Condensate retention of water-ethanol mixture on horizontal enhanced condensing tubes

Condensate retention has been found an important parameter for heat transfer on horizontal enhanced condensing tubes. In this research, five pin-fin (varying in circumferential pin spacing) and three integral-fin horizontal tubes are investigated for condensate retention angle (which is measured from the top of tooth to the fully flooded flank) using water-ethanol mixture. An attempt was made to find the optimum concentration of ethanol in water for maximum retention angle. Concentration of ethanol was varied in between 0.5% to 1.5% by weight. Data revealed the importance of integral-fin tube over pin-fin tube as significant increase in retention angle was observed for integral-fin tube (having same longitudinal spacing, tooth thickness, tooth height, inner and outer diameter) while retention angle for pin-fin tubes remain unchanged. Optimum ethanol concentration was observed to be 0.75%.