Effects of Concentration on Free Convective Heat Transfer in Glycerol

Abstract

In a gravitational field, density differences can drive fluid motion in a process known as free convection. Free convection and changing concentration of glycerol are related through the concept of density-driven flow. The effects of concentration on free convective heat transfer is studied for glycerol for the range of Rayleigh numbers 10^-6 ≤ Ra ≤ 10⁹ and Prandtl numbers 6.66 ≤ Pr ≤ 11630. Various appropriate correlations due to Churchill & Chu, Raithby & Holland, Kuehn & Goldstein, Fand et al and Jaluria are used to evaluate the free convective Nusselt number in glycerol as a function of Rayleigh number with fixed concentrations of 0%, 20%, 40%, 60%, 80% and 100%. Additionally, the Rayleigh number is kept fixed at three regimes of 10^-6, 10⁰ and 10⁹ and the free Nusselt number is evaluated as a function of concentration of glycerol. A maximum of 42% increase in Nusselt number with concentration is observed from the Fand et al correlation