微槽道表面喷雾冷却的实验研究

本文建立了以蒸馏水为工质的开放式喷雾冷却系统,研究了工质体积流量、槽道宽度、槽道高度对喷雾冷却系统换热性能的影响。结果表明:保持槽道高度为0.8 mm,喷雾流量为0.45 L/min时,随着槽底宽度从4 mm减小至1 mm,传热系数增加了41%;而当喷雾流量为1.25 L/min时,表面传热系数仅增加了8.5%,因此减小槽底宽度对喷雾冷却效果有一定的促进作用,但大流量时并不明显;保持槽底宽度为2 mm,改变槽道高度,当喷雾流量为0.45 L/min时槽道高度对热沉表面的换热影响较大,存在最优槽道高度(0.8 mm),此时热流密度和表面传热系数分别为198.5 W/cm~2、2.75 W/(cm~2·K),与光滑面相比增加了21.25%和30.95%,且存在最低表面温度;而当喷雾流量增至1.25 L/min时,喷雾冷却效果随着槽道高度的增加而持续增加。在以上基础上推导了微槽表面喷雾冷却强化换热机理,得出反映槽道尺寸对换热影响的微槽群表面无量纲准则方程。

Experimental Study on Spray Cooling of Surface with Micro-grooves

To investigate the influences of volume flow rate, groove depth, and groove width on the performance of the spray cooling system, an opened spray cooling system with distilled water was established. The experimental results indicate that if the groove depth is 0.8 mm, the surface coefficient of heat transfer increases by 41% and 8.5% at the volume flow rate of 0.45 L/min and 1.25 L/min respectively as the groove width reduces from 4 mm to 1 mm. If the groove width is 2 mm, the surface with a groove depth of 0.8 mm has the largest heat flux enhancement at the volume flow rate of 0.45 L/min, and the heat flux and surface coefficient of heat transfer are 198.5 W/cm2 and 2.75 W/(cm2?K) respectively, which are enhanced by 21.25% and 30.95% relative to the flat surface at the volume flow rate of 0.45 L/min. When the volume flow rate is 1.25 L/min, heat transfer is enhanced with the increase in groove depth. On the above basis, non-dimensional criterion equations about micro-grooves surface were derived, in which the structure parameters of micro-grooves surface on heat transfer were considered.