Studi Eksperimental Karakteristik Perpindahan Panas Dan Faktor Gesekan Pada Pipa Penukar Kalor Berpenampang Bujursangkar Dengan Half Length Dan Full Length Twisted Tape Insert

Abstract

Abstract : The work presents an experimental study on the mean Nusselt number, friction factor and thermal performance characteristics in the inner tube (square duct) of a concentric tube heat exchanger with half length and full length twisted tape insert. In the experiments, measured data are taken at Reynolds number range between 4000 and 16,000 with water as the test fluid. The full length twisted tape is inserted into the test tube at single twist ratio of y/w = 4.0 while the half length twisted tape with the equal twist ratio mounted at the entry test section. The half length twisted tape is introduced as a swirling flow device for generating a strong swirl flow at the tube entry until the half tube length before decaying along the tube.On the other hand, the full length twisted tape is expected to produce a strongly swirling flow over the whole tube. The variation of heat transfer and pressure loss in the form of Nusselt number (Nu) and friction factor (f) respectively is determined and depicted graphically. The experimental result indicates that heat transfer rate and friction factor associated by the half length and full length twisted tape consistently higher than those without twisted tape insert (plain tube). Under the similar operating conditions, the half length twisted tape perform lower Nusselt number and friction factor values than the full length twisted tape around 48.67% and 82.22%, respectively.In addition, it is apparent that the thermal performance of the inner tube with the half length twisted tape is found to be lower than that with the full length one.

Keywords : Friction factor, Full length twisted tape, Half length twisted tape, Nusselt number, Reynolds number