Thermo-Exergic Performance evaluation of Herringbone Finned Absorber Solar Air Heater

Abstract

This study evaluates the thermal and exergetic performance of a solar air heater with a herringbone finned absorber. Energy and exergy balance equations were formulated and solved iteratively in MATLAB to determine temperature fields and performance metrics under varying mass flow rate, fin pitch, and solar insolation. Herringbone fins enhanced heat transfer by increasing surface area and inducing swirl flow, resulting in higher thermal efficiency than a smooth absorber. Thermal efficiency increased monotonically with mass flow rate, reaching 77.4% at a mass flow rate of 0.41 kg/s for a 1 cm fin pitch. In contrast, exergy efficiency peaked at 5.23% at a flow rate of 0.002 kg/s before declining due to pumping losses. It also rose with insolation, from 1.7% at 400 W/m² to 4.0% at 1000 W/m². The study highlights the trade-off between thermal and exergy performance, offering guidelines for the optimal design of solar air heaters.