the refrigerant enters the compressor 8 again through the four-way reversing valve 9 for the next cycle.

[0050] like Figure 3 As shown, heat pump cooling mode / heat pump medium-temperature heating mode:

[0051] When there is sufficient solar energy and a demand for both cooling and medium-temperature heating, the solar photovoltaic module 7 drives the compressor 8 to work, the heat pump system circulates in the forward direction, the three-medium heat storage tank 10 acts as a condenser and heat exchanger, and the heat exchanger 5 acts as an evaporator. By adjusting the first three-way valve 1-1 and the second three-way valve 1-2, the cold terminal 3 is connected to the heat exchanger 5; by adjusting the third three-way valve 1-3 and the fourth three-way valve 1-4, the heat terminal 12 is connected to the three-medium heat storage tank 10.

[0052] After being compressed by the compressor 8, the refrigerant flows into the refrigerant coil 10-2 of the three-medium heat accumulator 10 for condensation. The condensation heat is transferred to the external heat exchange fluid in the external heat exchange fluid coil 10-1 through the fins 10-4, providing medium-temperature heating to the heat-using terminal 12. After condensation and heat release, the refrigerant enters the refrigerant channel 5-1 of the heat exchanger 5 through the expansion valve 6 for evaporation. The heat exchange fluid of the cold terminal 3 enters the heat exchanger 5 to absorb the cooling energy generated by the refrigerant evaporation. After evaporation, the refrigerant re-enters the compressor 8 through the four-way reversing valve 9 for the next cycle.

[0053] like Figure 4 As shown, the three-medium heat accumulator medium-temperature heating mode:

[0054] When solar energy is insufficient or there is a demand for medium-temperature heat at night, the heat pump does not work. By adjusting the third three-way valve 1-3 and the fourth three-way valve 1-4, the heat exchange fluid of the heat-using terminal 12 enters the external heat exchange fluid coil 10-1 of the three-medium heat storage device 10 through the medium-temperature heat-using cycle. The heat stored in the heat storage material 10-3 is transferred to 10-1 through the fins 10-4, supplying medium-temperature heat to the heat-using terminal 12.

[0055] like Figure 5As shown, the heat pump high-temperature heating mode:

[0056] When there is a high-temperature heat demand, the heat pump compressor 8 is driven by the solar photovoltaic module 7 or the power grid, the four-way reversing valve 9 is reversed, and the heat pump system operates in reverse cycle. The three-medium heat accumulator 10 is the evaporator, and the heat exchanger 5 is the condenser. By adjusting the first three-way valve 1-1, the second three-way valve 1-2, the third three-way valve 1-3, and the fourth three-way valve 1-4, the heat terminal 12 is connected to the heat exchanger 5, and the high-temperature heat cycle is turned on.

[0057] The refrigerant enters the refrigerant coil 10-2 of the three-medium heat accumulator 10, absorbs the heat released by the heat storage material 10-3 through the fins 10-4, evaporates at a medium temperature, and after being compressed by the compressor 8, enters the refrigerant channel 5-1 of the heat exchanger 5 to release high-temperature condensation heat. At this time, the heat exchange fluid of the heat-using terminal 12 enters the gap between the fins 5-2 of the heat exchanger 5, absorbs the high-temperature condensation heat of the refrigerant through the fins 5-2, and then supplies high-temperature heat to the heat-using terminal 12.

[0058] This system combines solar photovoltaics with heat pumps and thermal storage. It fully utilizes solar energy by switching between forward and reverse cycles of the heat pump. It can flexibly switch between different working modes in real time to regulate the output temperature according to different quality requirements. The system has the advantages of simple structure, high thermal storage density, low energy consumption, and low operating cost, and has great application potential in the field of heat pump building thermal management.

[0059] The above embodiments are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A heat pump system with thermal storage, characterized in that: It includes a heat exchanger (5), an expansion valve (6), a three-medium heat accumulator (10), a four-way reversing valve (9), and a heat pump compressor (8) connected in sequence through a refrigerant pipeline (2-2). The heat exchanger (5) is provided with a refrigerant channel (5-1) that connects to the refrigerant pipeline (2-2), and an external heat exchange fluid (5-3) circulates within the heat exchanger (5). The heat exchanger (5) is provided with an inlet and outlet for the external heat exchange fluid (5-3) to circulate, and a first three-way valve (1-1) and a second three-way valve (1-2) are respectively provided at the inlet and outlet. The cold terminal (3) is connected to the first three-way valve (1-1) and the second three-way valve (1-2) through the first external heat exchange fluid pipeline (2-1), and a first water pump (4) is provided on the first external heat exchange fluid pipeline (2-1). The three-medium heat accumulator (10) is provided with a refrigerant coil (10-2) connected to the refrigerant pipeline (2-2), an external heat exchange fluid coil (10-1) connected to the heat-using terminal (12), and heat storage material (10-3) filled in the three-medium heat accumulator (10); a third three-way valve (1-3) and a fourth three-way valve (1-4) connected to the inlet and outlet of the external heat exchange fluid coil (10-1) are provided outside the three-medium heat accumulator (10); the inlet and outlet ports of the heat-using terminal (12) are respectively connected to the third three-way valve (1-3) and the fourth three-way valve (1-4) through the third external heat exchange fluid pipeline (2-4); and a second water pump (11) is provided on the third external heat exchange fluid pipeline (2-4). The first three-way valve (1-1) and the third three-way valve (1-3) are connected through the second external heat exchange fluid pipeline (2-3); the second three-way valve (1-2) and the fourth three-way valve (1-4) are connected through the second external heat exchange fluid pipeline (2-3). The operating modes include heat pump thermal storage mode, heat pump cooling mode, heat pump medium temperature heating mode, three-medium accumulator medium temperature heating mode, and heat pump high temperature heating mode. The heat pump cooling mode / heat pump thermal storage mode: When solar energy is sufficient and cooling supply is required, the power provided by the solar photovoltaic module (7) drives the heat pump compressor (8) to work. The heat pump system works in a positive cycle. The three-medium heat storage tank (10) serves as the condenser and heat storage tank, and the heat exchanger (5) serves as the evaporator. After the refrigerant is compressed by the compressor (8), it flows into the refrigerant coil (10-2) of the three-medium heat storage tank (10) to condense. The condensation heat is transferred to the heat storage material (10-3) through the fins. The heat is stored. After the refrigerant releases heat after condensation, it enters the refrigerant channel (5-1) of the heat exchanger (5) through the expansion valve (6) to evaporate. At this time, by controlling the first three-way valve (1-1) and the second three-way valve (1-2), the cold terminal (3) is connected to the heat exchanger (5). The cold cycle is opened, and the heat exchange fluid of the cold terminal (3) enters the heat exchanger (5) to absorb the cooling generated by the evaporation of the refrigerant. After the refrigerant evaporates, it enters the compressor (8) again through the four-way reversing valve (9) for the next cycle. Heat pump cooling mode / Heat pump medium temperature heating mode: When there is sufficient solar energy and a demand for both cold and medium-temperature heat, the solar photovoltaic module (7) drives the compressor (8) to work, the heat pump system circulates in the forward direction, the three-medium heat storage tank (10) acts as a condenser and heat exchanger, and the heat exchanger (5) acts as an evaporator. By adjusting the first three-way valve (1-1) and the second three-way valve (1-2), the cold terminal (3) is connected to the heat exchanger (5); by adjusting the third three-way valve (1-3) and the fourth three-way valve (1-4), the heat-using terminal (12) is connected to the three-medium heat storage tank (10), and the medium-temperature heat cycle is turned on. After being compressed by the compressor (8), the refrigerant flows into the refrigerant coil (10-2) of the three-medium heat accumulator (10) and condenses. The condensation heat is transferred to the external heat exchange fluid coil (10-1) through the fins to provide medium-temperature heating to the heat-using terminal (12). After the refrigerant releases heat after condensation, it enters the refrigerant channel (5-1) of the heat exchanger (5) through the expansion valve (6) to evaporate. The heat exchange fluid of the cold terminal (3) enters the heat exchanger (5) to absorb the cold energy generated by the evaporation of the refrigerant. After the refrigerant evaporates, it enters the compressor (8) again through the four-way reversing valve (9) for the next cycle. Three-medium heat accumulator medium-temperature heating mode: When solar energy is insufficient or there is a medium-temperature heat demand at night, the heat pump does not work. By adjusting the third three-way valve (1-3) and the fourth three-way valve (1-4), the heat exchange fluid of the heat terminal (12) enters the external heat exchange fluid coil (10-1) of the three-medium heat accumulator (10) through the medium-temperature heat cycle. The heat stored in the heat storage material (10-3) is transferred to the external heat exchange fluid coil (10-1) through the fins, and medium-temperature heat is supplied to the heat terminal (12). Heat pump high-temperature heating mode: When there is a high-temperature heat demand, the heat pump compressor (8) is driven by the solar photovoltaic module (7) or the power grid. The four-way reversing valve (9) is reversed, and the heat pump system works in reverse cycle. The three-medium heat storage tank (10) is the evaporator, and the heat exchanger (5) is the condenser. By adjusting the first three-way valve (1-1), the second three-way valve (1-2), the third three-way valve (1-3), and the fourth three-way valve (1-4), the heat terminal (12) is connected to the heat exchanger (5), and the high-temperature heat cycle is turned on. The refrigerant enters the refrigerant coil (10-2) of the three-medium heat accumulator (10), absorbs the heat released by the heat storage material (10-3) through the fins, evaporates at a medium temperature, and after being compressed by the compressor (8), enters the refrigerant channel (5-1) of the heat exchanger (5) to release high-temperature condensation heat. At this time, the heat exchange fluid of the heat-using terminal (12) enters the fin gap of the heat exchanger (5), absorbs the high-temperature condensation heat of the refrigerant through the fins, and then supplies high-temperature heat to the heat-using terminal (12).

2. The heat pump system for thermal storage according to claim 1, characterized in that: Multiple fins are respectively provided in the heat exchanger (5) and the three-medium accumulator (10).

3. The heat pump system for thermal storage according to claim 1, characterized in that: The heat pump compressor (8) is driven by a solar photovoltaic module (7) or supplied with auxiliary power by the grid.

4. The heat pump system for thermal storage according to claim 1, characterized in that: The heat storage material (10-3) is one of phase change heat storage material, adsorption heat storage material or thermochemical heat storage material.

5. The heat pump system for thermal storage according to claim 1, characterized in that: The heat pump compressor (8) is one of the following: piston compressor, screw compressor, centrifugal compressor, and linear compressor.

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