Modelagem termodinâmica do equilíbrio líquido-vapor de fluidos refrigerantes com baixo potencial de aquecimento global

Abstract

This study aims to thermodynamically model three binary mixtures and one ternary mixture composed of refrigerant fluids R32 (difluoromethane), R1123 (2,3,3,3-tetrafluoropropene), and R1234yf (2,3,3,3-tetrafluoropropene), using the Peng-Robinson and Soave-Redlich-Kwong equations of state. The efficiency of these equations was assessed through comparisons with experimental vapor-liquid equilibrium (VLE) data available in the literature. The study is motivated by the growing need to replace refrigerants with high global warming potential with more sustainable alternatives, with thermodynamic modeling serving as a crucial tool for predicting the behavior of promising candidates. To calculate the pressure and temperature of pure fluids, as well as thermodynamic parameters and properties in the liquid-vapor equilibrium of the binary mixtures, the software Excel® with the XSEOS® add-in was used. This procedure enabled the correlation of VLE data for the binary mixtures, in addition to the prediction of VLE and density for the ternary system. The results showed that, for pure fluids, both models well predicted the pressure and temperature values, generating curves that showed R2 values greater than 0,98. For binary mixtures, in most cases, the calculated deviations of pressure and vapor mole fraction were below 5%, with the Peng-Robinson model demonstrating higher accuracy, particularly for more complex systems. However, both equations exhibited significant limitations in predicting density, with deviations greater than 10%, highlighting the need for more advanced methods to calculate the volumetric properties of these mixtures.