A review on effect of various artificial roughness on heat transfer enhancement in a channel flow

Abstract

Heat transfer improvement plays a vital role in several industrial applications as well as inthe transportation sector such as gas turbines, heat exchangers, various cooling devices, andcombustor liners. The extensive research to enhance the heat transfer rate in various sectorshas been carried out to achieve the objectives such as (i) to increase the system efficiency, (ii)to reduce thermal load, (ii) to reduce consumption of non-renewable energy, (iii) to reducethe production of emission, (iv) to develop new green technologies, (v) to lower energy pricesfor the consumer. The heat transfer in various sectors has been carried out by adopting threedifferent ways (i) increasing the surface area of the heat transfer systems, (ii) enhancing thefluid properties, (iii) by adding extra surface on the heat transferring surface. This article aimsto deliver a comprehensive review of the current research on heat transfer enhancement techniques by using artificial roughness elements such as rib tarbulator, fin, and dimple. It includesvarious types of rib tarbulators, fins, and dimples used for heat transfer enhancement of gasturbine blades of the power plant, combustion liners as well as solar air heaters. The physicalmechanism responsible for heat transfer enhancement in various artificial roughness elementshas been discussed and compared. The challenges and difficulties associated with the heattransfer techniques have been discussed. The parameters such as dimple depth, channel heightto dimple imprint diameter, pitch, the density of artificial roughness element, arrangement ofartificial roughness, relative roughness pitch, relative roughness height, angle of attack on flow,mass flow rate, Reynolds number on thermal performance, thermohydraulic performance,flow structure, friction characteristics have been studied and compared. From the comprehensive review, it may be recommended that the teardrop shape dimple can be used for furtherenhancement of heat transfer as compared to other artificial roughness elements. In the future,this teardrop may be used to enhance the heat transfer in the solar thermal system and someother relevant thermal systems.