微针肋内潜热型功能热流体换热特性研究

Heat transfer characteristics of latent functionally thermal fluid flows in the pin-fin Micro channels

引入潜热型功能热流体替换现有传统工质冷却大功率激光器,实验研究了潜热型功能热流体与传统工质去离子水在高4mm、宽2mm、间距1mm的微针肋内的层流流动换热特性。结果表明:在雷诺数Re为625～1125范围内,潜热型功能热流体均表现出比水更好的冷却性能及更低的壁面温度,且存在最佳的质量分数值;相同工况下,潜热型功能热流体平均努谢尔数Nu大于去离子水,平均努谢尔数Nu随着雷诺数Re的增加而增加。拟合了平均努谢尔数与流体雷诺数、普朗特数、质量分数的经验的关系式,最大偏差为16.9%,可以较好反映潜热型功能热流体的换热特性;潜热型功能热流体沿着流动长度的方向存在一个稳定的局部换热强化区,且强化换热存在最佳的长度。

In view of the cooling problem of high power lasers, the existing traditional working fluids are replaced by the latent functionally thermal fluid. The laminar flow and heat transfer characteristics of the latent heat functionally thermal fluid and that of deionized water in a piece of pin-fin micro channels with height of 4 mm, width 2 mm and spacing 1 mm were experimentally studied. The results show that when Reynolds Number ranges 625-1125, the latent functionally thermal fluid shows better cooling performance and lower wall temperature than the deionized water, and it has an optimum concentration value; Its average Nusselt number is greater than that of the deionized water, and the average Nusselt number increases with the Reynolds number. To clearly demonstrate the relationship between the average Nusselt number,Reynolds number,mass concentration and Prandtl number,an experimental formula was further fitted based on the experimental data,the maximum relative deviation is 16.9%, which is acceptable for experiments. Along the length in the direction of flow, there exists an optimal length for a stable local heat transfer enhancement section.