Molecular dynamics simulations on evaporation of a suspended binary mixture nanodroplet

XH Wu and Z Yang and YY Duan, INTERNATIONAL JOURNAL OF REFRIGERATION, 131, 197-205 (2021).

DOI: 10.1016/j.ijrefrig.2021.08.023

Mixture working fluids have the advantages of active design and adjustable physical properties, therefore it has a promising future in many power and refrigeration applications. Studies on the evaporation process of mixture nanodroplets are helpful to reveal the mechanism of heat transfer at the interface of mixture working fluids. However, at present, there are few studies on the evaporation of mixture droplet, and the conclusions on the pure fluids evaporation cannot be directly applied to the mixture working fluids, thus it is necessary to carry out specific research on the evaporation of mixtures. In this study, molecular dynamics simulation was used to study the evaporation process of R32/R1234yf nanodroplets with different compositions (x(R32)=0, 0.2, 0.4, 0.6, 0.8, 1) in a large space. The dynamic changes of evaporation rates of droplets with different components were compared, and the evaporation characteristics of droplet with different concentrations were analyzed in combination with the density, temperature and concentration field distribution near the liquid-vapor interface during the evaporation process. The results show that the evaporation rate of the mixture nanodroplets is lower than the linear interpolation with those of the two components, which is similar to the heat transfer deterioration of the mixture working fluids in pool or flow boiling. The prediction deviation of R32/R1234yf mixture nanodroplet evaporation by the D-2 law is around 80%. Considering the scale effect and the interfacial concentration gradient, the prediction accuracy of the D-2 law can be improved.

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