不同压力条件下水平平板的表面换热实验研究

为了解不同压力下水平平板的气体对流换热变化情况,搭建了一个提供不同气压和环境温度的实验舱,开展了在不同压力(0.1 Pa、0.1 k Pa、0.2 k Pa、0.5 k Pa、1 k Pa、10 k Pa、50 k Pa和常压)与几种加热量(75、150、300 W/m~2)组合条件下的水平平板换热实验研究。通过对辐射换热和自然对流换热的比较,得到不同压力下气体的对流换热系数。结果表明:对流换热系数在环境气体压力小于1 k Pa时非常小,而在1 k Pa以上时才较大;在大于1 k Pa时,对流换热系数随压力的升高呈二次方增加。

Experimental investigation of the thermal performance of horizontal flat's surface under different pressures

In order to understand the convective heat transfer of the horizontal flat at different pressures, a sealed cabin that can provide different pressures and temperatures is designed, and the thermal performance of the horizontal flat in several fixed heating input(75 W/m², 150 W/m², 300 W/m2) under different pressures (0.1 Pa, 0.1 kPa, 0.2 kPa, 0.5 kPa,1 kPa, 10 kPa, 50 kPa, ambient pressure) is experimentally investigated. By comparing the radiant heat exchange with the natural convection heat transfer, the convective heat transfer coefficient under different pressures is obtained. The experimental results show that the convective heat transfer coefficient is very small when the absolute environmental pressure is less than 1 kPa; it might be meaningful only when the absolute pressure is more than 1 kPa; and it increases quadratically along with the increase of the environmental pressure.