A semi-empirical model for predicting frost accretion on hydrophilic and hydrophobic surfaces

A first-principles model was used together with experimental data obtained in-house to validate a semi-empirical modeling approach for predicting frost accretion on hydrophilic and hydrophobic substrates. An algebraic expression for the frost thickness as a function of the time, the modified Jakob number, the humidity gradient, and the surface contact angle was devised from frost formation theory. At this stage, the correlation was fitted to 956 experimental data points for natural convection conditions spanning different surface temperatures and supercooling degrees, with the modified Jakob number ranging from 0.79 to 1.30, and contact angles ranging from 45 degrees (hydrophilic) to 160 degrees (hydrophobic). When compared to the experimental data for the frost thickness, the proposed semi-empirical model showed errors within +/- 15% bounds, and an average predictive error of 11.7%. Since the model carries the contact angle as an independent parameter, a sensitivity analysis of the frost growth rate in relation to it is also reported. (C) 2017 Elsevier Ltd and IIR. All rights reserved.