Thermohydraulic Performance Optimization of Solar Air Heater via Tailored Inverted L-Shaped Rib: A CFD Investigation

The solar air heater is a thermohydraulic equipment that increases convective heat transfer by artificially roughening the absorber plate with repeated ribs. In this study, 2-D Computational Fluid Dynamics (CFD) observation is done to analyze the properties of heat transfer and fluid flow friction of an artificially roughed Solar Air Heater (SAH) with inverted L-shaped ribs of varying thickness of relative roughness (0.2 ≤ t/e ≤ 0.8). The roughness parameters such as the thickness of relative roughness (0.2 ≤ t/e ≤ 0.8), the height of relative roughness (0.021 ≤ e/D ≤ 0.042), the pitch of constant relative roughness (P/e = 7.14) and Reynolds number (3800 ≤ Re ≤ 18000) are varied for the analysis. The impact of the thickness of relative roughness on the Thermohydraulic Performance Parameter (THPP) (Overall energy performance) is investigated in the study. Governing equations with RNG k-ε turbulence model are solved using ANSYS FLUENT. The contours of velocity, pressure, turbulent kinetic energy, and turbulent intensity are represented pictorially to understand the flow physics clearly. The study found that Nusselt Number (Nu), flow friction factor (f), and Thermohydraulic Performance Parameter (THPP) are greatly influenced by rib configurations. A maximum THPP of 1.69 is obtained using the rib configuration of t/e of 0.8 and e/D of 0.042.

American Institute of Physics