Polyethylene-Glycol-Added Water-Droplet Evaporative Cooling for Fast Cooling Operations

Abstract

The surface modification of the hot substrate and the alteration of thermophysical properties at the interface in the favorable direction of heat transfer significantly reduce the film boiling effect. The exact methodology describing the simultaneous attainment of the aforementioned variations has not been addressed in the literature. Therefore, in the current work, an attempt has been made to propose a process depicting enhanced dropwise evaporation due to simultaneous variation of the aforementioned parameters, and this is achieved by using polyethylene glycol (PEG) as an additive, which modifies the surface to hydrophilic at a very high temperature () and alters the thermophysical properties in the positive direction of heat transfer. The scanning electron microscope analysis confirms the deposition over the surface of the substrate that contributes hydrophilicity to the surface, and the Fourier-transform infrared (spectroscopy) analysis asserts the unaltered functional groups present in the PEG forming a coating over the surface. The heat transfer analysis depicts that the droplet lifetime decreases with increasing PEG concentrations and substrate temperature, and the dropwise evaporative cooling also follows the same trend line. The droplet impact mapping reveals the transition of the Leidenfrost point from 200 to 400°C. The nature of the boiling curve confirms the elimination of film boiling.