CN211552119U - Heat accumulation type direct expansion type photovoltaic-solar heat pump electricity and heat cogeneration system - Google Patents

Abstract

The utility model discloses a heat storage type direct expansion photovoltaic-solar heat pump electricity and heat cogeneration system; the system comprises a compressor, a condenser, an expansion valve, a three-way valve, a photovoltaic heat storage evaporator, a first one-way valve, an air-cooled evaporator and a second one-way valve; the outlet of the compressor is sequentially connected with a condenser, an expansion valve, a three-way valve, a photovoltaic heat storage evaporator, a first one-way valve and an air-cooled evaporator in series through pipelines, and is finally connected to the inlet of the compressor; the other passage of the three-way valve is directly connected with an inlet pipeline of the air-cooled evaporator through a second single-phase valve; the three-way valve is used as a selection switch of the two liquid working medium circulation loops; the solar energy is utilized to the maximum extent by the system, the photovoltaic module is protected from being damaged due to overhigh working temperature through selection of the two loops, the performance of the heat pump is improved, and domestic hot water and domestic electricity can be provided at the same time.

Description

A heat storage type direct expansion photovoltaic-solar heat pump combined electricity and heat supply system

technical field

The utility model relates to the field of solar heating, in particular to a heat storage type direct expansion photovoltaic-solar heat pump combined electricity and heat supply system.

Background technique

Solar energy resources are extremely common, non-polluting and inexhaustible, in line with the current requirements of the world's environmental protection. The traditional solar thermal utilization technology has been popularized in my country, but the development of the technology is restricted due to the problems of low energy density, non-uniformity and intermittency of solar energy. In the application of solar photovoltaic power generation, there are also cases where the module temperature is too high, which reduces the power generation efficiency.

The direct expansion photovoltaic-solar heat pump system is one of the comprehensive utilization technologies of solar thermal photovoltaics. The heat pump cycle is used as the heat transfer path of the system. The photovoltaic cell and the heat pump evaporator are integrated into one, and the heat obtained by the photothermal conversion is first converted by the working fluid. The evaporation process is absorbed, and the high temperature output at the condensation end is circulated through the heat pump. On the one hand, the terminal temperature of the heat output of the photothermal conversion can be guaranteed. On the other hand, under the evaporative cooling of the heat pump working fluid, the working temperature of the photovoltaic cell is lower, and the photoelectric efficiency is also improved.

Combined with phase-change heat storage materials with high thermal conductivity, it can effectively solve the problem of unconcentrated and unstable sunlight, and further improve the comprehensive utilization efficiency of solar energy and the heat collection efficiency of photovoltaic evaporators. Therefore, it is expected to design a simple and efficient photovoltaic-solar heat pump system that fully utilizes solar energy resources.

SUMMARY OF THE INVENTION

The utility model provides a heat storage type direct-expansion photovoltaic-solar heat pump combined electricity and heat supply system, which solves the factors of solar instability in the heat pump part in the direct-expansion photovoltaic-solar heat pump system, and damage caused by excessive working temperature. The technical problem; the utility model aims to make the most full use of solar energy resources to improve the solar energy utilization efficiency and the performance of the heat pump.

The utility model is realized through the following technical solutions:

A thermal storage type direct expansion photovoltaic-solar heat pump combined electricity and heat supply system, comprising two liquid working medium circulation loops composed of the following components: a compressor 1, a condenser 2, an expansion valve 3, a three-way valve 4, a photovoltaic storage Hot evaporator 5, first one-way valve 6, air-cooled evaporator 7, second one-way valve 8;

The outlet of the compressor 1 is connected in series with the condenser 2, the expansion valve 3, the three-way valve 4, the photovoltaic heat storage evaporator 5, the first one-way valve 6 and the air-cooled evaporator 7 in sequence through pipelines. inlet of compressor 1;

The other passage of the three-way valve 4 is directly connected to the inlet pipeline of the air-cooled evaporator 7 through the second one-way valve 8;

The three-way valve 4 is used as a selector switch for two liquid working medium circulation loops;

When the A passage of the three-way valve 4 is opened and the B passage is closed, the liquid working medium from the expansion valve 3 first enters the photovoltaic heat storage evaporator 5, and then enters the downstream components in sequence, and the first circuit is connected at this time;

When the A passage of the three-way valve 4 is closed and the B passage is opened, the liquid working medium from the expansion valve 3 passes through the second one-way valve 8, directly enters the air-cooled evaporator 7, and then enters the downstream components in sequence. circuit connected.

The photovoltaic heat storage evaporator 5 includes a heat exchange coil 66 for introducing a liquid working medium, a photovoltaic cell plate 11, a thermally conductive silica gel layer 22 that also serves as an adhesive, and a composite phase change material that are sequentially bonded together. layer 33 , insulation layer 44 and back plate 55 ; the outer wall of the heat exchange coil 66 is coated with thermally conductive silica gel, and then embedded in the composite phase change material layer 33 .

The phase change temperature range of the composite phase change material layer 33 is 20°C to 35°C; the phase change material layer is mainly composed of paraffin and expanded graphite in a ratio of 75 to 90:1; The paraffin is added into the expanded graphite and stirred thoroughly until the paraffin is fully absorbed by the expanded graphite; then it is pressed into a desired plate shape, and then adhered to the back of the photovoltaic cell panel 11 through the thermally conductive silica gel layer 22 . The specific phase transition temperature can be selected according to the environmental characteristics of different regions.

Both the photovoltaic thermal storage evaporator 5 and the condenser 2 have built-in temperature sensors; the built-in sensor of the photovoltaic thermal storage evaporator 5 is used to detect the working temperature of the photovoltaic cell panel 11 to generate electricity and the thermal storage temperature of the composite phase change material layer 33; The temperature sensor built into the condenser 2 is used to detect the water temperature.

The condenser 2 includes a cold water inlet and a hot water outlet.

The liquid working medium is a refrigerant.

The thermal insulation layer 44 is thermal insulation cotton; the back plate 55 is a metal back plate.

The photovoltaic cell panel 11 is a polycrystalline silicon photovoltaic cell panel; the polycrystalline silicon photovoltaic cell panel is connected to the battery unit 9 .

The three-way valve 4 is an L-shaped three-way valve.

The operation method of the heat storage type direct expansion photovoltaic-solar heat pump electric heating combined supply system of the utility model comprises the following steps:

The first loop cycle operation step; the A channel of the three-way valve 4 is opened, and the B channel is closed; the photovoltaic heat storage evaporator 5 receives solar radiation, and the short-wave part of the solar radiation is converted into electrical energy by the photovoltaic panel 11 and stored in the battery. In the unit 9, the long-wave part is absorbed and stored by the composite phase change material layer 33 to heat up the refrigerant in the heat exchange coil 66, and is then heated by the air-cooled evaporator 7 as an auxiliary heat exchanger for a second time and then enters into compression. Machine 1, the compressor 1 compresses and heats the refrigerant after the secondary temperature rise to a superheated steam state, and then sends it into the metal coil of the condenser 2, and exchanges heat with the water in the condenser 2, and the refrigerant in the condenser 2 At the same time, the water in the condenser 2 is heated and used for heating or directly used as domestic hot water, and the cooled steam is throttled and depressurized by the expansion valve 3 and then circulated downward in sequence to enter the subsequent evaporation. The first loop not only improves the comprehensive utilization efficiency of solar energy and the heat collection efficiency of the photovoltaic evaporator, but also effectively cools the photovoltaic panels, improves the photovoltaic power generation efficiency, and protects the photovoltaic modules.

The second loop cycle operation step; the A passage of the three-way valve 4 is closed and the B passage is opened; only the air-cooled evaporator 7 is used as a heat exchanger to provide energy for refrigerant evaporation, and the photovoltaic heat storage evaporator 5 is only used as a storage Heaters store or convert heat.

Compared with the prior art, the utility model has the following advantages and effects:

The utility model has two circulating operation loops, which can be switched freely according to the environmental conditions; the solar energy is utilized to the maximum extent, the photovoltaic components are protected from damage due to excessive working temperature, and the performance of the heat pump is improved at the same time. Water can also provide domestic electricity.

The first loop of the utility model operates cyclically, and the photovoltaic cell plate transfers the heat of sunlight to the composite phase-change material layer, and the composite phase-change material layer transfers the heat to the refrigerant to heat the refrigerant; the air-cooled evaporator is an auxiliary changer. The heat exchanger absorbs energy from the environment in the absence of sunlight or rainy weather to make up for the lack of heat absorption of the photovoltaic evaporator and ensure the normal operation of the heat pump system. When the solar radiation reaches a certain intensity during the day, the photovoltaic power generation system can provide users with electrical energy. The composite phase change material layer absorbs heat energy, which can slow down the heating rate of the photovoltaic panels and improve the uniformity of the heating of the photovoltaic panels. When the temperature is higher than 50 ℃, the first loop can be turned on to cool down the photovoltaic panels to prevent thermal damage to the photovoltaic modules.

The second loop of the utility model operates in a cycle as a single air-cooled evaporator heat pump circulation system; in this loop, the air-cooled evaporator acts as the only heat exchanger to provide energy for refrigerant evaporation, thus ensuring that the photovoltaic heat storage evaporator can be used as a The heat accumulator stores heat for use by the user at other times.

The phase change temperature range of the utility model is 20°C to 35°C; the phase change material layer is mainly composed of paraffin and expanded graphite in a ratio of 75 to 90:1; the compounding method is to add the heated and melted paraffin into the expanded graphite for Stir well until the paraffin is fully absorbed by the expanded graphite; then press it into the desired plate shape, and then adhere to the back of the photovoltaic cell panel through the thermally conductive silica gel layer. The composite phase change material layer has a simple preparation process and good heat exchange effect, that is, it can be applied to various outdoor temperatures and has a large phase change heat storage capacity. The heat transfer ability between the agents, thereby greatly improving the thermal conductivity.

Description of drawings

Fig. 1 is a structural block diagram of the thermal storage type direct expansion photovoltaic-solar heat pump combined electricity and heat supply system of the present invention.

FIG. 2 is a schematic structural diagram of the photovoltaic heat storage evaporator 5 in FIG. 1 .

FIG. 3 is a schematic diagram of the internal cross-sectional structure of FIG. 2 .

Detailed ways

The present utility model will be further described in detail below in conjunction with specific embodiments.

As shown in Figure 1-3. The utility model discloses a heat storage type direct expansion photovoltaic-solar heat pump combined electricity and heat supply system, comprising two liquid working medium circulation loops composed of the following components: a compressor 1, a condenser 2, an expansion valve 3, a three-way Valve 4, photovoltaic heat storage evaporator 5, first one-way valve 6, air-cooled evaporator 7, second one-way valve 8;

The outlet of the compressor 1 is connected in series with the condenser 2, the expansion valve 3, the three-way valve 4, the photovoltaic heat storage evaporator 5, the first one-way valve 6 and the air-cooled evaporator 7 in sequence through pipelines. inlet of compressor 1;

The other passage of the three-way valve 4 is directly connected to the inlet pipeline of the air-cooled evaporator 7 through the second one-way valve 8;

The three-way valve 4 is used as a selector switch for two liquid working medium circulation loops;

When the A passage of the three-way valve 4 is opened and the B passage is closed, the liquid working medium from the expansion valve 3 first enters the photovoltaic heat storage evaporator 5, and then enters the downstream components in sequence, and the first circuit is connected at this time;

When the A passage of the three-way valve 4 is closed and the B passage is opened, the liquid working medium from the expansion valve 3 passes through the second one-way valve 8, directly enters the air-cooled evaporator 7, and then enters the downstream components in sequence. circuit connected.

The photovoltaic heat storage evaporator 5 includes a heat exchange coil 66 for introducing a liquid working medium, a photovoltaic cell plate 11, a thermally conductive silica gel layer 22 that also serves as an adhesive, and a composite phase change material that are sequentially bonded together. layer 33 , insulation layer 44 and back plate 55 ; the outer wall of the heat exchange coil 66 is coated with thermally conductive silica gel, and then embedded in the composite phase change material layer 33 .

The phase change temperature range of the composite phase change material layer 33 is 20°C to 35°C; the phase change material layer is mainly composed of paraffin and expanded graphite in a ratio of 75 to 90:1; The paraffin is added into the expanded graphite and stirred thoroughly until the paraffin is fully absorbed by the expanded graphite; then it is pressed into a desired plate shape, and then adhered to the back of the photovoltaic cell panel 11 through the thermally conductive silica gel layer 22 . The specific phase transition temperature can be selected according to the environmental characteristics of different regions.

Other phase change materials that can achieve a phase transition temperature range of 20°C to 35°C can also be used according to specific application requirements; for example, according to the above ratio (or other ratios), sodium sulfate decahydrate is removed from expanded graphite or diatomaceous earth to composite preparation, etc. .

Both the photovoltaic thermal storage evaporator 5 and the condenser 2 have built-in temperature sensors; the built-in sensor of the photovoltaic thermal storage evaporator 5 is used to detect the working temperature of the photovoltaic cell panel 11 to generate electricity and the thermal storage temperature of the composite phase change material layer 33; The temperature sensor built into the condenser 2 is used to detect the water temperature.

The condenser 2 includes a cold water inlet and a hot water outlet. The liquid working medium is a refrigerant (working medium R22).

The thermal insulation layer 44 is thermal insulation cotton; the back plate 55 is a metal back plate.

The photovoltaic cell panel 11 is a polycrystalline silicon photovoltaic cell panel; the polycrystalline silicon photovoltaic cell panel is connected to the battery unit 9 .

The three-way valve 4 is an L-shaped three-way valve. The compressor 1 compresses and heats the refrigerant to a superheated vapor state of high temperature and high pressure to provide power for the heat pump cycle.

The condenser 2 is a 150L water tank, and a metal coil (heat exchange copper tube) is arranged in the water tank to exchange heat with the high-temperature and high-pressure steam in the metal coil and the water in the water tank, and the refrigerant is cooled in the condenser, and at the same time in the water tank. The water can be heated for domestic hot water for heating or direct use.

The expansion valve 3 throttles and reduces the pressure of the condensed refrigerant before sending it to the subsequent working medium evaporation stage.

The three-way valve 4 (L-type) acts as a channel selection switch, which determines the refrigerant circulation loop; in the first loop, the photovoltaic heat storage evaporator 5, on the one hand, absorbs the short wave in the solar radiation to generate electricity, and on the other hand acts as a The collector absorbs and stores the long-wave energy in the solar radiation, which can provide energy for the evaporation of the refrigerant, so that the refrigerant can reach a superheated state after sufficient heat exchange.

The air-cooled evaporator 7 is an auxiliary heat exchanger, which absorbs energy from the environment in insufficient sunlight or rainy weather to make up for the lack of heat absorbed by the photovoltaic heat storage evaporator 5 to ensure the normal operation of the heat pump system. In the second circuit, the air-cooled evaporator 7 acts as the only heat exchanger to provide energy for the evaporation of the refrigerant.

The system of the present invention converts solar energy into electrical energy through the photovoltaic effect; the photovoltaic cell panel 11 (polysilicon photovoltaic cell panel) is the photovoltaic component in the photovoltaic heat storage evaporator, which can directly convert the sunlight into electric energy to generate current.

The battery pack 9 includes a battery pack and a charge and discharge controller, which can store the electrical energy generated by the polycrystalline silicon photovoltaic panels and discharge it when the user needs to use it, and can decide to add inverters, AC power distribution cabinets, etc. according to the needs of the user. .

As shown in Figure 2. The photovoltaic heat storage evaporator 5 is a system composed of polycrystalline silicon photovoltaic panels and phase change materials. In the solar radiation received by the system, the short-wave part is converted into current output by the photovoltaic cells, and the long-wave part is absorbed by the phase change material and then used as a heat pump Heat source for the evaporator.

Photovoltaic panels use the photovoltaic effect to generate electricity and also act as collectors to absorb the energy of sunlight.

The thermally conductive silica gel 22 has a high thermal conductivity, and acts as an adhesive to connect the composite phase change material layer 33 and the photovoltaic cell panel 11 , so that the energy received by the photovoltaic cell panel 11 is conducted into the composite phase change material layer 33 .

The composite phase change material layer 33 can store energy by utilizing its latent heat of phase change, and can also conduct heat to the heat exchange coil 66 at the same time.

The thermal insulation layer 44 has a thermal insulation function, which can greatly reduce the heat dissipation stored in the composite phase change material layer 33 .

The back plate 55 serves as an outer frame to wrap the inner composite phase change material layer 33; the heat exchange coil 66 carries refrigerant, and the outer wall of the heat exchange coil 66 is embedded in the composite phase change material layer 33 through thermal conductive silica gel, and is the heat exchange coil 66 and the heat exchange coil 66. Refrigerant (working medium R22) heat exchange medium.

As mentioned above; the phase change temperature range of the composite phase change material layer 33 is 20°C to 35°C; the phase change material layer is mainly composed of paraffin wax and expanded graphite in a ratio of 75 to 90:1; the composite method is to heat and melt The last paraffin (RT28) was added to the expanded graphite and stirred thoroughly until the paraffin was fully absorbed by the expanded graphite; the composite phase change material was pressed by a tablet machine to form a 10cm×10cm×3cm square, and then adhered to the thermal conductive silica gel layer. Behind the photovoltaic panel; the composite phase change material formed by pressing has the phase change temperature platform of paraffin, that is, it can be applied to various outdoor temperatures and has a large phase change heat storage capacity. At the same time, it is obtained by compounding with expanded graphite. High thermal conductivity, which can increase the heat transfer capacity with the refrigerant. The specific phase transition temperature can be selected according to the environmental characteristics of different regions.

A temperature sensor can be set inside the photovoltaic heat storage evaporator to improve the accuracy of the collected data. It can be set between the back of the photovoltaic panel and the composite phase change material layer to detect the working temperature of the photovoltaic panel and the phase change material for power generation. The heat storage temperature can provide a reference for the appropriate time for the heat pump to start.

A temperature sensor can be set in the condenser to detect the temperature of the heated water in the condenser and provide temperature reference data for use.

When the solar radiation reaches a certain intensity during the day, the photovoltaic power generation system can provide users with electrical energy. The composite phase change material layer absorbs heat energy, which can slow down the heating rate of the photovoltaic panels and improve the uniformity of the heating of the photovoltaic panels. When the temperature is higher than 50°C, the first loop circulation mode can be turned on to cool down the photovoltaic panels to prevent thermal damage to the photovoltaic modules.

When the user needs heating or hot water during the day, the first loop circulation mode can be turned on by turning the three-way valve, and the heat received by the photovoltaic panels can be used to provide energy for the evaporation of the refrigerant and improve the performance of the heat pump.

When the user needs heating or hot water at night, the first loop circulation mode can be turned on, and the composite phase change material layer in the photovoltaic heat storage evaporator releases the energy stored during the day, which can provide energy for refrigerant evaporation.

When the temperature difference between day and night is large, if there is a demand for water during the day, the second loop circulation mode can be selected through the three-way valve. When the temperature is high, only the air-cooled evaporator can ensure the performance of the heat pump, and the photovoltaic heat storage evaporator can be used to ensure the performance of the heat pump. The solar energy is stored for heat, and the first circuit circulation mode can be turned on again when the temperature is low at night, and the heat storage during the day is used to heat the refrigerant to improve the performance of the heat pump; the whole system complements each other with energy to serve users for heating and electricity consumption.

The operation method of the heat storage type direct expansion photovoltaic-solar heat pump electric heating combined supply system of the utility model comprises the following steps:

The first loop cycle operation step; the A channel of the three-way valve 4 is opened, and the B channel is closed; the photovoltaic heat storage evaporator 5 receives solar radiation, and the short-wave part of the solar radiation is converted into electrical energy by the photovoltaic panel 11 and stored in the battery. In the unit 9, the long-wave part is absorbed and stored by the composite phase change material layer 33 to heat up the refrigerant in the heat exchange coil 66, and is then heated by the air-cooled evaporator 7 as an auxiliary heat exchanger for a second time and then enters into compression. Machine 1, the compressor 1 compresses and heats the refrigerant after the secondary temperature rise to a superheated steam state, and then sends it into the metal coil of the condenser 2, and exchanges heat with the water in the condenser 2, and the refrigerant in the condenser 2 At the same time, the water in the condenser 2 is heated and used as domestic hot water for heating or direct use, and the cooled steam is throttled and depressurized by the expansion valve 3 and then circulated downward in sequence, and has entered the subsequent evaporation. Stage reciprocating cycle; the first loop cycle is suitable for use in insufficient sunlight or rainy weather, and absorbs energy from the environment in insufficient sunlight or rainy weather to make up for the lack of heat absorption by the photovoltaic heat storage evaporator 5, so that the heat storage type is directly The expansion photovoltaic-solar heat pump cogeneration system is operating normally.

When the solar radiation reaches a certain intensity during the day, the photovoltaic power generation system can provide users with electrical energy. The composite phase change material layer absorbs heat energy, which can slow down the heating rate of the photovoltaic panels and improve the uniformity of the heating of the photovoltaic panels. When the temperature is higher than 50 °C, the first loop can be turned on to cool down the photovoltaic panels to prevent thermal damage to the photovoltaic modules.

The second loop cycle operation step; the A passage of the three-way valve 4 is closed and the B passage is opened; only the air-cooled evaporator 7 is used as a heat exchanger to provide energy for refrigerant evaporation, and the photovoltaic heat storage evaporator 5 is only used as a storage Heaters store or convert heat for use by users at other times.

The present invention will be further described below through two specific embodiments.

Example 1:

In the southern region of my country, taking a city as an example, the annual average temperature is between 20°C and 22°C, and the average temperature in summer is higher than 30°C. Therefore, paraffin and expanded graphite with a phase transition temperature of 28°C are selected to composite phase change materials. The composite method is to add the heated and melted paraffin into the expanded graphite for full stirring until the paraffin is fully absorbed by the expanded graphite; the composite phase change material is pressed by a tablet press to form a square, and then adhered to the photovoltaic cell panel by thermal conductive silica gel Behind; the composite phase change material formed by pressing has the phase transition temperature platform of paraffin, and the phase transition range is 20 ℃ ~ 36 ℃, that is, it can be used at outdoor temperature, and has a large phase change heat storage capacity. The composite of expanded graphite obtains a high thermal conductivity, which can increase the heat transfer capacity with the working medium.

When the heat pump is not turned on, the phase change material can store the heat energy in the solar radiation, and then control the temperature rise of the photovoltaic panel; during the operation of the first circuit, the heat energy in the solar radiation can pass through the phase The variable material is conducted into the heat exchange coil for refrigerant evaporation, which increases the evaporation temperature of the refrigerant and improves the performance of the heat pump. At the same time, the temperature of the photovoltaic panel is cooled by the refrigerant, and the photoelectric efficiency is greatly improved.

Example 2:

In the northern region of my country, taking a city as an example, the annual average temperature is 10°C to 12°C, the temperature in winter is low, and the pure heat pump water heater cannot meet the heating demand, the utility model can select a composite phase change material with a phase change temperature of 20°C;

In this embodiment, the composite phase change material is formed by compounding paraffin wax with a phase transition temperature of 20° C. and expanded graphite, and the compounding method is to add the heated and melted paraffin wax into the expanded graphite and fully stir until the paraffin wax is fully absorbed by the expanded graphite; The composite phase change material is pressed by a tablet press to form a square, and then adhered to the back of the photovoltaic cell panel through thermally conductive silica gel; the composite phase change material formed by pressing has the phase transition temperature platform of paraffin, and the phase transition range is 12°C～28°C , that is, it can be used at outdoor temperature, and has a large phase-change heat storage capacity, and at the same time, a high thermal conductivity is obtained by compounding with expanded graphite, which can increase the heat exchange capacity with the refrigerant.

In the case of low temperature in winter, the first loop is operated, and there is a sufficient temperature gradient between the phase change material and the working fluid, that is, the heat energy in the solar irradiation can be used to effectively provide a heat source for the evaporation of the refrigerant in the heat pump, so as to ensure the efficiency of the heat pump. Normal operation, and the heat pump frosting problem can be solved by the energy storage of the phase change material.

As described above, the present invention can be well realized. The utility model combines the phase-change heat storage material with high thermal conductivity, effectively solves the problem of unconcentrated and unstable sunlight, further improves the comprehensive utilization efficiency of solar energy and the heat collection efficiency of the photovoltaic evaporator, and can also effectively cool the photovoltaic panel. Improve photovoltaic power generation efficiency and protect photovoltaic modules.

The embodiments of the present invention are not limited by the above-mentioned examples, and any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principle of the present invention should be equivalent replacement methods. Included within the scope of protection of the present invention.

Claims (9)

1. The utility model provides a heat accumulation type directly expands formula photovoltaic-solar thermal energy pump electricity and heat allies oneself with confession system, its characterized in that includes two liquid working medium circulation circuit that following each part constitutes: the system comprises a compressor (1), a condenser (2), an expansion valve (3), a three-way valve (4), a photovoltaic heat storage evaporator (5), a first one-way valve (6), an air-cooled evaporator (7) and a second one-way valve (8);

an outlet of the compressor (1) is sequentially connected with the condenser (2), the expansion valve (3), the three-way valve (4), the photovoltaic heat storage evaporator (5), the first one-way valve (6) and the air-cooled evaporator (7) in series through pipelines, and finally connected to an inlet of the compressor (1);

the other passage of the three-way valve (4) is directly connected with an inlet pipeline of the air-cooled evaporator (7) through a second single-way valve (8);

the three-way valve (4) is used as a selection switch of two liquid working medium circulation loops;

when the A passage of the three-way valve (4) is opened and the B passage is closed, the liquid working medium from the expansion valve (3) firstly enters the photovoltaic heat storage evaporator (5) and then sequentially enters each component at the downstream, and at the moment, the first loop is communicated;

when the A passage of the three-way valve (4) is closed and the B passage is opened, the liquid working medium from the expansion valve (3) directly enters the air-cooled evaporator (7) through the second single valve (8) and then sequentially enters each component at the downstream, and at the moment, the second loop is communicated.

2. The heat storage type direct-expansion photovoltaic-solar heat pump combined heat and power system according to claim 1, wherein: the photovoltaic heat storage evaporator (5) comprises a heat exchange coil (66) for introducing a liquid working medium, a photovoltaic cell panel (11), a heat conduction silica gel layer (22) which is also used as an adhesive, a composite phase change material layer (33), a heat insulation layer (44) and a back plate (55) which are sequentially attached together; after the outer wall of the heat exchange coil (66) is coated with heat-conducting silica gel, the heat exchange coil is embedded in the composite phase change material layer (33).

3. The heat storage type direct-expansion photovoltaic-solar heat pump combined heat and power system according to claim 2, wherein: the phase change temperature range of the composite phase change material layer (33) is 20-35 ℃, and the composite phase change material layer is adhered to the back of the photovoltaic cell panel (11) through the heat conduction silica gel layer (22).

4. The heat storage type direct-expansion photovoltaic-solar heat pump combined heat and power system according to claim 3, wherein: temperature sensors are arranged in the photovoltaic heat storage evaporator (5) and the condenser (2); a sensor arranged in the photovoltaic heat storage evaporator (5) is used for detecting the working temperature of the photovoltaic cell panel (11) for power generation and the heat storage temperature of the composite phase change material layer (33); a temperature sensor built in the condenser (2) is used for detecting the water temperature.

5. The heat storage type direct-expansion photovoltaic-solar heat pump combined heat and power system according to claim 4, wherein: the condenser (2) comprises a cold water inlet and a hot water outlet.

6. The heat storage type direct-expansion photovoltaic-solar heat pump combined heat and power system according to claim 5, wherein: the liquid working medium is a refrigerant.

7. The heat storage type direct-expansion photovoltaic-solar heat pump combined heat and power system according to claim 6, wherein: the heat-insulating layer (44) is made of heat-insulating cotton; the back plate (55) is a metal back plate.

8. The heat storage type direct-expansion photovoltaic-solar heat pump combined heat and power system according to claim 7, wherein: the photovoltaic cell panel (11) is a polycrystalline silicon photovoltaic cell panel; the polycrystalline silicon photovoltaic cell panel is connected with a storage battery unit (9).

9. The heat storage type direct-expansion photovoltaic-solar heat pump combined heat and power system according to claim 8, wherein: the three-way valve (4) is an L-shaped three-way valve.

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