Study On The Performance Of Air-conditioning Heat Exchanger With Low GWP Working Fluids

With the improvement of social and people’s living standards, refrigeration andair conditioning enter people’s daily lives. Their energy consumption also occupies alarge proportion in total energy consumption and the refrigerants they use will have abad impact on the environment. The international community is concerning aboutenergy shortage and environmental issues increasingly. The efficient use of energyand refrigerant alternatives become the hot issues in the field of refrigeration and airconditioning.The heat exchanger is the key equipment of refrigeration and air conditioningsystems. The accurate simulation of operational performance is important foroptimization and reducing energy consumption of heat exchangers and coolingsystems. The analysis about performance of air conditioning heat exchanger with lowGWP fluids can provide theoretical basis for the refrigerant research alternatives. Insummary, this paper carried out the following work.Based on existing research results at home and abroad, a distributed parametermathematical model was set up for finned tube evaporator and condenser under steadystate, the actual flow condition and pressure drop were taken into consideration insidethe refrigerant in this model. Simulation program of the finned tube evaporator andcondenser was written and simulation software with friendly interface was developedwith Visual Basic language. Based on this simulation software, the characteristics ofthe flow and heat transfer of low GWP (Global Warming Potential) working fluidsR290, HFO1234yf and HFO1234ze in the finned tube heat exchanger were simulated.When the head-on wind speed, mass flow rate and pipe diameter size were altered, thechange situation of refrigerating capacity and pressure drop were analyzed and theperformance comparisons between the above low GWP refrigerants and the R410Awhich is now widely used were carried out.Enthalpy differential thermal balance room was used and the performance offinned tube evaporator and condenser were tested in R290refrigeration systems. Atthe same time, the above model was validated through the test data. In addition, themodel was also validated with the experimental data in the literature. Through thesetwo aspects of validation, the model was proved that it had a certain precision, which can be used for performance simulation of finned tube heat exchanger.A distributed parameter model was built for parallel flow condenser which isused in automotive air conditioning and the model was validated by experimental datain the literature. Flow and heat transfer characteristics of R134a and its potentialalternative refrigerant HFO1234yf were analyzed comparatively through this model.