Experimental study on thermal behaviors in squareduct with 45o discrete V-finned tape inserts with V-tip pointing downstream

Supattarachai  Suwannapan; Kanchit  Rongchai; Sura  Tundee

Supattarachai Suwannapan Department of Mechanical Engineering, Faculty of Engineering, Rajamangala University of Technology Isan, Khonkaen Campus
Kanchit Rongchai Department of Mechanical Engineering, Faculty of Engineering, Rajamangala University of Technology Isan, Khonkaen Campus
Sura Tundee Department of Mechanical Engineering, Faculty of Engineering, Rajamangala University of Technology Isan, Khonkaen Campus

Abstract

In the development of high performance compact heat exchangers, various flow tabulators used in the purpose of enhancing heat transfer have been studied. This article presents a new experimental study on thermal performance enhancement in a constant heat fluxed square duct inserted diagonally with a 45o discrete V-finned tape with V-tip pointing downstream (45o DFTVD). The study was conducted by varying the airflow rate through the tested square duct fitted with the 45o DFTVD for Reynolds number from 4000 to 25000. Various relative fin heights and pitches were tested to investigate the effect of the 45o DFTVD at on heat transfer and pressure drop. Heat transfer and pressure drop were presented in terms of Nusselt number and friction factor respectively. Several V-finned tape characteristics were introduced such as finto-duct height ratio or blockage ratio (BR=e/H=0.075, 0.1, 0.15 and 0.2), fin pitch to duct height ratio (PR=P/H=0.5, 1.0, 1.5 and 2.0) and fin attack angle,  =45o. The results have shown that the heat transfer and friction factor values with the 45o DFTVD increase with increasing BR but with decreasing PR. The highest heat transfer and friction factor were observed at BR=0.2 and PR=0.5 whereas the highest thermal enhancement factor was at BR=0.1 and PR=1.5. Considering measurement uncertainties, it was also found that changing the V-tip direction to pointing upstream results in an insignificant increase of 3% in thermal enhancement factor.