Experimental And Numerical Studies Of Interaction Between Liquid Droplets And Hot Surfaces Under Different Conditions

TL;DR

This study combines experimental and numerical methods to analyze how liquid droplets interact with hot metal surfaces under various conditions, focusing on impact, spreading, and Leidenfrost phenomena to improve spray cooling system design.

Contribution

It provides new insights into droplet behavior on different metals and temperatures using both high-speed imaging and CFD simulations, advancing understanding of thermal interactions.

Findings

Droplet spreading depends mainly on surface roughness.

Higher Weber numbers lead to greater droplet spreading.

Surface temperature has minimal effect on spreading ratio.

Abstract

In the present paper, experimental and numerical studies of interaction between different liquid droplets with different hot metal surfaces had been carried out and the obtained results were interpreted using graphs and pictures. Droplet impact, spreading, break-up, and leidenfrost phenomenon were observed with the help of video camera at 100 fps. The interaction studies were done at different surface temperatures and different droplet impinging velocities. Three metals and three liquids were selected for the present study. Copper, Aluminium and Steel were selected as metals with different roughness factors and at different temperatures, while in liquid entities, Methanol, Ethanol and Kerosene (Water was also used in some portion) were selected. The selections of the metals were based on thethermal diffusivity property as it influences the thermal interaction between droplet and the hot metal surface. The temperature range of metal surface was kept from 150{\deg} C to 425{\deg}C and the impinging velocity range of droplets were in the range of 2.4 - 4.9 m/s. For computational studies Ansys Fluent R3-2019 version was used. Numerical study for the interaction process was carried out using Volume of Fluid (VOF) method, solving Navier-Stokes and energy equations in a 2D-geometry transient simulation. Parameters like surface temperature, heat flux, and spreading ratio with respect to Weber number change were investigated and discussed in the present paper. The output of this study will be useful to understand the physical mechanisms better and to develop novel models for effective spray cooling system designs. The results show that for a lower value of Weber number, after impact the droplets spread less wide compare to high Weber number. The spreading ratio of droplets was almost constant or uniform for different surface temperature and it depends only on the surface roughness.