Size, temperature and composition of a spherical droplet as a function of time at the transient stage of nonisothermal binary condensation or evaporation

•Theory for transient stage of binary droplet condensation and evaporation.•Consideration of diffusion and free-molecular regimes.•Account of nonisothermal effects on the transient stage.•Numerical illustrations in the approximation of ideal solution.•Analysis of nonmonotonic change of the droplet radius with time. The transient stage of evolution in size, temperature and composition of a droplet, which nonisothermaly condenses or evaporates in the diffusion or free-molecular regime in the atmosphere of two condensable vapors and neutral carrier gas, is considered. On this stage, both solution concentration and temperature in the droplet approach their stationary values, and the steady rate of the droplet growth or evaporation establishes. The fact that the temperature adjusts fast to the current value of solution concentration in the droplet allows us to express the current solution concentration as an analytical function of temperature and to find general integral relations expressing the droplet radius and time as nonlinear functions of current droplet temperature. Some numerical illustrations of the theory have been done in the situation when the droplet size changes in the diffusion regime and the solution in the droplet can be considered ideal. In order to cover arbitrary initial droplet size and component concentrations, two opposite initial concentrations of solution related to pure first and pure second components in the droplet have been considered. In particular, the appearance of nonmonotonic change of the droplet radius with time has been analyzed.