Dropwise cooling: a numerical simulation code and its validation by infrared thermography tests

In this paper, a numerical code is presented, which simulates the evaporation of water droplets on hot solid surfaces. At the present stage of development, single-phase evaporation is addressed. The three-dimensional energy diffusion equation is employed to model the transient within both the droplets and the solid substrate and is discretized using the finite volume method. Infrared thermography is used to measure the transient contact temperature between impinging droplets and hot solid surfaces in order to validate the code by comparison with experimental data. Droplets are released onto the heated solid surface of a barium fluoride (BaF2) disk, which has high transmittance (about 90%) in the 8-12 um range (typical of longwave infrared cameras). The interface temperature is measured from below, through the solid material. Since the solid is IR-transparent, a black coating layer is used to allow radiative heating of the surface and provide a method to measure the liquid-solid interface temperature. The numerical predictions show very good agreement with the experimental data.