Stanton numbers

The dimensionless relations are usually indicated in either of two forms, each yielding identical resiilts. The preferred form is that suggested by Colburn ran.s. Am. In.st. Chem. Eng., 29, 174—210 (1933)]. It relates, primarily, three dimensionless groups the Stanton number h/cQ, the Prandtl number c Jk, and the Reynolds number DG/[L. For more accurate correlation of data (at Reynolds number <10,000), two additional dimensionless groups are used ratio of length to diameter L/D and ratio of viscosity at wall (or surface) temperature to viscosity at bulk temperature. Colburn showed that the product of the Stanton number and the two-thirds power of the Prandtl number (and, in addition, power functions of L/D and for Reynolds number <10,000) is approximately equal to half of the Fanning friction fac tor//2. This produc t is called the Colburn j factor. Since the Colburn type of equation relates heat transfer and fluid friction, it has greater utility than other expressions for the heat-transfer coefficient. 

Effects of Temperature on tiQ and tii The Stanton-number relationship for gas-phase mass transfer in packed beds,... 

The airflow pattern in rooms ventilated by linear attached jets with L/H ratio greater than that for effectively ventilated rooms was studied by Schwenke and Muller. The results of their air velocity measurements ami visualization studies indicate that there are secondary vortexes formed downstream in the room and in the room corners. The number of downstream vortexes and their size depend upon the room length (Fig. 736b). Mas,s transfer between the primary vortex and the secondary vortex depends upon the difference in characteristic air velocities in the corresponding flows (/, and Ui and can be described using the Stanton number, St . ... 

The external Stanton number is assumed not to vary over the range of conditions being studied. Considering ( pg/Cp. )(A.,gM,g)S/g as a constant C, Eq. (A4) then becomes... 

An alternative equation which is in many ways more convenient has been proposed by COLBURN 16 and includes the Stanton number (St = h/Cppu) instead of the Nusselt number. This equation takes the form ... 

Units in SI system Si Stanton number h/Cf,pu Dimensions depend ort order of reaction. Suffixes 0 Value in bulk of phase 1 Phase 1 2 Phase 2 A Component A B Component B AB Of A in B b Bottom of column equilibrium with bulk of other phase G Gas phase / Interface value. L Liquid phase u Overall value (for height and number of transfer units) value in bulk of phase i Top of column Dimensions in in M. N, 1. T. 

The simple Reynolds analogy gives a relation between the friction factor R/pu] and the Stanton number for heat transfer ... 

This expression will give the point value of the Stanton number and hence of the heat transfer coefficient. The mean value over the whole surface is obtained by integration. No general expression for the mean coefficient can be obtained and a graphical or numerical integration must be carried out after the insertion of the appropriate values of the constants. 

Similarly, substitution may be made from equation 11.39 into equation 12.130 to give the point values of the Stanton number and the heat transfer coefficient, thus ... 

Fig. 6.9 Dependence of the boiling Stanton number at ONB point. Experiments by Kennedy et al. (2000)...

It is the product of the bubble Reynolds and the liquid Prandtl number divided by the boiling Nusselt number (Nu,), which is equivalent to the Stanton number in single-phase convective heat transfer. 

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