Numerical Simulation Study On Thermal Dissipation Of Plain Heat Source At Small Temperature Difference

The good and efficient thermal decision is good for electronic equipments'reliability and performance. The improving of heat dissipation for electronic devices can make them work more steadily and have a longer life. Always the working temperature of electronic equipments is below 85℃. It's a small temperature difference heat dissipation comparing with ambient temperature. The usual electronic equipment has a plain heat resource surface, like the LED lighting products. So there is a great sense to do the research of plain heat resource with small temperature difference heat dissipation for improving the electronic products heat dissipation performance.In this paper, a new fin structure called grid plate heat sink with foursquare holes is proposed and its heat transfer performance with natural convection is researched. The basic functions group and the definite conditions describing the convection process are estimated. The main dimensionless parameters affecting the nature convection heat transfer performances are analyzed and proposed with dimensionless analytical method. We gain the relation formula Nu= f(Gr,H/S,b/δ).198 structures of grid plate heat sinks which are different in the ratio of the height and the space between fins H/S and the ratio of the hole side length and the fin thickness b/δare simulated with FLUENT and the orthogonal test design method.The effects of perforating to the heat transfer surface area A, the average convection heat transfer coefficient h, the heat dissipating capacity Q are researched and analyzed. The Nu-Gr relation graph is figured when different H/S and b/δin the area of 1≤H/S≤16/3,0≤b/δ≤4; After analyzing the data, the fitting correlations describing the heat transfer performance of this grid plate with foursquare holes are fitted out with the least square method: and the correction of fitting results are tested.At last, a high power LED street lamp 80W) is calculated, and two different heat sinks with the same basic sizes:a plate fin heat sink and a grid plate fin with foursquare holes heat sink are calculated and compared. The results show that:the highest temperature of grid plate fin heat sink is less 9℃than the plate fin heat sink's and the highest air velocity of grid plate fin heat sink is more 5.3% than the plate fin heat sink's. So we can see that the grid plate fin with foursquare holes heat sink has the better heat dissipation performance than the plate fin heat sink, which is valuable for engeering application.The scope of application is huge; This paper can provide theoretical guidance for the heat dissipation decision of temperature- sensitive electronic devices like LED lights.