为了确定展示柜CO2制冷系统的最佳充注量及充注量对系统性能的影响,首先运用实验数据法和额定工况法对系统的充注量进行理论计算,在此基础上,进行了一系列实验研究.结果表明:针对小型传统制冷系统的充注量理论计算方法也适用于CO2系统,计算结果误差很小；应用实验数据法和额定工况法计算小型CO2制冷系统充注量,结果几乎相同；对于CO2跨临界制冷系统,如果采用回热循环,系统运行一段时间后将达到假临界状态,吸、排气温度产生突降.本研究可为小型CO2制冷系统最佳充注量的确定及如何维持系统高效运行提供理论指导.%In order to determine the optimum charge of a display cabinet CO2 refrigeration system and study the effect of the refrigerant charge on the system performance, the experimental data method and the rated operating method were used to predict the refrigerant charge of the system, and then the experiments were conducted at different charges. The results show that the calculation methods for small conventional refrigeration systems can also be applied to the CO2 system with a very small calculation error. The calculation results of the experimental data method are almost the same as those of the rated operating method for the small CO2 refrigeration system. For the CO2 transcritical system, the pseudo critical state occurs after the system works for a while when the system adopts regenerative cycle, and the suction temperature and discharge temperature drop suddenly. The results of this study may be useful for determining optimal refrigerant charge and maintaining efficient operation of small CO2 refrigeration systems.
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