Thermohydraulic performance of solar air heater having discrete double arc roughness elements on absorber plate

Abstract

The creation of a laminar sub region near the absorber wall causes solar air heaters to have limited thermal performance. An experimental analysis indicated that artificial roughness is one of the best strategies for breaking this viscous sub layer and improving absorption efficiency. Artificial roughness stitched on the absorbent plate in manner of discrete double arc roughness elements is generated, generating turbulent flow inside the rectangular duct. The coefficient of heat transmission improves as the roughness element is developed. In the current study, developed a roughness element of the discrete double arc reverse arc manner is used to improve the THP of the solar collector. During testing, relative roughness pitch, p/e = 11.67, relative roughness height, e/ Dh = 0.027, and angle of arc, α = 30°, 45°, 60°, 75°, Reynolds Number, Re = 3000–14000 were utilised as fixed and variable parameters, respectively. After extensive testing, the outcomes have been compared to the above mentioned of a plain absorber plate under the same fluidity circumstances. Experimental investigation revealed that Nusselt number (Nu), and friction factor (f), are 2.59 & 1.96 contrast overhead plain (without roughness element) plates, respectively. At a p/e = 11.67 & α = 60°, overall THP was found to be 2.16.