Theoretical Analysis And Experimental Study On The Effect Of Regenerator On The Performance Of Cascade Refrigeration

R404A/CO₂ cascade refrigeration system can provide lower temperature,the range of evaporation temperature is-50℃^-30℃,which is mainly used in commercial refrigeration in various fields.In recent years,the cascade refrigeration system research is found that domestic and foreign research of the refrigerant is mainly about the main natural refrigerant.The system of high and low temperature refrigeration cycle of the working fluid are R404 A and CO₂.Other cascade systems are at low temperature using CO₂ natural working fluid,high temperature refrigeration with R290,R134 a,R1270,NH3 and so on.Due to the destruction of the ozone layer and the greenhouse effect,chlorofluorocarbon synthetic refrigerant will gradually be eliminated,people will focus on the study of CO₂ based natural refrigerant refrigeration system.The performance of the cascade refrigeration system in the system with the regenerator is analyzed theoretically.It is mainly included the following aspects: low temperature level subcooling,superheating of high temperature,mass flow ratio of system,cooling capacity of system,efficiency of regenerator.It is concluded that:（1）The relative cooling capacity of the system increases when the efficiency of regenerator increases with low temperature.（2）Only high temperature cycle has a overheating cycle,the system than the low temperature cycle with a regenerator,high and low temperature cycle with a regenerator is optimal.（3）The performance of the cascade refrigeration system increases with the increase of the low temperature supercooling degree.（4）The mass flow ratio（mass flow ratio of low temperature and mass ratio of high temperature stage mass）of the system under different working conditions,increases with the increase of the low temperature grade condensing temperature.At the same condition,when the high temperature has a overheating cycle,the system mass flow is relatively large.Designed and constructed the system with a regenerator,cooling system respectively,in the high and low temperature added regenerator,detection,vacuum,filling the refrigerant,installation and commissioning,safety protection and other operations,to ensure the smooth operation of the experimental bench.Finally,the effective experimental data is used to analyze the law of system performance.It is concluded that: Under the different working conditions,the lower the subcooling degree is,the better the system performance is.In the same condition,only high temperature cycle with regenerator,the system performance is optimal.At the samecondition,only high temperature system with a regenerator,the mass flow ratio of the system is the largest.In the same condition,low temperature with a regenerator,which is good for improving the system cooling capacity.