Two-stage injection-compression high-temperature heat pump system with subcooler

Abstract

The invention provides a two-stage injection-compression high-temperature heat pump system with a subcooler, and belongs to the technical field of compression heat pumps. The problems that a traditional high-temperature heat pump is large in expansion throttling loss and limited in energy efficiency, and complex intermediate cooling is needed are solved. Two stages of ejectors are designed to replace a traditional expansion valve and a middle throttling component respectively, so that the system effectively recovers throttling work of a refrigerant in the expansion process and converts the throttling work into kinetic energy for driving the compression process, the power consumption requirement of a compressor is remarkably reduced, and the overall energy utilization efficiency of the system is improved; the efficiency of the corresponding ejector is improved by introducing a single subcooler, and collaborative optimization of the system is realized by configuring double subcoolers, so that the system obtains better energy efficiency under a wide working condition; through the cascade design of the ejector and the gas-liquid separator, a complex middle liquid spraying cooling loop in a traditional high-temperature heat pump is omitted, the system structure is simplified, the control difficulty is lowered, the efficiency loss and the reliability problem possibly caused by liquid spraying are avoided, and the operation robustness is improved.

Description

Technical Field

[0001] This invention relates to the field of compression heat pump technology, and more specifically, to a two-stage ejector-compression high-temperature heat pump system with a subcooler. Background Art

[0002] Current high-temperature heat pump systems generally face core challenges such as severe expansion and throttling losses leading to low energy efficiency, the need for complex intermediate cooling devices in the high-temperature range increasing system complexity, and insufficient adaptability to a wide range of operating conditions. Therefore, there is an urgent need to develop a new type of heat pump system that can efficiently recover expansion work, simplify the cooling structure, and maintain stability under all operating conditions.

[0003] This invention innovatively replaces the expansion valve and intermediate throttling components with a two-stage ejector, achieving efficient recovery of refrigerant expansion work and conversion of compression power, significantly reducing compression power consumption. The integrated dual subcoolers enhance the ejection efficiency and low-temperature stability of the first-stage ejector, and precisely improve the subcooling of the working fluid in the second-stage ejector, comprehensively optimizing ejection performance. Based on an ejector-gas-liquid separation cascade design, it replaces the traditional liquid spray cooling stage, greatly simplifying the system structure and improving reliability. This design significantly improves the system's overall energy efficiency ratio and wide-temperature-range operational robustness, providing an efficient and compact solution for industrial waste heat recovery, district heating, and high-temperature process heating scenarios above 85°C. Summary of the Invention

[0004] The technical problem to be solved by this invention is:

[0005] To address the problems of large expansion and throttling losses, limited energy efficiency, and the need for complex intermediate cooling in traditional high-temperature heat pumps.

[0006] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows:

[0007] This invention provides a two-stage ejector-compressor high-temperature heat pump system with a subcooler, comprising an evaporator, a first ejector, a first gas-liquid separator, an expansion valve, a first subcooler, a first compressor, a second ejector, a second gas-liquid separator, a second compressor, and a condenser.

[0008] The evaporator is equipped with a heat medium inlet and a heat medium outlet.

[0009] The bottom liquid outlet of the second gas-liquid separator is connected to the working fluid inlet of the first ejector, and the evaporator refrigerant outlet is connected to the ejector fluid inlet of the first ejector. After the two pipelines merge, the mixed fluid outlet of the first ejector is connected to the inlet of the first gas-liquid separator, the bottom liquid outlet of the first gas-liquid separator is connected to the inlet of the expansion valve, and the outlet of the expansion valve is connected to the refrigerant inlet of the evaporator. The top gas outlet of the first gas-liquid separator is connected to the low-pressure fluid inlet of the first subcooler, the low-pressure fluid outlet of the first subcooler is connected to the inlet of the first compressor, and the outlet of the first compressor is connected to the ejector fluid inlet of the second ejector. The refrigerant outlet of the condenser is connected to the high-pressure fluid inlet of the first subcooler, and the high-pressure fluid outlet of the first subcooler is connected to the working fluid inlet of the second ejector. After the two pipelines merge, the mixed fluid outlet of the second ejector is connected to the inlet of the second gas-liquid separator, the top gas outlet of the second gas-liquid separator is connected to the inlet of the second compressor, and the outlet of the second compressor is connected to the refrigerant inlet of the condenser.

[0010] The condenser is provided with an inlet for the heated medium and an outlet for the heated medium.

[0011] This invention provides a two-stage ejector-compressor high-temperature heat pump system with a subcooler, comprising an evaporator, a first ejector, a first gas-liquid separator, an expansion valve, a first compressor, a second ejector, a second gas-liquid separator, a second compressor, a condenser, and a second subcooler.

[0012] The evaporator is equipped with a heat medium inlet and a heat medium outlet.

[0013] The bottom liquid outlet of the second gas-liquid separator is connected to the high-pressure fluid inlet of the second subcooler, and the high-pressure fluid outlet of the second subcooler is connected to the working fluid inlet of the first ejector. The refrigerant outlet of the evaporator is connected to the low-pressure fluid inlet of the second subcooler, and the second subcooler is connected to the ejector fluid inlet of the first ejector. After the two pipelines merge, the mixed fluid outlet of the first ejector is connected to the inlet of the first gas-liquid separator, the bottom liquid outlet of the first gas-liquid separator is connected to the inlet of the expansion valve, and the outlet of the expansion valve is connected to the refrigerant inlet of the evaporator. The top gas outlet of the first gas-liquid separator is connected to the inlet of the first compressor, and the outlet of the first compressor is connected to the ejector fluid inlet of the second ejector. The refrigerant outlet of the condenser is connected to the working fluid inlet of the second ejector. After the two pipelines mix, the mixed fluid outlet of the second ejector is connected to the inlet of the second gas-liquid separator, the top gas outlet of the second gas-liquid separator is connected to the inlet of the second compressor, and the outlet of the second compressor is connected to the refrigerant inlet of the condenser.

[0014] The condenser is provided with an inlet for the heated medium and an outlet for the heated medium.

[0015] This invention provides a two-stage ejector-compressor high-temperature heat pump system with a subcooler, comprising an evaporator, a first ejector, a first gas-liquid separator, an expansion valve, a first subcooler, a first compressor, a second ejector, a second gas-liquid separator, a second compressor, a condenser, and a second subcooler.

[0016] The evaporator is equipped with a heat medium inlet and a heat medium outlet.

[0017] The bottom liquid outlet of the second gas-liquid separator is connected to the high-pressure fluid inlet of the second subcooler, and the high-pressure fluid outlet of the second subcooler is connected to the working fluid inlet of the first ejector. The refrigerant outlet of the evaporator is connected to the low-pressure fluid inlet of the second subcooler, and the second subcooler is connected to the ejector fluid inlet of the first ejector. After the two pipelines merge, the mixed fluid outlet of the first ejector is connected to the inlet of the first gas-liquid separator, the bottom liquid outlet of the first gas-liquid separator is connected to the inlet of the expansion valve, and the outlet of the expansion valve is connected to the refrigerant inlet of the evaporator. The top gas outlet of the first gas-liquid separator is connected to the low-pressure fluid inlet of the first subcooler, and the low-pressure fluid outlet of the first subcooler is connected to the inlet of the first compressor. The outlet of the first compressor is connected to the ejector fluid inlet of the second ejector. The refrigerant outlet of the condenser is connected to the high-pressure fluid inlet of the first subcooler, and the high-pressure fluid outlet of the first subcooler is connected to the working fluid inlet of the second ejector. After the two pipelines merge, the mixed fluid outlet of the second ejector is connected to the inlet of the second gas-liquid separator, the top gas outlet of the second gas-liquid separator is connected to the inlet of the second compressor, and the outlet of the second compressor is connected to the refrigerant inlet of the condenser.

[0018] The condenser is provided with an inlet for the heated medium and an outlet for the heated medium.

[0019] Compared with the prior art, the beneficial effects of the present invention are:

[0020] (1) This invention replaces the traditional expansion valve and intermediate throttling component with two-stage ejectors, enabling the system to effectively recover the throttling work of the refrigerant during the expansion process and convert it into kinetic energy to drive the compression process. This design significantly reduces the power consumption of the compressor and improves the overall energy utilization efficiency of the system.

[0021] (2) This invention innovatively introduces a single subcooler, which can specifically improve the efficiency of the corresponding injector. At the same time, the configuration of dual subcoolers achieves system synergistic optimization, that is, the first subcooler enhances the performance of the second-stage injector, and the second subcooler improves the low-temperature stability of the first-stage injector. The two-pronged approach enables the system to achieve better energy efficiency under a wide range of operating conditions.

[0022] (3) By using the cascade design of the ejector and the gas-liquid separator, the present invention eliminates the complex intermediate liquid spraying cooling circuit in traditional high-temperature heat pumps. This not only simplifies the system structure and reduces the difficulty of control, but also avoids the efficiency loss and reliability problems that may be caused by liquid spraying, thus improving operational robustness. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of a two-stage ejector-compression high-temperature heat pump system with a subcooler according to the present invention. Figure 1 ;

[0024] Figure 2 This is a schematic diagram of the structure of a two-stage ejector-compression high-temperature heat pump system with a subcooler according to the present invention. Figure 2 ;

[0025] Figure 3 This is a schematic diagram of the structure of a two-stage ejector-compression high-temperature heat pump system with a subcooler according to the present invention. Figure 3 .

[0026] Explanation of reference numerals in the attached figures:

[0027] 1. Evaporator; 2. First ejector; 3. First gas-liquid separator; 4. Expansion valve; 5. First subcooler; 6. First compressor; 7. Second ejector; 8. Second gas-liquid separator; 9. Second compressor; 10. Condenser; 11. Second subcooler; 101. Heat medium inlet pipe; 102. First pipe; 103. Second pipe; 104. Third pipe; 105. Fourth pipe; 106. Sixth pipe; 107. Heat medium outlet pipe; 10 8. Seventh Pipeline; 109. Eighth Pipeline; 110. Ninth Pipeline; 111. Tenth Pipeline; 112. Eleventh Pipeline; 113. Twelfth Pipeline; 114. Thirteenth Pipeline; 115. Fourteenth Pipeline; 116. Heated Medium Inlet Pipeline; 117. Heated Medium Outlet Pipeline; 118. Fifteenth Pipeline; 119. Sixteenth Pipeline; 120. Seventeenth Pipeline; 121. Eighteenth Pipeline; 122. Nineteenth Pipeline; 123. Twentieth Pipeline. Detailed Implementation

[0028] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0029] Specific Implementation Plan 1: Combining Figure 1 As shown, the present invention provides a two-stage ejector-compressor high-temperature heat pump system with a subcooler, including an evaporator 1, a first ejector 2, a first gas-liquid separator 3, an expansion valve 4, a first subcooler 5, a first compressor 6, a second ejector 7, a second gas-liquid separator 8, a second compressor 9, and a condenser 10.

[0030] The heat medium inlet of evaporator 1 is connected to the heat medium input pipe 101, and the heat medium outlet of evaporator 1 is connected to the heat medium output pipe 107.

[0031] The bottom liquid outlet of the second gas-liquid separator 8 is connected to the working fluid inlet of the first ejector 2 via the second pipe 103. The refrigerant outlet of the evaporator 1 is connected to the ejector fluid inlet of the first ejector 2 via the first pipe 102. The mixed fluid outlet of the first ejector 2 is connected to the inlet of the first gas-liquid separator 3 via the third pipe 104. The bottom liquid outlet of the first gas-liquid separator 3 is connected to the inlet of the expansion valve 4 via the fourth pipe 105. The outlet of the expansion valve 4 is connected to the refrigerant inlet of the evaporator 1 via the sixth pipe 106. The top gas outlet of the first gas-liquid separator 3 is connected to the low-pressure fluid inlet of the first subcooler 5 via the seventh pipe 108. The low-pressure fluid outlet of the first subcooler 5 is connected to the eighth pipe... Pipe 109 is connected to the inlet of the first compressor 6. The outlet of the first compressor 6 is connected to the ejector fluid inlet of the second ejector 7 via pipe 110 (ninth pipe). The refrigerant outlet of the condenser 10 is connected to the high-pressure fluid inlet of the first subcooler 5 via pipe 111 (tenth pipe). The high-pressure fluid outlet of the first subcooler 5 is connected to the working fluid inlet of the second ejector 7 via pipe 112 (eleventh pipe). The mixed fluid outlet of the second ejector 7 is connected to the inlet of the second gas-liquid separator 8 via pipe 113 (twelfth pipe). The top gas outlet of the second gas-liquid separator 8 is connected to the inlet of the second compressor 9 via pipe 114 (thirteenth pipe). The outlet of the second compressor 9 is connected to the refrigerant inlet of the condenser 10 via pipe 115 (fourteenth pipe).

[0032] The inlet of the condenser 10 is connected to the input pipeline 116 of the heated medium, and the outlet of the condenser 10 is connected to the output pipeline 117 of the heated medium.

[0033] The operating principle of this implementation plan is as follows:

[0034] The operation of this high-temperature heat pump system begins with the evaporator 1 absorbing heat from a low-temperature heat source, causing the refrigerant to evaporate into a gas. The low-temperature gaseous refrigerant from the refrigerant outlet of evaporator 1 enters the first ejector 2 as the entrainer fluid, while the subcooled liquid from the bottom of the second gas-liquid separator 8 serves as the working fluid of the first ejector 2. After mixing in the first ejector 2, the two fluids enter the first gas-liquid separator 3 for gas-liquid separation: the separated liquid is throttled and depressurized by the expansion valve 4 and then returns to the evaporator 1 to complete the primary cycle; the separated gas enters the low-pressure side of the first subcooler 5 to absorb heat and increase its temperature, and is then compressed to an intermediate pressure by the first compressor 6. This intermediate-pressure gas enters the second ejector 7 as the entrainer fluid, while the high-pressure liquid refrigerant flowing from the condenser 10, after being subcooled on the high-pressure side of the first subcooler 5, enters the second ejector 7 as the working fluid. After the two fluids are mixed in the second ejector 7, they enter the second gas-liquid separator 8 for further separation: the separated liquid is circulated to the first ejector 2 as the working fluid, forming an interstage energy transfer; the separated gas enters the second compressor 9 and is compressed to a high temperature and high pressure state, and finally enters the condenser 10 to release heat to heat the medium, completing the high temperature heat output.

[0035] Overall, three effects were achieved: First, the working fluid entering the second ejector 7 was deeply subcooled by the first subcooler 5, which significantly improved the ejection efficiency and operational stability of the first ejector 2 and the second ejector 7, thereby optimizing the energy transfer process of the entire system. Second, the innovative two-stage ejector structure effectively recovered the throttling expansion work of the refrigerant in the expansion valve 4 (first stage) and from high pressure to intermediate pressure, converting it into the power of the compression process and greatly reducing the compression power consumption of the system. Third, thanks to the synergistic design of the two-stage ejection and gas-liquid separation, the system completely eliminated the intermediate liquid spraying cooling stage commonly found in traditional high-temperature heat pumps. This not only simplified the system structure and reduced control complexity, but also avoided the efficiency loss and potential reliability problems that may be caused by liquid spraying cooling, thus improving the overall efficiency and operational robustness of the system.

[0036] This invention innovatively designs a two-stage ejector-compression cycle structure with an integrated subcooler. This design significantly improves the ejection efficiency and stability of the two-stage ejectors, effectively recovers expansion throttling work, and eliminates the intermediate liquid cooling stage found in traditional high-temperature heat pumps. Compared with traditional single-stage compression or cascade high-temperature heat pump systems with intermediate cooling, this invention maintains high-temperature output capacity while offering significant advantages such as simpler structure, more convenient control, higher energy efficiency, and more stable and reliable operation. This invention is particularly suitable for industrial waste heat recovery, district heating, and process heating scenarios requiring medium-to-high temperature hot water or steam above 85℃, and can efficiently improve the utilization value of low-grade heat energy.

[0037] Specific Implementation Plan Two: Combining Figure 2 As shown, the present invention provides a two-stage ejector-compression high-temperature heat pump system with a subcooler, including an evaporator 1, a first ejector 2, a first gas-liquid separator 3, an expansion valve 4, a first compressor 6, a second ejector 7, a second gas-liquid separator 8, a second compressor 9, a condenser 10, and a second subcooler 11.

[0038] The heat medium inlet of evaporator 1 is connected to the heat medium input pipe 101, and the heat medium outlet of evaporator 1 is connected to the heat medium output pipe 107.

[0039] The bottom liquid outlet of the second gas-liquid separator 8 is connected to the high-pressure fluid inlet of the second subcooler 11 via the fifteenth pipe 118. The high-pressure fluid outlet of the second subcooler 11 is connected to the working fluid inlet of the first ejector 2 via the sixteenth pipe 119. The refrigerant outlet of the evaporator 1 is connected to the low-pressure fluid inlet of the second subcooler 11 via the seventeenth pipe 120. The second subcooler 11 is connected to the ejector fluid inlet of the first ejector 2 via the eighteenth pipe 121. The mixed fluid outlet of the first ejector 2 is connected to the inlet of the first gas-liquid separator 3 via the third pipe 104. The bottom liquid outlet of the first gas-liquid separator 3 is connected to the inlet of the expansion valve 4 via the fourth pipe 105. The outlet of the expansion valve 4 is connected to the sixth pipe 105 via the sixth pipe 106. Pipeline 106 is connected to the refrigerant inlet of evaporator 1; the top gas outlet of the first gas-liquid separator 3 is connected to the inlet of the first compressor 6 via the nineteenth pipe 122, and the outlet of the first compressor 6 is connected to the ejector fluid inlet of the second ejector 7 via the ninth pipe 110; the refrigerant outlet of condenser 10 is connected to the working fluid inlet of the second ejector 7 via the twentieth pipe 123, the mixed fluid outlet of the second ejector 7 is connected to the inlet of the second gas-liquid separator 8 via the twelfth pipe 113, the top gas outlet of the second gas-liquid separator 8 is connected to the inlet of the second compressor 9 via the thirteenth pipe 114, and the outlet of the second compressor 9 is connected to the refrigerant inlet of condenser 10 via the fourteenth pipe 115.

[0040] The inlet of the condenser 10 is connected to the input pipeline 116 of the heated medium, and the outlet of the condenser 10 is connected to the output pipeline 117 of the heated medium.

[0041] The operating principle of this implementation plan is as follows:

[0042] The operation of this high-temperature heat pump system begins with the evaporator 1 absorbing heat from a low-temperature heat source, causing the refrigerant to evaporate into a gas. The low-temperature gaseous refrigerant from the outlet of evaporator 1 first enters the low-pressure side inlet of the second subcooler 11, where it absorbs heat and its temperature rises. Then, it enters the first ejector 2 as an ejector fluid. Simultaneously, the subcooled liquid at the bottom of the second gas-liquid separator 8 enters the high-pressure side inlet of the second subcooler 11, where it is cooled to achieve deep subcooling. Then, it enters the first ejector 2 as a working fluid. The two fluids mix in the first ejector 2 and then enter the first gas-liquid separator 3 for gas-liquid separation: the separated liquid is throttled and depressurized by the expansion valve 4 and returns to the inlet of evaporator 1; the separated gas directly enters the first compressor 6 and is compressed to an intermediate pressure. This intermediate-pressure gas enters the second ejector 7 as an ejector fluid, while the high-pressure liquid refrigerant flowing from the condenser 10 directly enters the second ejector 7 as a working fluid. After the two fluids are mixed in the second ejector 7, they enter the second gas-liquid separator 8 for further separation: the separated liquid is circulated to the high-pressure side inlet of the second subcooler 11; the separated gas enters the second compressor 9 and is compressed to a high temperature and high pressure state, and finally enters the condenser 10 to release heat to heat the medium, completing the high temperature heat output.

[0043] Overall, three effects were achieved. First, the newly added second subcooler 11 was used to deeply subcool the working fluid of the first ejector 2 and preheat its ejector fluid at the same time. This dual effect significantly improved the ejection efficiency and operational stability of the first ejector 2, especially enhancing the system's performance in the low-temperature heat source section. Second, by retaining the two-stage ejector structure, the throttling expansion work of the refrigerant at the expansion valve 4 (first stage) and from the condensing pressure to the second stage ejector pressure was effectively recovered and converted into compression power, greatly reducing the system's compression power consumption. Third, thanks to the coordinated design of the ejector and the gas-liquid separator, the system eliminated the intermediate liquid spraying cooling stage required by traditional high-temperature heat pumps, simplifying the structure and making control more convenient. Furthermore, the integrated position of the second subcooler 11 allowed the system to maintain its compactness while achieving performance improvement.

[0044] This invention innovatively designs a two-stage ejector-compression high-temperature heat pump system integrating a second subcooler 11. This design significantly improves the first-stage ejector efficiency and low-temperature operating stability, while effectively recovering expansion throttling work and completely eliminating the traditional intermediate liquid spray cooling stage, simplifying the system structure. Compared with traditional heat pumps and Specific Implementation Scheme 1, this design has advantages in low-temperature heat source adaptability, primary energy efficiency improvement, and structural compactness, and is particularly suitable for medium- and high-temperature heat energy recovery scenarios with low-grade heat sources such as industrial wastewater and geothermal energy below 60℃.

[0045] Specific Implementation Plan Three: Combining Figure 3 As shown, the system includes both a first subcooler 5 and a second subcooler 11. The core advantage of integrating both subcoolers 5 and 11 lies in the synergistic optimization of the performance of the two-stage ejectors: the first subcooler 5 deeply cools the working fluid entering the second ejector 7, improving its ejection efficiency; the second subcooler 11 focuses on optimizing the first ejector 2, significantly enhancing its low-temperature performance and stability by subcooling its working fluid and preheating its ejector fluid. This dual-subcooler configuration enables the system to efficiently recover expansion work and reduce compression power consumption over a wider operating range, while completely eliminating the traditional intermediate liquid injection cooling stage, simplifying the structure and achieving a higher level of overall energy efficiency and reliability.

[0046] While the present invention has been disclosed above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and all such changes and modifications will fall within the scope of protection of the present invention.

Claims

1. A two-stage ejector-compression high-temperature heat pump system with a subcooler, characterized in that: It includes an evaporator (1), a first ejector (2), a first gas-liquid separator (3), an expansion valve (4), a first subcooler (5), a first compressor (6), a second ejector (7), a second gas-liquid separator (8), a second compressor (9), and a condenser (10). The evaporator (1) is equipped with a heat medium inlet and a heat medium outlet. The bottom liquid outlet of the second gas-liquid separator (8) is connected to the working fluid inlet of the first ejector (2), and the refrigerant outlet of the evaporator (1) is connected to the ejector fluid inlet of the first ejector (2). After the two pipelines merge, the mixed fluid outlet of the first ejector (2) is connected to the inlet of the first gas-liquid separator (3), the bottom liquid outlet of the first gas-liquid separator (3) is connected to the inlet of the expansion valve (4), and the outlet of the expansion valve (4) is connected to the refrigerant inlet of the evaporator (1). The top gas outlet of the first gas-liquid separator (3) is connected to the low-pressure fluid inlet of the first subcooler (5), the low-pressure fluid outlet of the first subcooler (5) is connected to the inlet of the first compressor (6), and the outlet of the first compressor (6) is connected to the ejector fluid inlet of the second ejector (7). The refrigerant outlet of the condenser (10) is connected to the high-pressure fluid inlet of the first subcooler (5), and the high-pressure fluid outlet of the first subcooler (5) is connected to the working fluid inlet of the second ejector (7). After the two pipelines merge, the mixed fluid outlet of the second ejector (7) is connected to the inlet of the second gas-liquid separator (8), the top gas outlet of the second gas-liquid separator (8) is connected to the inlet of the second compressor (9), and the outlet of the second compressor (9) is connected to the refrigerant inlet of the condenser (10). The condenser (10) is provided with a heated medium inlet and a heated medium outlet.

2. A two-stage ejector-compression high-temperature heat pump system with a subcooler, characterized in that: It includes an evaporator (1), a first ejector (2), a first gas-liquid separator (3), an expansion valve (4), a first compressor (6), a second ejector (7), a second gas-liquid separator (8), a second compressor (9), a condenser (10), and a second subcooler (11). The evaporator (1) is equipped with a heat medium inlet and a heat medium outlet. The bottom liquid outlet of the second gas-liquid separator (8) is connected to the high-pressure fluid inlet of the second subcooler (11), and the high-pressure fluid outlet of the second subcooler (11) is connected to the working fluid inlet of the first ejector (2); the refrigerant outlet of the evaporator (1) is connected to the low-pressure fluid inlet of the second subcooler (11), and the second subcooler (11) is connected to the ejector fluid inlet of the first ejector (2). After the two pipelines merge, the mixed fluid outlet of the first ejector (2) is connected to the inlet of the first gas-liquid separator (3), and the bottom liquid outlet of the first gas-liquid separator (3) is connected to the inlet of the expansion valve (4). The outlet of the first gas-liquid separator (3) is connected to the refrigerant inlet of the evaporator (1); the top gas outlet of the first gas-liquid separator (3) is connected to the inlet of the first compressor (6), and the outlet of the first compressor (6) is connected to the ejector fluid inlet of the second ejector (7); the refrigerant outlet of the condenser (10) is connected to the working fluid inlet of the second ejector (7). After the two pipelines are mixed, the mixed fluid outlet of the second ejector (7) is connected to the inlet of the second gas-liquid separator (8), the top gas outlet of the second gas-liquid separator (8) is connected to the inlet of the second compressor (9), and the outlet of the second compressor (9) is connected to the refrigerant inlet of the condenser (10). The condenser (10) is provided with a heated medium inlet and a heated medium outlet.

3. A two-stage ejector-compression high-temperature heat pump system with a subcooler, characterized in that: It includes an evaporator (1), a first ejector (2), a first gas-liquid separator (3), an expansion valve (4), a first subcooler (5), a first compressor (6), a second ejector (7), a second gas-liquid separator (8), a second compressor (9), a condenser (10), and a second subcooler (11). The evaporator (1) is equipped with a heat medium inlet and a heat medium outlet. The bottom liquid outlet of the second gas-liquid separator (8) is connected to the high-pressure fluid inlet of the second subcooler (11), and the high-pressure fluid outlet of the second subcooler (11) is connected to the working fluid inlet of the first ejector (2); the refrigerant outlet of the evaporator (1) is connected to the low-pressure fluid inlet of the second subcooler (11), and the second subcooler (11) is connected to the ejector fluid inlet of the first ejector (2). After the two pipelines merge, the mixed fluid outlet of the first ejector (2) is connected to the inlet of the first gas-liquid separator (3), the bottom liquid outlet of the first gas-liquid separator (3) is connected to the inlet of the expansion valve (4), and the outlet of the expansion valve (4) is connected to the refrigerant inlet of the evaporator (1); the top gas outlet of the first gas-liquid separator (3) is connected to the low-pressure fluid inlet of the first subcooler (5), the low-pressure fluid outlet of the first subcooler (5) is connected to the inlet of the first compressor (6), and the outlet of the first compressor (6) is connected to the ejector fluid inlet of the second ejector (7). The refrigerant outlet of the condenser (10) is connected to the high-pressure fluid inlet of the first subcooler (5), and the high-pressure fluid outlet of the first subcooler (5) is connected to the working fluid inlet of the second ejector (7). After the two pipelines merge, the mixed fluid outlet of the second ejector (7) is connected to the inlet of the second gas-liquid separator (8), the top gas outlet of the second gas-liquid separator (8) is connected to the inlet of the second compressor (9), and the outlet of the second compressor (9) is connected to the refrigerant inlet of the condenser (10). The condenser (10) is provided with a heated medium inlet and a heated medium outlet.

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