Heat and Mass Transfer in the Frost Layer

Abstract

Though the effective thermal conductivity of frost layer “λ_f” increased with the increase of the frost layer density, the relationship of them was not obvious, because the thermal conduction in the frost layer was affected not only by the thermal conductivity in solid phase, but also by heat transfer by moisture diffusion in gas phase.
To explain the relationship between λ_f and the frost layer density, a simple model was presented by assuming that the frost layer was consist of frost columns. By introducing λ_f to the model, simultaneous heat and masstransfer phenomena in frost layer could be fairly well simulated. This simulation showed that λ_f was affected mainly by surface temperature of plate covered with frost layer, surface temperature of frost layer and frost layer density.
Moreover, other simple model was presented by assuming that frost layer was consist of ice columns. In this model, character difference of ice columns and frost layer which piled up ice particles complicately, was expressed by correction factor “α₀” contained the irregularity of heat flow path in frost layer, constriction and contact resistance of ice particles. By using this model, λ_f was able to estimate relatively well.