冰箱冷藏控温系统中分离式热管的传热性能

Heat Transfer Performance of Separate Heat Pipe in Refrigerator Temperature Control System

本文提出了将分离式热管与直冷冰箱板管蒸发器相结合的新方案,在-25℃的冷源温度下,测试了热源温度为5、8、12℃下热管的稳态传热功率,获得了分离式热管的最佳充注量为120 g。基于该充注量下冷藏室内的降温过程,对系统内部各参数的变化进行了研究分析。实验结果表明:启动10 min左右,分离式热管内部参数基本达到稳定。分离式热管可以在60 min内使冰箱冷藏室内温度从16℃降至5℃,在135 min内降到0℃。通过电磁阀的自动开停控制,维持冷藏室内温度为8℃时,单周期运行时间约为6.5 min,停止时间约为42.8 min,开停比率约为15.2%,控温精度达到1.1℃,优于普通直冷冰箱2.5℃的控温精度,初步验证了分离式热管具有良好的传热特性及控温性能。

A new scheme using a separate heat pipe combined with the evaporator of a direct-cooling refrigerator is proposed. For a given heat sink temperature(-25 ℃) and different heat source temperatures(5, 8, and 12 ℃), the heat transfer rate of the separate heat pipe is tested. The result shows that the optimum filling amount is 120 g. Then, variation in the internal parameters of the system are studied and analyzed based on the cooling process. The experimental results show that after starting for approximately 10 min, the internal parameters of the separate heat pipe reaches a relatively stable state. The use of the separate heat pipe can reduce the temperature in the fresh food compartment from 16 to 5 ℃ in 60 min, which can satisfy the mid-range temperature requirements of a typical refrigerator. Meanwhile, it can also reduce the temperature in the fresh food compartment to 0 ℃ in approximately 135 min. Through automatic control of the solenoid valve, the temperature in the fresh food compartment can be maintained at 8 ℃, and the temperature fluctuation reaches to within 1.1 ℃, which is better than the 2.5 ℃ temperature of a direct-cooling refrigerator. In a on-off cycle, the running and stopping times of the separate heat pipe are approximately 6.5 and 42.8 min, respectively, indicating that the on-off ratio is approximately 15.2%. The good heat transfer characteristics and temperature control capabilities can meet the requirements of a new cool-storage refrigerator.