A Unified Review of Physical Modeling of Heat and Mass Transfer Processes in Frosting and Icing

Abstract This review adds information that has never been addressed in a review paper dealing with icing and frosting before. For example, in the icing problem, we start from the role of non-uniform distribution of large droplets in clouds to the effect of droplet impaction, splashing, and mixing of the water layer. We highlight the important assumptions that have traditionally been made and identify the ones that weaken the validity of the analysis. We emphasize the fact that the distribution of droplets in the cloud, their turbulent trajectory towards the airfoil, and the impingement and phase change processes on the airfoil are all stochastic processes. Similarly, in the frosting problem, the processes of ice crystal nucleation and deposition are also stochastic. However, much of the past investigations have focused on predicting the mean behavior. In this review, we focus on the need to quantify stochastic fluctuations about the mean, both in terms of proper estimation of associated uncertainties and the effect of fluctuations on features such as ice surface roughness, which in turn affects the overall performance. In the frosting problem, we address supersaturated air that may exist both in the bulk airstream and within the pores of the porous frost layer. This aspect has rarely been addressed in a review paper. Thus, while we review past icing and frosting related research findings, we identify gaps in the current approach and suggest areas of future research that can clarify the physics and improve the fidelity of future modeling and simulation.