Experimental Investigation of Heat Transfer and Friction Characteristics of a Multiple V-Rib Roughened Solar Air Heater

ABSTRACT

The use of artificial roughness on the underside of the absorber plate is an effective and economic way to improve the thermal performance of a solar air heater. Number of experimental investigations involving different types of roughness elements has been carried out in order to maximize the heat transfer from the absorber plate to flowing air in a solar air heater. An experimental investigation has been carried out to study the thermal performance of a solar air heater having its absorber plate roughened by using multiple v-ribs of circular cross-section. The experiment encompassed Reynolds number (Re) range from 2000 to 20000, duct aspect ratio (AR) value of 12:1, rib height (e) value of 0.90 mm, relative roughness height (e/D_h) value of 0.019, relative roughness pitch (p/e) value of 10, angle of attack (α) value of 30° and width ratio values varying from 1 to 10. The thermal and thermohydraulic performance of multiple v-ribs roughened solar air heater has been compared with those of single v-rib roughened and smooth solar air heaters under similar flow conditions.

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