A finite-volume diffusion-limited aggregation model for predicting the effective thermal conductivity of frost. (October 2016)

• Record Type: Journal Article
• Authors: Negrelli, Silvia; Cardoso, Rodrigo P.; Hermes, Christian J.L.
• Is Part Of: International journal of heat and mass transfer. Volume 101(2016:Oct.)
• Page Start: 1263
• Page End: 1272
• Publication Date: 2016-10
• Subjects: Frost formation -- Fractal growth -- Thermal conductivity -- Numerical simulation -- Experimental validation; Heat -- Transmission -- Periodicals; Mass transfer -- Periodicals; Chaleur -- Transmission -- Périodiques; Transfert de masse -- Périodiques; Electronic journals; 621.4022
• DOI: 10.1016/j.ijheatmasstransfer.2016.05.135
• Languages: English
• ISSNs: 0017-9310

Abstract

Highlights: A model to predict the thermal conductivity of heterogeneous frosted media is devised. The frost growth is modeled through the fractal diffusion-limited aggregation approach. The thermal conductivity is calculated from the finite-volume solution of the diffusion problem. The predictions for the thermal conductivity represent the experimental data within the ±15% thresholds. Abstract: The present work is aimed at advancing a computational model for predicting the thermal conductivity of frost formed under different working conditions and, therefore, spanning a wide range of frost morphologies. The frost growth was modeled by means of the fractal theory, particularly the diffusion-limited aggregation approach which forms heterogeneous porous media that emulate the morphology of the frost layer. The density of the frosted medium was determined straightforwardly by the principle of mass conservation, whereas the effective thermal conductivity was calculated from the inverse solution of the heat diffusion problem using the finite-volume method. It was found that the model predictions for the thermal conductivity were able to represent the experimental data obtained in-house within the ±15% thresholds. A sensitivity analysis of key operating conditions that affect the frost morphology is also reported.