Vol. 3, Issue 6, Part G (2017)

Abstract
Technique of providing artificial roughness on underside of absorber plate surface is an important practice to enhance heat transfer of air flowing in air heater duct. In the past years various types of rib geometries have been designed and used to investigate heat transfer and friction features of air heater. The design of the roughness shape and arrangement is very important to optimize the heat transfer parameters. The roughness parameters and ribs arrangement are accountable to vary the flow pattern. This flow pattern primarily governs the heat transfer mechanisms. In the present article, a critical review on various artificial roughness elements available in literature has been carried out and the effects of the roughness patterns are discussed. A comparison study of thermohydraulic performance of different roughness elements has also been underlined.