The effect of the diameter ratios on the effectiveness of the concentric tube heat exchanger

Abstract

This paper presents the effect of inner to outer diameter tube ratios ( D* ) on the effectiveness,thermal characteristics and pressure loss of the counter flow concentric tube heat exchanger having 1.2 mlong and 2 inch of outer diameter are experimentally investigated. Six different D* are introduced with 0.25,0.31, 0.38, 0.44, 0.5 and 0.56, flow rate of hot water and cold water ranging from 15 liter/min to 40 liter/min. Thehot water and cold water inlet heat exchanger at constant temperature of 70๐C and 30 ๐C respectively. Theexperimental results reveal that the effectiveness and the number of transfer unit increases with the rise ofD* , while the overall heat transfer decreases. For the pressure loss of hot water and cold water show thatwhen the D* increases, while the pressure loss of hot water increases but the pressure loss of cold waterdecreases.