Study Of Flow And Heat Transfer Characteristics In Multi-port Extruded Tube

With the development of the airborne electronic equipment,cooling has become an urgentproblem which needed to be solved. Force air cooling was often used in the past. But with theincrease of electronic equipment power,conventional air cycle refrigeration system requires morebleeding air.Also because air cycle refrigeration system affected by flight altitude and speed,theairborne evaporation cycle refrigeration system began to be widely used.In the airborne evaporationsystem,heat exchanger is the evaporator and condenser.How to development efficient and compactheat exchanger become very important. The multi-port extruded tube heat exchanger is a new channeltype. As a cooling device miniaturization direction, it has a broad application.But the flow and heattransfer performance in this small channels is still in the preliminary stage.Flow and heat transfer characteristics in multi-port extruded tube with equivalent diameterranging from0.6to0.8mm in an experimental method. Liquid water,air and R134a was employedas work fluid. The experimental results show that when single phase fluid flow in the tube,flow andheat transfer characteristics is same as the regular size tube,the characteristics are unrelated with tubesize and type of work fluid.But for the flow boiling heat transfer characteristics,pressure drop andboiling heat transfer coefficient increase with the mass flow rate increase.The formula under normalsize tube is not suitable for multi-port extruded tube. The data that predicted by formula under normalsize tube is small than that data we get from experiment.