Abstract: In this paper, an experiment was carried out to evaluate the impact of CO₂ mass charge on a CO₂ automotive air conditioner.The CO₂ air conditioner was designed to have heat exchanger dimensions nearly identical to conventional R134a systems.The heat exchanger was made of fin-tubes,the compressor was of swash plate design, and a manual expansion valve and an internal heat exchanger accumulator were used. The experimental results show that the coefficent of performance (COP)was strongly related to CO₂ mass charge and the formation of the trans-critical cycle depended on CO₂ mass charge greatly.The COP has a maximum value at a specific CO₂ mass charge. Undercharged CO₂ systems could result in a fast decrease of the cooling capacity and COP;however, overcharged CO₂ systems could cause an abrupt increase of compressor power consumption.The refrigerating cycle displayed different characteristics with different CO2 mass charges.The optimum CO₂ mass charge could be determined according to four state parameters.

摘要： 试验研究了CO₂充注量对跨临界轿车空调系统性能的影响.研究表明：CO₂充注量对跨临界制冷系统的性能影响很大，存在一个最佳的CO₂充注量，此时COP最大;CO₂充注量不足，会导致制冷量和COP降低，CO₂充注量过多，会导致压缩机耗功大幅度上升;制冷循环随CO₂充注量的不同，具有6个特征明显的工作循环.根据这些表现特征，提出了用4个参数作为判断CO₂充注量是否合适的特征参数.为确定跨临界制冷系统的最佳充注量、对系统进行优化设计和高效运行控制提供了参考.