Transient evaporation of a bi-component droplet at high temperature and pressure

Transient evaporation of a bi-component droplet at high temperature and pressure condition has been modeled numerically. In the gas phase, the equations of species, momentum, and energy, and in the liquid phase, the equations of species and energy by assuming fugacity equilibrium, and Peng-Robinson equation of state using the finite volume method have been solved. The droplet is assumed to be spherical, the solubility of the gas in the liquid and effect of gravity have been neglected. The results of the proposed model for heptane-hexadecane droplet in various temperatures and pressures have been validated against the available experimental data. Results were in good agreement. The effect of pressure on the evaporation showed that at a constant temperature, by increasing pressure up to 2 MPa the droplet lifetime increases but further increase in pressure (up to 2.5 MPa) reduces droplet lifetime. Evaporation behavior does not change with different compositions. The role of different equations of state on the prediction of binary droplet lifetime was studied, and finally the effect of ambient temperature and pressure on the surface temperature of the droplet was investigated. It was observed that at high enough pressure and temperature, the droplet surface could reach the critical condition.