Effects of Delta-Shaped Obstacles on the Thermal Performance of Solar Air Heater

An experimental investigation has been carried out to study the effect of delta-shaped obstacles mounted on the absorber surface of an air heater duct with an aspect ratio 6 : 1 resembling the conditions close to solar air heaters. This study encompassed the Reynolds number (Re) ranging from 3400 to 27600, longitudinal pitch of the obstacle ([Formula: see text]) varied from 3/2 to 11/2, and relative obstacle height ( e/ H) varied from 0.25 to 0.75. The relative obstacle transverse pitch [Formula: see text] and the angle of attack of flow on obstacle = 90° are kept constant during the whole experimentation. By comparing the heat transfer data obtained from the obstacle-mounted duct with that of smooth duct under similar geometrical and flow conditions, the obstacle-mounted duct enhances the heat transfer by 3.6-times at Re = 7276.82, [Formula: see text], and [Formula: see text].

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