Combustion characteristics of water-in-oil emulsion droplets

Various combustion modes of water-in-oil emulsion droplets are postulated based on the relative volatilities and concentrations of water and oil, the intensity of internal circulation, and the fact that water and oil do not mix. It is shown that the existence of internal circulation generally inhibits microexplosion, and that increasing the system pressure enhances the occurrence of microexplosion even allowing for the longer period of droplet heating at higher pressures. Other predicted phenomena of interest include droplet temperature being limited by the lower of the boiling points of water and oil, the formation of water residues and subsequently termination of combustion upon complete depletion of oil from the droplet, and the independence of the instantaneous combustion rate on the extent of water emulsification. Experimental results obtained on single droplet combustion with minimal and extensive internal circulation generally agree with the qualitative nature of the postulated combustion modes.