Experimental Studies on Wire Coiled Coil Matrix Turbulators with and Without Centre Core Rod

This paper presents the effect of with and without center core rod of wire coiled coil matrix turbulators (WCCMTs) with different pitch (P) to diameter (D) ratios (0.23, 0.45 and 0.68) on the heat transfer for a fully developed turbulent flow. The influence of bonding the WCCMTs with the wall of the tube is also studied. Experiments are conducted by maintaining constant wall temperature. The results show that both heat transfer and friction factor are considerably high for all the turbulators when compared with plain tube. For the turbulator P/D = 0.23, with centre core rod with bonding has resulted in almost 42 % enhancement when compared with plain tube. On the other hand, for P/D = 0.45 and P/D = 0.68, the enhancements were 34.7 and 25 %, respectively. The empirical correlations developed for turbulators with and without centre core rod result in ±6 % deviation for Nusselt number and ±7 % for friction factor. Similarly for P/D = 0.23, without centre core rod with bonding has resulted in almost 23.5 % enhancement. For P/D = 0.45 and 0.68, the enhancements were 17.3 and 10.2 %, respectively.