自然对流状态下深冷竖直平板霜层导热系数实验研究

Experimental study on frost layer's thermal conductivity of cryogenic vertical plate under natural convection condition

利用设计的竖直平板结霜实验台,对自然对流状态下竖直平板表面非稳态结霜过程进行了动态描述,分析了霜层厚度变化规律,描述了湿空气在竖直平板附近的流动状态及温度分布。基于实验观测,把竖直平板非稳态结霜过程分为沿平板法线方向增厚和沿平板切线方向推进两个阶段。利用最小二乘法,拟合了竖直平板霜层导热系数在推进阶段随推移距离的关系式。通过反复实验,不断完善数据,可使拟合结果具有更高的适用性,也为工程设计提供依据。

A frost test bench was designed, and unsteady frosting on vertical plate surface was dynamically described under natural convection condition. The variance of frost thickness was analyzed, and the flow state and temperature distribution of humid air near the vertical plate were described. Based on experimental observation, unsteady frosting on the vertical plate was divided into two stages： thickening along normal direction of plate and propulsion along tangent direction of plate. Using least square method, the relation of frost layer＇s thermal conductivity of vertical plate in the stage of propulsion was fitting relative to distance along tangent direction of vertical plate. It shows that repeating experiment and constantly optimizing data can effectively improve the applicability of fitting results, and also provide a basis for engineering design.