A spherical 1.5 mm diameter pure water droplet is in motion in dry air, with a relative velocity of 2 m/s. The air is at 25°C. Calculate the evaporation mass flux at the surface of the droplet,...

A spherical 1.5 mm diameter pure water droplet is in motion in dry air, with a relative velocity of 2 m/s. The air is at 25°C. Calculate the evaporation mass flux at the surface of the droplet, assuming that at the moment of interest the droplet bulk temperature is 5°C. For simplicity assume quasi-steady state, and for the liquid-side heat transfer coefficient (i.e., heat transfer between the droplet surface and the droplet liquid bulk), use the correlation by Kronig and Brink (1950) for the internal thermal resistance of a spherical droplet that undergoes internal recirculation according to Hill’s vortex flow: