Solar energy and geothermal energy complementary two-stage compression heat pump system

Abstract

The utility model provides a solar energy and geothermal energy complementary two-stage compression heat pump system which is characterized by comprising a two-stage compression heat pump unit and a clean energy heating unit, the two-stage compression heat pump unit comprises a condenser, an expansion valve, an intermediate heat exchanger, a heat compensation heat exchanger, a high-pressure compressor, an expansion valve, an evaporator and a low-pressure compressor; the clean energy heating unit comprises a heating circulating pump, a heat storage tank, a heat collection circulating pump, a buried pipe and a solar heat collector. The temperature difference between supply water and return water of a long-distance conveying pipe network and a primary network is increased, the circulating water flow of the heat supply network is reduced, the operation power consumption of a long-distance conveying heat supply network circulating water pump and a primary network circulating water pump is greatly reduced, clean energy is supplemented, the heating cost and the conveying cost are reduced, and the energy utilization rate and the heat supply economical efficiency are improved.

Description

Technical Field

[0001] This utility model belongs to the field of large temperature difference clean heating technology, and in particular relates to a solar and geothermal complementary two-stage compression heat pump system. Background Technology

[0002] With the large-scale expansion of cities, the heating area is increasing year by year. Combined heat and power (CHP) units, as the main source of heat for centralized urban heating, are gradually relocated to suburbs far from towns. This increases the heating distance, making the existing heating network's transmission and distribution capacity relatively insufficient, and increasing heating transmission costs, leading to cost inversion and heating losses. The temperature difference between long-distance heating networks and the primary and secondary networks is the main factor limiting the transmission and distribution capacity of heating networks. How to widen the temperature difference, increase the network's heat transmission capacity, and reduce heating transmission costs is the primary problem currently facing centralized heating systems. With the gradual implementation of the "Clean Heating Plan for Northern Regions," the demand for clean heating transformation in my country is increasing. As a major energy consumer, urban heating needs to actively respond to the national "dual-carbon" policy and build a clean, low-carbon, flexible, and efficient new heating system. How to efficiently introduce clean energy into the heating system is the main development direction for clean heating. Summary of the Invention

[0003] This invention aims to solve the problem that the temperature difference between long-distance heating pipelines and primary and secondary networks limits the transmission and distribution capacity of heating pipelines. It provides a two-stage compression heat pump system that complements solar and geothermal energy, increasing the temperature difference between the supply and return water of the long-distance pipeline and the primary network, reducing the circulating water flow rate of the heating network, significantly reducing the operating power consumption of the circulating water pumps in both the long-distance and primary networks, while supplementing with clean energy, reducing heating and transmission costs, improving energy utilization and heating economy, and reducing pollutant emissions from the heating system, thus constructing a clean, low-carbon, flexible, and efficient clean heating system.

[0004] To achieve the above-mentioned utility model objectives, this utility model provides a solar and geothermal complementary two-stage compression heat pump system, characterized in that it includes: a two-stage compression heat pump unit, a clean energy heating unit, a long-distance heat transmission network return water pipe, a heating circulating water pipe, and a heat collection circulating water pipe;

[0005] The two-stage compression heat pump unit includes a condenser, a first expansion valve, an intermediate heat exchanger, a supplementary heat exchanger, a high-pressure compressor, a second expansion valve, an evaporator, and a low-pressure compressor.

[0006] The condenser heat pump working fluid side outlet is divided into two paths: a heat replenishment loop and an evaporation loop. The heat replenishment loop is connected in sequence to the inlet and outlet of the first expansion valve, the inlet and outlet of the primary side of the intermediate heat exchanger, and the working fluid side inlet of the heat replenishment heat exchanger. The evaporation loop is connected in sequence to the inlet and outlet of the secondary side of the intermediate heat exchanger, the inlet and outlet of the second expansion valve, the working fluid side inlet and outlet of the evaporator, and the inlet of the low-pressure compressor. The evaporation loop pipeline at the outlet of the low-pressure compressor and the heat replenishment loop pipeline at the working fluid side outlet of the heat replenishment heat exchanger are merged and connected to the inlet of the high-pressure compressor. The outlet of the high-pressure compressor is connected to the working fluid side inlet of the condenser.

[0007] The clean energy heating unit includes a heating circulation pump, a heat storage tank, a heat collection circulation pump, a buried pipe, and a solar collector.

[0008] The heating circulating water pipeline is connected in sequence from the heat release side outlet of the heat storage tank to the inlet and outlet of the heating circulating pump, the water side inlet and outlet of the heat exchanger, and the heat release side inlet of the heat storage tank. The heat collection circulating water pipeline is connected in sequence from the heat collection side outlet of the heat storage tank to the inlet and outlet of the heat collection circulating pump, the inlet and outlet of the buried pipe, the inlet and outlet of the solar collector, and the heat collection side inlet of the heat storage tank.

[0009] Furthermore, it also includes a heat exchange unit for the heating network, a long-distance heating network water supply pipeline, a primary network water supply pipeline, and a primary network return water pipeline. The heat exchange unit for the heating network includes a plate heat exchanger, a primary network circulating water pump, a first electric isolation valve, a second electric isolation valve, a third electric isolation valve, a fourth electric isolation valve, a fifth electric isolation valve, and a sixth electric isolation valve.

[0010] The long-distance heat network water supply pipeline is connected to the long-distance side inlet of the plate heat exchanger. The long-distance heat network return water pipeline is connected in sequence to the plate heat exchanger outlet and the evaporator water side inlet and outlet before being sent to the heat source. The evaporator water side inlet and outlet pipelines are equipped with a first electric isolation valve and a second electric isolation valve. Return water bypass pipelines are set before and after the valves, and a third electric isolation valve is set on the bypass pipelines. The primary network return water pipeline is connected in sequence to the primary network circulating water pump inlet and outlet and the plate heat exchanger primary side inlet. The plate heat exchanger primary side outlet is connected to the primary network water supply pipeline to the heat exchange station. The primary network water supply pipeline is branched and connected in sequence to the condenser water side inlet and outlet. A fourth electric isolation valve and a fifth electric isolation valve are set on the branch. Bypass pipelines are set before and after the valves, and a sixth electric isolation valve is set on the bypass pipelines.

[0011] Compared with the prior art, the present invention has the following advantages:

[0012] (1) Solar energy and geothermal energy are combined as the medium-temperature heat source of the heat pump. The closed water system extracts geothermal energy of lower quality and solar energy of higher quality in sequence to meet the temperature requirements of the medium-temperature heat source. The clean energy is efficiently utilized in a cascade manner and participates in the heat pump heating, thereby improving the utilization rate of clean energy and reducing heating energy consumption and pollutant emissions.

[0013] (2) Divide the heat pump into two-stage compression, reduce the power consumption of the compressor under the premise of the same heating capacity, improve the COP of the heat pump, and reduce the power consumption of the heating system;

[0014] (3) Use the return water of the long-distance heating network as a low-temperature heat source, extract the waste heat of the return water on the long-distance side to heat the water supply on the primary network side, increase the temperature difference between the supply and return water on the long-distance side and the primary side, reduce the flow rate of the circulating water in the heating network on both sides, reduce the power consumption of the circulating water pump, reduce the heating transmission cost, and improve the heating quality and economy.

[0015] (4) Solar energy and geothermal energy are clean energy sources used as medium-temperature heat sources for heat pumps, which can reduce the operating temperature difference of heat pumps, improve the COP of heat pumps, further reduce the power consumption of compressors, reduce heating costs, and achieve the effect of emission reduction and carbon reduction, thereby improving the economic efficiency and environmental protection of heating.

[0016] (5) The medium-temperature heat source loop is equipped with a heat storage tank to balance the relationship between the intermittency of solar energy and the user's heat load. The solar energy extracted during the day is stored in the heat storage tank and supplied stably throughout the day, ensuring the stability of the heat pump COP throughout the day and improving the flexibility of the heating system operation and adjustment.

[0017] (6) During the non-heating season and other periods when the heat pump is not in operation, the heat absorbed by the solar collector is reinjected into the underground soil through buried pipes to maintain the temperature field balance of the underground soil. It can also achieve cross-seasonal heat storage, ensure the stability of the medium-temperature heat source during the heating season, increase the heat source temperature, and reduce system energy consumption. Attached Figure Description

[0018] Figure 1 Schematic diagram of a solar and geothermal complementary two-stage compression heat pump system

[0019] The components include: 1. Condenser; 2. First expansion valve; 3. Intermediate heat exchanger; 4. Compensation heat exchanger; 5. High-pressure stage compressor; 6. Second expansion valve; 7. Evaporator; 8. Low-pressure stage compressor; 9. Heating circulation pump; 10. Heat storage tank; 11. Heat collection circulation pump; 12. Buried pipe; 13. Solar collector; 14. Primary network circulation pump; 15. Plate heat exchanger; 16. First electric isolation valve; 17. Second electric isolation valve; 18. Third electric isolation valve; 19. Fourth electric isolation valve; 20. Fifth electric isolation valve; 21. Sixth electric isolation valve. Detailed Implementation

[0020] To better understand the purpose, structure, and function of this utility model, the following description, in conjunction with the accompanying drawings, provides a more detailed account of a solar and geothermal complementary two-stage compression heat pump system of this utility model.

[0021] Reference Figure 1The solar and geothermal complementary two-stage compression heat pump system mainly includes: a heat network heat exchange unit, a two-stage compression heat pump unit, a clean energy heating unit, a long-distance heat network water supply pipeline, a long-distance heat network return water pipeline, a heating circulating water pipeline, a heat collection circulating water pipeline, a primary network return water pipeline, and a primary network water supply pipeline.

[0022] The two-stage compression heat pump unit includes a condenser 1, a first expansion valve 2, an intermediate heat exchanger 3, a supplementary heat exchanger 4, a high-pressure stage compressor 5, a second expansion valve 6, an evaporator 7, and a low-pressure stage compressor 8.

[0023] The clean energy heating unit includes a heat replenishment circulation pump 9, a heat storage tank 10, a heat collection circulation pump 11, a buried pipe 12, and a solar collector 13.

[0024] The heat exchange unit of the heating network includes a plate heat exchanger 15, a primary network circulating water pump 14, a first electric isolation valve 16, a second electric isolation valve 17, a third electric isolation valve 18, a fourth electric isolation valve 19, a fifth electric isolation valve 20, and a sixth electric isolation valve 21.

[0025] The heat pump working fluid side outlet of condenser 1 is divided into two paths: a heat replenishment loop and an evaporation loop. The heat replenishment loop is connected in sequence to the inlet and outlet of the first expansion valve 2, the primary side inlet and outlet of the intermediate heat exchanger 3, and the working fluid side inlet of the heat replenishment heat exchanger 4. The evaporation loop is connected in the primary side inlet and outlet of the intermediate heat exchanger 3, the inlet and outlet of the second expansion valve 6, the working fluid side inlet and outlet of the evaporator 7, and the inlet of the low-pressure compressor 8. The evaporation loop pipeline of the low-pressure compressor 8 outlet and the heat replenishment loop pipeline of the working fluid side outlet of the heat replenishment heat exchanger 4 are combined and connected to the inlet of the high-pressure compressor 5. The outlet of the high-pressure compressor 5 is connected to the working fluid side inlet of the condenser (1).

[0026] The heating circulating water pipeline connects sequentially from the heat release side outlet of the heat storage tank 10 to the inlet and outlet of the heating circulating pump 9, the water side inlet and outlet of the heat exchanger 4, and the heat release side inlet of the heat storage tank 10. The heat collection circulating water pipeline connects sequentially from the heat collection side outlet of the heat storage tank 10 to the inlet and outlet of the heat collection circulating pump 11, the inlet and outlet of the buried pipe 12, the inlet and outlet of the solar collector 13, and the heat collection side inlet of the heat storage tank 10.

[0027] The long-distance heat network supply pipeline is connected to the long-distance side inlet of the plate heat exchanger 15. The long-distance heat network return pipeline is connected in sequence to the outlet of the plate heat exchanger 15 and the water-side inlet and outlet of the evaporator 7 before being sent to the heat source. The water-side inlet and outlet pipelines of the evaporator 7 are equipped with a first electric isolation valve 16 and a second electric isolation valve 17. Return water bypass pipelines are set before and after the valves, and a third electric isolation valve 18 is set on the bypass pipelines. The primary network return pipeline is connected in sequence to the inlet and outlet of the primary network circulating water pump 14 and the primary side inlet of the plate heat exchanger 15. The primary side outlet of the plate heat exchanger 15 is connected to the primary network supply pipeline to the heat exchange station. The primary network supply pipeline is branched and connected in sequence to the water-side inlet and outlet of the condenser 1. A fourth electric isolation valve 19 and a fifth electric isolation valve 20 are set on the branch. Bypass pipelines are set before and after the valves, and a sixth electric isolation valve 21 is set on the bypass pipelines.

[0028] During the heating season, the third electric isolation valve 18 and the sixth electric isolation valve 21 are closed, while the first electric isolation valve 16, the second electric isolation valve 17, the fourth electric isolation valve 19, and the fifth electric isolation valve 20 are open. Water from the long-distance heating network enters the plate heat exchanger 15 to heat the primary network circulating water on the other side. The outlet return water enters the evaporator 7 as a low-temperature heat source for the heat pump to extract waste heat, and then is sent back to the central heating source through the return water pipe. The primary network return water on the other side of the plate heat exchanger is circulated by the primary network circulating water pump 14. After passing through the circulator, the water enters the plate heat exchanger 15. Heated by the circulating water from the other side of the long-distance heating network, the primary network supply water enters the condenser 1 of the heat pump. There, it is further heated by the heat pump working fluid until it reaches the required supply temperature, then supplied to the heat exchange station via the primary network supply pipe. In the condenser 1, the heat pump working fluid heats the primary network supply water, causing it to condense and split into two streams. One stream, after being depressurized by the first expansion valve 2, absorbs heat from the second stream in the intermediate heat exchanger 3. The working fluid then absorbs heat from the clean energy heating unit via the supplementary heat exchanger 4, mixing with the second stream before entering the high-pressure stage. In compressor 5, the two working fluids are cooled and heated by intermediate heat exchanger 3, then depressurized by second expansion valve 6 before entering evaporator 7 to absorb waste heat from the return water of the long-distance heating pipeline on the other side. The outlet working fluid is compressed by low-pressure compressor 8 and mixed with the first working fluid before entering high-pressure compressor 5 for further compression. Then it enters condenser 1 to condense and release heat, completing the heat pump working fluid cycle. The circulating water in heat storage tank 10 is drawn out by heat collection circulation pump 11 into buried pipe 12 to extract geothermal energy, and then enters solar collector 13 to absorb heat. Solar energy is heated and then returned to the heat storage tank 10 to store the clean energy heat. The supplementary heat circulation pump 9 draws the circulating water from the heat storage tank into the supplementary heat exchanger 4 to heat the working fluid of one heat pump. The cooled circulating water returns to the heat storage tank 10. When it is necessary to disconnect the heat pump to participate in heating during the heating season, the third electric isolation valve 18 and the sixth electric isolation valve 21 are opened, and the first electric isolation valve 16, the second electric isolation valve 17, the fourth electric isolation valve 19, and the fifth electric isolation valve 20 are closed to disconnect the heat pump.

[0029] During the non-heating season, the first electric isolation valve 16, the second electric isolation valve 17, the fourth electric isolation valve 19, and the fifth electric isolation valve 20 are closed. The high-pressure stage compressor 5 and the low-pressure stage compressor 8 stop working, and the heat replenishment circulation pump 9 also stops working. At this time, the heating system and the heat pump are both in a shutdown state. The heat collection circulation pump 11 is running. The circulating water that has been heated by absorbing solar energy by the solar collector 13 enters the heat storage tank 10. The heat collection circulation pump 11 pumps the circulating water in the heat storage tank 10 and sends it into the buried pipe 12, releasing the solar heat to the underground soil, realizing cross-seasonal heat storage, increasing the soil temperature, and extracting the heat to participate in heating during the heating season.

[0030] A two-stage compression heat pump with solar and geothermal energy intermediate heating is installed in the heat exchange station between the long-distance heating pipeline and the primary network. The return water from the long-distance heating pipeline is introduced into the heat pump evaporator as a low-temperature heat source to extract waste heat from the return water, increasing the temperature difference between the supply and return water of the long-distance pipeline, reducing the flow rate of the heating network circulating water, and lowering the power consumption and transportation costs of the heating network circulating water pump. The intermediate heating unit consists of solar collectors, buried pipes, and a heat storage tank, which sequentially extracts geothermal and solar energy to raise the temperature of the closed-loop circulating water. The higher-temperature closed-loop circulating water is stored in the heat storage tank. During heat pump operation, the hot water in the heat storage tank is sent to the intermediate heating heat exchanger, serving as the intermediate-temperature heat source for the heat pump. Clean energy is extracted to generate heat to heat the heat pump's working fluid. During the non-heating season or other periods when the heat pump is not in operation... The heat absorbed by the solar collectors is reinjected into the underground soil through buried pipes, maintaining the soil temperature field balance throughout the year. It can also achieve cross-seasonal heat storage, ensuring the heating capacity of geothermal energy and the stability of medium-temperature heat sources during the heating season. The heat pump working fluid that extracts the waste heat from the return water of the long-distance heating network is compressed by the low-pressure stage compressor and then mixed with the heat pump working fluid that absorbs the heat of clean energy in the intermediate loop before entering the high-pressure stage compressor. Then, it releases heat in the condenser to heat the primary network water supply, thereby increasing the temperature difference between the primary network supply and return water, reducing the primary network circulating water flow and the power consumption of the primary network circulating water pump. At the same time, the addition of clean energy heat increases the system's heating capacity, further reducing the heating transmission cost and heating cost. The introduction of clean energy reduces the emissions of carbon dioxide and other pollutants from the heating system.

Claims

1. A solar-geothermal complementary dual-stage compression heat pump system, characterized in that, Comprise: Double-stage compression heat pump unit, clean energy heating unit, long-distance heat supply network return water pipeline, heating circulating water pipeline, heat collection circulating water pipeline; The double-stage compression heat pump unit comprises a condenser (1), a first expansion valve (2), an intermediate heat exchanger (3), a heat supplement heat exchanger (4), a high-pressure compressor (5), a second expansion valve (6), an evaporator (7), and a low-pressure compressor (8); The condenser (1) is divided into two paths on the outlet side of the heat pump working medium, a heat supplement loop and an evaporation loop, the heat supplement loop is sequentially connected to the inlet and outlet of the first expansion valve (2), the inlet and outlet of the primary side of the intermediate heat exchanger (3), and the inlet of the working medium side of the heat supplement heat exchanger (4), the evaporation loop is sequentially connected to the inlet and outlet of the secondary side of the intermediate heat exchanger (3), the inlet and outlet of the second expansion valve (6), the inlet and outlet of the working medium side of the evaporator (7), and the inlet of the low-pressure compressor (8), the outlet of the low-pressure compressor (8) is connected to the inlet of the high-pressure compressor (5) after the evaporation loop pipeline and the working medium side outlet of the heat supplement heat exchanger (4) are combined, and the outlet of the high-pressure compressor (5) is connected to the inlet of the working medium side of the condenser (1); The clean energy heating unit comprises a heating circulating pump (9), a heat storage tank (10), a heat collection circulating pump (11), a buried pipe (12), and a solar heat collector (13); The heating circulating water pipeline is sequentially connected to the inlet and outlet of the heating circulating pump (9), the inlet and outlet of the water side of the heat supplement heat exchanger (4), and the inlet of the heat release side of the heat storage tank (10) from the outlet of the heat release side of the heat storage tank (10), and the heat collection circulating water pipeline is sequentially connected to the inlet and outlet of the heat collection circulating pump (11), the inlet and outlet of the buried pipe (12), the inlet and outlet of the solar heat collector (13), and the inlet of the heat collection side of the heat storage tank (10) from the outlet of the heat collection side of the heat storage tank (10).

2. The solar and geothermal complementary dual-stage compression heat pump system according to claim 1, characterized in that: Further comprise a heat network heat exchange unit, a long-distance heat supply network water supply pipeline, a primary network water supply pipeline, and a primary network return water pipeline, the heat network heat exchange unit comprises a plate heat exchanger (15), a primary network circulating water pump (14), a first electric isolation valve (16), a second electric isolation valve (17), a third electric isolation valve (18), a fourth electric isolation valve (19), a fifth electric isolation valve (20), and a sixth electric isolation valve (21); The long-distance heat supply network water supply pipeline is connected to the inlet of the long-distance side of the plate heat exchanger (15), the long-distance heat supply network return water pipeline is sequentially connected to the outlet of the plate heat exchanger (15) and the water side inlet and outlet of the evaporator (7) and then sent to the heat source, the first electric isolation valve (16) and the second electric isolation valve (17) are arranged on the water side inlet and outlet pipeline of the evaporator (7), a return water bypass pipeline is arranged before and after the valves, and the third electric isolation valve (18) is arranged on the bypass pipeline; the primary network return water pipeline is sequentially connected to the inlet and outlet of the primary network circulating water pump (14) and the inlet of the primary side of the plate heat exchanger (15), the outlet of the primary side of the plate heat exchanger (15) is connected to the water supply pipeline of the primary network to the heat exchange station, the water supply pipeline of the primary network is branched and sequentially connected to the water side inlet and outlet of the condenser (1), the fourth electric isolation valve (19) and the fifth electric isolation valve (20) are arranged on the branch, bypass pipelines are arranged before and after the valves, and the sixth electric isolation valve (21) is arranged on the bypass pipeline.

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