Investigation of single and double pass solar air heater with transverse fins and a package wire mesh layer

Abstract

The purpose of this work is to construct and test single-pass and double-pass solar air heaters (SAHs) with four transverse fins. These fins were painted dark black and placed transversely to create four equal-spaced sections. Sixteen steel wire mesh layers were located between these fins as an alternative to an absorber plate; they had a cross-sectional area of 0.18 cm x 0.18 cm and an internal diameter of 0.02-cm. In this project, the thermal efficiency and outlet temperature were studied in a geographic area located in the city of Famagusta, North Cyprus. The experimental results indicate that the thermal efficiency increases as the air flow rate increases for the range of (0.011-0.032) kg/s. The maximum efficiency obtained using the 7.5-cm high collector was 62.50% for the double-pass SAH and 55% for the single-pass SAH at an air flow rate of 0.032 kg/s. Moreover, the thermal efficiency further increases by decreasing the height of the lower air pass of the double-pass SAH. The difference between the inlet temperature and outlet temperature, Delta T, indicated an inverse relationship with air flow rate: Delta T increased as the air mass flow rate decreased. The maximum differences (Delta T) observed were 4530 K for the double-passes SAH and 39.9 K for the single-pass SAM at 0.011 kg/s, which were recorded during the middle of the day with a maximum solar intensity. The results demonstrate a significant improvement in the thermal efficiency and outlet air temperature. (C) 2014 Elsevier Ltd. All rights reserved.