Study On Heat Dissipation Intensification Of Microchannel With Impinging Jets And Inclined Ribs

With the heat dissipation of high power and high heat flux electronic components becoming the bottleneck of the development of science and technology,it is urgent to solve this problem.It is an effective way to improve the heat transfer between fluid and solid by increasing the contact area of fluid and solid and the velocity of fluid.The jet structure,inclined fin structure and microchannel structure are combined into the jet inclined fin microchannel.The flow and heat transfer performance of the microchannel is studied by numerical simulation under the condition of mass flow rate range of 0.5 g/s～4 g/s and heat flow density of the heat source surface of 300 W/cm².Compared with the straight channel,inclined fin straight channel and jet microchannel,it is found that the jet inclined fin micro channel has the best heat transfer performance,and because of the complexity of the internal structure,it also produces greater inlet and outlet pressure drop,and has greater flow resistance.In addition to the most simple straight channel,it is found that when the mass flow rate is greater than 1.5 g/s,there is almost no difference among the three microchannels.In consideration of the high temperature problem of the heating device,it is the best to use the microchannel of jet inclined rib for heat dissipation.Six kinds of microchannel models with inclined fin height H₃ of 0.3 mm,0.5 mm,0.7mm,0.9 mm,1.1 mm and 1.3 mm were established to study the influence of the height of inclined fin on the flow and heat transfer performance of the microchannel.The results show that the higher the height of inclined fin,the lower the temperature of the channel wall and the greater the pressure drop.Compared with the overall performance,it is found that the higher inclined fin is,the better the overall performance of the microchannel is at low flow rate;when the flow rate is greater than 2.5 g/s,the microchannel with H₃=0.7 mm has the best overall performance.It is also found that a large number of vortices are generated in the microchannel due to the combined action of the inclined fin and the impinging jet.The inclined fin moves back and forth,and the corresponding center and local low-temperature area of the vortex flow also move correspondingly,and the heat exchange effect without moving the inclined fin is the best.Due to the influence of the upstream flow,the impinging jet at the downstream shifts backwards,so that the downstream jet fails to impinge on the wall surface and weakens its ability to strengthen heat transfer.In view of the problems found in the study,the extension wall of the jet hole was extended to alleviate this phenomenon.The study found that the addition of the extension wall of the jet hole effectively improved the phenomenon of the backward displacement of the jet beam.The longer the extension wall of the jet hole,the better the heat transfer performance on the channel wall and the greater pressure drop.Comparing the thermal performance factors of the three types of microchannel walls,it is found that when the mass flow rate is less than 1.85g/s,it is best to set the length of wall of the jet hole extension to 0.3 mm;when the mass flow rate is higher than 1.85g/s,On the contrary,the comprehensive effect of the microchannels flow heat transfer extended by the wall of the jet hole becomes worse.This paper also studies the effect of jet aperture size and depth on the flow and heat transfer performance of oblique rib microchannels.It is found that the impact velocity is also different due to different jet apertures,which results in different heat transfer performance of oblique rib microchannels.Aiming at the"drift"phenomenon and the pressure drop problem,a cross-flow jet inclined rib microchannel arranged at the inlet and outlet is proposed and numerically calculated.It is found that the channel effectively solves the"drift"phenomenon and reduces the pressure drop at the inlet and outlet.In the entire flow range,Nu,which is arranged at the inlet and outlet,is2%～15%higher than ordinary jet oblique rib microchannels,and the pressure drop is11%～28%.