The effect of sinusoidal fins’ amplitude on the thermo-hydraulic performance of a solar air heater

Abstract

Solar energy exploitation is growing consistently, as it is the cheapest and most accessible amongst all forms of renewable energies. Increasing the performance of solar air heaters can aid in developing clean energy use and subsiding the greenhouse gas emissions from in the world. This study, therefore, seeks to improve the thermo-hydraulic performance of solar air heaters using sinusoidal extended surfaces. The results show that Reynolds number increment contributes to the enhancement of Nusselt number and thermo-hydraulic performance, while it does not affect the friction factor considerably. The highest value of the Nusselt number belongs to the case with the highest fin amplitude and wavy fins configuration by about 7 times higher value in comparison to the simple solar air heater. It is shown that the wavy configuration can render higher thermohydraulic performance than that of raccoon fins, by about 10 percent. The finned configurations feature better fluid flow mixing at the outlet and lower maximum and gradient of temperature on the absorber plate compared to those of simple and common solar air heaters.

A Comprehensive Review of the Thermohydraulic Improvement Potentials in Solar Air Heaters through an Energy and Exergy Analysis

“…Rahmani et al [61] found an increase of 50% in the Nusselt number by increasing the sinusoidal fin height by 0.5 times the duct height. Similar results were found for wavy fins by Saboohi et al [62]. In the case of the relative height ratio (e/D), it was found that the Nu number and friction factor were raised by enhancing the relative rib height (e/D) for rectangular ribs, conical ribs, and equilateral triangular ribs, up to an optimum value of e/D [44][45][46].…”