Heat transfer enhancement in solar air heater with V-shaped perforated baffles

Abstract

This experimental study, investigates the heat transfer and friction characteristics in a rectangular duct having its one broad wall heated and roughened with periodic V-down shaped perforated baffles. This work covered a range of Reynolds number (Re) 3800–19 000, open area ratio (β) 12%–44%, relative hole position (l/e) 0.429–0.571 for the fixed values of relative baffle height (e/H) 0.4, relative roughness pitch (p/e) 5, and angle of attack of 60°. The effects of relative hole position on Nusselt number and friction factor have been discussed and results compared under similar flow and boundary conditions to investigate the enhancement in Nusselt number and friction factor. The maximum enhancement in Nusselt number and friction factor has been obtained at an open area ratio of 12% and is of the order of 2.2 and 5.2 times of that of smooth duct, respectively. Thermohydraulic performance of solar air heater has been found to be substantially improved by the application such perforated baffles.