The Research Of Heat Transfer Characteristics Of Carbon Dioxide In Microchannel Gascooler

With the rapid development of China's automobile industry and energy awareness,efficiency,energy saving,lightweight micro-channel heat exchanger has become the development direction of automobile air-conditioning heat exchanger.In this paper,a variety of methods ie the two-dimensional matlab programming,3D simulation analysis and experimental verification are used to evaluate the microchannel gas-cooled overall performance,from different angles ie air-side structure,flat tube and manifolds structure.Finally,the paper gives further optimization and recommendations on the microchannel gas-cooled.In this paper,the existing CO₂ heat transfer correlations was caopared and analysed,The author selected the appropriate heat exchanger correlations of CO₂,created a two-dimensional model of gas cooler.Flat tubes are divided into infinitesimal segments by using finite volume method,each cell using distributed parameter model,for each control volume according to the lumped parameter modeling calculate the flow and heat transfer conditions of each cell.Comparison of simulation and experimental results,show that the error of each parameter is within acceptable range,which proves the rationality of the established mathematical model,which proves the rationality of the established mathematical model.Simulation and analysis of air side fin spacing,fin height,fin thickness,fin width,air flow rate and air temperature et c physical quantities on the influence of heat transfer and pressure drop.Introducing signal-to-noise ratio?SNR?of Taguchi method,effectively evaluate the effects of fin parameters on the heat transfer effect.The results show that the contribution rates of various factors influencing the performance of heat exchanger:fin height 42.45%,25.73%fin pitch,fin width 24.32%,fin thickness was 7.50%,the contribution rate of fin high is the largest,fin thickness is the lowest.3D simulation based on the CFD platform of the microchannel gas cooler were analyzed,the position of inlet different has little effect on refrigerant flow in flat tube;the depth of flat tube insert manifold on the influence of flow distribution also were studied,the insertion depth of the flat tube is shallowest has more uniform flow distribution,and the increase of the inlet temperature of CO₂ is beneficial to improve the heat transfer performance of the heat exchanger;at last,the results show the simulation data agree well with the experimental results and the error of flat tube wall temperature are less than 10%,to verify the simulation results is rationality.