Evaporation of a suspended droplet in forced convective high-pressure environments

A comprehensive numerical model is developed to study the evaporation of a suspended droplet in forced convective high-pressure environments. This model includes real gas effects, liquid-phase internal circulation, variable thermophysical properties, high-pressure effects, solubility of inert species into the liquid phase, and gas- and liquid-phase transients. Numerical predictions for the suspended droplet within a zero-gravity environment are in very good agreement with the microgravity experimental data. Numerical results show that at higher ambient pressure the droplet swells initially due to the heat-up of the cold droplet, and its subsequent regression rate is far from following the d(2) law during the early stages of droplet evaporation. The numerical results also show that the droplet lifetime decreases with increasing ambient pressure or ambient temperature. The center temperature of the droplet at lower ambient pressure follows the surface temperature faster than at higher ambient pressure. The mass fraction of nitrogen dissolved at the droplet surface (liquid-phase side) increases with time at very high ambient pressure, such as 8 MPa, while it keeps almost the same level for its entire lifetime at the lower ambient pressure, such as 0.1 MPa. The results also indicate that the solubility of nitrogen cannot be neglected at higher ambient pressure; however, the solubility of nitrogen can be neglected at low ambient pressures.