“…The hot air produced by SAH can be used as a source of heat for process heating in industrial applications, crop drying in agriculture, preheating of air in boiler furnaces, etc. Thermal performances of SAHs can be improved passively by providing artificial ribs/protrusions on their absorber plates (Prasad and Saini, 1988;Gupta et al, 1997;Varshney and Saini, 1998;Momin et al, 2002;Jaurker et al, 2006;Bhushan and Singh, 2011;Lanjewar et al, 2011;Tanda, 2011;Yadav and Bhagoria, 2014;Jin et al, 2015;Mahmood et al, 2015;Rajaseenivasan et al, 2015;Maithani and Saini, 2016;Pandey and Bajpai, 2016;Lakshmi et al, 2017;Kumar and Layek, 2018;Kumar and Mohan Jagadeesh Kumar, 2019;Murali et al, 2019) and packed beds (Mittal and Varshney, 2006;Ho et al, 2013;Lakshmi et al, 2017;Mahmood et al, 2015;Singh et al, 2019;Singh, 2020). Prasad and Saini (1988) developed explicit equations to calculate the average Stanton number and average friction factor for the case of internal turbulent flow through SAH corrugated with small diameter protrusion wires.…”