7k 2 ]1/2 ]4/, (14)
where Equations (10) and (14) reduce to the form of Equations (3) and (41, only when the additive constants in Equations ( 5) and ( 6) (0.6 and 2.0, respectively) are negligible when compared to the term containing the Grashof number. Equations ( 10) and (14) are, therefore, somewhat more general than Equations ( 3) and ( 4 ) . Simmons (1976) used Equation ( 2 ) in determining the critical radius for combined convection and radiation. However, the algebraic simpli2cation that resulted from the use of Equation ( 2 ) in his analysis does not occur with the use of Equations ( 7) and ( 8) . Consequently, the use of these more general convective heat transfer coefficient correlations in Simmons' analysis does not produce an explicit solution for the critical radius in the case of combined convection and radiation. NOTATION C1, Cz, Cs, C4 = constants in Equations ( 7) and ( 8)
Equation (2) k kf m, n = constants in Equation ( 2 ) (k 0) Pr = Prandtlnumber q = heat transfer (W) r To T , = thermal conductivity of object (Wm-l "C-I) = thermal conductivity of surrounding fluid (Wm-' "C-1) = radius of the object (m) = surface temperature of the object ("C) = fluid temperature ( "C) LITERATURE CITED Balmer, R. T., and A. D. Strobusch, "Critical Size of Newborn
Homeotherms," J. Appl. Phys. 42, 571 (1977). [Note that Equations (31), (37), ( 38), (39), (40), and ( 4 2 ) are incorrect as a result of an error in Equation (31). This error has been corrected in the present note.]