Evaluation Of Thermo Hydraulic Performance Of Passive And Compound Inserts

In the present investigation, the heat transfer and pressure drop performance of a tube in tube heat exchanger fitted with Bakelite helical screw tape and aluminum hemispherical cup shape with threaded core rod insert is experimentally reported for turbulent flow in individual and compound insertion cases. Performance is evaluated using water in the Reynolds number range of 8000 to 32000. For helical screw tape, the average Nusselt number ratios for augmented tube case to plain tube case (Nua/Nup) were found to be ranging between 2.51 - 2.7 along with average friction factor ratios (fa/ fp) ranging between 4.12 - 4.13. For cup shape inserts, the average Nusselt number ratios for augmented tube case to plain tube case (Nua/Nup) were reported between 1.38 - 1.62 along with friction factor ratios ( fa/ fp) ranging between 4.93 - 5.44 . The average Nusselt number ratios (Nua/Nup) and friction factor ratios (fa/ fp) for two compound insertion cases are also reported by varying the cross-section of inserts for 1/3rd length of the heat exchanger and observed in the range of 2.26 - 2.65, and 4.06 - 4.8 respectively. For equal pumping power criteria, the average performance ratios (Nua/Nuc) are reported in the range of 1.02 -1.11 for helical screw tape, 0.6 - 0.67 for cup shape insert and 0.99 - 1.22 for two compound insertion cases.