Transient Thermal Analysis of a Double Duct Solar Roof Chimney Coupled With a Scaled Room

This research presents a detailed transient experimental and computational study of heat transfer and airflow in a scaled room linked with a double-duct vertical roof solar chimney (SC). The analysis was made in the coupled system, varying the heat flux supplied to the roof SC absorber during the day. Experimental temperature profiles were obtained at six different depths and heights, the empirical heat transfer coefficient was computed for the SC absorber, and the variation of air changes per hour was determined. A good agreement between experimental and numerical temperature profiles and average Nusselt number (Nut) is shown in the latter of average difference of 3.41%. The validated computational model was used to analyze the effect of the transient heating of the SC on temperature fields and flow patterns in the thermal system. Almost symmetrical temperature and y-velocity profiles are formed in the ducts at different hours of the day, with thermal boundary layers of about 4 mm. Correlations of the Nusselt number and air changes per hour (ACH) are provided as a function of the modified Rayleigh number.