Performance Study Of A Variable Cross-section Pin-shaped Louvered Fin Heat Exchange

Parallel flow heat exchanger is widely used in automobile air conditioning system because of its compact structure and high heat transfer efficiency.Improving the heat transfer efficiency of parallel flow heat exchanger is of practical significance to improve the energy efficiency of automobile air conditioning system and the endurance of pure electric vehicles.In this paper,the louver fins of parallel flow heat exchanger for vehicles are studied,and the flow heat transfer characteristics of louver fins are analyzed by numerical simulation and experimental research.The traditional louver fin model is established in the simulation software for numerical simulation.The results are compared with the experimental values.The maximum errors of heat transfer factor j and friction factor f are 9.15% and 7.18% respectively,which meet the allowable engineering errors,proving that the established model is reliable.The analysis of the velocity field,temperature field and pressure field of the air side of the traditional louver fin shows that the heat transfer of the louver fin is mainly concentrated before the middle steering zone,and with the increase of the inlet wind speed,more cooling air flows through the louver,the outlet air temperature decreases and the pressure drop increases.Based on the study of heat transfer characteristics of traditional louver fins,a new type of needle louver fin with variable section was proposed.The air side velocity,temperature and pressure distribution were obtained by numerical simulation,and the heat transfer factor j,friction factor f and comprehensive evaluation factor Ejf were calculated.The simulation results were compared with the traditional louver fins.Compared with traditional shutter fins,the heat transfer factor j of variable section pin shutter fin is increased by 8.01% ～ 8.80%,the friction factor f is reduced by 3.52% ～ 5.06%,and the comprehensive evaluation factor Ejf is increased by 9.11% ～ 10.36%.The comprehensive heat transfer performance of the variable section pin shutter fin is better than that of traditional shutter fin.On the basis of the above research,the structure of the variable section of the needle fin was optimized.The control variable method was used to change the parameters of the fin surface radius,the Angle of the louver,the distance between the louver and other parameters.Five different size fin models were established for each parameter,and the simulation was carried out.The combination of structural parameters to achieve the best heat transfer performance of the variable section pin louver fin is: surface radius R=17mm,louver Angleθ=25°,louver spacing LP=1.3mm.