Abstract: An experimental study
of natural convection heat transfer in vertical annular cylinders embedded with
porous medium at constant wall temperature has been undertaken. Two stainless
steel test sections of different aspect ratios were employed. Experiments are
designed adopting factorial design. The factors
considered in the study are temperature, aspect ratio, radius ratio and power
supply. All the main factors were found to have significant effect on Nusselt
number while all the interaction factors except have been found to have
insignificant effect on it. The modified Rayleigh number is found to be
influenced by temperature, aspect ratio, and radius ratio only. All the four
factors and their interactions were found to affect the heat transfer
coefficient significantly. Only temperature has significant effect on viscous
dissipation. Nusselt number is found to increase with increasing radius ratio
and Rayleigh number but decrease with increasing aspect ratio. Regression models
were developed to predict Nusselt number, modified Rayleigh number, heat
transfer coefficient and viscous dissipation.
Keywords and phrases: natural convection, vertical cylinder, factorial design.
