Role of Artificial Roughness in Solar Air Heaters

Solar air heaters have substantial potential for use in building space heating and for drying of agricultural products. Barriers to their wider use include lack of awareness of the cost-effectiveness of solar air heating and solar drying systems, the lack of technical information, and the lack of local practical experience. The growing number of installations and commercial applications are beginning to overcome these barriers. Nevertheless, improvements in design and technology may be able to improve efficiency and the scope for application. Heat transfer efficiency is one potential area of improvement. Here we address the potential for artificial roughness to improve heat transfer efficiency in solar air heaters. Specifically, the effect of v-shaped ribs are examined and shown to be superior to inclined ribs and to flat surfaces. Adoption of artificial roughness, as well as other design improvements, has the potential to increase the efficiency and range of application of solar air heaters.