A Revisit to Thermal Performance Enhancement of Sustainable Solar Air Heater

Solar energy is commonly recognized as effective and sustainable energy source that can be used in various purposes including heating, water desalination, crop drying etc. A solar air heater (SAH) is a device that transforms energy from the sun into thermal energy through the use of air. A flat plate SAH is commonly used to provide heated air for various industrial and space heating applications. An absorber plate allows solar radiation to be absorbed by passing air through a cross-section duct below it. As a result of their insufficient thermal transfer capabilities, SAHs generally have a low level of thermal efficiency. In order to make them economically viable, the SAHs need to be improved. An artificial roughness element can be added to the bottom side of the surface to increase the rate of heat transfer. An improved version of SAHs that are roughened can achieve higher heat-transfer properties than their plain counterparts. This benefit can be attributed to the different surface patterns and shapes that are utilized in the design of the SAHs. The paper presents the findings of a number of studies that are connected to this technique. The study aims to identify the best suited roughness components for solar air ducts that can meet the different requirements under different operating conditions. The findings of this study can also be used to select the best suited ribs for solar air duct systems. In addition to this, a discussion is held on the most important aspects that contribute to the enhanced heat transfer performance of roughened SAH.