EXPERIMENTAL INVESTIGATION OF FLOW BOILING HEAT TRANSFER IN NOVEL OBLIQUE-FINNED MICROCHANNELS

Abstract

THE OBLIQUE-FINNED MICROCHANNEL HEAT SINK HAS BEEN SHOWN TO BE ABLE TO SIGNIFICANTLY ENHANCE SINGLE-PHASE HEAT TRANSFER COUPLED WITH ONLY A SLIGHT PRESSURE DROP PENALTY. THE STRUCTURE, HOWEVER, HAS YET TO BE TESTED IN TWO-PHASE FLOW, WHICH FORMS THE MOTIVATION BEHIND THIS STUDY. FLOW BOILING EXPERIMENTS ARE CONDUCTED IN OBLIQUE-FINNED MICROCHANNELS USING THE FC-72 DIELECTRIC FLUID WITH MASS FLUX RANGE FROM 175 KG/M&178; S TO 395 KG/M&178; S AND IMPOSED EFFECTIVE HEAT FLUX FROM 6 W/CM&178; TO 120 W/CM&178;. ITS TWO-PHASE HEAT TRANSFER PERFORMANCE, FLOW BOILING REGIME, PRESSURE CHARACTERISTICS AND INSTABILITIES ARE STUDIED AND BENCHMARKED WITH THE STRAIGHT-FINNED MICROCHANNELS WITH THE USE OF HIGH-SPEED VISUALISATIONS TO EXAMINE THE PHYSICAL BOILING PHENOMENON IN THE MICROCHANNELS. THE EFFECTS OF OBLIQUE ANGLES AND SECONDARY CHANNEL WIDTHS ARE ALSO INVESTIGATED AND IT IS FOUND THAT THE OBLIQUE-FINNED CONFIGURATION CAN BE OPTIMISED TO ACHIEVE GREATER HEAT TRANSFER ENHANCEMENTS WITH MANAGE