Experimental Study of Wall Roughness Effects on the Frost Formation over a Cylinder

Frost formation has important effects on many fields, such as refrigeration industry, air-conditioning, aviation, etc. The frost develops when a humid air contacts with a cooler surface at its freezing point. Frost formation is a complicated transient phenomenon in which a variety of heat and mass transfer mechanisms are taking place simultaneously. In this work, effect of roughness on frost formation over horizontal cylinder in force convection conditions was investigated experimentally. For creating the force flow field, a wind tunnel was used. Results indicated that the frost thickness behind the cylinder is at the maximum and in the front of cylinder is in the minimum. Further increasing of the wall roughness, result in the frost thickness increases and increasing the thermal conductivity coefficient of rough surface, increases the frost thickness too.