无风条件下带有玻璃盖板的倾斜封闭矩形腔体散热特性实验研究

Experimental Investigation on Heat Loss of an Inclined Rectangular Enclosure With Glass Cover-plate Under No-wind Condition

为了对腔体内外部耦合散热特性进行研究,建立带有玻璃盖板的倾斜封闭矩形腔体热损失特性实验台,在无风条件下对封闭矩形腔体的底部进行电加热,研究在不同的倾角、热流梯度参数k以及热流密度下,腔体内部以及玻璃盖板外表面的复合换热系数h_（in）和h_（ex）、玻璃盖板外表面的平均对流热损失努谢尔特数Nu_（cm）和平均辐射热损失努谢尔特数Nu_（rm）的变化规律,并获得相关实验关联式。研究表明,在较小倾角下（q￡60°）腔体内部的复合换热系数h_（in）总是要比外部hex大,带有玻璃盖板的封闭矩形腔体热损失主要受玻璃盖板外表面的传热过程控制;随倾角的增大,h_（in）与h_（ex）差异减小;Nu_（cm）随倾角的增大而增大;Nu_（rm）随k的增大而减少,随热流密度的增加而增加。

In order to investigate the coupled heat loss characteristics inside and outside the enclosure,an experimental setup featured by inclined rectangular enclosure with a glass cover-plate was established.Under no-wind condition,the enclosure was heated electrically from bottom.In view of different thermal gradient parameter k,heat flux and tilt angle,the comparison of combined heat transfer coefficient on the external surface of glass cover-plate with that inside the enclosure has been conducted,and the variation characteristics and correlations of average radiative and convective heat loss Nusselt numbers for the external surface of glass cover-plate were investigated and obtained.The results show that the combined heat transfer coefficient inside the enclosure hin is always higher than that for the external surface of glass cover-plate hex under smaller tilt angle,which indicates that the heat loss for an inclined rectangular enclosure is mainly controlled by the heat transfer process of the external surface of glass cover-plate.However,the difference between hin and hexbecomes smaller when the tilt angle increases.Besides,the average radiative heat loss Nusselt number for the external surface of glass cover-plate Nurm increases with the augment of heat flux and decreases with the increase of k,while the convective heat loss Nusselt number Nucm increases with the augment of tilt angle.