小流量下喷雾冷却的理论及实验研究

THEORETICAL AND EXPERIMENTAL INVESTIGATION OF HEAT TRANSFER PERFORMANCE OF SPRAY COOLING UNDER LOW MASS FLUX

以水为冷却介质，对半实心旋流式机械雾化喷嘴的雾化性能及“无沸腾”区换热性能进行实验研究。PDPA的测试结果表明，该喷嘴在喷雾区有一明显的液滴速度、液滴直径减小的回流区，且距喷口越近，回流越明显。对质量通量为11．67-2906kg／（m^2s）之间的换热性能研究发现，热流、换热系数均随着流量通量的增加而增强；壁面温度对“无沸腾”区换热亦有一定的影响，且壁面温度愈高，换热性能亦愈强。给出了反映壁面温度影响的无量纲参数ξ，并对Reynolds数为116．2—289．2的实验数据进行拟合得到反映“无沸腾”区换热特性的无量纲关系式。

Using water as coolant, experiments were conducted to study the atomization performance of semi-solid swirl nozzles and the heat transfer performance in the non-boiling regime of spray cooling. The results measured by PDPA showed that there is a recirculating zone where the diameter and velocity of droplets both decreased and the phenomenon of reflow become more and more visible as the distance between the spout and measurement plane decreased. The heat transfer performance of spray cooling in the non-boiling regime was presented for mass flux ranged from 11.67 to 29.06 kg/m^2s. It was found that as the volumetric flux, wall temperature increasing, the heat transfer coefficient increased gradually. Furthermore, Generalized correlations were developed for local Nusselt number as a function of the spray Reynolds number （116.2〈 Re 〈289.2） and the non-dimensional temperature ξ in non-boiling regime of spray cooling.