A Further Look on Micro-Explosion of Water Emulsion Fuel Droplets

The nucleation and micro-explosion phenomenon of a water emulsified fuel droplet is re-examined theoretically and experimentally. The existence of micro-explosion is reaffirmed by recording the acoustic intensity during the explosion process. A theoretical model is developed to calculate the time required from nucleation to micro-explosion for a given surface heat flux.

Both the theoretical and experimental results indicate that, in addition to the droplet internal superheat temperature, there exists a necessary condition for micro-explosion to occur. The necessary condition is that a minimum heat flux at the droplet surface he exceeded. This minimum surface heat flux is a function of droplet size, water fraction in parent fuel and the composition of parent fuels. The intensity of micro-explosion is greatly affected by the rate of heat transfer at droplet surface. All five fuels display a preferable range of water volume fractions for greater violent fragmentation.