Comparative molecular dynamics simulations of homogeneous condensation of refrigerants

Performance improvement and environmental impact are very important issues in the selection of suitable refrigerant for domestic refrigeration systems. The homogeneous condensation of two hydrocarbon (HC) refrigerants, namely, R600 (butane) and R600a (isobutane) and two hydrofluorocarbon (HFC) refrigerants i.e. R134a (1,1,1,2-tetrafluoroethane) and R143a (1,1,1-trifluoroethane) was investigated by molecular dynamics simulations. The thermophysical properties of the four refrigerants, such as the density, internal potential energy, and cell volume of the molecular systems during the condensation process are compared. The influences of the various refrigerants on the potential energy and the cluster formation are described. The results show that vapor molecules undergo a rapid phase transition to a subcooled liquid within a specific time period. In the simulations, clusters of the substances are formed initially, which then aggregate to produce the condensate liquid droplets over time. The densities of all the refrigerants at the liquid phase after condensation agree with REFPROP data. A comparative analysis of the refrigerants was performed based on the saturation ratio to investigate the time of complete condensation in the homogeneous condensation process.