Experimental examination of condensation heat transfer enhancement with different perforated tube inserts

Abstract

ABSTRACT Heat transfer and pressure drop of vapor flow in a finned double-pipe heat exchanger with different geometrical structures of perforated tube inserts as turbulators have been experimentally investigated. For this purpose, the influence of the number of perforations, as well as their place, and diameter has been examined in the Reynolds number range of 2200–3850 in the annulus. The working fluids in the inner tube and annulus were vapor and cold water, respectively. Several perforation configurations, including the helical pattern, four-row pattern, and the patterns with perforations on the top, and on both top and bottom of the tube with two different perforation diameters have been tested. The results suggest that in all of the cases with the perforated tube inserts, the overall heat transfer coefficient was improved compared to the plain heat exchanger. Among the examined patterns, the perforated tube with a row of perforation on the top of the tube presented the highest heat transfer coefficient. The experimental results show that inserting the tubes with a row of perforation on the top, helical perforations, two rows of perforations on the top and bottom, four rows of perforations, and four rows of perforations with larger diameter present a heat transfer enhancement of 73%, 60%, 47%, 33%, and 20%, respectively, and offers a maximum thermal performance factor of 1.42. The results also suggest that with higher Reynolds numbers, the average heat transfer and the amount of condensed vapor increase.