Experimental study on frosting/defrosting characteristics of microgrooved metal surfaces

•Study of condensation-frosting on flat and microgrooved copper and aluminum surface.•The frost-water drainage from these surfaces during defrost is examined.•Microgrooved surfaces consistently exhibit improved frost-water drainage.•Cyclic variation of microgroove dimension did not affect the frost structure.•Frost-water retention on flat surfaces increased in the subsequent refrost cycles.

Effect of microgroove geometry on the frost formation and frost melt-water drainage is experimentally investigated on a number of aluminum surfaces. Condensation and frost formation processes are also examined on a set of microgrooved copper surfaces for which the dimensions of the microgroove geometry are varied in a cyclic manner. These metal surfaces are studied because of their technical importance as working materials and are fabricated by two different techniques, photolithography and wet etching, respectively. The morphology, distribution and growth pattern of the condensed and frozen water droplets are found to be considerably different on the microgrooved surfaces from that on the flat baseline surfaces. While the amount of frost melt-water retention on the flat surfaces is found to increase in the subsequent refrost cycles and is highest in the last frost cycle, the microgrooved aluminum surfaces consistently exhibit improved frost-water drainage in all frost cycles and under different operating conditions. Findings of this study will be useful in designing microgrooved metal surfaces operating under frosting/defrosting conditions to have improved frost-water drainage properties.