阅读说明：本技术 双级节流非共沸工质机械过冷co2跨临界制冷循环系统 (Twin-stage throttling non-azeotropic working medium mechanical super cooling CO2Trans-critical cycle cooling cycle system ) 是由 代宝民 杨茜茹 马牧宇 王璐 何小敏 杨和澄 郭梦迪 于 2019-09-05 设计创作，主要内容包括：本发明公开了一种双级节流非共沸工质机械过冷CO_2跨临界制冷循环系统。本发明CO_2跨临界制冷循环系统包括气体冷却器、中温级冷却蒸发器、低温级冷却蒸发器、膨胀阀、蒸发器、压缩机；非共沸工质机械过冷双级节流循环系统包括中温级压缩机、冷凝器、储液器、中温级节流阀、低温级节流阀、低温级压缩机。通过非共沸工质增压机械循环可对CO_2循环气体冷却器出口的CO_2流体进行一次和二次冷却,降低节流损失,提高系统整体能效。通过双级节流非共沸工质机械辅助过冷循环,使换热形成更良好的温度匹配,缩小了传热温差、减小了过程的不可逆损失,进而减小了冷凝器和蒸发器的传热不可逆损失,使制冷循环的效率得以提高。(The invention discloses a kind of twin-stage throttling non-azeotropic working medium mechanical super cooling CO 2 Trans-critical cycle cooling cycle system.CO of the present invention 2 Trans-critical cycle cooling cycle system includes gas cooler, medium temperature grade cooling evaporator, low-temperature level cooling evaporator, expansion valve, evaporator, compressor；Non-azeotropic working medium mechanical super cooling twin-stage circulating with choke system includes medium temperature grade compressor, condenser, liquid storage device, medium temperature grade throttle valve, low-temperature level throttle valve, low-temperature level compressor.It can be to CO by non-azeotropic working medium supercharging mechanical circulation 2 The CO of recyclegas cooler outlet 2 Fluid carries out primary and secondary cooling, reduces restriction loss, improves system entirety efficiency.SAPMAC method is crossed by twin-stage throttling non-azeotropic working medium mechanical-assisted, heat exchange is set to form more good Temperature Matching, it reduces heat transfer temperature difference, reduce the irreversible loss of process, and then reduce the heat transfer irreversible loss of condenser and evaporator, be improved the efficiency of refrigeration cycle.)

The non-azeotropic working medium mechanical super cooling CO 1. a kind of twin-stage throttles₂Trans critical cycle refrigeration system, which is characterized in that the circulatory system By non-azeotropic working medium mechanical super cooling twin-stage circulating with choke system and CO₂Trans-critical cycle cooling cycle system coupling composition；

The CO₂Trans-critical cycle cooling cycle system include gas cooler, medium temperature grade cooling evaporator, low-temperature level cooling evaporator, Expansion valve, evaporator, compressor；The compressor outlet is connected with gas cooler entrance, gas cooler outlet and medium temperature Grade cooling evaporator entrance is connected, and the medium temperature grade cooling evaporator outlet is connected with low-temperature level cooling evaporator entrance, low temperature The outlet of grade cooling evaporator is connect with expansion valve inlet, and expansion valve outlet is connected with evaporator inlet, evaporator inlet and compression Machine is connected；

The non-azeotropic working medium mechanical super cooling twin-stage circulating with choke system includes medium temperature grade compressor, condenser, liquid storage device, medium temperature Grade throttle valve, low-temperature level throttle valve, low-temperature level compressor；The medium temperature stage compressor outlet is connected with condenser inlet, condensation First via being connected respectively with medium temperature throttle valve and cryogenic throttle valve after liquid storage device, medium temperature throttling valve outlet and medium temperature are cooling for device outlet Evaporator inlet is connected, and the outlet of medium temperature cooling evaporator is connected with medium temperature suction port of compressor；Cryogenic throttle valve outlet with it is low Warm cooling evaporator entrance is connected, and sub-cooled evaporator outlet is connected with low-temperature level suction port of compressor, and low-temperature level compressor goes out Mouth is connected with medium temperature grade suction port of compressor.

The non-azeotropic working medium mechanical super cooling CO 2. twin-stage according to claim 1 throttles₂Trans critical cycle refrigeration system, it is special Sign is that the medium temperature cooling evaporator and sub-cooled evaporator are counter-flow heat exchanger.

The non-azeotropic working medium mechanical super cooling CO 3. twin-stage according to claim 1 throttles₂Trans critical cycle refrigeration system, it is special Sign is, CO₂Trans-critical cycle refrigeration cycle refrigerant uses natural refrigerant CO₂, non-azeotropic working medium mechanical super cooling twin-stage circulating with choke system Cryogen is CO₂/R1234ze、CO₂/R1234yf、R41/R1234ze、R41/R1234yf、R32/R1234ze、R32/R1234yf Or R32/R600a.

Technical field

The present invention relates to refrigeration technology fields, more particularly to a kind of twin-stage throttling non-azeotropic working medium mechanical super cooling CO₂Across Critical refrigeration cycle system.

Background technique

As global warming, ozone layer such as are destroyed at the increasingly prominent of environmental problems, there is destruction to ozone layer to substitute The working medium such as effect and CFCs, HCFCs, HFCs for generating greenhouse effects, the natural refrigerants for finding novel close friend become system The research emphasis of cold field of air conditioning.Wherein, CO₂By causing the universal of people in advantages such as its nontoxic non-combustible, safety and environmental protections Concern.

But due to CO₂Lower critical-temperature and higher critical pressure, make that its restriction loss is big, refrigerating efficiency is lower, Especially when environment temperature is higher, CO₂Refrigerating capacity sharply decline.If to the CO of gas cooler outlet₂Fluid carries out Supercooling, with the increase of degree of supercooling, restriction loss is reduced, and circulation cooling capacity increases, and circulation COP is promoted.CO₂Refrigeration cycle Supercooling can be realized by modes such as internal exchanger, mechanical super cooling, thermoelectricity supercoolings.Some scholars are used for CO to mechanical super cooling₂Across Critical refrigeration cycle has carried out theoretical research, i.e., by Vapor Compression Refrigeration Cycle to major cycle (CO₂Trans-critical cycle refrigeration cycle) The CO of gas cooler outlet₂It is cooled down.Mechanical super cooling can not only increase refrigerating capacity, and can reduce the fortune of major cycle Horizontal high voltage reduces Compressor Discharge Pressure, extends the service life of compressor

Conventional mechanical crosses SAPMAC method and is all made of pure refrigerant, and evaporative phase-change process temperature remains unchanged, but supercritical CO₂Stream Body cooling procedure is temperature-fall period, and the two heat transfer process temperature mismatches, and causes heat transfer process irreversible loss big.And for Environment temperature is higher, the lower application places of evaporating temperature, CO₂Degree of supercooling is up to 20 DEG C or more.Mechanical super cooling refrigeration cycle is cold Solidifying side exchanges heat with air, evaporation side and CO₂Fluid exchanges heat, and the temperature rise of air side is usually no more than 8 DEG C, and CO₂Temperature It is reduced to 20 DEG C or so.

If mechanical super cooling circulation uses non-azeotropic working medium, evaporation and the temperature glide for condensing phase transition process are close, cold Solidifying side and evaporation side cannot simultaneously with air and CO₂Good Temperature Matching is formed, so that biggish irreversible damage can be caused again It loses.

Summary of the invention

Present invention aims to overcome above-mentioned the deficiencies in the prior art, and it is non-total to provide a kind of twin-stage throttling Boil working medium mechanical super cooling CO₂Trans-critical cycle cooling cycle system.

The present invention is by mechanical super cooling refrigeration cycle and CO₂Trans-critical cycle refrigeration cycle forms, wherein mechanical super cooling refrigeration cycle For the vapor-compression refrigerant cycle of two evaporating pressures, refrigerant is the reasonable mix refrigerant CO of temperature glide₂/R1234ze、 CO₂/ R1234yf, R41/R1234ze, R41/R1234yf, R32/R1234ze, R32/R1234yf or R32/R600a.

The circulatory system of the present invention is by non-azeotropic working medium mechanical super cooling twin-stage circulating with choke system and CO₂Trans-critical cycle refrigeration cycle System coupling composition；

The CO₂Trans-critical cycle cooling cycle system includes gas cooler, medium temperature grade cooling evaporator, the cooling steaming of low-temperature level Send out device, expansion valve, evaporator, compressor；The compressor outlet is connected with gas cooler entrance, gas cooler outlet with Medium temperature grade cooling evaporator entrance is connected, and the medium temperature grade cooling evaporator outlet is connected with low-temperature level cooling evaporator entrance, Low-temperature level cooling evaporator outlet connect with expansion valve inlet, expansion valve outlet is connected with evaporator inlet, evaporator inlet and Compressor is connected；

The non-azeotropic working medium mechanical super cooling twin-stage circulating with choke system include medium temperature grade compressor, condenser, liquid storage device, Medium temperature grade throttle valve, low-temperature level throttle valve, low-temperature level compressor；The medium temperature stage compressor outlet is connected with condenser inlet, Condensator outlet with medium temperature throttle valve and cryogenic throttle valve first via being connected respectively after liquid storage device, medium temperature throttling valve outlet and medium temperature Cooling evaporator entrance is connected, and the outlet of medium temperature cooling evaporator is connected with medium temperature suction port of compressor, constitutes the first circuit；It is described low Temperature throttling valve outlet is connected with sub-cooled evaporator inlet, sub-cooled evaporator outlet and low-temperature level suction port of compressor phase Even, low temperature stage compressor outlet is connected with medium temperature grade suction port of compressor, constitutes second servo loop.

The medium temperature cooling evaporator and sub-cooled evaporator are counter-flow heat exchanger.

CO₂Trans-critical cycle refrigeration cycle refrigerant uses natural refrigerant CO₂, non-azeotropic working medium mechanical super cooling twin-stage circulating with choke Refrigerant is CO₂/R1234ze、CO₂/R1234yf、R41/R1234ze、R41/R1234yf、 R32/R1234ze、R32/ R1234yf or R32/R600a.

The advantages and positive effects of the present invention are:

(1)CO₂The refrigerant of refrigeration system is natural refrigerant CO₂。CO₂GWP be 1, ODP 0, it is safe and non-toxic it is non-combustible, It is cheap easily to obtain, do not decompose generation pernicious gas, mechanical super cooling cycle fluid CO under the high temperature conditions yet₂/R1234ze、CO₂/ The GWP of R1234yf, R41/R1234ze, R41/R1234yf, R32/R1234ze, R32/R1234yf or R32/R600a are lower, Refrigerant used in system is environmental-friendly refrigerant.

(2) mechanical super cooling circulation uses mixed non-azeotropic refrigerant CO₂/R1234ze、CO₂/R1234yf、 R41/ R1234ze, R41/R1234yf, R32/R1234ze, R32/R1234yf or R32/R600a are as working medium, and refrigerant is in condenser In with air form good Temperature Matching.Refrigerant throttles twice, recycles the twice evaporation process different there are high/low temperature, The evaporation process and CO of middle higher temperature₂Level-one is subcooled to form good Temperature Matching, the evaporation process and CO of lower temperature₂Two Grade supercooling carries out preferable Temperature Matching, finally further reduced CO₂The outlet temperature of gas cooler.Mechanical super cooling circulation Evaporation side and the heat exchange irreversible loss of condensation side reduce, circulation overall performance improves.

(3) by mechanical super cooling system to CO₂The CO of system gas cooler outlet₂It is subcooled, is lowered into expansion valve Preceding CO₂Temperature reduces expansion-loss, and further decreases CO₂Run high pressure.

Detailed description of the invention

Fig. 1 is twin-stage of the present invention throttling non-azeotropic working medium mechanical super cooling CO₂The CO of Trans-critical cycle cooling cycle system₂Trans-critical cycle The Sweet service of refrigeration cycle；

Fig. 2 is twin-stage of the present invention throttling non-azeotropic working medium mechanical super cooling CO₂The twin-stage of Trans-critical cycle cooling cycle system throttles The Sweet service of non-azeotropic working medium mechanical super cooling；

Fig. 3 is twin-stage of the present invention throttling non-azeotropic working medium mechanical super cooling CO₂The schematic diagram of Trans-critical cycle cooling cycle system.

Specific embodiment

The present invention will be further described with reference to the accompanying drawing.

As shown in Figure 1, the present invention includes the twin-stage throttling non-azeotropic working medium mechanical super cooling circulatory system and CO₂Trans-critical cycle refrigeration The circulatory system, heavy line CO₂Trans critical cycle (1 ' -2 ' -3 ' -4 ' -5 ' -6 ' -1 '), fine line are twin-stage throttling non-azeotrope work The low-temperature evaporation process (8-1) and high temperature evaporation process (7-3) of matter mechanical super cooling circulation.Fig. 2 is non-azeotropic working medium of the present invention increasing CO is subcooled in press mechanical pressing₂The Sweet service of the auxiliary supercooling refrigeration cycle of Trans-critical cycle cooling cycle system, wherein 3 ' -4 ' be CO₂Level-one Subcooling process, 4 ' -5 ' be CO₂Second level subcooling process.

Present system is as shown in Figure 3:

Step 1: compressor 1 sucks the saturation CO of the low-temp low-pressure in 6 exit of evaporator₂Gas compresses it into high temperature The gas of high pressure, temperature reduces after being exchanged heat in gas cooler 2 with air, flows separately through medium temperature cooling evaporator later 3 exchange heat with sub-cooled evaporator 4 with mixed non-azeotropic refrigerant, realize CO₂Fluid supercooling, enters back into 5 section of throttle valve Stream decompression, becomes gas-liquid two-phase state.Become overheated gas after 6 evaporation endothermic of evaporator again and enter compressor, completes CO₂Across Critical cycle.

Step 2: mechanical super cooling circulation low-temperature level compressor 12 absorbs the low-temp low-pressure in 4 exit of sub-cooled evaporator Refrigerant compresses it into the overheated gas of medium temperature and medium pressure, enters after mixing with the saturated gas that medium temperature cooling evaporator 3 exports Medium temperature grade compressor 7, is compressed into high temperature and high pressure gas, into condenser 8 and air heat-exchange.Refrigerant enters liquid storage device 9 later, Become the gas-liquid two-phase fluid of medium temperature and medium pressure after 10 expansion throttling of medium temperature grade throttle valve all the way, another way passes through low-temperature level section Become the gas-liquid two-phase fluid of low-temp low-pressure after stream 11 expansion throttling of valve.

Step 3: the non-azeotropic working medium gas-liquid two-phase fluid of mechanical super cooling circulation medium temperature and medium pressure passes through medium temperature cooling evaporator 3 and CO₂It carries out primary heat exchange and becomes saturated gas, the gas-liquid two-phase fluid of low-temp low-pressure passes through sub-cooled evaporator 4 and CO₂ It exchanges heat, further decreases CO₂The temperature of fluid, non-azeotropic working medium ultimately become saturated gas.

Although the preferred embodiment of the present invention is described above in conjunction with attached drawing, the invention is not limited to upper The specific embodiment stated, the above mentioned embodiment is only schematical, be not it is restrictive, this field it is common Technical staff under the inspiration of the present invention, without breaking away from the scope protected by the purposes and claims of the present invention, may be used also By make it is many in the form of, within these are all belonged to the scope of protection of the present invention.