Experimental studies on effect of wire coiled coil matrix turbulators with and without bonding on the wall of the test section of concentric tube heat exchanger

Abstract

This paper presents the effect of bonding and without bonding of wire coiled coil matrix turbulator on the heat transfer for a fully developed turbulent flow. Experiments are conducted by maintaining constant wall temperature. Tests are performed on 3 different wire coiled coil matrix turbulators of different pitches of 5, 10 and 15 mm without bonding of the turbulator. Three similar types of heat exchangers are fabricated and the wire coiled coil matrix turbulators with different pitches of 5, 10 and 15mm are inserted in the heat exchangers and bonding is done on the surface of the tube section. Results have indicated that the heat transfer rate enhances inversely with the pitch of the wire coiled coil matrix turbulator with bonding. With a pitch of 5 mm, the turbulators without bonding have resulted in almost 25.4% enhancement when compared with plain tube. On the other hand, for pitches of 10 mm and 15 mm the enhancement were 20.7% and 16.8%, respectively. The empirical correlations developed for turbulators with and without bonding results in ±6% deviation for Nusselt number and ±3% for friction factor. Similarly with a pitch of 5 mm, the turbulators with bonding have resulted in almost 42% enhancement. For pitches of 10mm and 15mm the enhancements were 34.7% and 25%, respectively

Experimental studies on effect of bonding the twisted tape with pins to the inner surface of the circular tube

“…Eiams7a-ard et al [13] presented the effects of peripherally-cut twisted tape insert on heat transfer, friction loss and thermal performance factor characteristics in a round tube. Selvam et al [17] experimentally studied the heat transfer and friction factor characteristics of turbulent flow through a circular tube fitted with wire coiled coil matrix turbulator inserts of various pitches with and without bonding, with water as working fluid. They also compared the numerical results with the experiment results, with discrepancy for Nusselt number in a range of 1.6% to 3.6% and for friction factor in a range of 8.2% to 13.6%.…”