CFD analysis of artificially roughened solar air heater: a comparative study of C-Shape, reverse C-Shape, and reverse R-Shape roughness element

Abstract

Solar Air Heater (SAH) serves as a pivotal device for converting solar radiation into heat applications. This study focuses on enhancing the performance of SAH through modifications to the absorber surface by introducing ribs as artificial roughness. A two-dimensional CFD analysis investigates the impact of C-shape, reverse C-shape, and reverse R-shape ribs on thermal and hydraulic performance within the SAH channel. RNG (k-ϵ) turbulence model is employed for numerical simulation and model accuracy is validated against established correlations and literature results. The numerical analysis involves the designing and modelling of the SAH using a constant pitch ratio (P/e) of 14.285 and a height ratio (e/D) of 0.021. The Reynolds number (Re) from 4000 to 18000 was considered for the present study. The result reveals that the present rib geometries significantly enhance heat transfer and fluid mixing, leading to substantial improvements in Nusselt number (Nu) and friction factor (f) by 2.5 to 3.3 times and 2.8 to 5.05 times respectively over smooth duct SAH. The C-shape rib configuration attains the highest Thermohydraulic Performance Factor (THPF) at approximately 2.0078 for a Re of 4000 over reverse C-shape, and reverse R-shape ribs.

KEYWORDS:

• Solar air heater
• Roughness geometries
• CFD
• Heat transmission
• Pressure drops
• Thermo-hydraulic performance

Disclosure statement

No potential conflict of interest was reported by the author(s).