Abstract
The objectives of this paper are to study the free convection in the air gap of a 45-degree inclined roofsolar chimney and to experimentally determine the correlation of Nusselt number (Nu). The experiment wascarried out in an open-ended air gap between the corrugated roof tile and the gypsum board attachedto a detached building with the inner width and length of 18 and 160 cm. located outdoor under the hotand humid climate. The surface temperatures of the corrugated roof tile are between 35-45°C duringthe daytime of May and June, exposed to the solar intensity of 200-1,000 W/m2. The data reduction usinglinear regression analysis yields linear relationships of mean bulk temperature, temperature difference of airat inflow and outflow, heat transfer rate and mass flow rate of the solar chimney against the temperaturedifference of hot roof surface and the mean bulk temperature (Th–Tb). Employing the derived linearrelationships, the correlation between the Nusselt number, Nus, Rayleigh number, Ras, and the aspectratio (air gap/length) are derived for 3°C≤Th–Tb≤ 9°C as Nus = 1.444⋅ [(S/L) Ras sin 45°] 0.249. It is the correlationthat could be used for determination of mean convection heat transfer coefficient of the roof solar chimney withsimilar geometry applied in the hot and humid climate, provided that it is in the same range of Ra value and thesame range of Ra (S/L) value.
Abstract by the authors, reproduced under the CC BY-NC-ND 4.0 licence. Original publication via the link below.