Research On Mechanism Of Microchannel With Multiple Impinging Jets For Electronic Cooling

With the continuous miniaturization of electronic components, the heat generation densities from the heat sources increase drastically, resulting in high working temperature that can greatly shorten their lives and reduce the reliability of the components without being cooled efficiently. However, the traditional cooling methods often cannot meet this demand. This thesis has investigated related innovative cooling method about microchannel heat sink with multiple impinging jets.Firstly, the fluid flow and heat transfer characteristics of microchannel and impinging jet and a combination of both models has been theoretically analyzed. And then I compared the performance of microchannel and microchannel with impinging jets, the result show that the microchannel has a good heat transfer characteristics, but the microchannel combined with jets can effectively improve the temperature uniformity and improve performance of heat sink significantly.A transient numerical investigation on a microchannel with impinging jets has been performed to explore the effects of unsteady heat flux and jet velocity on the fluid flow and heat transfer characteristics by computational fluid dynamics method. The cooling performance was evaluated by calculating the periodic average surface heat transfer coefficient and average temperature uniformity. The results indicated that transient heat flux and jet velocity will cause non-uniform and transient temperature distributions, which will cause the thermal fatigue phenomenon, and thereby have effect on the longevity of the microchannel with impinging jets heat sink.An idea of extending nozzles into microchannel has been introduced to enhance the thermal performance of a microchannel heat sink with extending-nozzle impinging jets. The velocity and temperature contours of symmetry plane, temperature contours and average temperature of cooled surface, pressure drop, Nu number has been studied to compare the fluid flow and heat transfer performance of different size of extending nozzles by numerical simulation. The results showed that increasing the length of extending nozzles will achieve better thermal performance of the microchannel with impinging jets heat sink.