Experimental investigation on heat transfer enhancement due to V-shaped perforated blocks in a rectangular duct of solar air heater

• Nu and f of perforated V-blocks in solar air heater are investigated.
• There exist an optimum value of e/H, P/e and β for maximum Nu and f are found.
• Better thermo hydraulic performance is achieved for perforated V-blocks.

In this work, the effect of geometrical parameters of the V-shaped perforated blocks on heat transfer and flow characteristics of rectangular duct, has been investigated experimentally. The experimental investigation encompassed the geometrical parameter namely, relative blockage height (e/H) of 0.4–1.0, relative pitch ratio (P/e) of 4–12 and open area ratio (β) of 5–25% at a fixed angle of attack (α) of 60°. The effect of V-shaped perforated blockages has been investigated for the range of Reynolds number from 2000 to 20,000. The maximum enhancement in Nusselt and friction factor has been found to be 6.76 and 28.84 times to that of smooth duct, respectively. Thermohydraulic performance of V-shaped perforated blockages is also compared to that of V-shaped solid blockages for same geometrical parameters.