CFD Analysis of Heat Transfer and Fluid Flow in Flat Plate Natural Convection Solar Air Heater
Abstract
A parametric study of flat plate natural convection solar air heater was conducted using CFD Analysis. A solar air heater with single glass cover flat plate solar collector with air gap is selected for the study under the climatic condition of Addis Ababa, Ethiopia. The study aims at finding optimum inclination angles taking into account the seasonal variation, finding optimum air gap depth, and characterizing the effect of incident radiation magnitude and ambient temperature on the collector output. For modeling the system, the governing continuity, momentum and energy equations were considered in multi dimensions. The coupled governing equations were simplified by neglecting effect of density in the continuity equation and by approximating the density difference in momentum equation as a linear function of temperature. The modeling was conducted by the CFD Software Fluent. By varying the inclination angle, it was found that the optimum inclination angle that gives maximum energy gain with better mass flow rate and temperature rise was 450 for November while it was 150 for May. The two angles of inclinations represent the two extreme seasons of the year. It was also found that a collector with 50mm channel depth yields better exit velocity and temperature and maximum energy gain but comparable with 60 mm and 70mm depth for 2 m long collector. The outputs of the simulation are comparable with the already available reported experimental results found in literatures.