冰箱冷量损失的实验测定与保温性能的改进

Measurement of Refrigerator Cooling Capacity Loss and Improvement of Its Thermal Insulation

本文通过实验的方法研究了冰箱空载时的冷量损失规律,提出一种减小冷量损失的冰箱结构改进方案。首先将冰箱各壁面的散热问题简化为一维导热模型。在全天候模拟实验平台上,为得到环境温度对冰箱冷量损失的影响,设置环境相对湿度为80%,环境温度分别为5~40℃(间隔为5℃);为得到环境相对湿度对冰箱冷量损失的影响,设置环境温度为25℃,环境相对湿度分别为55%~95%(间隔为10%)。在冰箱空载状态下分别测量以上两组条件下各壁面的内外表面温度,再根据傅里叶导热定律计算各壁面的热流量,进而得到冰箱冷量损失与环境温度和相对湿度的关系。结果表明:环境温度升高时冰箱冷量损失增大;环境相对湿度对冰箱冷量损失几乎没有影响;样本冰箱冷藏室后壁面的冷量损失明显高于其他壁面,顶部冷量损失较小;对后壁面采取加厚绝热层厚度的措施后降低了冰箱整体的冷量损失,同时为了保证冷藏室容积,减小冷藏室顶部绝热层的厚度,最终各壁面冷量损失接近一致。

In the present paper, the cold loss of a fridge when unloaded was studied through an experiment, and an improvement was pro- posed. First, the heat transfer process between the fridge interior and the external environment was simplified into a one-dimensional heat conduction process. On an all-weather simulation experiment platform, to investigate the effect of ambient temperature on cooling capacity loss, the ambient temperature was set to 5, 10, 15, 20, 25, 30, 35, and 40 ℃ with a fixed ambient relative humidity of 80%. To investigate the effect of ambient humidity on cooling capacity loss, the ambient relative humidity was set to 55% , 65%, 75%, 85%, and 95% with a fixed ambient temperature of 25 ℃. The temperature of the inner and outer walls for every combination of the above two series of parameters was measured when the refrigerator was unloaded. According to the Fourier heat conduction law, the heat flux of each wall can be obtained, and then the cold loss is calculated. The results show that the cold loss of the refrigerator increases with ambient temperature, and the ambient humidity has no effect on cooling capacity loss. The cold loss of the refrigerator back wall is obviously greater than that of the other walls, while that of the top wall is smaller. The insulation of the refrigerator back wall is thickened to decrease the entire cold loss, and the insulation of the refrigerator top wall is made thinner to guarantee the refrigerator storage capacity. This leads to an approximately uniform cold loss distribution of the refrigerator walls.