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Performance assessment of solar air heater duct roughened with perforated-winglet vortex generators
Author(s)
Date Issued
January 1, 2017
Type
Article
Abstract
An experimental study has been conducted to investigate heat transfer, friction loss and thermal performance characteristics of turbulent flow in a solar air heater channel artificially roughened on one side (absorber plate) with multiple perforated-winglet vortex generator (PWVG). Air as the working fluid enters the test duct having a uniform surface heat-flux with Reynolds number (Re) ranging from 5200 to 24,000 in the present work. Effects of four different punched hole/pore diameters of winglet (d=2 mm, 4 mm, 6 mm and 8 mm) at a single relative winglet height (RB=b/H=0.6), relative winglet pitch (RP=P/H=3) and attack angle (β= 60°) on thermal characteristics are examined. The experimental results show that the PWVG provides the drastic increase in Nusselt number (Nu) and friction factor (f) values over the flat/smooth channel. In addition, substantial increases in Nu and f values are found for the rise in hole sizes. The maximum Thermal Enhancement Factor (TEF) is found for the pore diameter of 2 mm at lower Reynolds number. The present results are also compared with the results from the typical or solid winglet, TWVG (non-punched hole of winglet).
Citation
International Journal of Smart Grid and Clean Energy, 6(1), 31-39, 2017