槽道热管压扁度对传热的影响

对直径为6mm，长为210mm的小型微槽道柱状热管通过机加工方法制成的扁平热管（扁平厚度δ分别为3.5、3、2.5和2mm）的轴向温度分布、极限传输功率、热阻以及蒸发换热系数等传热特性进行了研究。试验所用的热管为轴向梯形微槽道热管。对实验数据的分析表明，极限传输功率随着压扁度的增加而逐渐减小。将直径为6mm的柱状热管压扁成2mm扁平热管后，极限传输功率降至原来的1/4。将直径为6mm的柱状热管分别压扁至3.5、3及2.5mm时，热阻基本稳定在0.08℃/W左右，但压扁至2mm时，热阻明显增大。直径为6mm的柱状热管压扁成3.5mm扁平热管时，蒸发换热系数增大，但从3.5mm压扁至2mm后，蒸发换热系数急剧下降。

Experimental investigation of heat transfer characteristics inside a flattened mini-axial grooved heat pipe

An experimental study of heat transfer characteristics in a flattened copper water mini-axial grooved heat pipe (AGHP) using a round AGHP with an outer diameter of 6mm and length of 210mm as the base case is reported. This AGHP was subsequently flattened to heights of 3.5，3，2.5 and 2mm. The temperature distribution along the axial distance, maximum heat transfer rate (MHTR), thermal resistance and evaporation heat transfer coefficient were experimentally determined for both AGHP and flattened AGHPs with different flattening height at several saturated vapor temperatures. The MHTR was found to decrease by 75% when the AGHP was flattened from a height of 6mm to 2mm. The thermal resistance was 0.08℃/W for both the round AGHP and flattened AGHP when the flattening height was greater than 2.5mm. When the AGHP was flattened to a height of 2mm, a significantly higher thermal resistance was observed. The evaporation heat transfer coefficient at the same saturated vapor temperature increased as the AGHP was flattened from 6?mm to 3.5mm. However, when the AGHP was flattened in the range 3.5mm to 2mm, the evaporation heat transfer coefficient decreased.