风冷冰箱蒸发器除霜特性及箱温回升的实验研究

Experimental Investigation for Dynamic Characteristics of Defrosting Process and Effect on Freezer Compartment Temperature in Domestic Frost-Free Refrigerator

为了探究风冷冰箱除霜过程动态特性及其对箱温回升的影响,对某单循环风冷冰箱稳定运行时的除霜过程进行了实验研究,结果表明:在蒸发器温度升高到0℃的预热阶段,霜层堵塞翅片间隙,箱温基本无回升;在温度维持在0℃左右的融霜阶段,除霜电加热被布置在蒸发器下方以及霜层"上疏下密"分布使底部霜层最早开始融化,融化结束时刻比顶部提前8min,融霜时翅片间空气流通面积逐渐增大,进入箱体内部的热空气量增多,箱温在9.34min内平缓上升5.7℃;在温度高于0℃的排水阶段,因蒸发器右上方冷藏送风风道存在凸起,热空气会积聚在此处,导致阶段结束时该部位比左上温度高17.1℃,此时翅片间空气流通面积达到最大,箱温在6.5min内快速上升6.6℃。

The defrosting process of a frost-free refrigerator is investigated experimentally, and the effect on the freezing compartment temperature is analyzed. The results show that in the preheating stage of the defrosting, the bottom temperature of the evaporator firstly rises to 0 ℃, and the freezing compartment temperature almost remains unchanged because the evaporator is blocked up by frost. In the melting-frost stage, the frost on the evaporator bottom begins to melt firstly and totally melts 8 min earlier than that on the top of the evaporator because the defrost heater is placed under the evaporator and the frost distribution is non-uniform, in fact, the frost on the evaporator top is greatly thinner than that on the bottom. During this stage, the frost melting results in increasing flow area between adjacent fins and the freezing compartment temperature gently rises by 5.7℃ in 9.34 min. In the draining-water stage beyond 0 ℃, the topright temperature of the evaporator gets higher than the top-left temperature because the embossment of the air-supply duct of the refrigerating compartment leads to the warm air gathering there, and at the end of this stage the temperature difference between them increased significantly to 17.1℃. The freezing compartment temperature sharply rises by 6.6 ℃ in 6.5 rain because the flow area increases to the maximum.