Experimental studies on pressure drop characteristics of cryogenic cross-counter flow coiled finned tube heat exchangers

Cross-counter flow coiled finned tube heat exchangers used in medium capacity helium liquefiers/refrigerators were developed in our lab. These heat exchangers were developed using integrated low finned tubes. Experimental studies have been performed to know the pressure drop characteristics of tube side and shell side flow of these heat exchangers. All experiments were performed at room temperature in the Reynolds number range of 3000-30,000 for tube side and 25-155 for shell side. The results of present experiments indicate that available correlations for tube side can not be used for prediction of tube side pressure drop data due to complex surface formation at inner side of tube during formation of fins over the outer surface. Results also indicate that surface roughness effect becomes more pronounced as the value of di/D(m) increases. New correlations based on present experimental data are proposed for predicting the friction factors for tube side and shell side. (C) 2010 Elsevier Ltd. All rights reserved.