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

Abstract

Abstract. This review covers issues not addressed in a review paper dealing with icing and frosting before. For example, in icing, we start from the role of nonuniform 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 those that weaken the validity of the analysis. We emphasize that the distribution of droplets in the cloud, their turbulent trajectory toward the airfoil, and the impingement and phase change processes on the airfoil are all stochastic processes. Many of the investigations focused on predicting the mean behavior. In this review, we focus on quantifying the 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. Similarly, in frosting, the processes of ice crystal nucleation and deposition are also stochastic. We address supersaturated air that may exist both in the bulk airstream and within the pores of the porous frost layer. This aspect along with casting the problem in the context of psychrometric theory has never been addressed in a review paper before. 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.