Numerical study on natural convection between double glasses top cover of a flat plate solar collector

Double glasses cover typically used to decrease top heat loss of a flat plate solar collector. However, reported studies show that the top heat loss of a flat plate solar collector is very significant in comparison with other losses. The present work deals with a numerical study on natural convection between double glasses cover of flat plate solar collector. The main objectives are to investigate the heat transfer characteristics of the covers and to propose heat transfer coefficient correlation. Two-dimensional governing equations and boundary conditions are developed. The governing equations are discretized into linear equation system based on finite volume method. The effects of the aspect ratio (AR) and Rayleigh number are explored and fluid flow in the enclosure are plotted. The results show that AR affects fluid flow and heat transfer characteristics significantly. A correlation proposed by the previous researcher is recommended to calculate top heat loss.