Performance testing of a baffled duct at different air attack angles based on entropy generation and exergy analysis

Abstract

Solar air collectors (SACs) with efficient heat transfer designs are a sustainable solution for space heating, reducing energy use and pollution. This study examines the entropy generation and exergetic performance of a SAC duct featuring elongated racetrack-shaped perforated V-baffles on its heat-absorbing surface, comparing its performance to that of a smooth-surface absorber. Experiments conducted encompass varying the baffles’ geometric parameters like air attack angle (α) at 45°, 60°, 120°, and 135°; pitch ratio (p/e) at 2, 6, and 10; and perforation ratio (θ) at 0.27 and 0.29 with flow Reynolds number (Re) adjusted between 5400 and 14,400. The study analyses heat transfer and fluid flow losses using entropy generation numbers and exergy efficiencies as performance indicators. Baffles with α = 135° and θ = 0.29 achieve the lowest range of (Formula presented.) (augmentation entropy generation number), with a minimum value of 0.476 at a p/e of 2 and Re = 10,351. Similarly, baffles with α = 135° and θ = 0.27 achieve the highest (Formula presented.) (exergy efficiency), with a maximum value of 0.1319 (13.19%) at a p/e of 2 and Re = 8,731. Correlations for (Formula presented.), developed using R software, show a close alignment between experimental and predicted values.