Molecular-level simulation of bubble and dew points of fluid mixtures and application to refrigerant cycle design

•We developed molecular simulation algorithms for mixture dew and bubble points.•We applied the algorithms to a R32/R134a mixture.•We applied the algorithms to a refrigeration cycle involving the R32/R134a mixture.•The simulation results are in good agreement with those calculated from REFPROP.•Molecular simulation has potential advantages over the multi-parameter EOS approach.

Molecular simulation is an increasingly important and useful tool in the design of devices based on many types of chemical phenomena. Such methods for the simulation of all types of vapour–liquid equilibrium (VLE) are particularly important, because they potentially permit their direct application to the design of refrigeration processes. Several molecular simulation methods exist for the calculation of VLE in the cases of flash calculations and bubble-point calculations for fluid mixtures. However, implementations for other VLE problems such as dew-points remain challenging. We present an algorithm for the calculation of all four types of these VLE phenomena in binary mixtures. We illustrate it for a 30 mass% R32/R134a binary refrigerant mixture by means of example dew- and bubble-point problems, in addition to the calculation of P–h and T–h diagrams. We also demonstrate its application to the simulation of a vapour compression refrigeration cycle involving the refrigerant mixture.