Multi-energy complementary heating system and method suitable for dwellings in Tibet region

Abstract

The invention provides a multi-energy complementary heating system suitable for dwellings in Tibet regions, and relates to the technical field of building energy conservation and renewable energy utilization. The multi-energy complementary heating system suitable for the folk houses in the Tibet region comprises a solar heat collector, a phase change energy storage wall, a heat storage water tank, an outdoor air source heat pump unit and a tail end fan coil. The solar heat collector collects heat to provide heat for heating when the solar radiation intensity is high. When the solar radiation intensity is low or in cloudy and rainy days, the air source heat pump unit serves as an auxiliary heat source to absorb heat from outside air for indoor heating; the phase change energy storage wall can store redundant heat and release the heat at night or at low temperature, so that all-weather heating is ensured; when the system is in a non-working state in a cold environment, the water pump is started, so that a circulating medium in a pipeline keeps flowing slowly, and freezing is avoided; the special climate and building structure of Tibet are fully considered, the heating efficiency is improved, and the stability and economical efficiency of the system are enhanced.

Description

Technical Field

[0001] The present invention provides a multi - energy complementary heating system applicable to residential buildings in Tibet, which relates to the technical field of building energy conservation and renewable energy utilization. Background Art

[0002] Tibet region belongs to the plateau cold climate, with large temperature differences between day and night and long, cold winters. Heating has become a basic need in residents' lives. However, due to its remote location and relatively backward infrastructure construction, traditional centralized heating methods are difficult to cover. Especially in rural and pastoral areas, most residential buildings still rely on burning firewood, cow dung, etc. for heating, which not only has low thermal efficiency but also has serious soot pollution problems and has gradually become unsuitable for the requirements of green and low - carbon development. In recent years, with the development of clean energy utilization technologies, the application of solar energy, biomass energy, electric energy and heat pump technologies in the plateau region has gradually increased. Among them, solar energy resources are particularly rich in Tibet region, with long annual sunshine hours and good heat collection conditions. However, most of the existing heating systems are single - energy heating systems. For example, a pure solar heating system is limited by the large changes in sunshine conditions and lacks stability. Electric heating is clean, but has high operating costs. And heat pump systems are limited in efficiency in alpine regions. Therefore, how to achieve the organic integration of various energy forms to form a heating system with complementary synergy, stable operation, high efficiency and energy conservation has become an urgent problem to be solved.

[0003] Some existing patents have proposed some renewable energy utilization technologies and their applications. For example, Patent CN221802106U discloses a solar heating and heat supply circulation device, whose main features include a solar bracket, a water storage tank, solar heating tubes, radiators and a circulation pipeline system. A cleaning device is arranged inside the water storage tank, which uses water flow to drive a power fan to rotate, and then drives a cleaning brush to clean the surface of a filter plate through a rotating shaft, effectively preventing impurities from blocking the filter plate and improving the filtration efficiency of circulating water. Although this embodiment has a self-cleaning function while heating, which helps to improve the operation stability and service life of the device, its operation seriously depends on light conditions, is significantly affected by day-night changes and rainy weather, and the heat collection efficiency decreases in cold seasons, making it difficult to meet the all-weather and continuous stable heating demand. Patent CN218154446U discloses an air source heat pump heating system, whose main features include an air source heat pump, a plate heat exchanger and a water tank. The air source heat pump, the plate heat exchanger and the water tank are connected in sequence. A heat supply pipe and a return heat pipe are connected between the air source heat pump and the plate heat exchanger. An inlet pipe is arranged at the bottom of the plate heat exchanger, and an outlet pipe is arranged above the plate heat exchanger. A circulation pump is connected to the bottom of the water tank, and the water outlet end of the circulation pump is connected to a water using end and a floor heating system through a tee. Although this embodiment has the advantages of stable operation, not relying on sunlight and being able to work all-weather compared with solar heating, in the Tibetan Plateau region, due to low temperature and thin air, its heating efficiency decreases, and other energy sources need to be combined to optimize the system performance.

[0004] The present invention provides a multi-energy complementary heating system suitable for residential buildings in Tibet. By combining a solar heat collection system, an air source heat pump system and a phase change energy storage system, the deficiencies of a single energy system are overcome. The solar heating system efficiently collects heat for heating when the solar radiation intensity is high. When the solar radiation intensity is low or in rainy weather, the air source heat pump system serves as an auxiliary heat source to absorb heat from the external air and transfer it indoors for heating, while the phase change energy storage wall can store excess heat and release it at night or in low temperature, ensuring all-weather heating. This system fully considers the special climate and building structure in Tibet, not only improves the heating efficiency, reduces energy consumption, but also enhances the stability and economy of the system, meeting the concept of green buildings. Summary of the Invention

[0005] The purpose of the present invention is to provide a multi-energy complementary heating system suitable for residential buildings in Tibet, so as to solve the problems that the existing single energy heating system is greatly affected by climate, has unstable heat supply, low operation efficiency, and is difficult to meet the continuous heating demand of residents in alpine and high altitude areas.

[0006] To solve the above technical problems, the present invention provides the following technical solutions:

[0007] It includes a solar collector 1, a phase change energy storage wall 2, a hot water storage tank 3, an outdoor air source heat pump unit 4, and a terminal fan coil 5;

[0008] The solar collector 1 is connected to a first heat exchange coil in the hot water storage tank 3 through a first water supply pipe 6-1 and a first water return pipe 6-2. A first valve 7-1 and a first circulation pump 8-1 are successively arranged on the first water supply pipe 6-1, and a second valve 7-2 is arranged on the first water return pipe 6-2;

[0009] The phase change energy storage wall 2 includes hollow bricks 2-1, a hollow cavity 2-2, a phase change energy storage material 2-3, and a U-shaped heat exchange pipe 2-4. The hollow cavity 2-2 in the hollow bricks 2-1 is filled with the phase change energy storage material 2-3, and the U-shaped heat exchange pipe 2-4 is arranged inside the phase change energy storage material 2-3. The U-shaped heat exchange pipe 2-4 is in parallel with the terminal fan coil 5 and is connected to the hot water storage tank 3 through a third water supply pipe 6-5 and a third water return pipe 6-6, and is used for storing and releasing heat to stabilize the indoor temperature. A third circulation pump 8-3 and a first three-way valve 9-1 are successively arranged on the third water supply pipe 6-5, and a second three-way valve 9-2 is arranged on the third water return pipe 6-6;

[0010] On the upper left side of the hot water storage tank 3, there is a first heat exchange coil 3-1, and on the upper right side of the hot water storage tank 3, there is a second heat exchange coil 3-2. On the bottom left side of the hot water storage tank 3, there is a cold water inlet 3-3, and on the bottom right side of the hot water storage tank 3, there is a hot water outlet 3-4. The first heat exchange coil 3-1 is connected to the solar collector 1 through the first water supply pipe 6-1 and the first water return pipe 6-2. The second heat exchange coil 3-2 is connected to a water side heat exchanger 4-3 in the outdoor air source heat pump unit 4 through a second water supply pipe 6-3 and a second water return pipe 6-4. The hot water outlet 3-4 is connected to the phase change energy storage wall 2 and the terminal fan coil 5 respectively through the third water supply pipe 6-5 and is reconnected to the cold water inlet 6-6 of the hot water storage tank 3 through the third water return pipe 6-6;

[0011] The outdoor air source heat pump unit 4 includes a wind side heat exchanger 4-1, a compressor 4-2, a water side heat exchanger 4-3, and an expansion valve 4-4. The water side heat exchanger 4-3 of the outdoor air source heat pump unit 4 is connected to the hot water storage tank 3 through a second water supply pipe 6-3, a second water return pipe 6-4, and the second heat exchange coil 3-2. A second circulation pump 8-2 and a third valve 7-3 are successively arranged on the second water supply pipe 6-3, and a fourth valve 7-4 is arranged on the second water return pipe.

[0012] Furthermore, a multi-energy complementary heating system applicable to residential buildings in Tibet region is characterized in that:

[0013] The solar collector 1 is a flat-plate type, vacuum tube type or concentrating type solar collector to meet the heating requirements under different climate conditions; the solar collector 1 is fixed on the south-facing roof to fully absorb solar radiation energy and heat the water in the hot water storage tank 3 through the first heat exchange coil 3-1.

[0014] Furthermore, a multi-energy complementary heating system applicable to residential buildings in Tibet is characterized in that:

[0015] The phase change energy storage wall 2 is built with hollow bricks 2-1, and the hollow cavity 2-2 in the hollow bricks 2-1 is filled with a phase change energy storage material 2-3. A U-shaped heat exchange tube 2-4 is arranged inside the phase change energy storage material 2-3. The U-shaped heat exchange tube 2-4 is connected in parallel with the terminal fan coil 5 and is connected to the hot water storage tank 3 through a third water supply pipe 6-5 and a third water return pipe 6-6.

[0016] Furthermore, a multi-energy complementary heating system applicable to residential buildings in Tibet is characterized in that:

[0017] The phase change energy storage material 2-3 can adopt inorganic hydrates such as anhydrous sodium sulfate, organic phase change materials such as paraffin wax, or composite phase change materials such as paraffin-expanded graphite.

[0018] Furthermore, a multi-energy complementary heating system applicable to residential buildings in Tibet is characterized in that:

[0019] The U-shaped heat exchange tube 2-4, the first heat exchange coil 3-1, and the second heat exchange coil 3-2 are all made of copper tubes, stainless steel tubes or aluminum alloy tubes, and the circulating medium inside the tubes is antifreeze.

[0020] Furthermore, a multi-energy complementary heating system applicable to residential buildings in Tibet is characterized in that:

[0021] The hot water storage tank 3 is used to store the heat provided by the solar collector 1, the phase change energy storage wall 2 and the outdoor air source heat pump unit 4, and the hot water is transported to the terminal fan coil 5 through the third circulation water pump 8-3. The hot water storage tank 3 is provided with a heat preservation layer.

[0022] Furthermore, a multi-energy complementary heating system applicable to residential buildings in Tibet is characterized in that:

[0023] The outdoor air source heat pump unit 4 is arranged outdoors and heats the water in the hot water storage tank 3 through the second heat exchange coil 3-2, and is used to provide auxiliary heat to the heating system when the heat supply of the solar collector 1 is insufficient.

[0024] Furthermore, a multi-energy complementary heating system applicable to residential buildings in Tibet is characterized in that:

[0025] The terminal fan coil unit 5 is arranged in the indoor space and provides a heating function through hot water circulation.

[0026] Furthermore, a method for a multi - energy complementary heating system applicable to residential buildings in Tibet region is characterized in that:

[0027] When the solar radiation intensity is relatively high, the solar energy collection system is sufficient to meet the heating requirements of the room. Then the system operates in the mode of only the solar energy collection system for heating and heat storage. At this time, the first circulation pump 8 - 1 is turned on, and the circulating medium is transported to the solar energy collector 1 to be heated, and its temperature rises. After heating, the circulating medium is transported along the first return pipe 6 - 1 to the first heat exchange coil 3 - 1 in the hot water storage tank 3, and transfers the heat to the water in the hot water storage tank 3, gradually increasing the water temperature. After the temperature of the heat - exchanged circulating medium decreases, it flows back to the solar energy collector 1 to continue absorbing solar heat, forming a solar - side circulating heating process. When the temperature in the hot water storage tank 3 is higher than the heating temperature, the third circulation pump 8 - 3 is turned on, and the hot water in the hot water storage tank 3 is transported along the third water supply pipe 6 - 5 to the terminal fan coil unit 5 for indoor heating; at the same time, part of the hot water flows through the U - shaped heat exchange pipe 2 - 4 in the phase - change energy storage wall 2, causing the phase - change energy storage material 2 - 3 to absorb and store heat, and release heat to the indoor environment at night or when the temperature drops, balancing the indoor temperature and avoiding the phenomenon of over - cooling or over - heating caused by the day - night temperature difference; after the temperature of the hot water after heat exchange decreases, it flows back to the hot water storage tank 3, waiting for the next round of heating, forming a closed - loop heating system;

[0028] When the solar radiation intensity is low or in rainy or cloudy weather, the solar energy collection system is insufficient to meet the heating demand of the room. The outdoor air source heat pump unit 4 is turned on as an auxiliary heat source, and the system operates in the combined operation mode of the solar energy collection system and the air source heat pump system. At this time, the first circulation pump 8-1 is turned on, and the circulating medium is transported to the solar energy collector 1 to be heated, and its temperature rises. After heating, the circulating medium is transported along the first return pipe 6-1 to the first heat exchange coil 3-1 in the hot water storage tank 3, and transfers the heat to the water in the hot water storage tank 3, gradually increasing the water temperature. After the temperature of the heat-exchanged circulating medium decreases, it flows back to the solar energy collector 1 to continue absorbing solar heat, forming a solar-side circulating heating process. At the same time, the second circulation pump 8-2 is turned on, and the circulating medium is transported along the second supply pipe 6-3 to the water-side heat exchanger 4-3 of the outdoor air source heat pump unit 4, and exchanges heat with the high-temperature refrigerant in the water-side heat exchanger 4-3 to increase the temperature. Then it is transported along the second return pipe 6-3 to the second heat exchange coil 3-2 in the hot water storage tank 3, and transfers the heat to the water in the hot water storage tank 3, gradually increasing the water temperature. After the temperature of the heat-exchanged circulating medium decreases, it flows back to the water-side heat exchanger 4-3 to continue heat exchange, forming an air source heat pump-side circulating heating process. When the temperature in the hot water storage tank 3 is higher than the heating temperature, the third circulation pump 8-3 is turned on, and the hot water in the hot water storage tank 3 is transported along the third supply pipe 6-5 to the terminal fan coil 5 for indoor heating. At the same time, part of the hot water flows through the U-shaped heat exchange tube 2-4 in the phase change energy storage wall 2, causing the phase change energy storage material 2-3 to absorb and store heat, and release heat to the indoor at night or when the temperature drops to balance the indoor temperature.

[0029] Furthermore, the method of a multi-energy complementary heating system applicable to Tibetan residential buildings is characterized in that:

[0030] The first supply pipe 6-1, the first return pipe 6-2, the second supply pipe 6-3, the second return pipe 6-4, the third supply pipe 6-5, and the third return pipe 6-6 all use antifreeze as the circulating medium, and are wrapped with thermal insulation materials on the outside of the pipeline; when the multi-energy complementary heating system is in a non-working state in a cold environment, the first circulation pump 8-1, the second circulation pump 8-2, and the third circulation pump 8-3 are respectively turned on to keep the circulating medium in the pipeline flowing slowly to avoid freezing. Description of the Drawings

[0031] Appendix Figure 1 is a schematic diagram of a multi-energy complementary heating system applicable to Tibetan residential buildings according to the present invention;

[0032] Appendix Figure 1Label names in [figure]: 1. Solar collector, 2. Phase change energy storage wall, 3. Hot water storage tank, 3-1. First heat exchange coil, 3-2. Second heat exchange coil, 3-3. Cold water inlet, 3-4. Hot water outlet, 4-1. Air-side heat exchanger, 4-2. Compressor, 4-3. Water-side heat exchanger, 4-4. Expansion valve, 5. Terminal fan coil unit, 6-1. First water supply pipe, 6-2. First water return pipe, 6-3. Second water supply pipe, 6-4. Second water return pipe, 6-5. Third water supply pipe, 6-6. Third water return pipe, 7-1. First valve, 7-2. Second valve, 7-3. Third valve, 8-1. First circulation pump, 8-2. Second circulation pump, 8-3. Third circulation pump, 9-1. First three-way valve, 9-2. Second three-way valve.

[0033] Appendix Figure 2 is the structural schematic diagram of the phase change energy storage wall of the present invention;

[0034] Appendix Figure 2 Label names in [figure]: 2. Phase change energy storage wall, 2-1. Hollow brick block, 2-2. Hollow cavity, 2-3. Phase change energy storage material, 2-4. U-shaped heat exchange tube. Detailed implementation manners

[0035] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific implementation manners.

[0036] A multi-energy complementary heating system applicable to residential buildings in Tibet region includes a solar collector 1, a phase change energy storage wall 2, a hot water storage tank 3, an outdoor air source heat pump unit 4 and a terminal fan coil unit 5;

[0037] The solar collector 1 is communicated with the first heat exchange coil in the hot water storage tank 3 through the first water supply pipe 6-1 and the first water return pipe 6-2. A first valve 7-1 and a first circulation pump 8-1 are successively arranged on the first water supply pipe 6-1, and a second valve 7-2 is arranged on the first water return pipe 6-2;

[0038] The phase change energy storage wall 2 includes hollow bricks 2-1, a hollow cavity 2-2, a phase change energy storage material 2-3, and a U-shaped heat exchange tube 2-4. The hollow cavity 2-2 in the hollow bricks 2-1 is filled with the phase change energy storage material 2-3. A U-shaped heat exchange tube 2-4 is arranged inside the phase change energy storage material 2-3. The U-shaped heat exchange tube 2-4 is in parallel with the terminal fan coil unit 5 and is connected to the hot water storage tank 3 through the third water supply pipe 6-5 and the third water return pipe 6-6, and is used for storing and releasing heat to stabilize the indoor temperature. A third circulation pump 8-3 and a first three-way valve 9-1 are successively arranged on the third water supply pipe 6-5, and a second three-way valve 9-2 is arranged on the third water return pipe 6-6;

[0039] On the upper left side of the hot water storage tank 3, there is a first heat exchange coil 3-1, and on the upper right side of the hot water storage tank 3, there is a second heat exchange coil 3-2. On the bottom left side of the hot water storage tank 3, there is a cold water inlet 3-3, and on the bottom right side of the hot water storage tank 3, there is a hot water outlet 3-4. The first heat exchange coil 3-1 is connected to the solar collector 1 through a first water supply pipe 6-1 and a first water return pipe 6-2. The second heat exchange coil 3-2 is connected to the water side heat exchanger 4-3 in the outdoor air source heat pump unit 4 through a second water supply pipe 6-3 and a second water return pipe 6-4. The hot water outlet 3-4 is connected to the phase change energy storage wall 2 and the terminal fan coil 5 respectively through a third water supply pipe 6-5, and is reconnected to the cold water inlet 6-6 of the hot water storage tank 3 through a third water return pipe 6-6;

[0040] The outdoor air source heat pump unit 4 includes an air side heat exchanger 4-1, a compressor 4-2, a water side heat exchanger 4-3, and an expansion valve 4-4. The water side heat exchanger 4-3 of the outdoor air source heat pump unit 4 is connected to the hot water storage tank 3 through a second water supply pipe 6-3, a second water return pipe 6-4, and a second heat exchange coil 3-2. A second circulation pump 8-2 and a third valve 7-3 are arranged in sequence on the second water supply pipe 6-3, and a fourth valve 7-4 is arranged on the second water return pipe;

[0041] As shown in the appendix Figure 1 Shown, a multi-energy complementary heating system suitable for residential buildings in Tibet region, the working process of the system is as follows: When the solar radiation intensity is relatively high, the solar heat collection system is sufficient to meet the heating requirements of the room. Then the system works in the mode of only the solar heat collection system for heating and heat storage. At this time, the first circulation pump 8-1 is turned on, and the circulating medium is transported into the solar collector 1 to be heated, and the temperature rises. After heating, the circulating medium is transported along the first water return pipe 6-1 to the first heat exchange coil 3-1 in the hot water storage tank 3, and transfers the heat to the water in the hot water storage tank 3, gradually increasing the water temperature. After the temperature of the heat-exchanged circulating medium decreases, it flows back to the solar collector 1 to continue absorbing solar heat, forming a solar side circulating heating process. When the temperature in the hot water storage tank 3 is greater than the heating temperature, the third circulation pump 8-3 is turned on, and the hot water in the hot water storage tank 3 is transported along the third water supply pipe 6-5 to the terminal fan coil 5 for indoor heating; At the same time, part of the hot water flows through the U-shaped heat exchange tube 2-4 in the phase change energy storage wall 2, causing the phase change energy storage material 2-3 to absorb heat and store heat, and release heat to the indoor at night or when the temperature drops, balancing the indoor temperature and avoiding the overcooling or overheating phenomenon caused by the day-night temperature difference; After the temperature of the heat-exchanged hot water decreases, it flows back to the hot water storage tank 3, waiting for the next round of heating, forming a closed-loop heating system;

[0042] When the solar radiation intensity is low or in rainy or cloudy weather, the solar energy collecting system is insufficient to meet the heating demand of the room. The outdoor air source heat pump unit 4 is turned on as an auxiliary heat source, and the system operates in the combined operation mode of the solar energy collecting system and the air source heat pump system. At this time, the first circulation pump 8-1 is turned on, and the circulating medium is transported into the solar energy collector 1 to be heated, and the temperature rises. After heating, the circulating medium is transported along the first return water pipe 6-1 to the first heat exchange coil 3-1 in the hot water storage tank 3, and transfers the heat to the water in the hot water storage tank 3, gradually increasing the water temperature. After the temperature of the heat-exchanged circulating medium decreases, it flows back to the solar energy collector 1 to continue absorbing solar heat, forming a solar-side circulating heating process. At the same time, the second circulation pump 8-2 is turned on, and the circulating medium is transported along the second water supply pipe 6-3 to the water-side heat exchanger 4-3 of the outdoor air source heat pump unit 4, exchanges heat with the high-temperature refrigerant in the water-side heat exchanger 4-3, increases the temperature, and then is transported along the second return water pipe 6-3 to the second heat exchange coil 3-2 in the hot water storage tank 3, and transfers the heat to the water in the hot water storage tank 3, gradually increasing the water temperature. After the temperature of the heat-exchanged circulating medium decreases, it flows back to the water-side heat exchanger 4-3 to continue heat exchange, forming an air source heat pump-side circulating heating process. When the temperature in the hot water storage tank 3 is higher than the heating temperature, the third circulation pump 8-3 is turned on, and the hot water in the hot water storage tank 3 is transported along the third water supply pipe 6-5 to the terminal fan coil 5 for indoor heating. At the same time, part of the hot water flows through the U-shaped heat exchange tube 2-4 in the phase change energy storage wall 2, causing the phase change energy storage material 2-3 to absorb and store heat, and release heat to the indoor at night or when the temperature drops, balancing the indoor temperature;

[0043] The first water supply pipe 6-1, the first return water pipe 6-2, the second water supply pipe 6-3, the second return water pipe 6-4, the third water supply pipe 6-5, and the third return water pipe 6-6 all use antifreeze as the circulating medium and are wrapped with thermal insulation materials on the outside of the pipes; when the multi-energy complementary heating system is in a non-working state in a cold environment, the first circulation pump 8-1, the second circulation pump 8-2, and the third circulation pump 8-3 are respectively turned on to keep the circulating medium in the pipeline flowing slowly to avoid freezing.

Claims

1. A multi-energy complementary heating system suitable for residential buildings in Tibet, characterized by: It comprises a solar thermal collector (1), a phase change energy storage wall (2), a hot water storage tank (3), an outdoor air source heat pump unit (4) and a terminal fan coil unit (5); The solar thermal collector (1) is connected to a first heat exchange coil in a hot water storage tank (3) via a first water supply pipe (6-1) and a first water return pipe (6-2); a first valve (7-1) and a first circulating water pump are sequentially provided on the first water supply pipe (6-1); and a second valve (7-2) is provided on the first water return pipe (6-2); The phase change energy storage wall (2) comprises a hollow brick (2-1), a hollow cavity (2-2), a phase change energy storage material (2-3), and a U-shaped heat exchange tube (2-4); the hollow cavity (2-2) in the hollow brick (2-1) is filled with the phase change energy storage material (2-3); a U-shaped heat exchange tube (2-4) is arranged inside the phase change energy storage material (2-3); the U-shaped heat exchange tube (2-4) is connected in parallel with the terminal fan coil unit (5), and is connected to the hot water storage tank (3) through a third water supply pipe (6-5) and a third water return pipe (6-6) for storing and releasing heat to stabilize the indoor temperature; a third circulating water pump (8-3) and a first three-way valve (9-1) are arranged on the third water supply pipe (6-5) in sequence; and a second three-way valve (9-2) is arranged on the third water return pipe (6-6); A first heat exchange coil (3-1) is provided on the left side of the upper part of the hot water storage tank (3), and a second heat exchange coil (3-2) is provided on the right side of the upper part of the hot water storage tank (3). A cold water inlet (3-3) is provided on the left side of the bottom of the hot water storage tank (3), and a hot water outlet (3-4) is provided on the right side of the bottom of the hot water storage tank (3). The first heat exchange coil (3-1) is connected to the solar collector (1) through a first water supply pipe (6-1) and a first water return pipe (6-2). The second heat exchange coil (3-2) is connected to the water side heat exchanger (4-3) in the outdoor air source heat pump unit (4) through a second water supply pipe (6-3) and a second water return pipe (6-4). The hot water outlet (3-4) is connected to the phase change energy storage wall (2) and the terminal fan coil (5) respectively through a third water supply pipe (6-5), and is reconnected to the cold water inlet (6-6) of the hot water storage tank (3) through a third water return pipe (6-6); The outdoor air source heat pump unit (4) comprises an air side heat exchanger (4-1), a compressor (4-2), a water side heat exchanger (4-3), and an expansion valve (4-4); the water side heat exchanger (4-3) of the outdoor air source heat pump unit (4) is connected to the hot water storage tank (3) via a second water supply pipe (6-3), a second water return pipe (6-4), and a second heat exchange coil (3-2); a second circulating water pump (8-2) and a third valve (7-3) are sequentially provided on the second water supply pipe (6-3); and a fourth valve (7-4) is provided on the second water return pipe.

2. A multi-energy complementary heating system suitable for residential buildings in Tibet according to claim 1, characterized in that: The solar thermal collector (1) is a flat-plate type, vacuum tube type or concentrated solar thermal collector to meet the heating needs under different climatic conditions; the solar thermal collector (1) is fixed on the south-facing roof to fully absorb solar radiation energy and heat the water in the hot water storage tank (3) through the first heat exchange coil (3-1).

3. A multi-energy complementary heating system suitable for residential buildings in Tibet according to claim 1, characterized in that: The phase-change energy storage wall (2) is built with hollow bricks (2-1); the hollow cavity (2-2) in the hollow bricks (2-1) is filled with a phase-change energy storage material (2-3); a U-shaped heat exchange tube (2-4) is arranged inside the phase-change energy storage material (2-3); the U-shaped heat exchange tube (2-4) is connected in parallel with the terminal fan coil unit (5), and is connected to the hot water storage tank (3) via a third water supply pipe (6-5) and a third water return pipe (6-6).

4. The multi-energy complementary heating system suitable for residential buildings in Tibet according to claim 1 is characterized by: The phase change energy storage material (2-3) can be an inorganic salt hydrate (such as anhydrous sodium sulfate), an organic phase change material (such as paraffin) or a composite phase change material (such as paraffin-expanded graphite).

5. The multi-energy complementary heating system suitable for residential buildings in Tibet according to claim 1 is characterized in that: The U-shaped heat exchange tube (2-4), the first heat exchange coil (3-1) and the second heat exchange coil (3-2) are all made of copper tubes, stainless steel tubes or aluminum alloy tubes, and the circulating medium in the tubes is antifreeze liquid.

6. The multi-energy complementary heating system suitable for residential buildings in Tibet according to claim 1 is characterized by: The hot water storage tank (3) is used to store heat provided by the solar collector (1), the phase change energy storage wall (2) and the outdoor air source heat pump unit (4), and to transport hot water to the terminal fan coil unit (5) through a third circulating water pump (8-3); the hot water storage tank (3) is provided with a thermal insulation layer.

7. The multi-energy complementary heating system suitable for residential buildings in Tibet according to claim 1 is characterized by: The outdoor air source heat pump unit (4) is arranged outdoors and heats the water in the hot water storage tank (3) through the second heat exchange coil (3-2) to provide auxiliary heat to the heating system when the solar collector (1) does not provide sufficient heat.

8. The multi-energy complementary heating system suitable for residential buildings in Tibet according to claim 1 is characterized by: The terminal fan coil unit (5) is arranged in the indoor space and provides a heating function through hot water circulation.

9. The method of a multi-energy complementary heating system suitable for residential buildings in Tibet according to claim 1, characterized in that: When the solar radiation intensity is high, the solar thermal system is sufficient to meet the heating requirements of the room, so the system works in the solar thermal system heat storage mode. At this time, the first circulating water pump (8-1) is turned on, and the circulating medium is transported to the solar thermal collector (1) to be heated, and the temperature rises. The heated circulating medium is transported along the first return water pipe (6-1) to the first heat exchange coil (3-1) in the hot water storage tank (3), and transfers heat to the water in the hot water storage tank (3), so that the water temperature gradually increases. After the temperature of the circulating medium after heat exchange decreases, it flows back to the solar thermal collector (1) to continue to absorb solar heat, forming a solar side circulation heating process. In the process, when the temperature in the hot water storage tank (3) is greater than the heating temperature, the third circulating water pump (8-3) is turned on to transport the hot water in the hot water storage tank (3) along the third water supply pipe (6-5) to the terminal fan coil unit (5) for indoor heating; at the same time, part of the hot water flows through the U-shaped heat exchange pipe (2-4) in the phase change energy storage wall (2), so that the phase change energy storage material (2-3) absorbs and stores heat, and releases heat to the room at night or when the temperature drops, so as to balance the indoor temperature and avoid overcooling or overheating caused by the temperature difference between day and night; after the temperature of the hot water is lowered after heat exchange, it flows back to the hot water storage tank (3) and waits for the next round of heating, thus forming a closed-loop heating system; When the solar radiation intensity is low or it is rainy, the solar thermal system is insufficient to meet the heating demand of the room. The outdoor air source heat pump unit (4) is turned on as an auxiliary heat source. The system works in the joint operation mode of the solar thermal system and the air source heat pump system. At this time, the first circulation water pump (8-1) is turned on, and the circulating medium is transported to the solar thermal collector (1) to be heated. The temperature rises. The heated circulating medium is transported along the first return water pipe (6-1) to the first heat exchange coil (3-1) in the hot water storage tank (3), and the heat is transferred to the water in the hot water storage tank (3), so that the water temperature gradually increases. After the temperature of the circulating medium after heat exchange decreases, it flows back to the solar thermal collector (1) to continue to absorb solar heat, forming a solar side circulation heating process. At the same time, the second circulation water pump (8-2) is turned on, and the circulating medium is transported along the second water supply pipe (6-3) to the water side of the outdoor air source heat pump unit (4). The heat exchanger (4-3) exchanges heat with the high-temperature refrigerant in the water-side heat exchanger (4-3) to increase the temperature, and then transports the heat along the second return water pipe (6-3) to the second heat exchange coil (3-2) in the hot water storage tank (3), and transfers heat to the water in the hot water storage tank (3), so that the water temperature gradually increases. After the temperature of the circulating medium after heat exchange decreases, it flows back to the water-side heat exchanger (4-3) to continue heat exchange, forming a circulation heating process on the air source heat pump side. When the temperature in the hot water storage tank (3) is greater than the heating temperature, the third circulation water pump (8-3) is turned on to transport the hot water in the hot water storage tank (3) along the third water supply pipe (6-5) to the terminal fan coil (5) for indoor heating. At the same time, part of the hot water flows through the U-shaped heat exchange tube (2-4) in the phase change energy storage wall (2), so that the phase change energy storage material (2-3) absorbs and stores heat, and releases heat to the room at night or when the temperature drops, so as to balance the indoor temperature.

10. The method of a multi-energy complementary heating system applicable to residential buildings in Tibet according to claim 9, characterized in that: The first water supply pipe (6-1), the first water return pipe (6-2), the second water supply pipe (6-3), the second water return pipe (6-4), the third water supply pipe (6-5), and the third water return pipe (6-6) all use antifreeze as a circulation medium, and are wrapped with thermal insulation materials on the outside of the pipes; When the multi-energy complementary heating system is in a non-operating state in a cold environment, the first circulating water pump (8-1), the second circulating water pump (8-2), and the third circulating water pump (8-3) are respectively turned on to keep the circulating medium in the pipeline flowing slowly to avoid freezing.

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