Fuel Drop Vaporization under Pressure on a Hot Surface

The evaporation lifetime of liquid fuel drops in contact with a hot surface is investigated at pressures of up to 69 atm. Modes of evaporation and drop behaviour at subcriticai and supercritical conditions of temperature and pressure are described. It is shown that at any subcriticai pressure the lifetime is a minimum at a surface temperature just above the saturation temperature; the lifetime at all supercritical pressures is a constant minimum when the surface temperature is 60 degC or more than the critical temperature of the liquid. The heat flux to a drop in the contact modes of evaporation has a maximum value comparable to the peak heat flux obtained in boiling heat transfer work. Subsidiary tests at atmospheric pressure investigate the influence of surface material, surface finish, and initial drop temperature upon the lifetime; the transient surface interface temperature during evaporation is also investigated. The application of the data to deposited fuel in engines is discussed.