CORRELATIONS FOR PREDICTING THE AIR-SIDE NUSSELT NUMBERS AND FRICTION FACTORS IN CHILLED-WATER COOLING COILS

An experimental study was conducted to determine Nusselt numbers and friction factors on the air side of wavy-finned, chilled-water cooling coils. General correlations of the dry-surface Nusselt numbers and friction factors were developed from the data obtained from five different cooling coils. A comparison of the Nusselt number correlation to data from the literature revealed that the correlation was generally able to predict the reported Nusselt numbers within 20%. Under wet-surface conditions, the measured Nusselt numbers showed considerable scatter, with some of the results being higher than the corresponding dry-surface values, while others were lower than the dry-surface values. Friction factors were substantially higher under wet-surface conditions. A correlation to predict the friction factors for wet surfaces was also developed.