CN115823773A - Steam compression high-temperature heat pump system with double-nozzle ejector for synergism and circulation method thereof - Google Patents

Abstract

The invention discloses a vapor compression high-temperature heat pump system and its circulation method with double-nozzle injector synergistic effect. The system includes a low-pressure compressor and a high-pressure compressor; wherein the first condenser is connected with the low-pressure compressor, and the The second condenser is connected to the high-pressure side compressor for further heating of the heating medium; this cycle can obtain different condensation temperatures through dual compressors to achieve a stepwise increase in the temperature of the heating medium, thereby reducing the heat transfer rate. Irreversible loss of heat; at the same time, a regenerator is used to ensure that the suction of the compressor maintains a certain degree of superheat, avoiding wet compression of the compressor, and ensuring the reliability of the compressor operation. In addition, the expansion work of two high-pressure fluids can be recovered at the same time through the dual-nozzle ejector to increase the suction pressure of the compressor. At the same time, dual-temperature evaporation can be realized through the pressure boost effect of the dual-nozzle injector, which can effectively reduce the heat transfer temperature difference and irreversible loss of the evaporator, thereby improving the overall energy efficiency level of the system.

Description

A Vapor Compression High Temperature Heat Pump System and Its Cycle with Double Nozzle Ejector Synergistic method

technical field

The 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 and a circulation method thereof with double-nozzle injector synergistic effect.

Background technique

In recent years, the energy problem has become one of the important factors restricting the social and economic development of our country. Energy saving, emission reduction, energy consumption reduction and energy utilization rate improvement are the fundamental ways to solve the energy problem. At present, high-temperature heat pump technology is widely used in the field of waste heat recovery and utilization in chemical, food, petroleum, pharmaceutical, ceramic and other industries because of its high energy taste improvement effect. Therefore, the development of new high-efficiency high-temperature heat pump energy-saving technology is an important development direction of vapor compression heat pump technology.

For the traditional high-temperature heat pump technology, the single-stage compression heat pump system has the characteristics of single condensation temperature and evaporation temperature. When the heat source and heat sink temperature span is large, the compressor pressure is relatively large and the performance is attenuated. First of all, the high-temperature heat pump system with a single condensation temperature has a large heat transfer temperature difference when the refrigerant exchanges heat with the heating medium, especially when the temperature difference between the inlet and outlet of the heat sink fluid is large, the irreversible loss in the heat transfer process, the refrigerant and the heat sink The temperature of the medium is poorly matched; also at a single evaporation temperature, there will be a large heat transfer loss in the heat exchange process between the refrigerant and the heat source medium; finally, the traditional single-stage compression high-temperature heat pump cycle has a relatively high condensation temperature due to the high-temperature heating system. High, resulting in the increase of system condensing pressure and pressure ratio, the irreversible loss of the traditional throttling structure increases, and finally leads to the decline of system performance.

In view of the above problems, dual compressors can be used to form dual condensing pressures, thereby reducing the irreversible loss in the heat transfer process between the cold source medium and the condenser. The purpose of irreversible loss of heat transfer in thermal processes. In addition, in view of the problems of excessive throttling loss, increase in pressure ratio, and decrease in compressor performance during the heating process of a large-temperature span heat pump, a cycle system using double-nozzle injectors for parallel compression is proposed, which can maximize the recovery of expansion work and improve compression. The suction pressure of the machine can be reduced, the pressure ratio of the compressor can be reduced, and the energy consumption of the system can be reduced, so as to achieve the purpose of energy saving and efficiency enhancement.

Contents of the invention

The purpose of the present invention is to address the deficiencies in the existing high-temperature heat pump technology, and provide a double-nozzle ejector synergistic vapor compression high-temperature heat pump system and its circulation method. This system can not only meet the needs of high-temperature heating, but also further Improve the heating performance of the system.

For realizing above object, the technical scheme that the present invention adopts is:

A vapor compression high-temperature heat pump system with double-nozzle injector synergistic effect, which adopts dual-compressor parallel connection and double-nozzle injector coupling to realize high-temperature heating; the system includes: a low-pressure compressor 101, a high-pressure compressor 102, a first Condenser 103, second condenser 104, regenerator 105, double nozzle injector 106, first evaporator 107, second evaporator 108, gas-liquid separator 109 and 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 is connected to the inlet of the first nozzle of the double nozzle injector 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 inlet of the second nozzle of the double nozzle injector 106; the double nozzle The outlet of the injector 106 is connected with the inlet of the first evaporator 107; the outlet of the first evaporator 107 is connected with the inlet of the gas-liquid separator 109; the outlet of the liquid pipe of the gas-liquid separator 109 is connected with the inlet of the throttle device 110; the outlet of the throttle device 110 is connected with the The inlet of the second evaporator 108 is connected; the outlet of the second evaporator 108 is connected with the secondary inflow inlet of the double-nozzle injector 106; the gas pipe outlet of the gas-liquid separator 109 is connected with the inlet of the low temperature side of the regenerator 105; the outlet of the low temperature side of the regenerator 105 It is connected with the suction ports of the low-pressure compressor 101 and the high-pressure compressor 102 to form a complete heat pump circulation system;

The parallel connection of dual compressors 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 The suction of the low-pressure compressor 101 and the high-pressure compressor 102 has a certain degree of superheat, which effectively prevents the low-pressure compressor 101 and the high-pressure compressor 102 from working in the two-phase region, thereby ensuring the operation of the low-pressure compressor 101 and the high-pressure compressor 102 reliability. In addition, the dual-nozzle injector is used to recover the expansion work to the greatest extent; in order to achieve the purpose of energy saving.

The dual-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, and at the same time, the characteristics of the double-nozzle ejector to boost the pressure are used to increase the suction of the high compressor and the low pressure compressor. Air pressure, reduce the pressure ratio of the two compressors.

By coupling the injector and the evaporator, the system can realize double evaporators and double evaporating temperatures, and the evaporating temperature of the second evaporator is lower than that of the first evaporator.

The dual compressors and the dual condensers are coupled by dual nozzle injectors, the system can achieve dual condensation pressures and dual condensation temperatures under a single suction pressure, and the condensation pressure of the second condenser is higher than that of the first condensation The condensing pressure of the device.

The structural form of the dual-nozzle injector 106 includes but not limited to an adjustable injector and an injector with a fixed structure.

In the above-mentioned vapor compression high-temperature heat pump system with double-nozzle injector synergy and its circulation method, the low-pressure compressor 101 compresses the low-temperature gaseous refrigerant to an intermediate pressure, and then enters the first condenser 103 to condense and release heat into gas-liquid The two-phase medium-temperature and medium-pressure state, after passing through the regenerator 105, enters the first nozzle of the double-nozzle injector 106 as the primary flow of the injector; the high-pressure compressor 102 compresses the refrigerant into a high-temperature and high-pressure gaseous refrigerant and then enters the second condensation The condensing device 104 condenses and releases heat into a high-temperature and high-pressure two-phase state, and then enters the second nozzle of the dual-nozzle injector 106 as the primary flow of the injector after passing through the regenerator 105; the two-phase refrigerant at the outlet of the dual-nozzle injector 106 enters the first The evaporator 107 evaporates and releases heat, and the outlet of the first evaporator 107 maintains a two-phase state (refrigerant dryness increases) and enters the gas-liquid separator 109, and the saturated liquid refrigerant in the gas-liquid separator 109 passes through the throttling device 110, enter the second evaporator 108 in a two-phase state, and the gaseous or two-phase working medium at the outlet of the second evaporator 108 enters the dual-nozzle injector 106 as a secondary flow, and is mixed with the primary flow to increase the pressure; the gas-liquid separator The saturated gas refrigerant at the outlet of the air pipe 109 passes through the regenerator 105 and then enters the high compressor 101 and the low pressure compressor 102, thereby realizing a complete cycle.

The technical features of the present invention can use the first condenser to preheat the cold source medium first, heat the cold source medium to an intermediate temperature, and then use the second condenser to heat the cold source medium at the intermediate temperature to the target Temperature, while realizing the heating condition of high-temperature heat pump, it reduces the heat transfer loss caused by the mixing of cold source working fluid. Double condensers and double evaporators are successfully coupled through double-nozzle injectors and gas-liquid separators to effectively reduce the heat transfer temperature difference of heat exchangers, and at the same time increase compressor suction pressure through injectors and reduce compressor pressure ratio , to reduce system power consumption. The system is an economical, efficient and feasible improvement scheme, which will effectively promote the development of heat pump technology.

Description of drawings

FIG. 1 is a schematic diagram of the system of Embodiment 1 of the present invention.

Fig. 2 is the pressure-enthalpy diagram (p-h diagram) of the working process of the high-temperature heat pump circulation system of Embodiment 1 of the present invention

Detailed ways

In order to make the object, technical solution and advantages of the present invention more clear and concise, the present invention will be further described in detail below in conjunction with the accompanying drawings and two embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

Embodiment one

As shown in Figure 1, the types of the low-pressure compressor 101 and the high-pressure compressor 102 include but are not limited to types such as rolling rotor compressors, screw compressors and scroll compressors, and the outlet of the low-pressure compressor 101 is connected to the first The inlet of the condenser 103 is connected; the outlet of the high-pressure compressor 102 is connected with the inlet of the second condenser 104; the outlet of the first condenser 103 is connected with the inlet of the middle temperature side of the regenerator 105, and the outlet of the middle temperature side of the regenerator 105 is connected with the double nozzle ejector 106 The inlet of the first nozzle is connected; the outlet of the second condenser 104 is connected with 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 with the inlet of the second nozzle of the double nozzle injector 106; The inlet of the evaporator 107 is connected; the inlet of the gas-liquid separator 109 is connected with the outlet of the first evaporator 107; the outlet of the liquid pipe of the gas-liquid separator 109 is connected with the throttling device 110; the inlet of the second evaporator 108 is connected with the outlet of the throttling device 110; The outlet of the second evaporator 108 is connected with the secondary flow inlet of the dual-nozzle injector 106; the gas-liquid separator 109 gas pipe outlet is connected with the inlet of the low temperature side of the regenerator 105; the outlet of the low temperature side of the regenerator 105 is connected with the low pressure compressor 101 and the high pressure compressor The suction port of the machine 102 is connected to form an ejector synergistic high-temperature heat pump system with double evaporating temperature and double condensing temperature. The low-temperature water (point 14 in FIG. 1 ) exchanges heat with the first condenser 103 and the second condenser 104 in turn and is heated to high-temperature water (point 15 in FIG. 1 ), so as to provide heat to the high-temperature zone. The heat source medium at the evaporator (point 16 in FIG. 1 ) exchanges heat with the first evaporator 107 and the second evaporator 108 in turn and is cooled to a lower temperature (point 17 in FIG. 1 ). This enhances the temperature matching of the system heat exchanger and reduces the irreversible loss of heat transfer.

Fig. 2 is a pressure-enthalpy diagram (p-h diagram) of the working process of the heat pump circulation system of the first embodiment. The specific working process of the present invention is: part of the low-pressure superheated refrigerant gas (point 1 in Figure 2) enters the low-pressure compressor 1 as suction and is compressed to an intermediate pressure (point 2 in Figure 2), and then the refrigerant passes through the first condenser After 103 condenses and releases heat, the saturated liquid refrigerant (point 5 in Figure 2) passes through the regenerator 105 and becomes subcooled (point 7 in Figure 2) and enters the first nozzle of the dual-nozzle injector 106 as a primary flow In the process, the subcooled refrigerant becomes a low-pressure two-phase refrigerant after being throttled by the first nozzle (point 7' in Figure 2); at the same time, another part of the low-pressure superheated refrigerant gas (point 1 in Figure 2) is used as the suction After entering the high-pressure compressor 102, it is compressed into a high-temperature and high-pressure state (point 3 in Figure 2), and then the refrigerant passes through the second condenser 104 to condense and release heat, and then the saturated liquid refrigerant (point 4 in Figure 2) passes through the regenerator 105 for exchange. The heated supercooled refrigerant (point 6 in Figure 2) enters the second nozzle of the dual-nozzle ejector 106 as a primary flow, and the high-pressure supercooled refrigerant becomes a low-pressure two-phase refrigerant after being throttled by the second nozzle. refrigerant (point 6' in Figure 2), and then the refrigerant at the outlet of the two nozzles is fully mixed with the refrigerant coming from the second evaporator (point 8' in Figure 2), and the refrigerant passes through the diffuser section of the ejector. After pressure, it becomes a two-phase state (point 8 in Figure 2); then the two-phase refrigerant at the outlet of the ejector enters the first evaporator 107 for evaporation and cooling, and then maintains a two-phase state (point 9 in Figure 2) and enters the gas-liquid separator In 109, the liquid refrigerant in the gas-liquid separator 109 (point 11 in Figure 2) becomes a two-phase state (point 12 in Figure 2) after being throttled by the throttling device 110, and then enters the second evaporator 108 to evaporate and refrigerate Afterwards, the saturated gaseous refrigerant (point 13 in Fig. 2) is ejected by the double-nozzle injector; the saturated gas refrigerant (point 10 in Fig. 2) in the gas-liquid separator 109 becomes The superheated gas (point 1 in Fig. 2) returns to the high compressor 101 and the low pressure compressor 102 as suction air, thus completing the whole heat pump cycle.

Claims (6)

1. A vapor compression high-temperature heat pump system with synergy of a double-nozzle ejector is characterized in that high-temperature heating is realized by coupling a mode that double compressors are connected in parallel with the double-nozzle ejector; the system comprises: the system comprises a low-pressure compressor (101), a high-pressure compressor (102), a first condenser (103), a second condenser (104), a heat regenerator (105), a double-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 with the inlet of the first condenser (103); the outlet of the high-pressure compressor (102) is connected with the inlet of the second condenser (104); an outlet of the first condenser (103) is connected with a medium-temperature side inlet of a heat regenerator (105), and an outlet of the medium-temperature side of the heat regenerator (105) is connected with a first nozzle inlet of a double-nozzle ejector (106); the outlet of the second condenser (104) is connected with the inlet of the high-temperature side of the heat regenerator (105), and the outlet of the high-temperature side of the heat regenerator (105) is connected with the inlet of a second nozzle of the double-nozzle ejector (106); the outlet of the double-nozzle ejector (106) is connected with the inlet of the first evaporator (107); the outlet of the first evaporator (107) is connected with the inlet of a gas-liquid separator (109); the outlet of the liquid pipe of the gas-liquid separator (109) is connected with the inlet of the throttling device (110); the outlet of the throttling device (110) is connected with the inlet of the second evaporator (108); the outlet of the second evaporator (108) is connected with the secondary flow inlet of the double-nozzle ejector (106); the outlet of the gas pipe of the gas-liquid separator (109) is connected with the inlet of the low-temperature side of the heat regenerator (105); the outlet of the low-temperature side of the heat regenerator (105) is connected with the air suction ports of the low-pressure compressor (101) and the high-pressure compressor (102), so that a complete heat pump circulating system is formed;

the discharge capacity of the two compressors can be optimized in a parallel connection mode of the two compressors, the heat supply load of the first condenser (103) and the second condenser (104) is adjusted, and the overall performance of the system is improved; meanwhile, the heat regenerator (105) ensures that the suction gas of the low-pressure compressor (101) and the suction gas of the high-pressure compressor (102) have certain superheat degree, and effectively prevents the low-pressure compressor (101) and the high-pressure compressor (102) from working in a two-phase region, so that the running reliability of the low-pressure compressor (101) and the high-pressure compressor (102) is ensured. In addition, the expansion work is recovered to the maximum extent by using the double-nozzle ejector; so as to achieve the purpose of energy conservation.

2. The synergistic vapor compression high-temperature heat pump system of claim 1, characterized in that the expansion work of the refrigerant expansion process at the outlet of the first condenser (103) and the second condenser (104) is recovered by the dual-nozzle ejector (106), and the suction pressure of the high-pressure compressor and the low-pressure compressor is increased and the pressure ratio of the two compressors is reduced by the characteristic of injecting the pressure rise by the dual-nozzle ejector.

3. The synergistic vapor compression high temperature heat pump system of claim 1, wherein the system is capable of dual evaporator and dual evaporation temperature by coupling the ejector and the evaporator, and the evaporation temperature of the second evaporator is lower than the evaporation temperature of the first evaporator.

4. The synergistic vapor compression high temperature heat pump system of claim 1, wherein the dual compressors and the dual condensers are coupled by the dual nozzle ejector, the system can achieve dual condensing pressures and dual condensing temperatures at a single suction pressure, and the condensing pressure of the second condenser is higher than the condensing pressure of the first condenser.

5. The synergistic vapor compression high temperature heat pump system of the two-nozzle ejector of claim 1, characterized in that the two-nozzle ejector (106) is an adjustable ejector or an ejector of fixed structure.

6. A method of cycling a synergistic vapor compression high temperature heat pump system with two nozzles ejector according to any of claims 1 to 5, characterized in that the low pressure compressor (101) compresses the low temperature gaseous refrigerant to an intermediate pressure, then it enters the first condenser (103) to condense it into a gas-liquid two-phase medium temperature and pressure state, and after passing through the regenerator (105) it enters the first nozzle of the two nozzles ejector (106) as the ejector primary stream; the high-pressure compressor (102) compresses the refrigerant into a high-temperature high-pressure gaseous refrigerant, the high-temperature high-pressure gaseous refrigerant enters the second condenser (104) to be condensed and release heat into a high-temperature high-pressure two-phase state, and then the high-temperature high-pressure gaseous refrigerant passes through the heat regenerator (105) and enters a second nozzle of the double-nozzle ejector (106) as primary flow of the ejector; the two-phase refrigerant at the outlet of the double-nozzle ejector (106) enters a first evaporator (107) for partial evaporation refrigeration, the two-phase refrigerant is kept in a two-phase state at the outlet of the first evaporator (107) and enters a gas-liquid separator (109), the saturated liquid refrigerant in the gas-liquid separator (109) passes through a throttling device (110) and enters a second evaporator (108) in a two-phase state, and 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 boosting pressure; saturated gas refrigerant at the outlet of the gas pipe of the gas-liquid separator (109) passes through the heat regenerator (105) and then enters the high-pressure compressor (101) and the low-pressure compressor (102), so that complete circulation is realized.

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