Computational analysis of the effect of flow parameters on friction factor and thermal performance of an artificially broken arc rib solar air heater

Abstract

The use of solar air heaters (SAH), which convert solar energy into heat energy, is one of the most efficient methods currently available for capturing the energy of the sun. However, because SAH have lower thermal efficiency, researchers have been concentrating on developing methods to modify the flow field to artificially boost thermal performance. In this work, a numerical investigation that focuses on a SAH that has been deliberately roughened using broken arc ribs is presented. This numerical analysis aims to determine the impact of incorporating broken arc ribs compared to smooth ones and how various roughness factors affect the friction factor and Nusselt number (Nu). The RNG k-[Formula: see text] turbulence model was used for the simulation. To solve the continuity, momentum, and energy equations, version R19.2 of Ansys FLUENT software was used. The results of the CFD study show that the average Nusselt number increases if there is a greater relative roughness pitch, and it achieves its highest value once relative roughness pitch ([Formula: see text]. The friction factor, on the other side, decreases as the Reynolds number (Re) increases, reaching its lowest value when [Formula: see text] and [Formula: see text]. Maximum value of the thermohydraulic performance factor is observed to be 1.92 when applied to the geometry that corresponds to relative roughness height ([Formula: see text], ([Formula: see text], and [Formula: see text].