Colburn /-factor

From these unique functions of RCp the numerical value of jh and jd can be calculated. From the definitions of the Colburn factors, the transfer coefficients hg and kg can be evaluated since all other variables are physical properties, independent of flow. For correctness, the physical properties... 

Pierce proposes and illustrates good agreement between the test data and the correlation for a smooth continuous curve for the Colburn factor over the entire range of Reynolds numbers for the laminar, transition, and turbulent flow regimes inside smooth tubes ... 

J4 = Colburn factor given by equation proposed by Pierce length of tube, m = Prandtl number Reynolds number = velocity, m/sec p = dynamic viscosity, sPa (pascal-sec) p = density, kg/m b = evaluate at bulk temperature w = evaluate at wall temperature kg = kilogram... 

This can be written in terms of correlations for the coefficients of heat and mass transfer. The Chilton-Colburn factors are... 

In packed beds, mass transfer coefficients are often correlated by means of a Chilton—Colburn factor, Ju, analogous to their Jh heat transfer (Sect. 4.4.4)... 

Chilton-Colburn factor), (Sherwood number), (Schmidt number), (Reynolds number). 

The mass transfer coefficient kc is estimated by the correlation of dimensionless j, or Colburn factor, with Sherwood number (Sh), Schmidt number (Sc), and void fraction as described by Cookson (36). 

This heat-transfer correlation is in terms of the Colburn /-factor, defined as... 

Individual heat-transfer coefficient, W/m -°C or Btu/ft -h-°F Mass flux relative to a plane of zero velocity, kg mol/m -s or lb mol/ft -h J, Jg, of components A and B, respectively average value of component A, caused by turbulent action Colburn factor for heat transfer, hlCpG) Cgfifkfl, dimensionless Colburn j fector for mass transfer, (ky MlG lpD Y, dimensionless Overall mass-transfer coefficient in gas phase, kg mol/m -s-unit mole fraction or lb mol/ft -h-unit mole fraction Ky, new value in Example 21.5... 

FIGURE 17.55 Colburn factors and friction factors for ideal crossflow in tube bundles, 90° inline layout [106]. 

Here / h is the Chilton-Colburn factor for mass transport, i th mass transport coefficient, u the linear flow velocity. Sc = V/D is the Schmidt number and / is the friction coefficient. As a consequence, a higher shear stress also means a higher mass transport rate and vice versa. 

The literature abounds with references that are related to the study of convective heat transfer in packed beds. Although these studies have been primarily developed for ambient or warmer temperatures, the correlations that have been developed in terms of the Colburn factor or the Nusselt number versus Reynolds number are usually also applicable to low-temperature systems. For example, the heat transfer coefficient and pressure drop per unit length for a regenerator with a randomly stacked spherical-particle packing can be estimated from... 

Frequently the mass transfer coefficient is expressed as a Chilton-Colburn factor, which is defined as... 

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