Micro-channel PVT heat collection evaporator comprehensively utilizing solar energy and air energy and heat pump system

Abstract

The invention discloses a micro-channel type PVT heat collection evaporator comprehensively utilizing solar energy and air energy and a heat pump system, and relates to the technical field of PVT heat pumps. The PVT heat collection evaporator comprises a photovoltaic panel, heat conduction silica gel, a ribbed micro-channel heat exchanger, a rear cover plate and a fan which are sequentially arranged from top to bottom. Wherein the photovoltaic panel and the ribbed micro-channel heat exchanger are bonded through heat-conducting silica gel; the rear cover plate is bonded with the photovoltaic panel through EVA glue. The fan is mounted on the rear cover plate through bolts; a low-temperature refrigerant is arranged in the ribbed micro-channel heat exchanger, an oil return pipe is arranged on the side, close to an outlet, of the bottom of the heat exchanger, and the oil return pipe is used for collecting and conveying lubricating oil deposited due to the gravity effect. The technical problems that an existing PVT heat pump is low in energy utilization rate, low in building roof space utilization rate, low in evaporation temperature and difficult in oil return can be solved, the resource utilization variety is rich and comprehensive, the building roof space is reasonably planned, and the heat exchange performance is comprehensively improved.

Description

Technical Field

[0001] This invention relates to the field of PVT heat pump technology, and in particular to a microchannel PVT heat collector evaporator and heat pump system that integrates solar energy and air energy. Background Technology

[0002] As a clean and renewable energy source, solar energy, by establishing a building energy supply system based on solar energy utilization, can effectively promote the development of green building energy conservation and emission reduction in China. However, currently common solar thermal and solar power generation technologies only utilize solar energy resources in a single form, which to some extent limits the widespread application of solar energy in the building sector. In contrast, PVT heat pumps (Photovoltaic Thermal Heat Pumps) combine heating and power generation functions, showing great development and application potential.

[0003] The PVT (Polymer Transformer) evaporator is a key component of a PVT heat pump system, directly impacting its heat collection and power generation performance. Existing PVT heat pump systems either employ a single PV-side heat-extracting evaporator, relying solely on intermittent solar energy for heating and power generation, resulting in poor stability and an inability to meet users' nighttime heating and summer cooling needs; or they use a PV-side heat-extracting evaporator and an air-side heat-extracting evaporator in parallel; or they separate the PV collector and evaporator into two components, failing to achieve efficient utilization of building roof space. Therefore, developing a heat-extracting evaporator that integrates solar and air energy to achieve uninterrupted heating throughout the day will help achieve integrated heat pump system structures and diversified operating modes.

[0004] To increase the evaporation temperature of PVT (Polymer Transformer) evaporators, it is necessary to develop an evaporator that provides sufficient heat exchange area, heat exchange time, and sufficiently low flow resistance. Currently, commonly used PVT evaporators either employ complex blow-through channels such as honeycomb or serpentine designs to increase the heat exchange area between the refrigerant and the PV side, or use plate-tube parallel channels to achieve line contact heat transfer between the refrigerant tubes and the PV side to reduce refrigerant flow resistance. However, the utilization rate of a single photovoltaic panel area is less than 20%, failing to simultaneously meet the requirements of "large heat exchange area and low flow resistance" for evaporators, thus resulting in generally low evaporation temperatures. Microchannel heat exchangers, as a new type of high-efficiency heat exchanger, show significantly improved heat exchange performance when the channel size is less than 3mm, with the convective heat transfer coefficient increasing by 50%-100% or even higher. Therefore, applying microchannels to the flow channels of PVT evaporators is a more ideal choice.

[0005] To ensure complete refrigerant vaporization within the evaporator, when assembling the evaporator with the tilted photovoltaic panel, its outlet is typically positioned on the upper side of the tilted surface to facilitate the smooth discharge of the less dense gaseous refrigerant. However, regardless of whether a U-shaped loop layout with the inlet on the upper side or a bottom-in, top-out flow channel with the inlet on the lower side is used, there is a risk of lubricating oil remaining in the evaporator and failing to return to the compressor. Over long-term operation, this will lead to insufficient compressor lubrication, severely damaging its service life and affecting the heat exchange performance of the PVT collector evaporator. Therefore, designing a flow channel scheme that balances complete refrigerant vaporization with effective lubricating oil return is of practical engineering significance. Summary of the Invention

[0006] The purpose of this invention is to provide a microchannel PVT collector evaporator and heat pump system that integrates solar energy and air energy, aiming to solve or improve at least one of the above-mentioned technical problems.

[0007] To achieve the above objectives, the present invention provides the following solution:

[0008] A microchannel PVT collector evaporator that integrates solar and air energy utilization includes:

[0009] The components, arranged sequentially from top to bottom, include a photovoltaic panel, thermally conductive silicone, a ribbed microchannel heat exchanger, a rear cover plate, and a fan. The photovoltaic panel and the ribbed microchannel heat exchanger are bonded together using the thermally conductive silicone. The rear cover plate is bonded to the photovoltaic panel using EVA adhesive. The fan is bolted to the rear cover plate. The ribbed microchannel heat exchanger contains a low-temperature refrigerant and has an oil return pipe at its bottom near the outlet. This oil return pipe collects and transports lubricating oil deposited due to gravity.

[0010] Optionally, the ribbed microchannel heat exchanger specifically includes: a gas collecting pipe, a flat pipe, a liquid conveying pipe, a dividing element, a liquid dispensing pipe, fins, and an oil return pipe;

[0011] The ribs are welded at equal intervals onto the flat tube, dividing the flat tube into two conveying areas. Both conveying areas are symmetrically arranged along the center line. One end of one conveying area is connected to the liquid distribution pipe, and one end of the other conveying area is connected to the gas collecting pipe. The other ends of both conveying areas are connected to the liquid delivery pipe, forming a U-shaped loop. The oil return pipe is connected to the side of the liquid delivery pipe near the refrigerant outlet. The dividing element is used to separate the liquid distribution pipe and the gas collecting pipe. The liquid distribution pipe and the gas collecting pipe are located on the upper side of the inclined photovoltaic panel, and gaseous refrigerant flows out from the upper gas collecting pipe. The liquid delivery pipe and the oil return pipe are located on the lower side of the inclined photovoltaic panel, and lubricating oil flows out from the lower oil return pipe.

[0012] Optionally, the heat exchange area of ​​the ribbed microchannel heat exchanger is calculated according to the following formula:

[0013]

[0014] U -1 =R conv,a-PV +R cond,PV-mic +R conv,a-ri +R cond,ri-mic +R conv,mic-re

[0015] Among them, A eva Calculate the area of ​​the solar collector evaporator, in meters. 2 U is the heat transfer coefficient of the microchannel structure, W / (m²). 2 ·K); △T m R is the average temperature difference between the refrigerant and the ambient air, expressed in K. conv，a-PV The convective heat transfer resistance of the photovoltaic panel to the air is (m) 2 ·K) / W;R cond，PV-mic The thermal resistance of the photovoltaic panel to the microchannel is (m 2 ·K) / W;R conv，a-ri The convective heat transfer thermal resistance between air and the ribbed surface of the microchannel, (m 2 ·K) / W;R conv，ri-mic The thermal resistance of the fins to the microchannel is (m 2 ·K) / W;R conv，mic-re The convective heat transfer thermal resistance between the microchannel and the refrigerant, (m 2 ·K) / W.

[0016] Optionally, the rear cover plate is made of iron cold-rolled sheet into an Ω-shaped integrated structure, with the four sides bent to form an adhesive plane with the photovoltaic panel, and is bonded to the photovoltaic panel with EVA adhesive.

[0017] Optionally, multiple guide grooves are provided on both long sides of the rear cover plate as air inlets, and two air outlets are provided on the top surface. The inner top surface of the rear cover plate is attached to the top of the fins of the ribbed microchannel heat exchanger to form an air duct.

[0018] The present invention also provides a heat pump system that integrates solar energy and air energy, using the microchannel PVT collector evaporator as described above, including: microchannel PVT collector evaporator, compressor, indoor unit, electronic expansion valve, gas-liquid separator, reheater, oil return valve, reheat valve, four-way reversing valve, inverter, battery, controller and temperature sensor.

[0019] The microchannel PVT evaporator, the compressor, the indoor unit, the electronic expansion valve, the gas-liquid separator, the reheater, the oil return valve, the reheat valve, and the four-way reversing valve form a refrigerant evaporation-condensation loop through refrigerant pipelines; the microchannel PVT evaporator, the inverter, the battery, and the compressor form a power supply loop through cables;

[0020] In the refrigerant evaporation-condensation loop, the microchannel PVT collector evaporator is connected to the fourth port D of the four-way reversing valve, the reheater, the electronic expansion valve, and the oil return valve, respectively; the second port B of the four-way reversing valve is connected to the indoor unit; the third port C of the four-way reversing valve is connected to the gas-liquid separator; the first port A of the four-way reversing valve is connected to the compressor; the compressor is also connected to the gas-liquid separator; the fourth port D is also connected to the reheater; the reheater is also connected to the oil return valve; the indoor unit is also connected to the reheat valve and the electronic expansion valve; the reheat valve is also connected to the electronic expansion valve through the reheater; the temperature sensor is located at the outlet of the microchannel PVT collector evaporator.

[0021] In the power supply and distribution loop, the microchannel PVT collector evaporator is also connected to the inverter; the inverter is also connected to the compressor, the battery and the indoor unit respectively.

[0022] The controller is connected to the four-way reversing valve, the reheat valve, the temperature sensor, the electronic expansion valve, the oil return valve, and the microchannel PVT evaporator, respectively, and is used for:

[0023] The system switches between the corresponding operating modes and outputs the corresponding equipment parameters according to the meteorological environment and user needs, so as to meet the user's needs for uninterrupted heating and hot water throughout the day in winter and cooling in summer. The operating modes include solar-air dual-source heating mode, single-source heating mode, single-source cooling mode and oil return mode.

[0024] Optionally, when switching operating modes, the controller specifically includes: controlling the four-way reversing valve to switch between heating and cooling in all modes; controlling the fan to start in air source heating mode, solar-air dual source heating mode, and single source cooling mode; and controlling the oil return valve and reheat valve to start in oil return mode.

[0025] Optionally, the controller may specifically include the following when outputting device parameters:

[0026] Based on the outlet refrigerant temperature fed back by the temperature sensor, calculate the refrigerant superheat and perform the following operations:

[0027] In heating mode, when the refrigerant superheat is below 5°C, the electronic expansion valve is controlled to reduce its opening. When the electronic expansion valve reaches its minimum opening or the heat pump system cannot meet the indoor heat demand, the fan is controlled to turn on, and the refrigerant absorbs heat from the air and the photovoltaic panel at the same time. When the refrigerant superheat is above 5°C, the fan is controlled to reduce its speed. When the fan stops, the electronic expansion valve is controlled to increase its opening.

[0028] In oil return mode, the control oil return valve and reheat valve are opened. The refrigerant flowing out of the microchannel PVT collector evaporator carries the lubricating oil from the bottom of the evaporator and flows out through the oil return pipe. In the reheater, it exchanges heat with the high-temperature refrigerant at the indoor unit outlet and then flows to the compressor, thus realizing the oil return function. At the same time, the refrigerant flowing out of the indoor unit is divided into two paths: one path flows directly to the electronic expansion valve, and the other path enters the reheater to release heat and then flows to the electronic expansion valve, so as to ensure that the refrigerant flowing out of the oil return pipe can be completely vaporized.

[0029] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0030] This invention discloses a microchannel PVT (Photovoltaic Transformer) collector evaporator and heat pump system that comprehensively utilizes solar and air energy. The PVT collector evaporator includes, from top to bottom, a photovoltaic panel, thermally conductive silicone, a finned microchannel heat exchanger, a rear cover plate, and a fan. The photovoltaic panel and the finned microchannel heat exchanger are bonded together with thermally conductive silicone; the rear cover plate is bonded to the photovoltaic panel with EVA adhesive; and the fan is bolted to the rear cover plate. The finned microchannel heat exchanger contains a low-temperature refrigerant, and an oil return pipe is located at the bottom of the heat exchanger near the outlet. This oil return pipe collects and transports lubricating oil deposited due to gravity. This invention solves the technical problems of low energy utilization, low roof space utilization, low evaporation temperature, and difficult oil return in existing PVT heat pumps, resulting in more comprehensive resource utilization, more rational planning of building roof space, and a comprehensive improvement in heat exchange performance. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This is a schematic diagram of the microchannel PVT collector evaporator in this embodiment;

[0033] Figure 2 This is an exploded view of the microchannel PVT collector evaporator in this embodiment;

[0034] Figure 3This is a flow chart of the heat exchanger operation of the microchannel PVT collector evaporator in this embodiment;

[0035] Figure 4 This is a flow chart of the heat exchanger oil return process for the microchannel PVT collector evaporator in this embodiment.

[0036] Figure 5 This is a view of the rear cover plate of the microchannel PVT collector evaporator in this embodiment;

[0037] Figure 6 This is a schematic diagram of the microchannel PVT collector evaporator used in the heat pump system in this embodiment;

[0038] Figure 7 This is a system schematic diagram of the microchannel PVT heat pump system used in the heating mode in this embodiment;

[0039] Figure 8 This is a system schematic diagram of the microchannel PVT heat pump system used in the oil return mode in this embodiment;

[0040] Figure 9 This is a system schematic diagram of the microchannel PVT heat pump system used in heating mode in this embodiment;

[0041] Figure 10 This is a system schematic diagram of the microchannel PVT heat pump system used in the cooling mode in this embodiment.

[0042] Reference numerals: 1. Microchannel PVT collector evaporator; 2. Photovoltaic panel; 3. Thermally conductive silicone; 4. Finned microchannel heat exchanger; 401. Gas collection pipe; 402. Flat tube; 403. Liquid delivery pipe; 404. Divider; 405. Liquid distribution pipe; 406. Fin; 407. Oil return pipe; 5. Rear cover plate; 501. Air inlet; 502. Air outlet; 6. Fan; 7. Battery; 8. Four-way reversing valve; 9. Compressor; 10. Gas-liquid separator; 11. Reheater; 12. Electronic expansion valve; 13. Reheat valve; 14. Oil return valve; 15. Indoor unit; 16. Inverter; 17. Temperature sensor; 18. Water pump; 19. Hot water storage tank. Detailed Implementation

[0043] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] The purpose of this invention is to provide a microchannel PVT collector evaporator and heat pump system that integrates solar energy and air energy, aiming to solve or improve at least one of the above-mentioned technical problems.

[0045] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0046] This invention provides a microchannel PVT collector evaporator 1 that integrates solar and air energy. It adopts a multi-layer composite structure design. Its features are that it is composed of a photovoltaic panel 2, a thermally conductive silicone 3, a ribbed microchannel heat exchanger 4, a rear cover plate 5, and a fan 6 from top to bottom. The thermally conductive silicone 3 bonds the photovoltaic panel 2 and the ribbed microchannel heat exchanger 4. The rear cover plate 5 is bonded to the back of the photovoltaic panel 2 with EVA adhesive. The fan 6 is bolted to the rear cover plate 5.

[0047] Specifically, the photovoltaic panel 2 achieves photoelectric conversion under solar irradiation, and the generated electricity is directly supplied to users. At the same time, the unconverted solar radiation energy is transferred to the back ribbed microchannel heat exchanger 4 in the form of heat energy to provide a low-temperature heat source for the heat pump system.

[0048] Specifically, the ribbed microchannel heat exchanger 4 is tightly attached to the back of the photovoltaic panel 2 via the thermally conductive silicone 3. The thermally conductive silicone 3 has excellent thermal conductivity, with a thermal conductivity coefficient 6-10 times that of ordinary EVA adhesive. Specifically, the ribbed microchannel heat exchanger 4 includes a flat tube 402, a liquid distribution tube 405, fins 406, a liquid delivery tube 403, a dividing element 404, a gas collecting tube 401, and an oil return tube 407. The flat tube 402 is divided into two regions according to the different flow directions and is symmetrically arranged along the center line. One half of the flat tube 402 is connected at its upper end to the liquid distribution pipe 405, and the other half of the flat tube 402 is connected at its upper end to the gas collecting pipe 401. The other ends of the two sections of the flat tube 402 are connected through the liquid delivery pipe 403, forming a highly efficient "U"-shaped loop system. Furthermore, the oil return pipe 407 is connected to the side of the liquid delivery pipe 403 near the refrigerant outlet. Furthermore, the fins 406 are welded at equal intervals to the lower surface of the flat tube 402 to increase the heat transfer area on the air side of the microchannel. The structural dimensions of the fins 406 are rationally designed based on fin efficiency and wind resistance. Furthermore, the diameters of the gas collecting pipe 401 and the oil return pipe 407 are 1.5 times the diameter of the liquid distribution pipe 405.

[0049] Specifically, the required heat exchange area of ​​the ribbed microchannel heat exchanger 4 is calculated based on the building heating load under the most unfavorable working conditions at night in winter. The relevant calculation formulas are shown in equations (1) and (2), and the relevant design parameters refer to the "Code for Design of Heating, Ventilation and Air Conditioning of Civil Buildings" (GB50736-2012) and "Room Air Conditioners" (GB7725-2022). Furthermore, when the ribbed microchannel heat exchanger 4 is assembled with the photovoltaic panel 2, the liquid distribution pipe 405 and the gas collection pipe 401 should be placed on the upper side of the inclined plate surface, and the liquid delivery pipe 403 and the oil return pipe 407 should be placed on the lower side.

[0050]

[0051] U -1 =R conv,a-PV +R cond,PV-mic +R conv,a-ri +R cond,ri-mic +R conv,mic-re (2)

[0052] In the formula, A eva The required area (m²) for the heat collector evaporator 2 U is the heat transfer coefficient of the microchannel structure, W / (m²). 2 ·K); △T m R is the average temperature difference between the refrigerant and the ambient air, expressed in K. conv，a-PV The convective heat transfer resistance of air to photovoltaic panel 2 is (m 2 ·K) / W;R cond，PV-mic The thermal resistance of the photovoltaic panel 2 pairs of microchannels is (m 2 ·K) / W;R conv，a-ri The convective heat transfer thermal resistance between air and the ribbed surface of the microchannel, (m 2 ·K) / W;R conv，ri-mic The thermal resistance of the fin 406 to the microchannel is (m 2 ·K) / W;R conv，mic-re The convective heat transfer thermal resistance between the microchannel and the refrigerant, (m 2 ·K) / W.

[0053] Specifically, the rear cover plate 5 is made of refrigerated rolled iron into an Ω-shaped integrated structure, which not only serves as the mounting base for the fan 6, but also provides air channels through the pre-reserved guide grooves on both sides. Specifically, the rear cover plate 5 is bent around its perimeter to form a bonding plane with the photovoltaic panel 2, and is bonded to the photovoltaic panel 2 with EVA adhesive; the long sides of the rear cover plate 5 are slotted, and several air inlets 501 are set along the length direction, and two air outlets 502 are opened on the top surface; during installation, the inner top surface of the rear cover plate 5 is attached to the top of the fins 406 of the ribbed microchannel heat exchanger 4 to form an air duct, thereby ensuring that air is evenly swept across the surface of the fins 406 from the air duct between the ribbed microchannel heat exchanger 4 and the rear cover plate 5.

[0054] Specifically, the selected fan 6 should be able to meet the air volume and air pressure requirements of 2-3 m / s for the oncoming wind speed between the fins 406.

[0055] Based on the microchannel PVT collector evaporator 1 described above, a heat pump system equipped with a microchannel PVT collector evaporator 1 that integrates solar energy and air energy is also provided. The system includes the microchannel PVT collector evaporator 1, compressor 9, indoor unit 15, electronic expansion valve 12, gas-liquid separator 10, reheater 11, oil return valve 14, reheat valve 13, four-way reversing valve 8, inverter 16, battery 7, controller and temperature sensor 17.

[0056] Specifically, the microchannel PVT evaporator 1, compressor 9, indoor unit 15, electronic expansion valve 12, gas-liquid separator 10, reheater 11, oil return valve 14, reheat valve 13, and four-way reversing valve 8 form a refrigerant evaporation and condensation loop through refrigerant pipelines. The first port A and the third port C of the four-way reversing valve 8, the gas-liquid separator 10, and the compressor 9 are connected sequentially through pipelines; the second port B of the four-way reversing valve 8 is connected to the inlet of the indoor unit 15, and the outlet of the indoor unit 15 is connected to two paths: one path is connected to the inlet of the electronic expansion valve 12 via the reheat valve 13 and the reheater 11, and the other path is bypassed and directly connected to the inlet of the electronic expansion valve 12. The outlet of the electronic expansion valve 12 is connected to the liquid distribution pipe 405 of the PVT solar collector evaporator; the fourth port D of the four-way reversing valve 8 is connected to two paths, one of which is directly connected to the gas collection pipe 401 of the PVT solar collector evaporator, and the other path is connected to the oil return pipe 407 of the PVT solar collector evaporator via the reheater 11 and the oil return valve 14.

[0057] Specifically, the microchannel PVT evaporator 1, the inverter 16, the battery 7, the compressor 9, and the fan 6 form a power supply loop via cables. The controller is connected to the temperature sensor 17, the fan 6, the electronic expansion valve 12, the four-way reversing valve 8, the oil return valve 14, and the reheat valve 13 to form a control loop. Furthermore, the temperature sensor 17 is installed at the gas collection pipe 401 of the PVT evaporator.

[0058] Specifically, the controller switches between solar heating, air source heating, solar-air dual-source heating, air source cooling, and oil return mode according to meteorological conditions and user needs; the controller controls the four-way reversing valve 8 to switch between heating and cooling modes; furthermore, the controller controls the fan 6 to turn on in air source heating mode, solar-air dual-source heating mode, and cooling mode; furthermore, the controller controls the oil return valve 14 and reheat valve 13 to turn on in periodic oil return mode so that the lubricating oil accumulated at the bottom of the evaporator can periodically return to the compressor 9.

[0059] Specifically, the controller calculates the refrigerant superheat based on the refrigerant temperature at the outlet of the microchannel PVT collector evaporator 1 fed back by the temperature sensor 17, and makes the following judgments: In heating mode, when the refrigerant superheat at the evaporator outlet is lower than 5°C, the electronic expansion valve 12 is preferentially controlled to reduce its opening. When the electronic expansion valve 12 reaches its minimum opening or the heat pump system cannot meet the indoor heat demand, the fan 6 is controlled to turn on, and the refrigerant absorbs heat from the air and the photovoltaic panel 2 at the same time. When the refrigerant superheat at the evaporator outlet is higher than 5°C, the fan 6 is preferentially controlled to reduce its speed. When the fan 6 stops, the electronic expansion valve 12 is controlled to increase its opening to adapt to the load of the evaporator.

[0060] The PVT (Polymer Transformer) evaporator in this invention features a finned microchannel heat exchanger 4 installed on the back of the photovoltaic panel 2. When the PVT evaporator operates, the low-temperature refrigerant in the microchannels absorbs heat from the photovoltaic panel 2, reducing its temperature and increasing its power generation efficiency. The generated electricity prioritizes meeting the system's own power needs, with surplus electricity available for grid connection. Simultaneously, the low-temperature refrigerant also absorbs heat from the air. The heat absorbed by the PVT evaporator is upgraded by a heat pump system and can then be used to meet users' heating needs. Specifically, during summer nights, by activating the fan 6 to enhance heat exchange, the device can be switched to condenser mode for cooling, forming a comprehensive energy system integrating power generation, heating, and cooling.

[0061] The upper side of the microchannel of the PVT collector evaporator in this invention is a flat plate, which is bonded to the photovoltaic panel 2 by thermally conductive silicone 3 with good thermal conductivity. The lower side is welded with parallel straight ribs with an efficiency of more than 80%, which are in direct contact with the air. Two fans 6 are installed perpendicular to the ribs 406 on the side of the ribs 406. The air heat source can directly perform forced convection heat exchange on the surface of the component. Even at night, the system can still exchange heat with the air to meet the user's heating needs, expanding the application scenarios of the PVT collector evaporator. The specific operating modes are shown in Table 1.

[0062] Table 1. Determination of Annual Operation Mode for Microchannel PVT Collector Evaporator

[0063]

[0064]

[0065] Note: √ indicates that the operating mode is operable, × indicates that the operating mode is not operable, and ○ indicates that the system can be operated depending on user needs and weather conditions.

[0066] The refrigerant flow channel of the PVT collector evaporator in this invention adopts a parallel microchannel flow channel, which is laid flat on the back of the entire photovoltaic panel 2. The heat exchange area can be regarded as the entire area of ​​the photovoltaic panel 2, which is increased compared with tube sheet and blown plate PVT modules. Moreover, the parallel flow channel reduces the local resistance introduced by honeycomb, teardrop and other blown flow channels. Therefore, this PVT collector evaporator has a higher evaporation temperature than tube sheet and blown plate evaporators, thereby improving the heat collection performance of the heat pump system.

[0067] The PVT collector evaporator in this invention employs a flow channel design that balances complete refrigerant vaporization with effective lubricating oil return. Its inlet and outlet are both located on the upper side, forming a U-shaped loop layout. This allows the less dense gaseous refrigerant to be discharged smoothly, ensuring complete refrigerant vaporization within the evaporator. Simultaneously, an oil return pipe 407 is connected to the bottom of the evaporator. When the oil return pipe 407 is open, it enables periodic oil return to the system, extending the service life of the compressor 9. To prevent incomplete refrigerant vaporization during the oil return process, a reheater 11 is included in the system. This reheater allows for thorough heat exchange between the refrigerant in the oil return pipe 407 and the high-temperature refrigerant flowing from the indoor unit 15, further preventing wet compression issues in the compressor 9.

[0068] As a specific implementation method, such as... Figures 1-10 The example shown.

[0069] like Figure 1 and Figure 2As shown in the figure, the microchannel PVT collector evaporator 1 proposed in this embodiment, which integrates solar energy and air energy, adopts a multi-layer composite structure design, including, from top to bottom, a photovoltaic panel 2, thermally conductive silicone 3, a finned microchannel heat exchanger 4, a rear cover plate 5, and a fan 6. Specifically, the thermally conductive silicone 3 is used to bond the photovoltaic panel 2 and the finned microchannel heat exchanger 4; the rear cover plate 5 is bonded to the back of the photovoltaic panel 2 with EVA adhesive; the fan 6 is bolted to the rear cover plate 5, and its selection should be able to meet the air volume and air pressure requirements of 2-3 m / s for the face wind speed between the fins 406.

[0070] like Figure 3 As shown, the ribbed microchannel heat exchanger 4 includes a gas collecting pipe 401, a flat pipe 402, a liquid delivery pipe 403, a dividing element 404, a liquid distribution pipe 405, fins 406, and an oil return pipe 407. Specifically, the flat pipe 402 is divided into two regions according to the different flow directions, and is arranged symmetrically along the center line. One half of the flat tube 402 is connected at its upper end to the liquid distribution pipe 405, and the other half of the flat tube 402 is connected at its upper end to the gas collecting pipe 401. The other ends of the flat tubes 402 in both areas are connected through the liquid delivery pipe 403, forming a highly efficient "U"-shaped loop system. Furthermore, the oil return pipe 407 is connected to the side of the liquid delivery pipe 403 near the refrigerant outlet. Furthermore, the fins 406 are welded at equal intervals to the surface of the flat tube 402 to increase the heat transfer area on the air side of the microchannel. The structural dimensions of the fins 406 are rationally designed based on fin efficiency and wind resistance. Furthermore, the diameters of the gas collecting pipe 401 and the oil return pipe 407 are 1.5 times the diameter of the liquid distribution pipe 405. Furthermore, when the ribbed microchannel heat exchanger 4 is assembled with the photovoltaic panel 2, the liquid distribution pipe 405 and the gas collecting pipe 401 are placed on the upper side of the inclined plate surface, and the liquid delivery pipe 403 and the oil return pipe 407 are placed on the lower side. At this time, the gaseous refrigerant flows out from the upper gas collecting pipe 401, and the lubricating oil flows out periodically from the lower oil return pipe 407.

[0071] When the microchannel PVT collector evaporator 1 is working, the oil return pipe 407 is normally closed. Low-temperature liquid refrigerant flows into the distributor pipe 405, then into the flat pipe 402, and subsequently into the delivery pipe 403. From there, it is transported into the other half of the flat pipe 402, and finally flows into the gas collecting pipe 401, exiting the PVT collector evaporator. High-temperature ambient air flows evenly across the surface of the fins 406 from both sides of the finned microchannel heat exchanger 4, and exits through the fan 6 outlet. The airflow direction is perpendicular to the refrigerant flow direction. During its flow within the pipes, the low-temperature liquid refrigerant absorbs heat from both the photovoltaic panel 2 and the air, gradually evaporating and increasing in dryness, eventually exiting the PVT collector evaporator as a superheated gas. When solar irradiance is good, the fan 6 can be turned off, allowing the low-temperature refrigerant to absorb heat from the photovoltaic panel 2 and exchange heat through natural convection with the air.

[0072] like Figure 4As shown, when the PVT collector evaporator periodically returns oil, the oil return pipe 407 is opened. The refrigerant in the liquid delivery pipe 403 carries the lubricating oil at the bottom of the evaporator and flows directly to the compressor 9 through the oil return pipe 407, thereby realizing the recovery of lubricating oil.

[0073] like Figure 1 and Figure 5 As shown, the rear cover plate 5 is made of refrigerated rolled iron into an integrated "Ω" shape, serving not only as the mounting base for the fan 6, but also providing air channels through the pre-reserved guide grooves on both sides. Specifically, the rear cover plate 5 is bent around its perimeter to form a bonding plane with the photovoltaic panel 2, and is bonded to the photovoltaic panel 2 with EVA adhesive; the long sides of the rear cover plate 5 are slotted, with several air inlets 501 arranged along its length, and two air outlets 502 are opened on the top surface; during installation, the inner top surface of the rear cover plate 5 is attached to the top of the fins 406 of the ribbed microchannel heat exchanger 4, forming an air duct, thereby ensuring that air flows evenly across the surface of the fins 406 from the air duct between the ribbed microchannel heat exchanger 4 and the rear cover plate 5.

[0074] like Figure 6 As shown, a heat pump system using a microchannel PVT collector evaporator 1 that integrates solar energy and air energy includes the microchannel PVT collector evaporator 1, compressor 9, indoor unit 15, electronic expansion valve 12, gas-liquid separator 10, reheater 11, oil return valve 14, reheat valve 13, four-way reversing valve 8, inverter 16, battery 7, controller and temperature sensor 17.

[0075] Specifically, the microchannel PVT evaporator 1, compressor 9, indoor unit 15, electronic expansion valve 12, gas-liquid separator 10, reheater 11, oil return valve 14, reheat valve 13, and four-way reversing valve 8 form a refrigerant evaporation and condensation loop through refrigerant pipelines. Specifically, the first port A and third port C of the four-way reversing valve 8, the gas-liquid separator 10, and the compressor 9 are connected sequentially through pipelines; the second port B of the four-way reversing valve 8 is connected to the inlet of the indoor unit 15; the outlet of the indoor unit 15 is connected to two paths: one path connects to the inlet of the electronic expansion valve 12 via the reheat valve 13 and reheater 11, and the other path bypasses and directly connects to the electronic expansion valve 12. The outlet of the electronic expansion valve 12 is connected to the liquid distribution pipe 405 of the PVT solar collector evaporator; the fourth port D of the four-way reversing valve 8 is connected to two paths, one of which is directly connected to the gas collection pipe 401 of the PVT solar collector evaporator, and the other path is connected to the oil return pipe 407 of the PVT solar collector evaporator via the reheater 11 and the oil return valve 14.

[0076] Specifically, the microchannel PVT evaporator 1, inverter 16, battery 7, compressor 9, fan 6 and other power supply equipment form a power supply loop through cables.

[0077] Specifically, the controller is connected to the temperature sensor 17, the fan 6, the electronic expansion valve 12, the four-way reversing valve 8, the oil return valve 14, and the reheat valve 13 to form a control loop. Furthermore, the temperature sensor 17 is installed at the outlet of the PVT collector evaporator.

[0078] Specifically, the controller switches between solar heating, air source heating, solar-air dual-source heating, air source cooling, and oil return mode according to meteorological conditions and user needs; specifically, the controller controls the four-way reversing valve 8 to switch between heating and cooling modes; furthermore, the controller controls the fan 6 to start in air source heating mode, solar-air dual-source heating mode, and cooling mode; furthermore, the controller controls the oil return valve 14 and reheat valve 13 to start in periodic oil return mode.

[0079] Specifically, the controller calculates the refrigerant superheat based on the refrigerant temperature at the outlet of the microchannel PVT collector evaporator 1 fed back by the temperature sensor 17, and makes the following judgments: In heating mode, when the refrigerant superheat at the evaporator outlet is lower than 5°C, the electronic expansion valve 12 is preferentially controlled to reduce its opening. When the electronic expansion valve 12 reaches its minimum opening or the heat pump system cannot meet the indoor heat demand, the fan 6 is controlled to turn on, and the refrigerant absorbs heat from the air and the photovoltaic panel 2 at the same time. When the refrigerant superheat at the evaporator outlet is higher than 5°C, the fan 6 is preferentially controlled to reduce its speed. When the fan 6 stops, the electronic expansion valve 12 is controlled to increase its opening to adapt to the load of the evaporator.

[0080] Figure 7 A system schematic diagram of a heat pump system with the microchannel PVT collector evaporator 1 of the present invention is shown for use in heating mode. In this mode, the indoor unit 15 is used as the condenser of the heat pump system. When the heat pump system is working, the low-temperature liquid refrigerant flows into the PVT collector evaporator through the pipe. After absorbing heat from the photovoltaic panel 2 and the air in the PVT collector evaporator, it vaporizes and flows into port D of the four-way reversing valve 8. It flows out from port C and enters the compressor 9. The low-temperature gaseous refrigerant is compressed into a high-temperature and high-pressure refrigerant in the compressor 9 and then flows into the indoor unit 15 through ports A and B of the four-way reversing valve 8. The indoor air exchanges heat fully with the refrigerant in the indoor unit 15 and blows high-temperature hot air into the room. After the refrigerant releases heat and condenses, it flows into the electronic expansion valve 12 for adiabatic throttling and becomes low-temperature liquid refrigerant to continue to participate in the cycle. While the heat pump system is working, the temperature of the photovoltaic panel 2 decreases, thereby improving the power generation efficiency. The DC power generated is converted into AC power by the inverter 16 and then used to power the fan 6, compressor 9, and indoor unit 15. The surplus power can be stored in the battery 7 or connected to the grid.

[0081] Figure 8A system schematic diagram of a heat pump system with the microchannel PVT collector evaporator 1 of this invention is shown for a periodic oil return mode. Its working principle is similar to that of the heating mode. The difference lies in that, in the periodic oil return mode, the oil return valve 14 and the reheat valve 13 are open. The refrigerant flowing out of the PVT collector evaporator, carrying the lubricating oil from the bottom of the evaporator, flows out through the oil return pipe 407. It exchanges heat with the high-temperature refrigerant at the outlet of the indoor unit 15 in the reheater 11 before flowing to the compressor 9, thus achieving the oil return function. Simultaneously, the refrigerant flowing out of the indoor unit 15 is divided into two paths: one flows directly to the electronic expansion valve 12, and the other enters the reheater 11 to release heat before flowing back to the electronic expansion valve 12, ensuring that the refrigerant flowing out of the oil return pipe 407 can be completely vaporized.

[0082] Figure 9 A system schematic diagram of a heat pump system with the microchannel PVT collector evaporator 1 of this invention is shown for hot water production mode, and its working principle is similar to that of the heating mode. The difference is that a hot water storage tank 19 is used as the condenser of the heat pump system. The water in the hot water storage tank 19 absorbs heat from the high-temperature refrigerant and is then pumped to the user via a water pump 18 to meet the user's domestic hot water needs.

[0083] Figure 10 A system schematic diagram of a heat pump system with the microchannel PVT collector evaporator 1 of this invention is shown for use in cooling mode. Its working principle is similar to that in heating mode. The difference is that the functions of the PVT collector evaporator and the indoor unit 15 are interchanged, and the refrigerant flow circulation is reversed. Specifically, when the system is working, the fan 6 is turned on, and the PVT collector evaporator acts as a condenser. Thanks to the large heat dissipation area of ​​the photovoltaic panel 2, the high-temperature gaseous refrigerant can be fully dissipated and condensed into liquid refrigerant. The indoor unit 15 acts as an evaporator, and the indoor air exchanges heat fully with the refrigerant in the indoor unit 15, blowing cool air into the room, thereby achieving the cooling function.

[0084] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0085] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A microchannel PVT collector evaporator that comprehensively utilizes solar energy and air energy, characterized in that, include: The components, arranged sequentially from top to bottom, include a photovoltaic panel, thermally conductive silicone, a ribbed microchannel heat exchanger, a rear cover plate, and a fan. The photovoltaic panel and the ribbed microchannel heat exchanger are bonded together using the thermally conductive silicone. The rear cover plate is bonded to the photovoltaic panel using EVA adhesive. The fan is bolted to the rear cover plate. The ribbed microchannel heat exchanger contains a low-temperature refrigerant and has an oil return pipe at its bottom near the outlet. This oil return pipe collects and transports lubricating oil deposited due to gravity.

2. The microchannel PVT collector evaporator for comprehensively utilizing solar and air energy as described in claim 1, characterized in that, The ribbed microchannel heat exchanger specifically includes: a gas collecting pipe, a flat pipe, a liquid conveying pipe, a dividing component, a liquid dispensing pipe, fins, and an oil return pipe; The ribs are welded at equal intervals onto the flat tube, dividing the flat tube into two conveying areas. Both conveying areas are symmetrically arranged along the center line. One end of one conveying area is connected to the liquid distribution pipe, and one end of the other conveying area is connected to the gas collecting pipe. The other ends of both conveying areas are connected to the liquid delivery pipe, forming a U-shaped loop. The oil return pipe is connected to the side of the liquid delivery pipe near the refrigerant outlet. The dividing element is used to separate the liquid distribution pipe and the gas collecting pipe. The liquid distribution pipe and the gas collecting pipe are located on the upper side of the inclined photovoltaic panel, and gaseous refrigerant flows out from the upper gas collecting pipe. The liquid delivery pipe and the oil return pipe are located on the lower side of the inclined photovoltaic panel, and lubricating oil flows out from the lower oil return pipe.

3. The microchannel PVT collector evaporator for comprehensively utilizing solar and air energy as described in claim 1, characterized in that, The heat exchange area of ​​the ribbed microchannel heat exchanger is calculated according to the following formula: U -1 =R conv,a-PV +R cond,PV-mic +R conv,a-ri +R cond,ri-mic +R conv,mic-re Among them, A eva Calculate the area of ​​the solar collector evaporator, in meters. 2 U is the heat transfer coefficient of the microchannel structure, W / (m²). 2 ·K); △T m R is the average temperature difference between the refrigerant and the ambient air, expressed in K. conv，a-PV The convective heat transfer resistance of the photovoltaic panel to the air is (m) 2 ·K) / W;R cond，PV-mic The thermal resistance of the photovoltaic panel to the microchannel is (m 2 ·K) / W;R conv，a-ri The convective heat transfer thermal resistance between air and the ribbed surface of the microchannel, (m 2 ·K) / W;R conv，ri-mic The thermal resistance of the fins to the microchannel is (m 2 ·K) / W;R conv，mic-re The convective heat transfer thermal resistance between the microchannel and the refrigerant, (m 2 ·K) / W.

4. The microchannel PVT collector evaporator for comprehensively utilizing solar and air energy as described in claim 1, characterized in that, The rear cover plate is made of iron cold-rolled plate into an Ω-shaped integrated structure, with the four sides bent to form an adhesive plane with the photovoltaic panel, and is bonded to the photovoltaic panel with EVA adhesive.

5. The microchannel PVT collector evaporator for comprehensively utilizing solar and air energy as described in claim 1, characterized in that, Multiple air inlets are provided on the long sides of the rear cover plate, and two air outlets are provided on the top surface. The inner top surface of the rear cover plate is attached to the top of the fins of the ribbed microchannel heat exchanger to form an air duct.

6. A heat pump system that comprehensively utilizes solar energy and air energy, employing the microchannel PVT collector evaporator as described in any one of claims 1-5, characterized in that, include: Microchannel PVT evaporator, compressor, indoor unit, electronic expansion valve, gas-liquid separator, reheater, oil return valve, reheat valve, four-way reversing valve, inverter, battery, controller and temperature sensor; The microchannel PVT evaporator, the compressor, the indoor unit, the electronic expansion valve, the gas-liquid separator, the reheater, the oil return valve, the reheat valve, and the four-way reversing valve form a refrigerant evaporation-condensation loop through refrigerant pipelines; the microchannel PVT evaporator, the inverter, the battery, and the compressor form a power supply loop through cables; In the refrigerant evaporation-condensation loop, the microchannel PVT collector evaporator is connected to the fourth port D of the four-way reversing valve, the reheater, the electronic expansion valve, and the oil return valve, respectively; the second port B of the four-way reversing valve is connected to the indoor unit; the third port C of the four-way reversing valve is connected to the gas-liquid separator; the first port A of the four-way reversing valve is connected to the compressor; the compressor is also connected to the gas-liquid separator; the fourth port D is also connected to the reheater; the reheater is also connected to the oil return valve; the indoor unit is also connected to the reheat valve and the electronic expansion valve; the reheat valve is also connected to the electronic expansion valve through the reheater; the temperature sensor is located at the outlet of the microchannel PVT collector evaporator. In the power supply and distribution loop, the microchannel PVT collector evaporator is also connected to the inverter; the inverter is also connected to the compressor, the battery and the indoor unit respectively. The controller is connected to the four-way reversing valve, the reheat valve, the temperature sensor, the electronic expansion valve, the oil return valve, and the microchannel PVT evaporator, respectively, and is used for: The system switches between the corresponding operating modes and outputs the corresponding equipment parameters according to the meteorological environment and user needs, so as to meet the user's needs for uninterrupted heating and hot water in winter and cooling in summer. The operating modes include solar-air dual-source heating mode, single-source heating mode, single-source cooling mode and oil return mode.

7. The heat pump system for comprehensively utilizing solar energy and air energy according to claim 6, characterized in that, The controller, when switching operating modes, specifically includes: controlling the four-way reversing valve to switch between heating and cooling in all modes; controlling the fan to start in air source heating mode, solar-air dual source heating mode, and single source cooling mode; and controlling the oil return valve and reheat valve to start in oil return mode.

8. The heat pump system for comprehensively utilizing solar energy and air energy according to claim 6, characterized in that, The controller specifically includes the following when outputting device parameters: Based on the outlet refrigerant temperature fed back by the temperature sensor, calculate the refrigerant superheat and perform the following operations: In heating mode, when the refrigerant superheat is below 5°C, the electronic expansion valve is controlled to reduce its opening. When the electronic expansion valve reaches its minimum opening or the heat pump system cannot meet the indoor heat demand, the fan is controlled to turn on, and the refrigerant absorbs heat from the air and the photovoltaic panel at the same time. When the refrigerant superheat is above 5°C, the fan is controlled to reduce its speed. When the fan stops, the electronic expansion valve is controlled to increase its opening. In oil return mode, the control oil return valve and reheat valve are opened. The refrigerant flowing out of the microchannel PVT collector evaporator carries the lubricating oil from the bottom of the evaporator and flows out through the oil return pipe. In the reheater, it exchanges heat with the high-temperature refrigerant at the indoor unit outlet and then flows to the compressor, thus realizing the oil return function. At the same time, the refrigerant flowing out of the indoor unit is divided into two paths: one path flows directly to the electronic expansion valve, and the other path enters the reheater to release heat and then flows to the electronic expansion valve, so as to ensure that the refrigerant flowing out of the oil return pipe can be completely vaporized.

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