SECOND LAW ANALYSIS OF HEAT EXCHANGER TUBE FITTED WITH TWISTED TAPE INSERT HAVING MULTIPLE V CUTS AND PERFORATIONS

The perforated twisted tapes are known to produce higher heat transfer rates with lower friction losses. The present study deals with the heat transfer and tube flow characteristics of a heat exchanger with a twisted tape having multiple V cuts with circular and elliptical perforations. Experimental data for the STT, PTT, MDVCT-CP, and MDVCT-EP tape geometries are collected for the twist ratio of 2-6 by varying the Reynolds number in the range from 2700 to 22,800. The effects of tape geometries on the Nusselt number in conjunction with friction factor are discussed and the entropy generation analysis is carried out to see the performance of different types of inserts. The formation of elliptical perforations with V cuts in a twisted-tape insert showed an improved thermohydraulic performance by reducing the energy loss due to friction. The maximum values of normalized Nusselt number Nu* and thermohydraulic performance factor eta are found to be 3.26 and 1.88, respectively, corresponding to the elliptical perforated twisted tape with multiple V cuts having V cut depth ratio d(c)/W and V cut width ratio w(c)/W of 0.27, and twist ratio of 2.

Automated summary

The experimental results of this study show that twisted tapes with V-shaped cuts and circular elliptical perforations can improve heat transfer efficiency, reduce friction losses, and have higher heat transfer rates.