In the present research, thermohydraulic performance of a solar air heater having artificial roughness in the form of arc-shaped ribs with multiple gaps has been investigated experimentally and compared with that of a solar air heater having smooth absorber plate. Performance has been investigated in terms of enhancement in Nusselt number and friction factor. Results of the present work have also been compared with previously published work. Reynolds number and arc angle (α) were varied from 3000 to 18000 and 30° to 75°, respectively. Present roughness results into a higher rate of heat transfer from absorber surface to air, but it also imposes a penalty in terms of increased friction factor. Maximum enhancement in Nusselt number, friction factor and thermo-hydraulic performance parameter for roughened absorber surface is found to be 3.74, 2.69 and 2.75 times that of smooth plate, respectively. Correlations for heat transfer and friction factor for proposed roughness have also been developed.

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