A numerical model for predicting frost layer growth based on computational fluid dynamics is developed. This model can predict the growth behavior of a highly porous frost layer formed by desublimation. A new volumetric mass transfer rate equation is proposed, which can consider water vapor penetration into a frost layer. The model is validated through experimental results under various operating conditions and used for analyzing the frost layer growth process. The density distribution inside the frost layer is almost linearly changed in the direction perpendicular to the cooling surface under the operating conditions favorable for desublimation, showing different characteristics from the case in the operating conditions favorable for freezing after condensation. In addition, the average mass transfer rate is analyzed as a function of time. As time passes, the porosity of the frost layer decreases and the mass transfer rate due to water vapor penetration decreases gradually. (C) 2018 Elsevier Ltd. All rights reserved.