Paper Contents
Abstract
Artificial roughness in the form of repeated ribs is one of the effective way of improving the performance of a solar air heater ducts. Various studies have been carried out to determine the effect of different artificial roughness geometries on heat transfer and friction characteristics in solar air heater ducts. The objective of this paper is to review various studies, in which different artificial roughness elements are used to enhance the heat transfer coefficient with little penalty of friction factor. The present paper is a review of research work on heat transfer enhancement in a rectangular duct with rib turbulators. Detailed information about the heat transfer and flow characteristics in ribbed ducts is very important in proper designing of rectangular ducts, heat exchangers and cooling systems of gas turbine engines. The application of rib turbulator in the form of fine wires of different shapes has been recommended to enhance the heat transfer coefficient by several investigators. It has been found that the main thermal resistance to the convective heat transfer is due to the presence of laminar sub layer on the heat-transferring surface. The ribs break the laminar sub layer and create local wall turbulence due to flow separation and reattachment between consecutive ribs, which reduce the thermal resistance and greatly enhance the heat transfer. However, the use of rib turbulator results in higher friction and hence higher pumping power requirements.
Copyright
Copyright © 2023 Suraj Kumar. This is an open access article distributed under the Creative Commons Attribution License.
