Compound Compression Multi-Cycle PVT-Air Source Multi-Split Heat Pump Air Conditioning System with Outdoor Heat Source Defrosting

Abstract

The present invention belongs to the technical field of solar heat pumps, and provides a cascaded compression multi-cycle PVT-air source multi-connected unit heat pump air conditioning system for defrosting with an outdoor heat source, which includes a low-temperature compressor, a high-temperature compressor, an outdoor fin heat exchanger, a PVT module, a throttle valve, a condensation evaporator, a check valve, a stop valve, a four-way reversing valve, an indoor heat exchanger, and an inverter. The cascaded compression multi-cycle PVT-air source multi-connected unit heat pump air conditioning system for defrosting with an outdoor heat source provided by the present invention can operate throughout the year in six cycles, namely single-stage compression PVT heating, cascaded compression PVT heating, single-stage compression air source heating, cascaded compression air source heating, single-stage compression air source refrigeration, and defrosting of the outdoor fin heat exchanger. When the outdoor fin heat exchanger needs to be defrosted during continuous operation in the single-stage or cascaded compression air source heating cycle, defrosting is performed in a defrosting mode that does not extract heat from the indoor environment. The heat pump air conditioning system has strong environmental adaptability, high heating efficiency, high equipment utilization rate, and high photovoltaic cell power generation efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of solar heat pumps, and particularly to a cascade compression multi-cycle PVT-air source multi-connected heat pump air conditioner system for defrosting outdoor heat sources. Background Art

[0002] In the Photovoltaic-thermal (PVT) technology, while the heat exchange medium takes away the waste heat generated by the photovoltaic module for utilization, the working temperature of the photovoltaic module is reduced and the photovoltaic power generation efficiency is improved. The PVT heat pump system is a combination of heat pump technology and PVT technology, which can improve the heating efficiency of the heat pump cycle and the power generation efficiency of the photovoltaic cell at the same time, and output heat energy and electric energy on one system. Combining the air source heat pump cycle with the PVT heat pump cycle can form a PVT-air source heat pump system. Such a system overcomes the defects of both to a certain extent, achieves the complementary advantages of the two heat sources, and has high engineering application value. The existing PVT-air source heat pump systems have the following two deficiencies:

[0003] First, the operating conditions change drastically, while the operating cycle mode is single. On the evaporation side of the heat pump system, the environmental temperature changes due to the rotation of seasons and the alternation of day and night. Especially, the large change in the heat dissipation of the photovoltaic cell caused by the change in the light intensity in the early morning and evening of the day and the heating effect on the evaporator cause a large change in the evaporation pressure of the system. The existing PVT-air source heat pump systems usually adopt a single-stage compression cycle, which is not suitable for operating under variable working conditions with drastic changes in evaporation pressure caused by the rotation of seasons and the alternation of day and night.

[0004] Second, the defrosting efficiency of the finned evaporator is low, and the utilization rate of the heat exchanger equipment is low. When the air source heat pump system operates in winter, due to the low outdoor air temperature, frosting easily occurs on the surface of the outdoor evaporator, affecting the system performance. Solar energy can provide a high heat source during the day. The PVT-air source heat pump system combined with the air source heat pump system can greatly increase the evaporator temperature due to the heat dissipation of the photovoltaic cell under light, and can prevent the evaporator from frosting to a certain extent. However, on cloudy and rainy days without light or at night with low temperature, the PVT-air source heat pump system needs to switch to the air source outdoor finned heat exchanger for heat extraction. At this time, the PVT-air source heat pump system is the same as the ordinary air source heat pump system, and the outdoor finned heat exchanger will still frost. For this, there are mainly two existing defrosting methods: reverse cycle defrosting and energy storage defrosting. Reverse cycle defrosting extracts heat from the indoor heat exchanger, resulting in a large temperature fluctuation in the indoor environment and a switch in the refrigerant flow direction, bringing a large impact to the system. Energy storage defrosting requires an additional energy storage heat exchanger in the system. At present, due to problems such as energy storage materials and structures, the energy storage heat exchanger cannot be widely promoted. In addition, on cloudy and rainy days or at night, when the existing PVT-air source heat pump system defrosts, no matter which of the above two defrosting methods is used, the PVT module will be idle during defrosting. Summary of the Invention

[0005] The object of the present invention is to provide a cascaded compression multi-cycle PVT-air source multi-connected heat pump air conditioner system for defrosting of outdoor heat sources, which can not only switch between single-stage compression and cascaded compression cycles during heating, but also avoid taking heat from the indoor environment during defrosting.

[0006] The technical solution adopted to achieve the object of the present invention is as follows: A cascaded compression multi-cycle PVT-air source multi-connected heat pump air conditioner system for defrosting of outdoor heat sources, including a low-temperature compressor 1-1, a high-temperature compressor 1-2, an outdoor finned heat exchanger 2, a PVT module 3, a throttle valve, a condensation-evaporation heat exchanger 5, a check valve, a stop valve, a four-way reversing valve, an indoor heat exchanger 9 and an inverter 10;

[0007] The PVT module 3 is connected to the inverter 10; One end of the PVT module 3 branches, one branch passes through the third stop valve 7-3 and connects to the suction port of the low-temperature compressor 1-1, and the discharge port of the low-temperature compressor 1-1 passes through the third check valve 6-3 and connects to the first interface of the condensation-evaporation heat exchanger 5; Another branch of one end of the PVT module 3 passes through the second check valve 6-2 and connects to the first interface of the first four-way reversing valve 8-1; The second interface of the first four-way reversing valve 8-1 is connected to the suction port of the high-temperature compressor 1-2, and the discharge port of the high-temperature compressor 1-2 is connected to the first interface of the second four-way reversing valve 8-2; The third interface of the first four-way reversing valve 8-1 is connected to the second interface of the condensation-evaporation heat exchanger 5; The fourth interface of the first four-way reversing valve 8-1 is connected to the fourth interface of the condensation-evaporation heat exchanger 5; The second interface of the second four-way reversing valve 8-2 passes through the indoor heat exchanger 9 and the third throttle valve 4-3 in sequence and then connects to the third interface of the condensation-evaporation heat exchanger; The third interface of the second four-way reversing valve 8-2 passes through the first check valve 6-1 and connects to the suction port of the high-temperature compressor 1-2; The fourth interface of the second four-way reversing valve 8-2 is connected to the pipeline between the outdoor finned heat exchanger 2 and the suction port of the low-temperature compressor 1-1;

[0008] The other end of the PVT module 3 passes through the second throttle valve 4-2 and the second stop valve 7-2 in sequence and then divides into two branches; One branch passes through the first stop valve 7-1, the first throttle valve 4-1 and the outdoor finned heat exchanger 2 in sequence and connects to the pipeline between the third stop valve 7-3 and the suction port of the low-temperature compressor 1-1; The other branch passes through the fourth stop valve 7-4 and connects to the pipeline between the fourth interface of the first four-way reversing valve 8-1 and the fourth interface of the condensation-evaporation heat exchanger 5.

[0009] The cascaded compression multi-cycle PVT-air source multi-connected heat pump air conditioner system for defrosting of outdoor heat sources operates throughout the year in six cycles: single-stage compression PVT heating cycle, single-stage compression air source heating cycle, cascaded compression PVT heating cycle, cascaded compression air source heating cycle, outdoor finned heat exchanger defrosting cycle, and single-stage compression air source refrigeration cycle.

[0010] When the cascade compression multi-cycle PVT-air source multi-connected heat pump air conditioning system for outdoor heat source defrosting operates in a single-stage compression PVT heating cycle, the first cut-off valve 7-1 and the third cut-off valve 7-3 are closed, and the second cut-off valve 7-2 and the fourth cut-off valve 7-4 are opened; the first interface of the second four-way reversing valve 8-2 is communicated with the second interface of the second four-way reversing valve 8-2, and the third interface of the second four-way reversing valve 8-2 is communicated with the fourth interface of the second four-way reversing valve 8-2; the low-temperature compressor 1-1 stops running, and the high-temperature compressor 1-2 starts running; the photovoltaic cells in the PVT module 3 generate electricity under sunlight irradiation and are adjusted by the inverter 10 to become electricity that can be used by users.

[0011] When the cascade compression multi-cycle PVT-air source multi-connected heat pump air conditioning system for outdoor heat source defrosting operates in a single-stage compression air source heating cycle, the first cut-off valve 7-1, the third cut-off valve 7-3, and the fourth cut-off valve 7-4 are opened, and the second cut-off valve 7-2 is closed; the first interface of the first four-way reversing valve 8-1 is communicated with the second interface of the first four-way reversing valve 8-1, and the third interface of the first four-way reversing valve 8-1 is communicated with the fourth interface of the first four-way reversing valve 8-1; the first interface of the second four-way reversing valve 8-2 is communicated with the second interface of the second four-way reversing valve 8-2, and the third interface of the second four-way reversing valve 8-2 is communicated with the fourth interface of the second four-way reversing valve 8-2; the low-temperature compressor 1-1 stops running, and the high-temperature compressor 1-2 starts running; the photovoltaic cells in the PVT module 3 generate electricity under sunlight irradiation and are adjusted by the inverter 10 to become electricity that can be used by users;

[0012] When the cascade compression multi-cycle PVT-air source multi-connected heat pump air conditioning system for outdoor heat source defrosting operates in a cascade compression PVT heating cycle, the first cut-off valve 7-1 is closed, and the second cut-off valve 7-2, the third cut-off valve 7-3, and the fourth cut-off valve 7-4 are opened; the first interface of the first four-way reversing valve 8-1 is communicated with the fourth interface of the first four-way reversing valve 8-1, and the second interface of the first four-way reversing valve 8-1 is communicated with the third interface of the first four-way reversing valve 8-1; the first interface of the second four-way reversing valve 8-2 is communicated with the second interface of the second four-way reversing valve 8-2, and the third interface of the second four-way reversing valve 8-2 is communicated with the fourth interface of the second four-way reversing valve 8-2; both the low-temperature compressor 1-1 and the high-temperature compressor 1-2 start running; the photovoltaic cells in the PVT module 3 generate electricity under sunlight irradiation and are adjusted by the inverter 10 to become electricity that can be used by users;

[0013] When the cascade-compressed multi-cycle PVT-air source multi-connected heat pump air conditioner system for outdoor heat source defrosting operates in the cascade-compressed air source heating cycle, the first stop valve 7-1 and the fourth stop valve 7-4 are opened, the second stop valve 7-2 and the third stop valve 7-3 are closed, the first interface of the first four-way reversing valve 8-1 is connected to the fourth interface of the first four-way reversing valve 8-1, the second interface of the first four-way reversing valve 8-1 is connected to the third interface of the first four-way reversing valve 8-1, the first interface of the second four-way reversing valve 8-2 is connected to the second interface of the second four-way reversing valve 8-2, the third interface of the second four-way reversing valve 8-2 is connected to the fourth interface of the second four-way reversing valve 8-2, and both the low-temperature compressor 1-1 and the high-temperature compressor 1-2 are started; the photovoltaic cells in the PVT module 3 generate electricity under sunlight irradiation and are adjusted by the inverter 10 to become electricity that can be used by users;

[0014] When the cascade-compressed multi-cycle PVT-air source multi-connected heat pump air conditioner system for outdoor heat source defrosting operates in the outdoor fin heat exchanger defrosting cycle, the first stop valve 7-1 and the second stop valve 7-2 are opened, the third stop valve 7-3 and the fourth stop valve 7-4 are closed, the first interface of the first four-way reversing valve 8-1 is connected to the second interface of the first four-way reversing valve 8-1, the third interface of the first four-way reversing valve 8-1 is connected to the fourth interface of the first four-way reversing valve 8-1, the first interface of the second four-way reversing valve 8-2 is connected to the fourth interface of the second four-way reversing valve 8-2, the second interface of the second four-way reversing valve 8-2 is connected to the third interface of the second four-way reversing valve 8-2, the low-temperature compressor 1-1 is shut down, the high-temperature compressor 1-2 is started, and the opening of the first throttle valve 4-1 is adjusted to the maximum; the photovoltaic cells in the PVT module 3 generate electricity under sunlight irradiation and are adjusted by the inverter 10 to become electricity that can be used by users;

[0015] When the cascade-compressed multi-cycle PVT-air source multi-connected heat pump air conditioner system for outdoor heat source defrosting operates in the single-stage compressed air source refrigeration cycle, the first stop valve 7-1 and the fourth stop valve 7-4 are opened, the second stop valve 7-2 and the third stop valve 7-3 are closed, the first interface of the first four-way reversing valve 8-1 is connected to the second interface of the first four-way reversing valve 8-1, the third interface of the first four-way reversing valve 8-1 is connected to the fourth interface of the first four-way reversing valve 8-1, the first interface of the second four-way reversing valve 8-2 is connected to the fourth interface of the second four-way reversing valve 8-2, the second interface of the second four-way reversing valve 8-2 is connected to the third interface of the second four-way reversing valve 8-2, the low-temperature compressor 1-1 is shut down, the high-temperature compressor 1-2 is started, and the opening of the first throttle valve 4-1 is adjusted to the maximum.

[0016] The PVT component 3 is of a flat box type, tube plate type, blown plate type or flat plate type; the high-temperature compressor 1-2 and the low-temperature compressor 1-1 are any one of a scroll compressor, a rotor compressor, a screw compressor and a piston compressor; the first throttle valve 4-1, the second throttle valve 4-2 and the third throttle valve 4-3 are an electronic expansion valve, a thermostatic expansion valve, a capillary tube or an orifice throttling device; the first stop valve 7-1, the second stop valve 7-2, the third stop valve 7-3 and the fourth stop valve 7-4 are a solenoid valve, a manual valve or a ball valve.

[0017] The cascade compression multi-cycle PVT-air source multi-connected unit heat pump air conditioner system for defrosting outdoor heat sources according to the present invention realizes six cycle operations of single-stage compression PVT heating, cascade compression PVT heating, single-stage compression air source heating, cascade compression air source heating, defrosting of the outdoor fin heat exchanger and single-stage compression air source refrigeration according to the ambient temperature, light intensity, heating, refrigeration and defrosting requirements.

[0018] During the day in the transition season when the ambient temperature is relatively high and the light is strong, the cascade compression multi-cycle PVT-air source multi-connected unit heat pump air conditioner system for defrosting outdoor heat sources according to the present invention operates in a single-stage compression PVT heating cycle, and the operating schematic diagram is as Figure 2 shown.

[0019] During the day in the transition season when the ambient temperature is relatively high and the light is weak or at night without light, the cascade compression multi-cycle PVT-air source multi-connected unit heat pump air conditioner system for defrosting outdoor heat sources according to the present invention operates in a single-stage compression air source heating cycle, and the operating schematic diagram is as Figure 3 shown.

[0020] During the day in the cold winter when the ambient temperature is relatively low and the light is strong, the cascade compression multi-cycle PVT-air source multi-connected unit heat pump air conditioner system for defrosting outdoor heat sources according to the present invention operates in a cascade compression PVT heating cycle, and the operating schematic diagram is as Figure 4 shown.

[0021] During the day in the cold winter when the ambient temperature is relatively low and the light is weak or at night without light, the cascade compression multi-cycle PVT-air source multi-connected unit heat pump air conditioner system for defrosting outdoor heat sources according to the present invention operates in a cascade compression air source heating cycle, and the operating schematic diagram is as Figure 5 shown.

[0022] During the day with low light or at night without light, the cascade compression multi-cycle PVT-air source multi-connected unit heat pump air conditioner system for defrosting outdoor heat sources according to the present invention continuously operates in a single-stage compression air source heating cycle or a cascade compression air source heating cycle for a period of time. When the outdoor fin heat exchanger needs to be defrosted, the cascade compression PVT multi-connected unit system with a defrosting function according to the present invention operates in an outdoor fin heat exchanger defrosting cycle, and the operating schematic diagram is as Figure 6 shown.

[0023] In the hot summer, the cascade-compressed multi-cycle PVT-air source multi-connected heat pump air conditioning system for defrosting of outdoor heat sources of the present invention operates in a single-stage compressed air source refrigeration mode, and the operating schematic diagram is as Figure 7 shown.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] 1. The cascade-compressed multi-cycle PVT-air source multi-connected heat pump air conditioning system for defrosting of outdoor heat sources of the present invention can operate in a single-stage compressed PVT heating cycle or a single-stage compressed air source heating cycle in a medium-temperature outdoor environment during the transitional season, and can also operate in a cascade-compressed PVT heating cycle or a cascade-compressed air source heating cycle in a low-temperature outdoor environment in winter. It can also operate in a single-stage compressed air source refrigeration cycle in the hot summer. The heat pump multi-connected system of the present invention can flexibly switch between various heating and refrigeration cycles, has strong environmental adaptability and high efficiency;

[0026] 2. When the cascade-compressed multi-cycle PVT-air source multi-connected heat pump air conditioning system for defrosting of outdoor heat sources of the present invention needs defrosting after long-term operation in a single-stage compressed air source heating cycle or a cascade-compressed air source heating cycle, it can obtain heat from the idle PVT components in the same outdoor ambient temperature instead of taking heat from the indoor environment. The indoor comfort is relatively high, the defrosting efficiency of the outdoor fin heat exchanger is high, the speed is fast, the pressure change of the multi-connected system before and after defrosting is relatively slow, the impact on the system is small, and the system stability is good. By using the idle PVT components, the equipment utilization rate is relatively high;

[0027] 3. When the cascade-compressed multi-cycle PVT-air source multi-connected heat pump air conditioning system for defrosting of outdoor heat sources of the present invention operates in a cascade-compressed PVT heating cycle in a low-temperature and sunny outdoor environment, the temperature of the PVT components is lower and the power generation efficiency of the photovoltaic cells is relatively high. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The figure shows a schematic diagram of the cascade-compressed multi-cycle PVT-air source multi-connected heat pump air conditioning system for defrosting of outdoor heat sources of the present invention;

[0029] In the figure: 1-1, low-temperature compressor; 1-2, high-temperature compressor; 2, outdoor fin heat exchanger; 3, PVT components; 4-1, first throttle valve; 4-2, second throttle valve; 4-3, third throttle valve; 5, condensation evaporator; 6-1, first check valve; 6-2, second check valve; 7-1, first stop valve; 7-2, second stop valve; 7-3, third stop valve; 7-4, fourth stop valve; 8-1, first four-way reversing valve; 8-2, second four-way reversing valve; 9, indoor heat exchanger; 10, inverter.

[0030] Figure 2 The figure shows the schematic diagram of the cascade compression multi-cycle PVT-air source multi-connected unit heat pump air conditioner for defrosting of outdoor heat sources of the present invention operating in a single-stage compression PVT heating cycle;

[0031] Figure 3 The figure shows the schematic diagram of the cascade compression multi-cycle PVT-air source multi-connected unit heat pump air conditioner for defrosting of outdoor heat sources of the present invention operating in a single-stage compression air source heating cycle;

[0032] Figure 4 The figure shows the schematic diagram of the cascade compression multi-cycle PVT-air source multi-connected unit heat pump air conditioner for defrosting of outdoor heat sources of the present invention operating in a cascade compression PVT heating cycle;

[0033] Figure 5 The figure shows the schematic diagram of the cascade compression multi-cycle PVT-air source multi-connected unit heat pump air conditioner for defrosting of outdoor heat sources of the present invention operating in a cascade compression air source heating cycle;

[0034] Figure 6 The figure shows the schematic diagram of the cascade compression multi-cycle PVT-air source multi-connected unit heat pump air conditioner for defrosting of outdoor heat sources of the present invention operating in an outdoor fin heat exchanger defrosting cycle;

[0035] Figure 7 The figure shows the schematic diagram of the cascade compression multi-cycle PVT-air source multi-connected unit heat pump air conditioner for defrosting of outdoor heat sources of the present invention operating in a single-stage compression air source refrigeration cycle;

[0036] Figure 8 The figure shows the schematic diagram of the interfaces of the condensing evaporator in the cascade compression multi-cycle PVT-air source multi-connected unit heat pump air conditioner for defrosting of outdoor heat sources of the present invention;

[0037] In the figure: 5a, the first interface of the condensing evaporator; 5b, the second interface of the condensing evaporator; 5c, the third interface of the condensing evaporator; 5d, the fourth interface of the condensing evaporator.

[0038] Figure 9 The figure shows the schematic diagram of the interfaces of the four-way reversing valve in the cascade compression multi-cycle PVT-air source multi-connected unit heat pump air conditioner for defrosting of outdoor heat sources of the present invention;

[0039] In the figure: 8a, the first interface of the four-way reversing valve; 8b, the second interface of the four-way reversing valve; 8c, the third interface of the four-way reversing valve; 8d, the fourth interface of the four-way reversing valve. Detailed implementation manners

[0040] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "high pressure", "medium pressure", and "low pressure" should be understood in a broad sense, referring to the relative pressure values in the same refrigerant loop. For example, in the cascade heating mode, the "high pressure" and "medium pressure" in the high-temperature loop refer to the relative comparison values within the same high-temperature refrigerant loop. The pressure between the suction port of the high-temperature compressor and the outlet of the throttle valve is the medium pressure, and the pressure between the discharge port of the high-temperature compressor and the inlet of the throttle valve is the high pressure. The "medium pressure" and "low pressure" in the low-temperature loop refer to the relative comparison values within the same low-temperature refrigerant loop. The pressure between the suction port of the low-temperature compressor and the outlet of the throttle valve is the low pressure, and the pressure between the discharge port of the low-temperature compressor and the inlet of the throttle valve is the medium pressure.

[0041] In addition, the terms "first" and "second" are used only for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "a plurality of" means two or more unless otherwise specifically defined.

[0042] The schematic diagram of the cascade compression multi-cycle PVT-air source multi-connected unit heat pump air conditioning system for defrosting of the outdoor heat source of the present invention is as Figure 1As shown in the figure, the system includes a low-temperature compressor 1-1, a high-temperature compressor 1-2, an outdoor finned heat exchanger 2, a PVT module 3, a first throttle valve 4-1, a second throttle valve 4-2, a third throttle valve 4-3, a condensation evaporator 5, a first check valve 6-1, a second check valve 6-2, a third check valve 6-3, a first stop valve 7-1, a second stop valve 7-2, a third stop valve 7-3, a fourth stop valve 7-4, a first four-way reversing valve 8-1, a second four-way reversing valve 8-2, an indoor heat exchanger 9, and an inverter 10. The exhaust port of the low-temperature compressor 1-1 is connected to the first interface of the condensation evaporator 5 through the third check valve 6-3. The suction port of the low-temperature compressor 1-1 is connected to one end of the PVT module 3 through the third stop valve 7-3. The suction port of the low-temperature compressor 1-1 is also connected to one end of the outdoor finned heat exchanger 2 and the fourth interface of the second four-way reversing valve 8-2. The exhaust port of the high-temperature compressor 1-2 is connected to the first interface of the second four-way reversing valve 8-2. The third interface of the second four-way reversing valve 8-2 is connected to the suction port of the high-temperature compressor 1-2 through the first check valve 6-1. The suction port of the high-temperature compressor 1-2 is also connected to the second interface of the first four-way reversing valve 8-1. The second interface of the second four-way reversing valve 8-2 is connected to the indoor heat exchanger 9. The indoor heat exchanger 9 is connected to the third interface of the condensation evaporator 5 through the third throttle valve 4-3. The second interface of the condensation evaporator 5 is connected to the third interface of the first four-way reversing valve 8-1. The fourth interface of the condensation evaporator 5 is connected to the fourth interface of the first four-way reversing valve 8-1 and one end of the fourth stop valve 7-4. The other end of the fourth stop valve 7-4 is connected to one end of the first stop valve 7-1 and one end of the second stop valve 7-2. The other end of the first stop valve 7-1 is connected to the other end of the outdoor finned heat exchanger 2 through the first throttle valve 4-1. The other end of the second stop valve 7-2 is connected to the other end of the PVT module 3 through the second throttle valve 4-2. The first interface of the first four-way reversing valve 8-1 is connected to one end of the PVT and the other end of the third stop valve 7-3 through the second check valve 6-2.

[0043] The cascade compression multi-cycle PVT-air source multi-connected unit heat pump air conditioner system for defrosting of outdoor heat sources according to the present invention realizes six operation modes: single-stage compression PVT heating, cascade compression PVT heating, single-stage compression air source heating, cascade compression air source heating, defrosting of the outdoor finned heat exchanger 2, and single-stage compression air source refrigeration according to the ambient temperature, light intensity, heating, refrigeration, and defrosting requirements.

[0044] During the day in the transitional season when the ambient temperature is relatively high and the light is relatively strong, the cascade compression multi-cycle PVT-air source multi-connected unit heat pump air conditioner system for defrosting of outdoor heat sources according to the present invention operates in a single-stage compression PVT heating cycle, and the operation principle diagram is as Figure 2As shown in the figure. Close the first stop valve 7-1 and the third stop valve 7-3, and open the second stop valve 7-2 and the fourth stop valve 7-4; the first interface of the second four-way reversing valve 8-2 is communicated with the second interface of the second four-way reversing valve 8-2, and the third interface of the second four-way reversing valve 8-2 is communicated with the fourth interface of the second four-way reversing valve 8-2; the low-temperature compressor 1-1 stops running, and the high-temperature compressor 1-2 starts running; the photovoltaic cells in the PVT module 3 generate electricity under sunlight irradiation and are adjusted by the inverter 10 to become electricity that can be used by users.

[0045] The refrigerant thermodynamic process is as follows: The low-pressure and low-temperature refrigerant gas is transported from one end of the PVT module 3, passes through the second check valve 6-2, the first interface of the first four-way reversing valve 8-1, and the second interface of the first four-way reversing valve 8-1 in sequence, and is transported to the suction port of the high-temperature compressor 1-2; the low-pressure and low-temperature refrigerant gas is compressed and boosted to become a high-pressure and high-temperature superheated gas, passes through the first interface of the second four-way reversing valve 8-2 and the second interface of the second four-way reversing valve 8-2, and is transported to the indoor heat exchanger 9; the high-pressure and high-temperature superheated gas is condensed by the indoor air in the indoor heat exchanger 9 to become a high-pressure liquid, and at the same time, heating occurs indoors; the high-pressure liquid flowing out of the indoor heat exchanger 9 is expanded and depressurized by the third throttle valve 4-3 to become a medium-pressure gas-liquid mixture and flows into the third interface of the condensation evaporator 5; the medium-pressure gas-liquid mixture passes through the second interface of the condensation evaporator 5, the third interface of the first four-way reversing valve 8-1, the fourth interface of the first four-way reversing valve 8-1, the fourth stop valve 7-4, and the second stop valve 7-2 in sequence, enters the second throttle valve 4-2, and becomes a low-pressure gas-liquid mixed refrigerant after expansion and pressure reduction and enters the other end of the PVT module 3; the low-pressure gas-liquid mixed refrigerant absorbs the heat of the photovoltaic cells in the PVT module 3 and becomes a low-pressure and low-temperature refrigerant gas, and then is output from the other end of the PVT module 3 to complete the refrigeration cycle.

[0046] In the transitional season, during the day with relatively high ambient temperature and weak sunlight or at night without sunlight, the cascade compression multi-cycle PVT-air source multi-connected unit heat pump air conditioner system for outdoor heat source defrosting operates in a single-stage compression air source heating cycle, and the operating schematic diagram is as Figure 3 shown. The first stop valve 7-1, the third stop valve 7-3, and the fourth stop valve 7-4 are opened, the second stop valve 7-2 is closed, the first interface of the first four-way reversing valve 8-1 is communicated with the second interface of the first four-way reversing valve 8-1, the third interface of the first four-way reversing valve 8-1 is communicated with the fourth interface of the first four-way reversing valve 8-1, the first interface of the second four-way reversing valve 8-2 is communicated with the second interface of the second four-way reversing valve 8-2, the third interface of the second four-way reversing valve 8-2 is communicated with the fourth interface of the second four-way reversing valve 8-2, the low-temperature compressor 1-1 stops running, and the high-temperature compressor 1-2 starts running; the photovoltaic cells in the PVT module 3 generate electricity under sunlight irradiation and are adjusted by the inverter 10 to become electricity that can be used by users.

[0047] The refrigerant thermodynamic process is as follows: One end of the outdoor finned heat exchanger 2 conveys low-pressure and low-temperature refrigerant gas, which successively passes through the third cut-off valve 7-3, the second check valve 6-2, the first interface of the first four-way reversing valve 8-1, and the second interface of the first four-way reversing valve 8-1 to the suction port of the high-temperature compressor 1-2. The low-pressure and low-temperature refrigerant gas is compressed and boosted by the high-temperature compressor 1-2 to become high-pressure and high-temperature superheated gas, and then passes through the first interface of the second four-way reversing valve 8-2 and the second interface of the second four-way reversing valve 8-2 and is conveyed to the indoor heat exchanger 9. The high-pressure and high-temperature superheated gas is condensed by the indoor air in the indoor heat exchanger 9 to become high-pressure liquid, and at the same time, a heating phenomenon occurs indoors. The high-pressure liquid flowing out of the indoor heat exchanger 9 is expanded and depressurized by the third throttle valve 4-3 to become a medium-pressure gas-liquid mixture, and then successively passes through the third interface of the condensation evaporator 5, the second interface of the condensation evaporator 5, the third interface of the first four-way reversing valve 8-1, the fourth interface of the first four-way reversing valve 8-1, the fourth cut-off valve 7-4, and the first cut-off valve 7-1 and enters the first throttle valve 4-1. After expansion and depressurization, it becomes low-pressure gas-liquid mixed refrigerant and enters the other end of the outdoor finned heat exchanger 2. The low-pressure gas-liquid mixed refrigerant absorbs heat from the air in the outdoor finned heat exchanger 2 and becomes low-pressure and low-temperature refrigerant gas, which is output from the other end of the outdoor finned heat exchanger 2 to complete the refrigeration cycle.

[0048] In the cold winter with a relatively low ambient temperature and strong sunlight during the day, the cascade compression multi-cycle PVT-air source multi-connected unit heat pump air conditioner system for defrosting the outdoor heat source of the present invention operates in a cascade compression PVT heating cycle, and the operating schematic diagram is as Figure 4 shown. The first cut-off valve 7-1 is closed, the second cut-off valve 7-2, the third cut-off valve 7-3, and the fourth cut-off valve 7-4 are opened. The first interface of the first four-way reversing valve 8-1 is communicated with the fourth interface of the first four-way reversing valve 8-1, the second interface of the first four-way reversing valve 8-1 is communicated with the third interface of the first four-way reversing valve 8-1, the first interface of the second four-way reversing valve 8-2 is communicated with the second interface of the second four-way reversing valve 8-2, and the third interface of the second four-way reversing valve 8-2 is communicated with the fourth interface of the second four-way reversing valve 8-2. The low-temperature compressor 1-1 and the high-temperature compressor 1-2 are started. The photovoltaic cells in the PVT module 3 generate electricity under sunlight irradiation and are adjusted by the inverter 10 to become electricity that can be used by users.

[0049] The refrigerant thermodynamic process is as follows: The cascade compression system includes a low-temperature loop and a high-temperature loop. The low-temperature refrigerant circulates in the low-temperature loop, and the high-temperature refrigerant completes the cycle in the high-temperature loop.

[0050] Low-temperature refrigerant cycle: The low-pressure and low-temperature refrigerant gas output from one end of the PVT component 3 passes through the third cut-off valve 7-3 and is input into the suction port of the low-temperature compressor 1-1. The low-pressure and low-temperature refrigerant gas is compressed and boosted by the low-temperature compressor 1-1 to become a medium-pressure superheated gas, passes through the third one-way valve 6-3, and enters the first interface of the condensation evaporator 5. The medium-pressure superheated gas transfers the heat of the low-temperature loop to the high-temperature loop of the condensation evaporator 5 and is then condensed into a medium-pressure liquid, which flows out from the fourth interface of the condensation evaporator 5, passes through the fourth cut-off valve 7-4 and the second cut-off valve 7-2 in sequence, and enters the second throttle valve 4-2. The medium-pressure liquid is expanded and depressurized by the second throttle valve 4-2 to become a low-pressure gas-liquid mixed refrigerant and enters the other end of the PVT component 3. The low-pressure gas-liquid mixed refrigerant absorbs the heat of the photovoltaic cell in the PVT component 3 and becomes a low-pressure and low-temperature refrigerant gas, which is output from the other end of the PVT component 3 to complete the low-temperature loop cycle;

[0051] High-temperature refrigerant cycle: The medium-pressure and medium-temperature refrigerant gas output from the second interface of the condensation evaporator 5 passes through the third interface of the first four-way reversing valve 8-1 and the second interface of the first four-way reversing valve 8-1 and enters the high-temperature compressor 1-2 in sequence; The medium-pressure and medium-temperature refrigerant gas is compressed and boosted by the high-temperature compressor 1-2 to become a high-pressure superheated gas, passes through the first interface of the second four-way reversing valve 8-2 and the second interface of the second four-way reversing valve 8-2 in sequence, and enters the indoor heat exchanger 9. The high-pressure superheated gas is condensed by the indoor air in the indoor heat exchanger 9 to become a high-pressure liquid, and at the same time, heating occurs indoors; The high-pressure liquid flowing out from the indoor heat exchanger 9 is expanded and depressurized by the third throttle valve 4-3 to become a medium-pressure gas-liquid mixture, enters the third interface of the condensation evaporator 5, and the medium-pressure gas-liquid mixture absorbs the heat of the low-temperature loop in the condensation evaporator 5 to become a medium-pressure and medium-temperature refrigerant gas, which is output from the second interface of the condensation evaporator 5 to complete the high-temperature loop cycle. The medium-pressure value in the high-temperature loop is lower than the medium-pressure value in the low-temperature loop.

[0052] In cold winter with low ambient temperature, during the low-light daytime or the night without light, the cascade compression multi-cycle PVT-air source multi-connected unit heat pump air conditioner system for outdoor heat source defrosting of the present invention operates in a cascade compression air source heating cycle, and the operation principle diagram is as Figure 5 shown. The first cut-off valve 7-1 and the fourth cut-off valve 7-4 are opened, the second cut-off valve 7-2 and the third cut-off valve 7-3 are closed, the first interface of the first four-way reversing valve 8-1 is communicated with the fourth interface of the first four-way reversing valve 8-1, the second interface of the first four-way reversing valve 8-1 is communicated with the third interface of the first four-way reversing valve 8-1, the first interface of the second four-way reversing valve 8-2 is communicated with the second interface of the second four-way reversing valve 8-2, the third interface of the second four-way reversing valve 8-2 is communicated with the fourth interface of the second four-way reversing valve 8-2, and the low-temperature compressor 1-1 and the high-temperature compressor 1-2 are started; The photovoltaic cell in the PVT component 3 generates electricity under sunlight irradiation and is adjusted by the inverter 10 to become electricity that can be used by users.

[0053] The refrigerant thermodynamic process is as follows: the cascade compression system includes a low-temperature loop and a high-temperature loop, in which a low-temperature refrigerant circulates, and in which a high-temperature refrigerant circulates.

[0054] Low-temperature refrigerant cycle: one end of the outdoor fin heat exchanger 2 outputs low-pressure low-temperature refrigerant gas to the suction port of the low-temperature compressor 1-1. The low-pressure low-temperature refrigerant gas is compressed and pressurized by the low-temperature compressor 1-1 to become medium-pressure superheated gas, and enters the first interface of the condenser evaporator 5 through the third one-way valve 6-3. The low-temperature loop heat of the medium-pressure superheated gas is transferred to the high-temperature loop of the condenser evaporator 5 and is condensed into medium-pressure liquid, and flows out from the fourth interface of the condenser evaporator 5, and passes through the fourth stop valve 7-4 and the first stop valve 7-1 in turn to enter the first throttle valve 4-1. The medium-pressure liquid is expanded and reduced in pressure by the first throttle valve 4-1 to become a low-pressure gas-liquid mixed refrigerant and enter the other end of the outdoor fin heat exchanger 2; the low-pressure gas-liquid mixed refrigerant absorbs heat from the air in the outdoor fin heat exchanger 2 and becomes a low-pressure low-temperature refrigerant gas, and is output from one end of the outdoor fin heat exchanger 2 to complete the low-temperature loop cycle;

[0055] High-temperature refrigerant circulation: The second interface of the condenser evaporator 5 outputs medium-pressure medium-temperature refrigerant gas, which is successively delivered to the suction port of the high-temperature compressor 1-2 through the third interface of the first four-way reversing valve 8-1 and the second interface of the first four-way reversing valve 8-1; the medium-pressure medium-temperature refrigerant gas is compressed and pressurized by the high-temperature compressor 1-2 to become high-pressure superheated gas, and successively passes through the first interface of the second four-way reversing valve 8-2 and the second interface of the second four-way reversing valve 8-2 to enter the indoor heat exchanger 9, and the high-pressure superheated gas is condensed by the indoor air in the indoor heat exchanger 9 to become high-pressure liquid, and at the same time, heating is generated indoors, and the high-pressure liquid flowing out of the indoor heat exchanger 9 is expanded and depressurized through the third throttle valve 4-3 to become a medium-pressure gas-liquid mixture, and enters the third interface of the condenser evaporator 5, and the medium-pressure gas-liquid mixture absorbs the heat of the low-temperature loop in the condenser evaporator 5, becomes a medium-pressure medium-temperature refrigerant gas, and is output from the second interface of the condenser evaporator 5, completing the high-temperature loop circulation. The medium-pressure pressure value in the high-temperature loop is lower than the medium-pressure pressure value in the low-temperature loop.

[0056] During low-light daytime or dark nighttime, the cascade compression multi-cycle PVT-air source multi-split heat pump air conditioning system with outdoor heat source defrosting of the present invention operates continuously for a period of time in a single-stage compressed air source heating cycle or a cascade compressed air source heating cycle. When the outdoor fin heat exchanger 2 needs to be defrosted, the cascade compression PVT multi-split system with defrosting function of the present invention operates in the outdoor fin heat exchanger 2 defrosting mode. The operating principle diagram is shown in FIG. Figure 6As shown. The first stop valve 7-1 and the second stop valve 7-2 are opened, the third stop valve 7-3 and the fourth stop valve 7-4 are closed, the first interface of the first four-way reversing valve 8-1 is connected to the second interface of the first four-way reversing valve 8-1, the third interface of the first four-way reversing valve 8-1 is connected to the fourth interface of the first four-way reversing valve 8-1, the first interface of the second four-way reversing valve 8-2 is connected to the fourth interface of the second four-way reversing valve 8-2, the second interface of the second four-way reversing valve 8-2 is connected to the third interface of the second four-way reversing valve 8-2, the low-temperature compressor 1-1 is turned off, the high-temperature compressor 1-2 is turned on, and the opening of the first throttle valve 4-1 is adjusted to the maximum; the photovoltaic cells in the PVT assembly 3 generate electricity under sunlight, which is adjusted by the inverter 10 to become electricity that can be used by users.

[0057] The refrigerant thermal process is as follows: the low-pressure and low-temperature refrigerant gas output from one end of the PVT component 3 passes through the second one-way valve 6-2, the first interface of the first four-way reversing valve 8-1, and the second interface of the first four-way reversing valve 8-1 to the suction port of the high-temperature compressor 1-2 in sequence; the low-pressure and low-temperature refrigerant gas is compressed and pressurized by the high-temperature compressor 1-2 to become high-pressure superheated gas; the high-pressure superheated gas passes through the first interface of the second four-way reversing valve 8-2 and the fourth interface of the second four-way reversing valve 8-2 to enter the other end of the outdoor fin heat exchanger 2; the high-pressure superheated gas releases heat in the outdoor fin heat exchanger 2 It becomes a high-pressure liquid, and the frost layer on the surface of the fin melts due to the heat; the high-pressure liquid flowing out from one end of the outdoor fin heat exchanger 2 enters the second throttle valve 4-2 through the first throttle valve 4-1, the first stop valve 7-1, and the second stop valve 7-2. The high-pressure liquid is expanded and reduced in pressure by the second throttle valve 4-2 and becomes a low-pressure gas-liquid mixed refrigerant and enters the other end of the PVT component 3. The low-pressure gas-liquid mixed refrigerant absorbs heat from the PVT component 3 and the outdoor air in the PVT component 3 and becomes a low-pressure, low-temperature refrigerant gas, which is output from one end of the PVT component 3 to complete the defrost cycle.

[0058] In the hot summer, the cascade compression PVT multi-connected system with defrosting function of the present invention operates in a single-stage compressed air source refrigeration mode. The operating principle diagram is as follows: Figure 7As shown. The first stop valve 7-1 and the fourth stop valve 7-3 are open, the second stop valve 7-2 and the third stop valve 7-3 are closed, the first interface of the first four-way reversing valve 8-1 is connected to the second interface of the first four-way reversing valve 8-1, the third interface of the first four-way reversing valve 8-1 is connected to the fourth interface of the first four-way reversing valve 8-1, the first interface of the second four-way reversing valve 8-2 is connected to the fourth interface of the second four-way reversing valve 8-2, the second interface of the second four-way reversing valve 8-2 is connected to the third interface of the second four-way reversing valve 8-2, the low-temperature compressor 1-1 is turned off, the high-temperature compressor 1-2 is turned on, and the first throttle valve 4-1 is opened to the maximum. The photovoltaic cells in the PVT assembly 3 generate electricity under sunlight, which is adjusted by the inverter 10 to become electricity that can be used by users.

[0059] The refrigerant thermal process is as follows: the indoor heat exchanger 9 outputs low-pressure and low-temperature refrigerant gas, which is sequentially input to the suction port of the high-temperature compressor 1-2 through the second interface of the second four-way reversing valve 8-2, the third interface of the second four-way reversing valve 8-2, and the first one-way valve 6-1. The low-pressure and low-temperature refrigerant gas is compressed and pressurized by the high-temperature compressor 1-2 to become high-pressure superheated gas, and enters the other end of the outdoor fin heat exchanger 2 through the first interface of the second four-way reversing valve 8-2 and the fourth interface of the second four-way reversing valve 8-2; the high-pressure superheated gas is cooled by air in the outdoor fin heat exchanger 2 and becomes high-pressure liquid, and is heat exchanged by the outdoor fins. The high-pressure liquid flowing out of one end of the device 2 enters the third throttle valve 4-3 through the first throttle valve 4-1, the first stop valve 7-1, the fourth stop valve 7-4, the fourth interface of the first four-way reversing valve 8-1, the third interface of the first four-way reversing valve 8-1, the second interface of the condenser evaporator 5, and the third interface of the condenser evaporator 5. The high-pressure liquid is expanded and reduced in pressure by the third throttle valve 4-3 and becomes a low-pressure gas-liquid mixed refrigerant and enters the indoor heat exchanger 9. The low-pressure gas-liquid mixed refrigerant absorbs heat from the indoor air in the indoor heat exchanger 9 and becomes a low-pressure and low-temperature refrigerant gas and is then output, completing the refrigeration cycle of the indoor heat exchanger 9.

[0060] The PVT assembly may be of flat box type, tube sheet type, blown plate type or flat plate type.

[0061] The compressor is any one of a scroll compressor, a rotor compressor, a screw compressor and a piston compressor.

[0062] The first throttle valve, the second throttle valve and the third throttle valve are electronic expansion valves, thermal expansion valves, capillary tubes or orifice plate throttling devices.

[0063] The first stop valve, the second stop valve, the third stop valve and the fourth stop valve are solenoid valves, manual valves or ball valves.

[0064] like Figure 8As shown in the figure: The specific positions of the interfaces of the condensing evaporator 5 are as follows, namely the first interface 5a of the condensing evaporator, the second interface 5b of the condensing evaporator, the third interface 5c of the condensing evaporator, and the fourth interface 5d of the condensing evaporator.

[0065] As Figure 9 As shown in the figure: The specific positions of the interfaces of the four-way reversing valve are as follows, namely the first interface 8a of the four-way reversing valve, the second interface 8b of the four-way reversing valve, the third interface 8c of the four-way reversing valve, and the fourth interface 8d of the four-way reversing valve.

[0066] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A cascade compression multi-cycle PVT-air source multi-connected heat pump air conditioner system for outdoor heat source defrosting, characterized in that, The cascade compression multi-cycle PVT-air source multi-connected unit heat pump air conditioning system for outdoor heat source defrosting includes a low-temperature compressor (1-1), a high-temperature compressor (1-2), an outdoor fin heat exchanger (2), a PVT module (3), a throttle valve, a condensation evaporator (5), a check valve, a stop valve, a four-way reversing valve, an indoor heat exchanger (9), and an inverter (10); The PVT module (3) is connected to the inverter (10); one end of the PVT module (3) branches, one branch passes through the third stop valve (7-3) and is connected to the suction port of the low-temperature compressor (1-1), and the discharge port of the low-temperature compressor (1-1) passes through the third check valve (6-3) and is connected to the first interface of the condensation evaporator (5); another branch of one end of the PVT module (3) passes through the second check valve (6-2) and is connected to the first interface of the first four-way reversing valve (8-1); the second interface of the first four-way reversing valve (8-1) is connected to the suction port of the high-temperature compressor (1-2), and the discharge port of the high-temperature compressor (1-2) is connected to the first interface of the second four-way reversing valve (8-2); the third interface of the first four-way reversing valve (8-1) is connected to the second interface of the condensation evaporator (5); the fourth interface of the first four-way reversing valve (8-1) is connected to the fourth interface of the condensation evaporator (5); the second interface of the second four-way reversing valve (8-2) sequentially passes through the indoor heat exchanger (9) and the third throttle valve (4-3) and is connected to the third interface of the condensation evaporator; the third interface of the second four-way reversing valve (8-2) passes through the first check valve (6-1) and is connected to the suction port of the high-temperature compressor (1-2); the fourth interface of the second four-way reversing valve (8-2) is connected to the pipeline between the outdoor fin heat exchanger (2) and the suction port of the low-temperature compressor (1-1); The other end of the PVT module (3) sequentially passes through the second throttle valve (4-2) and the second stop valve (7-2) and then branches into two paths; one path sequentially passes through the first stop valve (7-1), the first throttle valve (4-1), and the outdoor fin heat exchanger (2) and is connected between the third stop valve (7-3) and the suction port of the low-temperature compressor (1-1); the other path passes through the fourth stop valve (7-4) and is connected to the pipeline between the fourth interface of the first four-way reversing valve (8-1) and the fourth interface of the condensation evaporator (5).

2. The cascade compression multi-cycle PVT-air source multi-connected heat pump air conditioning system for defrosting of outdoor heat sources according to claim 1, wherein, The cascade compression multi-cycle PVT-air source multi-connected unit heat pump air conditioning system for outdoor heat source defrosting operates in six cycles: single-stage compression PVT heating cycle, single-stage compression air source heating cycle, cascade compression PVT heating cycle, cascade compression air source heating cycle, outdoor fin heat exchanger defrosting cycle, and single-stage compression air source refrigeration cycle.

3. The cascade compression multi-cycle PVT-air source multi-connected heat pump air conditioning system for outdoor heat source defrosting according to claim 2, wherein When the cascade compression multi-cycle PVT-air source multi-connected unit heat pump air conditioning system for outdoor heat source defrosting operates in a single-stage compression PVT heating cycle, the first shut-off valve (7-1) and the third shut-off valve (7-3) are closed, and the second shut-off valve (7-2) and the fourth shut-off valve (7-4) are opened; the first interface of the first four-way reversing valve (8-1) is communicated with the second interface of the first four-way reversing valve (8-1), and the third interface of the first four-way reversing valve (8-1) is communicated with the fourth interface of the first four-way reversing valve (8-1); the first interface of the second four-way reversing valve (8-2) is communicated with the second interface of the second four-way reversing valve (8-2), and the third interface of the second four-way reversing valve (8-2) is communicated with the fourth interface of the second four-way reversing valve (8-2); the low-temperature compressor (1-1) stops operating, and the high-temperature compressor (1-2) starts operating; the photovoltaic cells in the PVT module (3) generate electricity under sunlight irradiation and are adjusted by the inverter (10) to become electricity for user use.

4. The cascade compression multi-cycle PVT-air source multi-connected heat pump air conditioning system for defrosting outdoor heat sources according to claim 2, wherein, When the cascade compression multi-cycle PVT-air source multi-connected unit heat pump air conditioning system for outdoor heat source defrosting operates in a single-stage compression air source heating cycle, the first shut-off valve (7-1), the third shut-off valve (7-3), and the fourth shut-off valve (7-4) are opened, and the second shut-off valve (7-2) is closed; the first interface of the first four-way reversing valve (8-1) is communicated with the second interface of the first four-way reversing valve (8-1), and the third interface of the first four-way reversing valve (8-1) is communicated with the fourth interface of the first four-way reversing valve (8-1); the first interface of the second four-way reversing valve (8-2) is communicated with the second interface of the second four-way reversing valve (8-2), and the third interface of the second four-way reversing valve (8-2) is communicated with the fourth interface of the second four-way reversing valve (8-2); the low-temperature compressor (1-1) stops operating, and the high-temperature compressor (1-2) starts operating; the photovoltaic cells in the PVT module (3) generate electricity under sunlight irradiation and are adjusted by the inverter (10) to become electricity for user use.

5. The cascade compression multi-cycle PVT-air source multi-connected heat pump air conditioning system for defrosting of outdoor heat sources according to claim 2, characterized in that, When the cascade compression multi-cycle PVT-air source multi-connected unit heat pump air conditioning system for outdoor heat source defrosting operates in a cascade compression PVT heating cycle, the first shut-off valve (7-1) is closed, and the second shut-off valve (7-2), the third shut-off valve (7-3), and the fourth shut-off valve (7-4) are opened; the first interface of the first four-way reversing valve (8-1) is communicated with the fourth interface of the first four-way reversing valve (8-1), and the second interface of the first four-way reversing valve (8-1) is communicated with the third interface of the first four-way reversing valve (8-1); the first interface of the second four-way reversing valve (8-2) is communicated with the second interface of the second four-way reversing valve (8-2), and the third interface of the second four-way reversing valve (8-2) is communicated with the fourth interface of the second four-way reversing valve (8-2); both the low-temperature compressor (1-1) and the high-temperature compressor (1-2) start operating; the photovoltaic cells in the PVT module (3) generate electricity under sunlight irradiation and are adjusted by the inverter (10) to become electricity for user use.

6. The cascade compression multi-cycle PVT-air source multi-connected heat pump air conditioning system for outdoor heat source defrosting according to claim 2, characterized in that, When the cascade compression multi-cycle PVT-air source multi-connected heat pump air-conditioning system for outdoor heat source defrosting operates in the cascade compression air source heating cycle, the first stop valve (7-1) and the fourth stop valve (7-4) are opened, the second stop valve (7-2) and the third stop valve (7-3) are closed. The first port of the first four-way reversing valve (8-1) is connected to the fourth port of the first four-way reversing valve (8-1), and the second port of the first four-way reversing valve (8-1) is connected to the third port of the first four-way reversing valve (8-1). The first port of the second four-way reversing valve (8-2) is connected to the second port of the second four-way reversing valve (8-2), and the third port of the second four-way reversing valve (8-2) is connected to the fourth port of the second four-way reversing valve (8-2). Both the low-temperature compressor (1-1) and the high-temperature compressor (1-2) are started. The photovoltaic cells in the PVT module (3) generate electricity under sunlight irradiation and are adjusted by the inverter (10) into electricity for user use.

7. The cascade compression multi-cycle PVT-air source multi-connected heat pump air-conditioning system for defrosting of outdoor heat source according to claim 2, wherein When the cascade compression multi-cycle PVT-air source multi-connected heat pump air-conditioning system for outdoor heat source defrosting operates in the outdoor fin heat exchanger defrosting cycle, the first stop valve (7-1) and the second stop valve (7-2) are opened, the third stop valve (7-3) and the fourth stop valve (7-4) are closed. The first port of the first four-way reversing valve (8-1) is connected to the second port of the first four-way reversing valve (8-1), and the third port of the first four-way reversing valve (8-1) is connected to the fourth port of the first four-way reversing valve (8-1). The first port of the second four-way reversing valve (8-2) is connected to the fourth port of the second four-way reversing valve (8-2), and the second port of the second four-way reversing valve (8-2) is connected to the third port of the second four-way reversing valve (8-2). The low-temperature compressor (1-1) is shut down and the high-temperature compressor (1-2) is started. The opening degree of the first throttle valve (4-1) is adjusted to the maximum. The photovoltaic cells in the PVT module (3) generate electricity under sunlight irradiation and are adjusted by the inverter (10) into electricity for user use.

8. The cascade compression multi-cycle PVT-air source multi-connected heat pump air conditioning system for outdoor heat source defrosting according to claim 2, characterized in that, When the cascade compression multi-cycle PVT-air source multi-connected heat pump air-conditioning system for outdoor heat source defrosting operates in the single-stage compression air source refrigeration cycle, the first stop valve (7-1) and the fourth stop valve (7-4) are opened, the second stop valve (7-2) and the third stop valve (7-3) are closed. The first port of the first four-way reversing valve (8-1) is connected to the second port of the first four-way reversing valve (8-1), and the third port of the first four-way reversing valve (8-1) is connected to the fourth port of the first four-way reversing valve (8-1). The first port of the second four-way reversing valve (8-2) is connected to the fourth port of the second four-way reversing valve (8-2), and the second port of the second four-way reversing valve (8-2) is connected to the third port of the second four-way reversing valve (8-2). The low-temperature compressor (1-1) is shut down and the high-temperature compressor (1-2) is started. The opening degree of the first throttle valve (4-1) is adjusted to the maximum.

9. The cascade compression multi-cycle PVT-air source multi-connected heat pump air conditioning system for defrosting of outdoor heat sources according to any one of claims 1-8, characterized in that, The PVT component (3) is of flat box type, tube plate type, blown plate type or flat plate type; the high-temperature compressor (1-2) and the low-temperature compressor (1-1) are any one of scroll compressors, rotary compressors, screw compressors and piston compressors; the first throttle valve (4-1), the second throttle valve (4-2) and the third throttle valve (4-3) are electronic expansion valves, thermostatic expansion valves, capillary tubes or orifice throttling devices; the first stop valve (7-1), the second stop valve (7-2), the third stop valve (7-3) and the fourth stop valve (7-4) are solenoid valves, manual valves or ball valves.

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