Three approaches to modelling heating and evaporation of monocomponent droplets

Three approaches to modelling the heating and evaporation of monocomponent droplets are compared. Firstly, the heat rate supplied to the droplets to raise their internal energy is calculated based on the observation that steady-state equations for heat and mass balance in the gas phase should lead to the same droplet evaporation rates. The direct calculation of the above-mentioned heat rate is used in the second approach; the value of this rate is then used for the estimation of the droplet evaporation rate using the Spalding heat transfer number. In the third approach, the same algorithm as in the second approach is used to calculate the heat rate but the mass evaporation rate in this approach is inferred from the coupled solution to the momentum, mass and energy conservation equations in the gas phase; the gas mixture density in this approach depends on temperature. The predictions of the numerical algorithms for these approaches are compared with experimentally observed time dependencies of the rates of change of radii and average temperatures of n-decane droplets at initial temperatures and radii equal to 300 K and 0.85 mm, respectively, placed in a gas at temperatures 500 K and 760 K. It is shown that the algorithm for the third approach predicts values which are close to the experimental data.