# Effect of pitch spring of delta-winglets on thermal characteristics in a heat exchanger tube

## Main Article Content

## Abstract

In this paper, the heat transfer, pressure loss and thermal performance by using delta-winglet pairs placed on double-sided straight tape inserted into a constant heat-fluxed tube are experimentally studied. Experimental work is conducted for the tape with different values of axial winglet pitch spacing (P) or winglet pitch ratio (P/D=PR= 0.5, 1.0, 1.5, 2.0 and 2.5). Air used as the working fluid and flows into the tube for Reynolds numbers (Re) ranging from 4100 to 25,400. The use of the delta-winglet tape (DWT) with the winglet attack angle of 45° is to generate two pairs of longitudinal vortex flows. The experimental results show that the DWT provides higher heat transfer rate and pressure loss than the smooth tube. The peak heat transfer rate is at PR=0.5 and is approximately 2.98–4.30 times above the smooth tube while the friction loss is around 10.01–36.34 times. To access the real benefits of the 45° DWT insert, thermal enhancement factor (TEF) is examined and found to be in the range of 1.22–1.55 for PR = 1.5.

## Article Details

*Journal of Research and Applications in Mechanical Engineering*,

*4*(2), 166–174. Retrieved from https://ph01.tci-thaijo.org/index.php/jrame/article/view/138646

This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.

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