Influence of fin height on the performance of a glazed and bladed entrance single-pass solar air heater

Abstract

This paper communicates experimentally improving the performance of an entrance-modified single-pass Solar Air Heater (SAH) having nineteen longitudinal fins. The longitudinal fins were used to increase the heat transfer area and to distribute the air flow uniformly in the channel. Experiments were conducted at three various heights of fins (3, 5, and 8 cm) to investigate the effect of the height. To increase the heating area exposed to solar radiation, the entrance region was covered by a glass instead of steel cover. As well, guide blades were attached to the entrance for ensuring good air distribution over the surface of the absorber, and hence enhancing the performance. Experiments were conducted under four values of air flow rates ranged from 0.013 to 0.04 kg/s. Experimental results were compared with that obtained from a conventional SAH at the same operating conditions to evaluate the proposed SAH performance. The maximum daily efficiency of the ordinary finned SAH was 43.1% at 0.04 kg/s and 8 cm fins’ height. Modifying the entrance region led to good enhancement in both output temperature and efficiency. For the modified finned SAH, the highest daily efficiency was 57% at 0.04 kg/s with fins’ height of 8 cm. While for the conventional SAH, the highest daily efficiency was about 32%.