Refrigerant, Equation of State, HFO-1234yf, Modeling, Thermodynamic Property
The need for a consistent and reliable calculation of thermodynamic property of refrigerants has been a topic of research since the past decade. This paper reports a study of various cubic equations of state (EOS) for a refrigerant to be used in automotive applications. Thermodynamic properties of refrigerant 2,3,3,3-tetrafluoropropene (HFO- 1234yf) using three different cubic equations of state, i.e. Peng-Robinson (PR), Yu-Lu (YL) and Guo-Du (GD), are modeled, compared and analyzed. A generic technique applicable to any fluid based on the concept of departure functions is employed. The thermodynamic properties generated using each cubic equation is validated against data from most acceptable NIST-REFPROP database. The PR and YL equations are found to be far more accurate and than Gu-Du equation of state in the operating region of a vehicle. The maximum error in vapor pressure and saturated liquid density is found to be 0.62 % and 0.19 % respectively using co-relations developed by Leck. The maximum error of less than 0.4 % in vapor enthalpy and entropy, using PR and YL equations make them an attractive alternative to NIST tables. The GD method without parameter tuning is not suggested for use through this study. Our studies show that error increases as we move away from the saturated region and maximum around the critical point. We propose an optimal set of simple thermodynamic models for use in vehicular applications. These models are computationally less expensive and hence an advantage. Future work involves using these thermodynamic models at a vehicular level for refrigeration cycle simulation.