A dual-nozzle ejector efficiency-enhanced vapor compression high-temperature heat pump system and its circulation method

Abstract

The present invention discloses a vapor compression high-temperature heat pump system with dual-nozzle ejector efficiency enhancement and its circulation method, the system includes a low-pressure compressor and a high-pressure compressor; wherein the first condenser is connected to the low-pressure compressor for preliminary heating of the heated medium; the second condenser is connected to the high-pressure side compressor for further heating of the heating medium; the cycle can obtain different condensation temperatures through the dual compressors, realize step-by-step temperature increase of the heating medium, thereby reducing the irreversible loss of heat transfer; at the same time, a regenerator is used to ensure that the compressor suction maintains a certain degree of superheat, avoids wet compression of the compressor, and ensures the reliability of the compressor operation. In addition, the dual-nozzle ejector can simultaneously recover the expansion work of two high-pressure fluids and increase the compressor suction pressure. At the same time, the pressure-boosting effect of the dual-nozzle ejector can achieve dual-temperature evaporation, effectively reducing the evaporator heat transfer temperature difference and irreversible loss, thereby improving the overall energy efficiency level of the system.

Description

Technical Field

[0001] The present invention belongs to the technical field of vapor compression heat pump heating, and in particular relates to a vapor compression high-temperature heat pump system with double-nozzle ejector efficiency enhancement and a circulation method thereof. Background Art

[0002] Currently, high-temperature heat pump technology, due to its high energy efficiency, is widely used in waste heat recovery and utilization in industries such as chemical, food, petroleum, pharmaceutical, and ceramics. Therefore, the development of new and efficient high-temperature heat pump energy-saving technologies is an important development direction for steam compression heat pump technology.

[0003] For traditional high-temperature heat pump technology, the single-stage compression heat pump system has a single condensing temperature and evaporating temperature. When the heat source and heat sink temperatures span a large operating range, the compressor pressure ratio is large and the performance degradation is serious. First, the high-temperature heat pump system with a single condensing temperature has a large heat exchange temperature difference when the refrigerant and the heating medium are exchanging heat. Especially when the temperature difference between the inlet and outlet of the heat sink fluid is large, the heat transfer process has irreversible losses and the temperature matching between the refrigerant and the heat sink medium is poor. Similarly, at a single evaporating temperature, the heat exchange process between the refrigerant and the heat source medium will also have large heat transfer losses. Finally, due to the high condensing temperature of the high-temperature heating system, the traditional single-stage compression high-temperature heat pump cycle leads to an increase in the system condensing pressure and pressure ratio, and an increase in the irreversible loss of the traditional throttling structure, which ultimately leads to a decline in system performance.

[0004] To address the above issues, dual compressors can be used to create dual condensing pressures, thereby reducing the irreversible losses in the heat transfer process between the cold source medium and the condenser. At the same time, the ejector's pressure-boosting capability can be used to create a dual-temperature evaporation effect, which can also achieve the goal of reducing the irreversible losses in the heat transfer process during the heat absorption process. In addition, to address the problems of excessive throttling losses, increased pressure ratio, and decreased compressor performance during the high-temperature cross-heat pump heating process, a circulation system using dual-nozzle ejectors in parallel compression is proposed. This can maximize the recovery of expansion work, increase the compressor's suction pressure, reduce the compressor's pressure ratio, and reduce system energy consumption, thereby achieving the goal of energy saving and efficiency improvement. Summary of the Invention

[0005] The purpose of the present invention is to address the shortcomings of existing high-temperature heat pump technology and provide a steam compression high-temperature heat pump system with dual nozzle ejector efficiency enhancement and its circulation method. The system can not only meet the needs of high-temperature heating, but also further improve the heating performance of the system.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is:

[0007] A dual-nozzle ejector efficiency-enhanced vapor compression high-temperature heat pump system employs dual compressors connected in parallel and coupled with dual-nozzle ejectors to achieve high-temperature heating. The system comprises: a low-pressure compressor 101, a high-pressure compressor 102, a first condenser 103, a second condenser 104, a regenerator 105, a dual-nozzle ejector 106, a first evaporator 107, a second evaporator 108, a gas-liquid separator 109, and a throttling device 110.

[0008] The outlet of the low-pressure compressor 101 is connected to the inlet of the first condenser 103; the outlet of the high-pressure compressor 102 is connected to the inlet of the second condenser 104; the outlet of the first condenser 103 is connected to the inlet of the medium-temperature side of the regenerator 105, and the outlet of the medium-temperature side of the regenerator 105 is connected to the first nozzle inlet of the double-nozzle ejector 106; the outlet of the second condenser 104 is connected to the inlet of the high-temperature side of the regenerator 105, and the outlet of the high-temperature side of the regenerator 105 is connected to the second nozzle inlet of the double-nozzle ejector 106; the outlet of the double-nozzle ejector 106 is connected to the inlet of the first evaporator 107 The outlet of the first evaporator 107 is connected to the inlet of the gas-liquid separator 109; the liquid pipe outlet of the gas-liquid separator 109 is connected to the inlet of the throttling device 110; the outlet of the throttling device 110 is connected to the inlet of the second evaporator 108; the outlet of the second evaporator 108 is connected to the secondary flow inlet of the double-nozzle ejector 106; the gas pipe outlet of the gas-liquid separator 109 is connected to the low-temperature side inlet of the regenerator 105; the low-temperature side outlet of the regenerator 105 is connected to the intake ports of the low-pressure compressor 101 and the high-pressure compressor 102, thereby forming a complete heat pump circulation system;

[0009] The use of two compressors in parallel optimizes the displacement of the two compressors, adjusts the heating load of the first condenser 103 and the second condenser 104, and improves the overall performance of the system. At the same time, the regenerator 105 ensures that the intake air of the low-pressure compressor 101 and the high-pressure compressor 102 has a certain degree of superheat, effectively preventing the low-pressure compressor 101 and the high-pressure compressor 102 from operating in the two-phase region, thereby ensuring the reliability of the low-pressure compressor 101 and the high-pressure compressor 102. In addition, the dual-nozzle ejector is used to maximize the recovery of expansion work, thereby achieving energy conservation.

[0010] The double-nozzle ejector 106 is used to recover the expansion work of the refrigerant expansion process at the outlet of the first condenser 103 and the second condenser 104. At the same time, the double-nozzle ejector's injection and pressure-boosting characteristics are used to increase the suction pressure of the high-pressure compressor and the low-pressure compressor, thereby reducing the pressure ratio of the two compressors.

[0011] By coupling the ejector with the evaporator, the system can realize dual evaporators and dual evaporation temperatures, and the evaporation temperature of the second evaporator is lower than the evaporation temperature of the first evaporator.

[0012] By coupling the dual compressors and the dual condensers through dual nozzle ejectors, the system can achieve dual condensing pressures and dual condensing temperatures under a single suction pressure, and the condensing pressure of the second condenser is higher than that of the first condenser.

[0013] The structure of the dual-nozzle injector 106 includes but is not limited to an adjustable injector and a fixed-structure injector.

[0014] The described dual-nozzle ejector efficiency-enhanced vapor compression high-temperature heat pump system and its circulation method, the low-pressure compressor 101 compresses the low-temperature gaseous refrigerant into an intermediate pressure, and then enters the first condenser 103 to condense and release heat into a medium-temperature and medium-pressure state of gas-liquid two-phase, and then enters the first nozzle of the dual-nozzle ejector 106 as an ejector primary flow after passing through the regenerator 105; the high-pressure compressor 102 compresses the refrigerant into a high-temperature and high-pressure gaseous refrigerant and then enters the second condenser 104 to condense and release heat into a high-temperature and high-pressure two-phase state, and then enters the second nozzle of the dual-nozzle ejector 106 as an ejector primary flow after passing through the regenerator 105; the dual-nozzle ejector The two-phase refrigerant at the outlet of 106 enters the first evaporator 107 to evaporate and release heat. At the outlet of the first evaporator 107, it still maintains a two-phase state (the dryness of the refrigerant increases) and enters the gas-liquid separator 109. The saturated liquid refrigerant in the gas-liquid separator 109 passes through the throttling device 110 and enters the second evaporator 108 in a two-phase state. The gaseous or two-phase working fluid at the outlet of the second evaporator 108 enters the double-nozzle ejector 106 as a secondary flow and is mixed with the primary flow to increase the pressure; the saturated gas refrigerant at the gas pipe outlet of the gas-liquid separator 109 passes through the regenerator 105 and enters the high-pressure compressor 102 and the low-pressure compressor 101, thus completing the complete cycle.

[0015] The technical features of the present invention are that the first condenser can be used to preheat the cold source medium, heating the cold source medium to an intermediate temperature, and then the second condenser can be used to heat the cold source medium at the intermediate temperature to the target temperature, thereby achieving a high-temperature heat pump heating condition while reducing the heat transfer loss caused by the mixing of the cold source medium. The dual condenser and dual evaporator are successfully coupled together through a dual-nozzle ejector and a gas-liquid separator, effectively reducing the heat transfer temperature difference of the heat exchanger while also increasing the compressor suction pressure through the ejector, reducing the compressor pressure ratio and reducing the system power consumption. This system is an economical, efficient and feasible improvement solution that will effectively promote the development of heat pump technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Schematic diagram of the system of Example 1 of the present invention.

[0017] Figure 2 This is a pressure-enthalpy diagram (ph diagram) of the working process of the high-temperature heat pump circulation system of Example 1 of the present invention. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solutions and advantages of the present invention more clear and concise, the present invention is further described in detail below with reference to the accompanying drawings and two embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0019] Example

[0020] like Figure 1 As shown, the types of the low-pressure compressor 101 and the high-pressure compressor 102 include but are not limited to rolling rotor compressors, screw compressors and scroll compressors. The outlet of the low-pressure compressor 101 is connected to the inlet of the first condenser 103; the outlet of the high-pressure compressor 102 is connected to the inlet of the second condenser 104; the outlet of the first condenser 103 is connected to the inlet of the medium-temperature side of the regenerator 105, and the outlet of the medium-temperature side of the regenerator 105 is connected to the first nozzle inlet of the double-nozzle ejector 106; the outlet of the second condenser 104 is connected to the inlet of the high-temperature side of the regenerator 105, and the outlet of the high-temperature side of the regenerator 105 is connected to the second nozzle inlet of the double-nozzle ejector 106 The outlet of the double-nozzle ejector 106 is connected to the inlet of the first evaporator 107; the inlet of the gas-liquid separator 109 is connected to the outlet of the first evaporator 107; the liquid pipe outlet of the gas-liquid separator 109 is connected to the throttling device 110; the inlet of the second evaporator 108 is connected to the outlet of the throttling device 110; the outlet of the second evaporator 108 is connected to the secondary flow inlet of the double-nozzle ejector 106; the gas pipe outlet of the gas-liquid separator 109 is connected to the low-temperature side inlet of the regenerator 105; the low-temperature side outlet of the regenerator 105 is connected to the intake ports of the low-pressure compressor 101 and the high-pressure compressor 102, thereby forming an ejector-enhanced high-temperature heat pump system with dual evaporation temperatures and dual condensation temperatures. Low-temperature water ( Figure 1 14 o'clock) and then heat exchange with the first condenser 103 and the second condenser 104 in turn and are heated to high temperature water ( Figure 1 15 o'clock in the middle), so as to realize the heat supply to the high temperature area. The heat source medium at the evaporator ( Figure 1 16 o'clock) and then exchange heat with the first evaporator 107 and the second evaporator 108 in sequence and are cooled to a lower temperature ( Figure 1 17 points). This enhances the temperature matching of the system heat exchanger and reduces irreversible heat transfer losses.

[0021] Figure 2 The pressure-enthalpy diagram of the working process of the heat pump circulation system of Example 1 ( ph Figure). The specific working process of the present invention is: part of the low-pressure superheated refrigerant gas ( Figure 2 1 point) as the suction gas into the low-pressure compressor 1 and is compressed to the intermediate pressure ( Figure 2 2 points), after which the refrigerant passes through the first condenser 103 and condenses and releases heat, the saturated liquid refrigerant ( Figure 25 points) after heat exchange in the regenerator 105 and becomes a supercooled state ( Figure 2 7) as the primary flow into the first nozzle of the double nozzle ejector 106, and the supercooled refrigerant becomes a low-pressure two-phase refrigerant after throttling through the first nozzle ( Figure 2 7 ' point); at the same time, another part of the low-pressure superheated refrigerant gas ( Figure 2 1 point) enters the high-pressure compressor 102 as the suction air and is compressed into a high-temperature and high-pressure state ( Figure 2 3 points), after which the refrigerant passes through the second condenser 104 and condenses and releases heat, the saturated liquid refrigerant ( Figure 2 (4 points) After the subcooled refrigerant has been heated in the regenerator 105 ( Figure 2 6) as the primary flow into the second nozzle of the double nozzle ejector 106, and the high-pressure subcooled refrigerant becomes a low-pressure two-phase refrigerant after throttling through the second nozzle ( Figure 2 Middle 6 ' point), and then the refrigerant at the two nozzle outlets is fully mixed with the refrigerant coming from the second evaporator ( Figure 2 Middle 8 ' point), the refrigerant becomes a two-phase state after the speed is reduced and the pressure is increased in the ejector expansion section ( Figure 2 8 o'clock); then the two-phase refrigerant at the ejector outlet enters the first evaporator 107 and remains in a two-phase state after evaporation and cooling ( Figure 2 9 o'clock) enters the gas-liquid separator 109, and the liquid refrigerant in the gas-liquid separator 109 ( Figure 2 11 o'clock) after throttling by the throttling device 110, it becomes a two-phase state ( Figure 2 12 o'clock), and then enters the second evaporator 108 to evaporate and cool to become a saturated gaseous refrigerant ( Figure 2 13 o'clock) is ejected by the double nozzle ejector; the saturated gas refrigerant in the gas-liquid separator 109 ( Figure 2 10 o'clock) after heat exchange in the regenerator 105, it becomes superheated gas ( Figure 2 1 point), returns to the high-pressure compressor 102 and the low-pressure compressor 101 as suction air, thereby completing the entire heat pump cycle.

Claims

1. A steam compression high temperature heat pump system with double nozzle ejector efficiency enhancement, characterized in that: High-temperature heating is achieved by coupling dual compressors in parallel with dual nozzle ejectors; the system comprises: a low-pressure compressor (101), a high-pressure compressor (102), a first condenser (103), a second condenser (104), a regenerator (105), a dual nozzle ejector (106), a first evaporator (107), a second evaporator (108), a gas-liquid separator (109), and a throttling device (110); The outlet of the low-pressure compressor (101) is connected to the inlet of the first condenser (103); the outlet of the high-pressure compressor (102) is connected to the inlet of the second condenser (104); the outlet of the first condenser (103) is connected to the inlet of the medium-temperature side of the regenerator (105), and the outlet of the medium-temperature side of the regenerator (105) is connected to the first nozzle inlet of the double-nozzle ejector (106); the outlet of the second condenser (104) is connected to the inlet of the high-temperature side of the regenerator (105), and the outlet of the high-temperature side of the regenerator (105) is connected to the second nozzle inlet of the double-nozzle ejector (106); the outlet of the double-nozzle ejector (106) is connected to the first evaporator (107) The inlet of the first evaporator (107) is connected to the inlet of the gas-liquid separator (109); the outlet of the liquid pipe of the gas-liquid separator (109) is connected to the inlet of the throttling device (110); the outlet of the throttling device (110) is connected to the inlet of the second evaporator (108); the outlet of the second evaporator (108) is connected to the secondary flow inlet of the double-nozzle ejector (106); the gas pipe outlet of the gas-liquid separator (109) is connected to the low-temperature side inlet of the regenerator (105); the low-temperature side outlet of the regenerator (105) is connected to the air intake of the low-pressure compressor (101) and the high-pressure compressor (102), thereby forming a complete heat pump circulation system; The use of a dual compressor parallel connection can optimize the displacement of the two compressors, adjust the heat supply load of the first condenser (103) and the second condenser (104), and improve the overall performance of the system; at the same time, the regenerator (105) ensures that the suction air of the low-pressure compressor (101) and the high-pressure compressor (102) has a certain degree of superheat, effectively avoiding the low-pressure compressor (101) and the high-pressure compressor (102) from operating in the two-phase region, thereby ensuring the reliability of the operation of the low-pressure compressor (101) and the high-pressure compressor (102); in addition, the dual-nozzle ejector is used to recover the expansion work to the greatest extent, so as to achieve the purpose of energy saving.

2. A dual-nozzle ejector efficiency-enhanced vapor compression high-temperature heat pump system according to claim 1, characterized in that: The double-nozzle ejector (106) is used to recover the expansion work of the refrigerant expansion process at the outlet of the first condenser (103) and the second condenser (104). At the same time, the double-nozzle ejector's injection pressure-boosting characteristic is used to increase the suction pressure of the high-pressure compressor and the low-pressure compressor, thereby reducing the pressure ratio of the two compressors.

3. The dual-nozzle ejector efficiency-enhanced vapor compression high-temperature heat pump system according to claim 1, characterized in that: By coupling the ejector with the evaporator, the system can realize dual evaporators and dual evaporation temperatures, and the evaporation temperature of the second evaporator is lower than the evaporation temperature of the first evaporator.

4. The dual-nozzle ejector efficiency-enhanced vapor compression high-temperature heat pump system according to claim 1, characterized in that: By coupling the dual compressors and the dual condensers through dual nozzle ejectors, the system can achieve dual condensing pressures and dual condensing temperatures under a single suction pressure, and the condensing pressure of the second condenser is higher than that of the first condenser.

5. The dual-nozzle ejector efficiency-enhanced vapor compression high-temperature heat pump system according to claim 1, characterized in that: The double nozzle injector (106) is an adjustable injector or a fixed structure injector.

6. A circulation method for a dual-nozzle ejector-enhanced vapor compression high-temperature heat pump system according to any one of claims 1 to 5, characterized in that: The low-pressure compressor (101) compresses the low-temperature gaseous refrigerant into an intermediate pressure, and then enters the first condenser (103) to condense and release heat to a medium-temperature and medium-pressure state of gas-liquid two-phase. After passing through the regenerator (105), the refrigerant enters the first nozzle of the double-nozzle ejector (106) as an ejector primary flow. The high-pressure compressor (102) compresses the refrigerant into a high-temperature and high-pressure gaseous refrigerant and then enters the second condenser (104) to condense and release heat to a high-temperature and high-pressure two-phase state. After passing through the regenerator (105), the refrigerant enters the second nozzle of the double-nozzle ejector (106) as an ejector primary flow. The two-phase refrigerant at the outlet of the double-nozzle ejector (106) enters the first vaporizer. The evaporator (107) partially evaporates and refrigerates, and the outlet of the first evaporator (107) still maintains a two-phase state and enters the gas-liquid separator (109). The saturated liquid refrigerant in the gas-liquid separator (109) passes through the throttling device (110) and enters the second evaporator (108) in a two-phase state. The gaseous or two-phase working medium at the outlet of the second evaporator (108) enters the double-nozzle ejector (106) as a secondary flow and is mixed with the primary flow for pressure increase. The saturated gas refrigerant at the gas pipe outlet of the gas-liquid separator (109) passes through the regenerator (105) and enters the high-pressure compressor (102) and the low-pressure compressor (101), thereby realizing a complete cycle.

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