Experimental Study on Effect of Length of Twisted Tape on Performance of Externally Helical Wire Wound Double Pipe Heat Exchanger for Parallel and Counter Flow

Externally Helical wire wound Double pipe heat exchanger (DPHE) or concentric tube heat exchanger is a modified form of simple DPHE as in this case a copper wire is externally wounded over outer periphery of inner tube of DPHE. This modification increases some thermal efficiency as compare to simple DPHE. This kind of heat exchanger is widely used in chemical, food, oil and gas industries. Commonly methods used by the researchers to enhance the heat flow rate are Active method, Passive method and compound method. And present work is based on passive method. In the present work experiment is carried out on double pipe heat exchanger in which hot water is flowing through inner tube where as cold water is flowing through the annulus and hot water to cold water heat exchange is taken into consideration. During the experiment cold water flow rate is kept constant at 45LPH (liters per hour) where as hot water flow rate is varies from 15LPH to75LPH. Two twisted tape inserts of different lengths as one is full and another is half of same pitch length of 2.5" insert are used and inlet and outlet temperature of hot and cold water is measured by K type thermocouple to calculate different parameters of double pipe heat exchanger like Effectiveness, LMTD, Overall Heat Transfer Coefficient and Heat Transfer for performance in parallel and counter flow arrangement.