The effect of unstable emulsion of water-in-diesel on micro-explosion phenomena

Water-in-diesel emulsions are known to lead to micro-explosions when exposed to high temperatures, thereby offering a technology that could improve the mixing of fuels with the ambient gas. Several factors such as the surfactant type, dispersed water droplet size, water content and coalescence rate play a key role in the onset of micro-explosion occurrence. Although these factors are likely to alter the properties of emulsion stability, however the effect of unstable emulsion on the micro-explosion occurrence is not well addressed. To address this issue, we prepared stable emulsion (SE) and unstable emulsion (UE) with 10% water content by volume and visualized during Leidenfrost effect. Our measurements indicate that the strength of micro-explosion affected by coalescence rate, which probably arises from decomposition of the emulsion. UE has a positive influence on micro-explosion occurrence, which probably again due to thermal conduction of coalesced water droplets. The study suggested that the micro-explosion caused due coalescence of a few big droplet (in case UE) rather than evaporated and cooperative of fine droplets to explode the droplet (in case SE). The temperature of micro-explosion was found to be lower in case of UE compared to SE.