Leidenfrost Effect in the Flash Vaporization of Hydrogen Peroxide and Water Mixtures: Droplet Dynamics and Evaporation Efficiency

The Leidenfrost effect can significantly impact the flash vaporization of binary mixtures comprising hydrogen peroxide and water, a process widely employed to obtain sterilizing atmospheres. Through high-speed visualisations of droplets using shadowgraph imagery, the influence of varying hydrogen peroxide concentrations and surface temperatures on the dynamics of Leidenfrost droplets is explored. Our results provide insights into the complex interactions between hydrogen peroxide concentration, surface temperature, droplet dynamics, and evaporation efficiency in Leidenfrost phenomena, more specifically within the context of flash vaporization. Notably, a relationship between droplet fate, namely vaporization or ejection away from the heated plate, and evaporation efficiency is established, underscoring the importance of maintaining surface temperatures below the Leidenfrost point, and of understanding the dynamics associated with phase change in binary mixtures. We demonstrate that hydrogen peroxide concentration has minimal influence on droplet dynamics, with surface temperature being the primary driver of droplet behavior. The results show that hundreds of sub-millimetre droplets can be ejected following contact with the hot surface, with size distribution following a log-normal trend. Velocities may reach amplitudes of meters per second, magnitudes over their equivalent diameter. Most of these droplets will not evaporate due to their velocity bringing them out of bounds of the hot surface.