Journal
INTERNATIONAL COMMUNICATIONS IN HEAT AND MASS TRANSFER
Volume 139, Issue -, Pages -Publisher
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.icheatmasstransfer.2022.106503
Keywords
Swirl flow; Primary vortex flow; Secondary vortex flow; CPE; Nusselt number; Friction factor
Categories
Ask authors/readers for more resources
This study investigates the effects of swirl flow, primary and secondary vortex flow, v-cut, and teeth on a toothed v-cut twisted tape insert on heat transfer rate, friction factor, and performance evaluation criterion. The experiments were conducted on a double pipe heat exchanger and the results show that including teeth on the v-cut enhances the secondary vortex flow and increases the heat transfer rate.
It is generally recognized that the heat transfer rate can be improved using active, passive and compound methods. The use of twisted tape inserts in a pipe flow is one of the passive methods. The influence of swirl flow, primary and secondary vortex flow generated due to twist in tape, v-cut on the tape, and the teeth on the v-cut respectively on Nu (heat transfer rate), f (friction factor), and CPE (criterion for performance evaluation) of an inserted toothed v-cut twisted tape is investigated in this study. Experiments were carried out on a double pipe heat exchanger using water as the working medium for a Reynolds number range of 6000-13,000, with the uncertainty analysis of the relevant parameters taken into account. The correlations for Nu and f in terms of factors such as Re (Reynolds number), Pr (Prandtl number), b/c (ratio of depth of v-cut to width of cut), and e/c (ratio of depth of teeth on v-cut to depth of v-cut) are also developed using regression analysis. The results of correlations lie within +/- 10% for Nu whereas within +/- 15% for f. The investigations show that the inclusion of teeth on the v-cut develops a secondary vortex flow which further enhances the Nu (though not up to the comparable magnitudes of the primary vortex) and is capable of minimizing the percent decrement of heat transfer rate with increasing depth of cut at higher Re. The friction factor increased up to 7.7 times for e/c ratio equals 0.14 (depth of the tooth to depth of the v-cut) in comparison to the plain tube, while the increase in heat transfer rate for the same was 84% for Re = 6000.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available