Molecular dynamics simulations of R32/R1234yf nanoscale boiling on a smooth substrate

XH Wu and Z Yang and YY Duan, INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER, 182, 121944 (2022).

DOI: 10.1016/j.ijheatmasstransfer.2021.121944

The boiling process of mixture fluids is of great significance in both natural research and industrial applications. Among the various mixtures, R32/R1234yf has a great application potential in power system such as refrigeration and Organic Rankine Cycle. Liquid film boiling is a key link to reveal the boiling heat transfer mechanism of mixtures. In this study, MD was used to study the boiling phenomenon of nanoscale liquid film with different concentrations of R32/R1234yf (x(R32) = 0, 0.34, 0.58, 0.75, 1) on the heated smooth copper surface. The different stages of liquid film boiling were systematically described, and the differences in bubble inception time, concentration distribution near the wall, vertical density and temperature distribution of liquid film with different com ponents were compared. The heat flux and surface wettability of different composition was regulated and the sensitivity of pure fluids boiling and mixtures boiling to the heat flux and wettability were compared. It was found that similar boiling processes occur on the heated surface of the thin liquid film with different compositions. With the increase of R32 concentration, the film boiling process becomes more intensely. The boiling process of the mixture liquid film is closer to that of pure R32 liquid film because R32 is more easily adsorbed by the solid surface than R1234yf. The vaporization rate obtained by simulation is significantly lower than the prediction value. The main reason is that the difference of the inertial forces between the two working fluids causes the saturation pressure at the bubble interface to be lower than that predicted by the nominal components. For mixture liquid film boiling, a more volatile component has a greater influence, it can be reasonably speculated that adding component of more solvophilic to the heat surface can effectively accelerate the boiling process. (c) 2021 Elsevier Ltd. All rights reserved.

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