变加热功率下不同形状微肋阵热沉内的对流换热

为探索变加热功率下微肋阵热沉内的对流换热规律,采用精密机械加工获得圆形、菱形和三角形微肋阵热沉,建立一体式加热试验系统,测试了微肋阵热沉的压力降、流动阻力系数、热阻等对流换热参数,研究Re为0~1 000时微肋阵内阻力及对流换热受加热功率的影响规律。研究结果表明,微肋阵内阻力系数先随加热功率增加而增大,圆形和菱形截面微肋阵中该现象在Re>400时消失,而三角形微肋阵在Re>250时消失。加热功率的增加强化了圆形和菱形截面微肋阵内的对流换热,三角形微肋阵的Nu在Re<250时随加热功率的增加而增大,当Re>250后则有所降低;加热功率对于圆形和菱形微肋阵热沉热阻的影响在Re<600时较为明显,而对于三角形微肋阵当Re>250后加热功率对于热阻的影响基本可以忽略。

Convective heat transfer in micro pin fin heat sinks with different cross section shapes under variable heating loads

In order to investigate the flow and convective heat transfer characteristics under different heating loads in micro pin fins,test sections of micro pin fins with different cross section shapes of circle, diamond and triangle were precision machined. An integraed heating system was used to to measure the pressure drops, frictional resistance factors and thermal resistance in micro pin fins. Based on the experimental results, the impact of heating load on the flow resistance and the heat transfer in micro pin fins with Reynolds number ranging from 0~1 000 was explored. It was found that the friction factors in the three types of micro pin fins became large with the increase of the heating load, but this phenomenon disappeared when Re>400 for the circle and diamond micro pin fins, and Re>250 for the triangular micro pin fins. The convective heat transfer in micro pin fins with cross section shapes of circle, diamond was enhanced by increasing the heating load, but the Nu in triangular micro pin fins became large with the increase of the heating load when Re<250, and then it became slightly smaller when Re>250.