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An experimental study of the thermal performance of R-134a and refrigerant blends in an air conditioning system.

机译：R-134a和制冷剂混合物在空调系统中的热性能的实验研究。

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摘要

This document presents the findings of an experimental study of the effects of changing refrigerants on the performance of a refrigeration system. The different refrigerants studied are considered to be less harmful to the environment than R-12 which is currently widely used. Environmentally harmful effects include global warming and ozone depletion. The findings are based on the results of over one hundred independent tests using four refrigerants, namely R-12, R-134a, and two R-22 blends.; The test equipment consisted of a 3-ton vapor compression refrigeration system, an air flow loop used to control evaporator conditions, and a water flow loop used to control condenser conditions. The instrumentation provided information needed to determine the system COP, cooling capacity, mass flow rates, and thermodynamic states of the refrigerant at the inlet and exit of each component in the system. The parameters varied in the study were the evaporator and condenser sink temperatures and the amount of refrigerant used in the system. The evaporator exit superheat was maintained constant at 13.5 F for all tests.; The performance with each refrigerant at several refrigerant charges is presented as a function of operating conditions. Curve fits of several system variables (COP, capacity, mass flow rate, and system temperatures and pressures) allow for comparisons to be made among refrigerants. The performance with each alternative refrigerant was compared to the performance with R-12 at the same operating conditions. The other system variables were also compared with R-12. These comparisons are used to explain the observed differences in performance, and they provide information needed for design and for making system modifications.; The experimental results show equal or slightly better COPs with the alternative refrigerants compared to R-12. The capacities are also similar with the exception of MP-52 which had a lower capacity than R-12. The differences in performance were somewhat dependent on the operating conditions.; Several models for the compressor are presented and compared with experimental data. The models are based on the ideas of polytropic compression and isentropic efficiency. Heat exchanger models are also examined and compared with experimental data. The validity of some of the models is questioned as they do not represent the test data well.
机译：该文件介绍了改变制冷剂对制冷系统性能影响的实验研究结果。与目前广泛使用的R-12相比，研究的不同制冷剂对环境的危害较小。对环境有害的影响包括全球变暖和臭氧消耗。这些发现是基于使用四种制冷剂（即R-12，R-134a和两种R-22混合物）进行的一百多次独立测试的结果得出的；该测试设备包括一个3吨蒸气压缩制冷系统，一个用于控制蒸发器状况的空气流通回路和一个用于控制冷凝器状况的水流通回路。仪器提供了确定系统COP，冷却能力，质量流量以及制冷剂在系统中每个组件的入口和出口处的热力学状态所需的信息。研究中变化的参数是蒸发器和冷凝器的水槽温度以及系统中使用的制冷剂量。对于所有测试，蒸发器出口过热均保持恒定在13.5F。每种制冷剂在多个制冷剂充量下的性能均根据运行条件给出。几个系统变量（COP，容量，质量流量以及系统温度和压力）的曲线拟合允许在制冷剂之间进行比较。在相同的工作条件下，将每种替代制冷剂的性能与R-12的性能进行了比较。其他系统变量也与R-12进行了比较。这些比较用于解释观察到的性能差异，并提供设计和进行系统修改所需的信息。实验结果表明，与R-12相比，替代制冷剂的COP相同或稍好。除了MP-52的容量比R-12低之外，其他容量也相似。性能上的差异在一定程度上取决于操作条件。介绍了压缩机的几种模型，并与实验数据进行了比较。这些模型基于多向压缩和等熵效率的思想。还检查了热交换器模型，并将其与实验数据进行了比较。一些模型的有效性受到质疑，因为它们不能很好地代表测试数据。

著录项

  • 作者

    Crown, Stephen W.;

  • 作者单位

    Iowa State University.;

  • 授予单位 Iowa State University.;
  • 学科 Engineering Mechanical.
  • 学位 Ph.D.
  • 年度 1993
  • 页码 217 p.
  • 总页数 217
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 机械、仪表工业;
  • 关键词

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