Frost formation and development on flat plate: Experimental investigation and comparison to predictive methods

This paper proposes new experimental data on frost formation and development on flat plate. The experimental data have been obtained on a 300×300mm2 aluminum plate, with humid air flowing inside a closed-loop wind-tunnel. The effect of environmental conditions has been studied with a sensitivity analysis. Air velocity ranges between 1 and 4 m.s-1, air temperature between 5 and 16 °C, air relative humidity between 50% and 80% and plate temperature between −25 and 0 °C. First, the Lewis analogy boundary layer frequently used to simplify frost phenomenon formulation is checked successfully. Results provided by the sensitivity analysis showed that plate temperature and air relative humidity are the most influential parameters on frost properties (thickness, density and thermal conductivity). Tortuosity, depending on the frost crystal shapes, is also identified as a key parameter which needs deeper investigations. A comparison of experimental data with models from the literature is proposed. Predictive methods have been tested. Reliable predictive methods have been identified for frost thickness and frost conductivity. Correlations for predicting frost density need to be improved. This work also highlights the important role of crystal shape in frost deposition mechanisms.