Application Of Low GWP Refrigerant In Train Air Conditioning

At present,some trains,such as high speed rail,train and subway,have used R407 C as refrigerant,and the rest of the trains still use R22 as refrigerant,and R407 C will be replaced because of its high greenhouse effect.Therefore,choosing a low GWP,safe and efficient refrigerant for train air conditioning is undoubtedly the development direction of refrigerant replacement for train air conditioners.The energy saving and environmental protection of the train air conditioner were studied.A complete set of technical routes has been developed for the replacement of refrigerants in train air conditioners.Firstly,The dynamic load model of the "four longitudinal and four horizontal" trains in China is established.The load of different lines is quite different.On the basis of the comparison of the on-line control mode and the fixed frequency mode based on the dynamic load formulation,the power consumption of the train air conditioning in the four longitudinal and four horizontal lines in China has been reduced in varying degrees.The maximum power saving rate is 30.4%.The application of low GWP refrigerant to train air conditioning should take full consideration of the characteristics of the refrigerant itself,such as safety,environmental protection,thermal rationality and economy.The application of different refrigerants is different.The theoretical comparison and perfusion experiment of different refrigerants are carried out.The application characteristics of several refrigerants are analyzed,and R32 is selected from them.Theoretical comparison and experimental study on different refrigerants were carried out,and the application characteristics of several refrigerants were analyzed.Before R32 refrigerants are actually used for train air conditioners,R22 and R407 C train air conditioning units have been studied.The results show that the rated cooling of R22 train air conditioning system is 23.8kW,the refrigerant charge volume is 7.6kg,and the exhaust temperature and exhaust pressure are 104 ℃ and 1.84 MPa respectively.Meanwhile,the R32 of 5kg is perfused into the R22 system.The cooling capacity is 36 kW,and the exhaust temperature and exhaust pressure of R32 are 110 ℃ and 2.97 MPa respectively.The direct and indirect system of the R32 train air conditioning is set up,and the experimental research is carried out.Under the rated condition,the R32 charge of the direct refrigerating system is 6kg,the cooling capacity is 27 kW,the COP is 5.08,and the exhaust temperature and the exhaust pressure are respectively 91℃and 3.1MPa.At the rated condition the R32 charge of the indirect refrigeration system is 2.6kg,the cooling capacity is 11.5kW,the COP is 3.66,the exhaust temperature and the exhaust pressure are 118.5 ℃ and 3.58 MPa respectively.The heat transfer efficiency of the plate type heat exchanger is 74.5%.The filling quantity of R32 in the train air conditioning meets the limitation of combustible standard about the use of combustible refrigerants in the closed space,and guarantees the safety of the R32 used in the train air conditioning.Based on the first law of thermodynamics and the second law of thermodynamics,the prototype of three different refrigerants in R22,R407 C and R32 is compared from the angle of energy "quantity" and "quality" respectively.Under the rated condition,R32 has the largest exergy loss and R22 has the minimum exergy loss,and the evaporator has the largest exergy loss in component of the three systems.