Impact of emulsion drops on a plane solid: Effect of composition and wall temperature

The paper reports the impact of water-in-Jatropha biodiesel emulsion drops on a heated solid surface. The role of the surface temperature (T-S) and the composition of the emulsion on the impact dynamics are examined. Experiments are conducted taking three low water content emulsions samples for five surface temperatures, and the results are compared with pure Jatropha biodiesel (JBD) from the available literature. Due to the early evaporation of water micro-droplets inside the emulsion drop, internal vapor pressure is formed. The internal vapor pressure and the thin vapor film formed beneath the drop due to the high vaporization rate play a crucial role in the impact of emulsions. Emulsification results in a decrease in the Leidenfrost temperature when compared with JBD, affecting the sticking and bouncing behavior. The normalized average spreading velocity and the average receding velocity increase with T-S, and their maxima are found at higher T-S in case of emulsions as compared to JBD. Several differences are observed in the impact morphology of the emulsions when compared to JBD. The internal vapor pressure overcomes the viscous dissipation for the emulsions at higher T-S resulting in a higher maximum spreading factor and spreading velocity than JBD.

Automated summary

The impact of water-in-Jatropha biodiesel emulsion drops on a heated solid surface is influenced by internal vapor pressure and thin vapor film formation, affecting sticking and bouncing behavior. The spreading and receding velocities of emulsions increase with surface temperature, with differences observed in impact morphology compared to JBD. The internal vapor pressure in emulsions at higher temperatures results in a higher maximum spreading factor and spreading velocity than JBD.