Drainage of frost melt water from vertical brass surfaces with parallel microgrooves

Drainage of frost melt water from a number of microgrooved brass surfaces, fabricated by micro-end-milling process, is investigated experimentally and compared to that of a flat baseline surface. Frost is grown on sample surfaces (45 mm x 45 mm in dimension) inside a thermally controlled chamber, at a plate temperature of about -25 degrees C in the presence of cold air (-6 degrees C) and retention of water on these surfaces after defrosting is studied for three different defrosting energy inputs. Microgrooved surfaces drain up to 70% more condensate than does the flat baseline. The groove geometry is found to considerably affect the water retention. Drainage is promoted by an increase in the pillar width but is relatively insensitive to the changes in the groove depth. Effects of defrosting heating rate on the frost surface temperature and substrate temperature during defrosting process is also investigated. Frost mass per unit area is found to be lower for the grooved surfaces in the 1st frost and 2nd frost cycles. (C) 2011 Elsevier Ltd. All rights reserved.