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 in the transportation sector such as gas turbines, heat exchangers, various cooling devices, and combustor liners. The extensive research to enhance the heat transfer rate in various sectors has 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 reduce the production of emission, (iv) to develop new green technologies, (v) to lower energy prices for the consumer. The heat transfer in various sectors has been carried out by adopting three different ways (i) increasing the surface area of the heat transfer systems, (ii) enhancing the fluid properties, (iii) by adding extra surface on the heat transferring surface. This article aims to 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 includes various types of rib tarbulators, fins, and dimples used for heat transfer enhancement of gas turbine blades of the power plant, combustion liners as well as solar air heaters. The physical mechanism responsible for heat transfer enhancement in various artificial roughness elements has been discussed and compared. The challenges and difficulties associated with the heat transfer techniques have been discussed. The parameters such as dimple depth, channel height to dimple imprint diameter, pitch, the density of artificial roughness element, arrangement of artificial 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 further enhancement 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 some other relevant thermal systems.