基于辐射原理狭窄垂直封闭空腔热阻强化措施的实验研究

列车车体围护结构中普遍存在的狭窄空腔增加了车体围护结构的热阻,同时也为进一步降低空腔的辐射换热份额创造了条件。通过实验方法,利用粘贴铝箔方式改变空腔内壁面辐射特性,以期改善空腔热工性能效果进行了研究。结果发现:常规车体壁面空腔辐射换热份额很大,不容忽视;在空腔内壁面附着铝箔等高反射率表层,可有效降低空腔的辐射换热份额,且随着空腔厚度的增大,空腔当量导热系数降低的效果更为明显,最大可达无铝箔空腔的62%左右;冷面单面粘贴铝箔方式的效果与热面单面粘贴铝箔方式的效果几乎相同,双面粘贴铝箔方式效果最好,优于单面铝箔方式5%左右。

Experimental study on improvinging thermal resistance of vertical enclosures based on radiation principle

The narrow space in a railcar body increase its thermal resistance and also enable improving the thermal resistance of the railcar body based on the radiation principle. In this study, the improvement of the thermal resistance by pasting aluminum foils on the inner surfaces of the enclosure has been tested. The results show that the heat radiation in the enclosure cannot be neglected because the amount of radiated heat is very large. An effective method to reduce the heat radiation in the enclosure involves pasting aluminum foils on the inner surfaces, and the effect becomes increasingly obvious, with up to 62% reduction in the radiated heat, as the enclosure thickness. Further, the improvement in the enclosure thermal resistance by pasting aluminum foils on one of the inner surfaces is almost the same whether on the cold side or the hot side, and the improvement when both inner surfaces are covered with aluminum foils is about 5% better than that when one surface is covered.