Experimental investigation of thermal performance enhancement in tubular heat exchanger fitted with rectangular-winglet-tape vortex generator

Abstract

The article presents an experimental study on thermal characteristics in a constant heat-fluxed circular tube fitted with rectangular-winglet tape (RWT) vortex generators. Air was employed as the working fluid based on Reynolds numbers (Re) in the turbulent regime between 4100 and 26,000. The effect of the RWT insert on heat transfer rate and friction loss was experimentally investigated. The RWT parametric study includes five winglet-to-tube height ratios or blockage ratios (b/D=BR= 0.15, 0.2, 0.25 and 0.3) at a single winglet inclination angle (q = 45°) and a pitch ratio (P/D=PR=2). The experimental results show that the heat transfer and friction loss for the RWT insert increase with the increment of BR. The Nu for the inserted tube was approximately 3.7–4.3 times higher than that for the smooth tube, while the f was approximately 19.4–45 times greater. For the studied BR ranges, the highest thermal enhancement factor (h) of 1.46 is obtained for BR = 0.2 at lower Re.