A Numerical Study of the Effect of Rectangular Shaped Ribs Organized in Different Patterns on the Thermal Performance of a Solar Air Heater

Abstract

Abstracts: A solar air heater is a useful device that can be used to raise the temperature of a roomby capturing heat from solar energy This paper is about a two-dimensional numerical study that was done to predict the influence of transverse rectangular cross-sectioned ribs on the convective heat transfer properties of a solar air heater. It is a rectangular duct with an absorber plate on top, and heat only falls on the top of the absorber plate. The thermal performance of air flowing through the rectangular duct is significantly altered when different shapes and orientations of ribs/baffles are introduced just beneath the absorber plate. A comparison was made between the results of thin (high aspect ratio) and square ribs arranged in three patterns, namely, single wall arrangement ,staggered arrangement and in-line arrangement on two opposite walls. The Nusselt number variation with Reynolds number range 4000-25000 was checked at a fixed rib pitch (p) and height (e) values. Computational fluid dynamics (CFD) simulations were performed using commercially available software ANSYS FLUENT v15.0..The results revealed that the thin ribs yielded better performance than the squared ones. Out of the three arrangements, the best thermal performance was given by thin inline ribs whose convective heat transfer coefficient was 1.93 times smooth duct’s convective heat transfer coefficient.