Numerical Simulation Of Louvered Heat Exchanger Fins With Vortex Generator

Parallel flow heat exchanger is widely used in automotive air conditioning system because of its small size,light weight and good heat transfer effect.With the popularization and application of new energy vehicles,automotive air conditioning heat exchangers have put forward higher requirements in terms of performance and quality.In this paper,the parallel flow louver heat exchanger for vehicle is simulated,and a new louver fin structure with vortex generator is proposed.The heat transfer factor j,the resistance factor f and the comprehensive factor Ejf are used as the evaluation indexes to evaluate the performance of the louvered fin,and theΩcriterion is used to improve the performance of the louvered fin.The main conclusions are as follows:(1)Compared with the traditional louver fin,the heat transfer factor of the louver fin with vortex generator is increased by 3.6%～4.6%,the resistance factor is increased by 8%～10.5%,and the comprehensive factor is increased by 0.6%～1.2%.(2)Through the temperature field distribution perpendicular to the fin and parallel to the fin,it is found that the vortex generator produces a thermal wake effect in the louver channel,and the fluid temperature growth rate is faster than the traditional louver fin.Through the local pressure field distribution,it is found that the vortex generator will produce a large pressure gradient.Through the distribution of temperature field and pressure field under different Re conditions,it is found that the vortex generator has a significant effect on the heat transfer performance of the fin,and the pressure drop also increases slightly,but the final comprehensive factor is improved.(3)The longitudinal vortex generated by the vortex generator in the louvered fin flow channel is different from the independent longitudinal vortex distribution of the traditional fin,which forms a dense network vortex.According to the analysis of the eddy current intensity and eddy current streamline in the vertical fin direction,it can be seen that the eddy current generator divides the eddy current with the original intensity of±250 into two small eddy currents with the opposite rotation direction and the average intensity of±1500.The eddy current effect is obviously improved,thus strengthening the heat transfer.(4)Taking the comprehensive factor as the evaluation index of the performance of the fin,the diameter d,the fin spacing Fd,the arrangement position of the vortex generator x and the ratio of the long and short diameters m are optimized.Finally,it is found that the diameter d=0.8mm,the fin spacing F_d=1.4mm,the vortex generator is arranged in the middle of the fin,and the ratio of the long and short diameters is 1:4.The contribution rate of fin spacing Fp is 82%,the contribution rate of vortex generator diameter d is 5%,the contribution rate of arrangement position x is 8%,and the contribution rate of long and short diameter ratio m is 6%.