出口过热度对CO_2微通道蒸发器性能的影响

Effect of Superheat on the Performance of CO_2 Micro-channel Evaporator

本文理论分析了影响CO_2微通道蒸发器制冷能力的关键因素,搭建CO_2微通道蒸发器测试实验台,采用CO_2电子膨胀阀实现过热度调节,研究了蒸发器出口过热度对制冷能力以及出风温度的影响。研究表明:相比于其他制冷剂,CO_2出口过热度对蒸发器制冷能力的影响较大,蒸发器的性能随出口过热度的减小而提升,随着过热度的减小,制冷能力的提升存在3个具有显著差异的阶段,系统中蒸发器的性能随过热度减小最多提升57.9%。此外,采用了红外线热像仪拍摄和均布热电偶的方法,得到出风温度和蒸发器表面温度的分布规律,结果表明出风温度随过热度的减小有更好的均匀性。

As a natural refrigerant,CO2 has received increasing attention from the international community,particularly in the European market,and domestic demand is also increasing. This study analyzes the key factors influencing the cooling capacity of a CO2 micro-channel evaporator,where a CO2 micro-channel evaporator test bench was built and a superheat adjustment was realized using the CO2 electronic expansion valve. The results show that the CO2 superheat has a greater effect on the cooling capacity of the evaporator than other refrigerants,and the evaporator capacity is considerably improved with a decrease in superheat,the rate of increase can be categorized into three obvious periods with different characteristics. The increase in evaporator capacity described in this study can reach up to 57. 9%. In addition,thermocouples and infrared thermal imaging were used to obtain the distribution of outlet air temperatures,where the outlet air temperatures achieve better uniformity with a decrease in superheat.