Two-stage cascade enhanced-vapor-injection low-temperature refrigerating system

Abstract

The invention relates to a two-stage cascade enhanced-vapor-injection low-temperature refrigerating system and belongs to the field of low-temperature storage. The two-stage cascade enhanced-vapor-injection low-temperature refrigerating system comprises a compressor, a first oil separator, a bipolar condenser, a first drying filter, a first capillary tube, an intermediate heat exchanger, a second oil separator, a second drying filter, a throttle valve, a plate heat exchanger, a second capillary tube, an evaporator and an enhanced-vapor-injection compressor. According to the two-stage cascade enhanced-vapor-injection low-temperature refrigerating system, a high-temperature-stage refrigerant and a low-temperature-stage refrigerant operate separately, a gas-liquid separator is omitted, it is not necessary to empty the refrigerants during later maintenance, the start-stop ratio of the system is lowered while the cost is saved, the service life of a unit is prolonged, and the operating stability of the system is improved; supercooling of the high-temperature refrigerant is achieved by winding the first capillary tube around a first gas return tube and supercooling of the low-temperature refrigerant is achieved by winding the second capillary tube around a second gas return tube for lowering the evaporation pressure of the low-temperature refrigerant; and by using the four-row-tube-bundle finned tube type condenser, condensation of the high-temperature refrigerant and precooling of the low-temperature refrigerant are achieved, two-stage independent operation is achieved, and the heat load of the intermediate heat exchanger is reduced.

Description

technical field [0001] The invention relates to the field of low-temperature storage, in particular to a two-stage cascading air injection enthalpy-increasing low-temperature refrigeration system. Background technique [0002] In the fields of medical specimen preservation, biomedicine, and gas liquefaction, low-temperature storage environments below -80°C are often required. In order to achieve low temperatures below -80°C, cascade refrigeration cycle systems are often used, including classic cascade systems and natural complex systems. stacking system. [0003] The natural cascade system uses a gas-liquid separator to realize the self-separation of high and low temperature refrigerants to obtain a lower evaporation temperature, but the disadvantage of this system is that it has poor stability. Proportional recharging causes great difficulty in system maintenance. Due to the preciousness of medical specimens, no problems are allowed during the preservation process, which ...

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Problems solved by technology

[0003] The natural cascade system uses a gas-liquid separator to realize the self-separation of high and low temperature refrigerants to obtain a lower evaporation temperature, but the disadvantage of this system is that it has poor stability. Proportional recharging, causing great difficulty in system maintenance

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