Performance Study And Structure Design Of Microchannel Heat Exchanger With Fan-shaped Cavities

The cooling demand of the new generation of electronic equipment has been far beyond the design limits of the traditional cooling technology.In this paper,microchannel heat exchangers are more and more concerned and become the current research hotspots.In this work,a new type of microchannel heat exchanger with fan-shaped cavities is designed and fabricated.Then,the performance difference between the microchannel heat exchanger and the traditional rectangular microchannel heat exchanger is compared and analyzed by means of numerical simulation.Furthermore,the influence of the deviation degree,coincidence degree and arrangement on the pressure drop,heat transfer and velocity distribution characteristics of the microchannel heat exchanger with fan-shaped cavities is studied.Finally,the test platform of heat transfer performance is built to verify the simulation results.The main conclusions are as follows.The fluid flow through the microchannel heat exchanger with fan-shaped cavities requires a greater pressure drop than the rectangular straight microchannel heat exchanger.In the investigated flow range,the heat transfer performance of the rectangular microchannel heat exchanger is increasing before decreasing with the increase of the flow rate.The heat transfer performance of microchannel heat exchanger with fan-shaped cavities increases with the increase of the flow rate,while the increasing trend is slow.In the case of small inlet flow,the heat transfer performance of microchannel heat exchanger with fan-shaped cavities does not present the advantage,but with the increase of the flow,the heat transfer performance of microchannel heat exchanger with fan-shaped cavities is obviously better than that of rectangular straight microchannel heat exchanger.A higher pressure drop is required when the deviation degree of the cavity is greater.The deviation degree of the fan-shaped cavities affects the generation of secondary flow in the cavities,the greater deviation degree of the cavities,the formation of the secondary flow is more complex,the greater the interference effect on the mainstream.Consequently,the greater deviation degree will lead to the better heat transfer performance.The coincidencedegree and arrangement of the fan-shaped cavities have little effect on the overall pressure drop of the heat exchanger.The greater coincidence degree can strengthen the interference effect of the cavities on mainstream,resulting in a better heat transfer performance.In the case of small flow,the heat transfer performance of the micro-channel heat exchanger with a cavity arrangement from dense to sparse is the best.The exchanger with evenly distributed cavities is the most outstanding in the medium flow.When the flow rate is larger,the microchannel heat exchanger with a cavity arrangement from sparse to dense exhibits the best heat transfer performance.The experimental results are in good agreement with the simulation results,but the experimental results show that the heat transfer coefficient per unit volume Kv is smaller than the simulation value,and the Kv curve appeared downward trend in advance.