Study of the micro-explosion temperature of water in oil emulsion droplets during the Leidenfrost effect

The burning of water in oil emulsions is considered as an effective alternative to bring out waste oil because of a significant reduction in carbon monoxide, nitrogen oxides and particulates in the exhaust. These advantages have different origins, an important contribution is provided by the phenomenon of micro-explosion. In this work, the influence of the size of the dispersed water droplets in the micro-explosion phenomenon is studied by the hot plate technique. The variation of the temperature and the evolution of the phenomenon have been investigated using a synchronized thermocouple/high speed imaging system. Three emulsions with the same amount of water (30%mass) but with different distribution of the size of the dispersed water droplets have been tested.The results show that the size distribution of the dispersed water droplets plays an important role in the phenomenon of micro-explosion. Moreover, some internal phenomenon as the separation process between water and oil seems to affect significantly the phenomenon.

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► We measure the temperature of water/oil emulsion droplets during micro-explosion.
► The emulsion droplets were heated by using the Leidenfrost regime.
► The size of the dispersed water droplets affects the temperature of micro-explosion.
► Temperature of m-e and size of water droplets are not monotonically correlated.
► Very high metastable temperature of the water were reached before micro-explosion.