【作者】 宋世亮；

【导师】 沈永年；

【作者基本信息】 浙江大学 ， 制冷与低温工程， 2005， 硕士

【摘要】 复叠式制冷系统通常用于获取-40℃以下的低温,根据温区的不同而应用于不同的领域,如食品的速冻,低温生物的保存,传感器的冷却等。自行复叠制冷循环采用非共沸混合工质作为制冷剂,而且只采用一台压缩机,正是这些独特的优点使其受到了广泛的关注。 本文旨在通过理论计算和实验分析,研究-40℃左右温区时天然工质应用于自行复叠制冷系统的循环性能,以期得到应用于该温区的天然工质的类型、配比及其运行特性。 为指导实验,我们以热力学分析和RKS状态方程为基础,编写了混合工质物性计算程序,建立了自行复叠制冷循环的理论模型,并对系统进行了仿真计算。通过理论分析,研究了混合工质的选取原则,得出了一些非常具有实际意义的结论,而且得到了不同配比的混合工质在不同工况下的循环性能。 本文以不同配比的二元混合工质R744/R290和三元混合工质R744/R290/R600a为制冷剂进行了一系列试验研究。该制冷机采用单级油润滑空调压缩机,实现了低于-40℃的制冷温度,性能稳定。通过试验研究,对本文理论计算部分的结果进行了验证,并得到了一些新的结论。更多还原

【Abstract】 Cascade refrigerating systems are widely used in quick freezing, preservation of biological tissues, cooling detectors. The Auto Cascade Refrigeration Cycle (ACR) requires only one compressor with the non-azeotropic refrigerant mixture (NARM), which is very popular for its particular excellence.The aim of this paper is to study the performance of ACR system used in -40℃ temperature range, and get some useful results, such as suitable refrigerants, their mixing proportion and the working performance through theoretical computation and experimental study.Based on the thermodynamic analysis and equation of state (EOS) of RKS, the material properties were calculated by programming. Then the theoretical model of ACR system is established, and the simulation results are got. Through theoretical analysis, the selection principle of mixed refrigerants is studied, and some useful results are got. The system’s performances of mixed refrigerants of different proportion at different working conditions are gainedA series of experiments are carried out using mixed refrigerants of R744/R290 and R744/R290/R600a of different proportion. A one-stage compressor used in air-conditioning is applied in this refrigerator. The refrigerating temperature can reach below 230K, the refrigerator can run steadily and the performance is very good. Through experimental study, the theoretical results are validated, and some new conclusions are got.更多还原