Evaporation, boiling and explosive breakup of oil-water emulsion drops under intense radiant heating

An experimental study on conditions and main characteristics for high-temperature (more than 700 K) evaporation of oil water drops is presented. The high-temperature water purification from impurities can be the main practical application of research results. Thus, the heating of drops is implemented by the two typical schemes: on a massive substrate (the heating conditions are similar to those achieved in a heating chamber) and in a flow of the heated air. In the latter case, the heating conditions correspond to those attained while moving water drops with impurities in a counter high-temperature gaseous flow in the process of water purification. Evaporation time and rate as functions of heating temperature and conditions for the heat energy supply to an emulsion drop are illustrated. The influence of oil product concentration in an emulsion drop on evaporation characteristics is discussed. The conditions for intensive flash boiling of an emulsion drop and its explosive breakup (fragmentation) with formation of the fine droplets cloud are pointed out. High radiant heat fluxes required in the boundary layer of a drop for intensive flash boiling and explosive breakup of drops with further formation of the fine aerosol. The fundamental differences between flash boiling and explosive breakup of an emulsion drop when heated on a substrate and in a flow of the heated air are described. The main prospects for the development of the high-temperature water purification technology are detailed taking into account the fast emulsion drop breakup investigated in the paper. (C) 2017 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.