Numerical investigation on heat transfer enhancement of solar air heater using sinusoidal corrugations on absorber plate

Abstract

This paper presents the effect of sinusoidal profiled absorber plate on augmented heat transfer and corresponding thermo-hydraulic performance of solar air heater using three dimensional Computational Fluid Dynamics (CFD) simulation for the flow Reynolds number ranging between 4,000 and 24,000. The effect of variation of design parameters of corrugated absorber plate such as the non-dimensional wavelength and aspect ratio on the thermo-hydraulic performance is brought out. The aspect ratio is varied between 1.5 and 4.0 while the normalized wavelength is varied between 1.0 and 6.0. The study reveals that the presence of sinusoidal corrugations provides increased flow disturbances leading to considerable enhancement in heat transfer. It is found that the use of lower values of non-dimensional wavelength and aspect ratio leads to higher thermal efficiency. The average increase in thermal efficiency is about 12.5% as compared to the base model for the configuration having an aspect ratio of 1.5 and non-dimensional wavelength of 1.0. In terms of effective efficiency, the sinusoidal corrugations are found to be highly effective at lower flow rate conditions and generally have a relatively narrow useful operating range of flow Reynolds number. The aspect ratio and non-dimensional wavelength have significant influence on the effective efficiency. The pumping power requirement is generally found to be relatively higher as compared to the base model owing to increased flow obstruction by the corrugations.