Experimental analysis of evaporation heat transfer domains of capillary-assisted thin-film developed on radial parabolic sub-millimeter fin-groove geometries

Abstract

Evaporation through the capillary-assisted thin-film is an innovative approach to overcome the challenges in heat transfer enhancement and reduce the charge amount of the refrigerant in refrigeration systems. The present study attempts to illustrate the theoretical details of the capillary-assisted evaporation heat transfer domains on radial parabolic sub-millimeter fin-groove geometries that were partially submerged in a refrigerant, i.e., water. A semi-flooded evaporator was used for the evaporation heat transfer experiments under sub-atmospheric pressures of 0.93, 1.00, and 1.07 kPa. The influence of the water filling level on the evaporation heat transfer domains was investigated with three different fin-groove geometries. The highest evaporation heat transfer was obtained when the water filling level was approximately zero to five millimeters with smaller fin-groove dimensions, that is, fin distance, fin pitch, and groove perimeter. Denser fine grooves led to an increase in the number of evaporating thin-film zones, and it was noted that a significant portion of the enhancement in the evaporation heat transfer was contributed majorly by thin-film evaporation developed through the fin-groove structures.