Thermodynamic performance evaluation of an indoor designed solar air heater duct equipped with V-down baffle blocks having racetrack-shaped staggered openings of varying aspect ratio – an experimental study

Abstract

ABSTRACT 1This paper presents the thermodynamic performance assessment of an indoor-designed solar air heater (SAH) duct with its absorber affixing the racetrack perforated 45o V-down baffle blocks in staggered holes array. The experimentation work encompasses studying the effect of parameters like – the mass flow rate of air () and the hole aspect ratio (w/d) of baffle blocks on the air temperature rise (), the energy (), the exergy () and the thermohydraulic () efficiencies of the duct under turbulent airflow conditions. The open area ratio (Φ), relative roughness height (e/H) and relative roughness pitch (p/e) of the baffle blocks are maintained constant in this study. The result showed drastic improvement in the performance assessing parameters due to ‘w/d‘ affecting the heat transfer and friction characteristics significantly in the duct. Increasing ‘w/d’ at lower airflow rate results in a uniform downfall of ‘’, and ‘’. At an increased flow rate, the energy and exergy efficiencies decrease. The exergy destruction and pressure drop show non-monotonous variations with the hole-aspect ratio. The smallest hole aspect ratio (w/d of 1.04) baffle blocks outperform in all assessment segments providing maximum values as 14.86oC, 96.81%, 17.46% and 93.95%, respectively, for the air temperature rise, the energy, the exergy and the thermohydraulic efficiency.