A novel gridded solar air heater and an investigation of its conversion efficiency

摘要

A new design of a cost-effective single pass gridded solar air heater (SAH) is presented featuring the optimization of flow resistance, mass flow rate, and efficiency. The SAH uses six layers of blackened aluminum grids as an absorber. The ensemble of six grids are corrugated in a triangular fashion such that the air has to traverse the six grids 16 times on one passage through the SAH. A special distribution manifold is used to achieve a relatively uniform flow profile across the width of the collector. Our investigation particularly studies the effect of mass flow rate on the output efficiency. We found that the conversion efficiency of our SAH approaches 80% as the mass flow rate is increased to (m) over dot approximate to 0.06 kg/s. The increased efficiency can be attributed to reduced conductive, radiative, and convective losses at the higher mass flow rates. The experimental data confirms the theoretical prediction of the SAH's efficiency as a function of mass flow rate. Our findings have important implications for studies of matrix absorber SAHs, packed bed SAHs, and passive SAHs. (C) 2016 Elsevier Ltd. All rights reserved.