Document Type


Date of Award

Spring 5-31-1959

Degree Name

Master of Science in Chemical Engineering - (M.S.)


Chemical Engineering

First Advisor

Peter L. Silveston

Second Advisor

Joseph Joffe

Third Advisor

C. L. Mantell


The rate of heat transfer due to natural convection in confined, horizontal, fluid layers can be expressed by equations involving the dimensionless parameters Nusselt No., Rayleigh No., and Prandtl No., where Rayleigh No. equals the product of Grashof and Prandtl Nos.

Statistical correlation by stepwise multiple regression of experimental data obtained from four different investigators, on both gases and liquids, yields three separate equations corresponding to three distinct regimes of convection. The total range spanned by the data is from the onset of convection to Rayleigh = 109.

The equations are Regime Ra Range Equation Std. Error of Estimate Initial 1600-3000 Nu = 0.00238(ra).816 ± 4% Laminar 3000-105 Nu = 0.221 (ra).256 ± 7% Turbulent 105-109 Nu = 0.0891(ra).316 (pr).0853 ± 12%

The standard error of estimate, which is the probable error in the prediction of Nu from a regression equation, is obtained for each regime. A very high degree of accuracy was obtained for all correlations.



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