Influence of solar insolation on energy and exergy efficiency of a rectangular duct solar air heater with various types of V rib roughness: An analytical approach

In the current work, the energy and exergy evaluations for several V ribs in a rectangular duct SAH are evaluated and compared with smooth SAH for a heat flux range of 800 to 1200 W/m². The analysis uses correlations for the friction factor and Nusselt number for different V ribs that have been developed by various researchers. The investigators' recommended optimum design parameters are employed to analyse the specific rib. The thermohydraulic and exergy efficiency of various V ribs are evaluated using the MATLAB code and comparisons of the findings are provided. The staggered discrete multi-V-shape rib configurations achieves the maximum thermal efficiency of 76.63% for Reynolds number of 21,000 and solar radiation heat flux of 800 W/m². Corresponding to a Reynolds number of 21,000 and solar radiation heat flux of 1200 W/m², the perforated multi-V-shaped rib gives a maximum thermohydraulic efficiency of 74.82%. At 800 W/m² of heat flux, a maximum exergy efficiency of 5.17% is obtained for the staggered discrete multi-V-shape rib configuration at lower Reynolds number. Whereas, corresponding to higher Reynolds number, the maximum exergy efficiency is 4.18% for perforated multi-V rib.