Numerical Simulation Of Longitudinal Vortex Generator And Combinational Fin For Fin And Tube Heat Exchanger

Fin-and-tube heat exchanger is a kind of highly-efficient heat transfer facility which is wide used in petrochemical industry,metal smelting,mechanical processing and manufacturing,power engineering etc.In this paper,the curved rectangular vortex generator?CRVG?with offset distance?OD?is a passive technology about enhanced heat transfer for fin-and-tube heat exchangers which can increase the effect of secondary flow,the flow-guided and fluid jet impingement as a result of improving the heat transfer performance of heat exchanger.A numerical simulation was carried out to research the effects of curved rectangular vortex generators with offset distance,rectangular winglet vortex generators?RWVGs?and CRVG&slit combinational construction on characteristics of heat transfer and flow between heat exchangers.In order to study the influence of the curved rectangular vortex generators fin with offset distance on the characteristics of heat transfer and flow between the air-side and fin,flow field was discussed through different views which includes the changes of the wake-region,formation and development of secondary flow with different cross-sections and the effect of fluid jet impingement,meanwhile,the flow field is compared with that of curved rectangular vortex generators with no offset distance.The comparison of Nu_m,the factor of resistance,JF₁ and JF₂ with Reynolds number shows that the heat transfer performance of curved rectangular vortex generators with offset distance is better than CRVGs with no offset distance.By comparing Nu_m,the,the factor of resistance,JF₁ and JF₂,the influence of different offset distance on the heat transfer characteristics of curved rectangular vortex generators fin is analyzed.A modified dimensionless evaluation factor is proposed.By comparing the numerical simulation results of the OD=1 curved rectangular vortex generators fin with the rectangular winglet vortex generators fin,the effects of the two fins in flow-guided,formation and strength of secondary flow are analyzed and compared by the view of flow field of air-side.With comparison of the both fins on characteristics of heat transfer and flow by the Nu_m,the factor of resistance,JF₁and JF₂ factor,the results show that the heat transfer performance of the rectangular winglet vortex generators fin is better under the condition of equal heat flow.The effect of rectangular winglet vortex generator on heat transfer performance at different relative distances is analyzed.By comparing the simulation results of OD=1 curved rectangular vortex generators fin with OD=1 vortex generator and slit combinational fin,the heat transfer performance of the two kinds of fin is analyzed from the aspects of Nu_m,factor of resistance JF₁ and JF₂ factor.The results show that the heat transfer performance of the combinational fin is inferior to that of the single curved rectangular vortex generators fin.In order to improve the heat transfer performance of the combinational fin,an optimized construction of combinational fin is proposed.The results show that the heat transfer performance of the modified composite fin is better than that of the former one,and the heat transfer performance of the modified composite fin is better than that of the single OD=1 curved rectangular vortex generators fin under the larger Reynolds number.