Chilton-Colburn

Chilled surface drying ChiUproofing Chilton-Colburn analogy Chimeramycins Chimeras... 

The penetration theory predicts that should vary by the square root of the molecular difriisivity, as compared with film theoiy, which predicts a first-power dependency on D. Various investigators have reported experimental powers of D ranging from 0.5 to 0.75, and the Chilton-Colburn analogy suggests a 2/3 power. 

Chilton-Colburn analogies, Ns = 1-0, (gases), f = drag coefficient. Corresponds to item 5-21-F and refers to same conditions. 8000 < Nr < 300,000. Can apply analogy, jo =//2, to entire plate (including laminar portion) if average values are used. 

U. Tubes, turbulent, smooth tubes, Chilton-Colburn analogy... 

On occasion one will find that heat-transfer-rate data are available for a system in which mass-transfer-rate data are not readily available. The Chilton-Colburn analogy provides a procedure for developing estimates of the mass-transfer rates based on heat-transfer data. Extrapolation of experimental or Jh data obtained with gases to predict hquid systems (and vice versa) should be approached with caution, however. When pressure-drop or friction-factor data are available, one may be able to place an upper bound on the rates of heat and mass transfer, according to Eq. (5-308). 

For systems other than air-water vapor, the value of h /k c, may differ appreciably from unity, and the wet-bulb and adiabatic-saturation temperatures are no longer equal. For these systems the psychrometric ratio may be obtained by determining h /k from heat- and mass-transfer an ogies such as the Chilton-Colburn analogy [Ind. Eng. Chem., 26, 1183 (1934)]. For low humidities this analogy gives... 

Equations (13-115) to (13-117) contain terms, for rates of heat transfer from the vapor phase to the hquid phase. These rates are estimated from convective and bulk-flow contributions, where the former are based on interfacial area, average-temperature driving forces, and convective heat-transfer coefficients, which are determined from the Chilton-Colburn analogy for the vapor phase and from the penetration theoiy for the liquid phase. 

Several analytical studies have sought to extend the application of the basic method of Chen. For fluids of Prandtl number different from unity, Bennett and Chen (1980) extended the analysis by a modified Chilton-Colburn analogy to give... 

For turbulent flow, we shall use the Chilton-Colburn analogy [12] to derive an expression for mass transfer to the spherical surface. This analogy is based on an investigation of heat and mass transfer to a flat plate situated in a uniform flow stream. At high Schmidt numbers, the local mass transfer rate is related to the local wall shear stress by... 

The Chilton-Colburn analogy can be also used to estimate the local mass transfer rate in laminar flow where the wall shear stress is related to the azimuthal velocity gradient by... 

An equally important objective of these turbulent mass-transfer measurements was the establishment of the exact dependence of k on the Reynolds number. The well-known empirical Chilton-Colburn equation for turbulent transfer (C3) predicts that... 

Hubbard and Lightfoot (HI la) earlier reported a Sc,/3 dependence on the basis of measurements in which the Schmidt number was varied over a very large range. The data did not exclude a lower Reynolds number exponent than 0.88, and reaffirmed the value of the classical Chilton-Colburn equation for practical purposes. Recent measurements on smooth transfer surfaces in turbulent channel flow by Dawson and Trass (D8) also firmly suggest a Sc13 dependence and no explicit dependence of k+ on the friction coefficient, with Sh thus depending on Re0,875. The extensive data of Landau... 

The most convenient mathematical form for correlating mass transfer data is in terms of the well-known Chilton-Colburn (75, 76) jD factor. 

The temperature difference is thus directly proportional to the heat of reaction per mole of diffusing species and to the difference in concentration between the bulk fluid and the exterior surface of the solid. If we recognize that jD jH from the Chilton-Colburn relation, and that the ratio of Prandtl and Schmidt numbers is close to unity for many simple gas mixtures, the previous relation may be approximated as... 

For the conditions cited, it was shown that jD was 0.235 and, by the Chilton-Colburn analogy Jh = 0.235. From the definition of the heat transfer factor jH, it follows that... 

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

Chili peppers, 23 163, 164 Chili powder, 23 164 adulterated, 23 163 Chilled castings, tellurium in, 24 424 Chilled surface drying, in bar soap manufacture, 22 750-751 Chill proofing enzymes, 10 294 Chilton-Colburn analogy, 1 47 Chimeric embryos, 12 458... 

The correlation due to Kelly (1965) indicates relatively modest coefficients below 200Wm-2K i for particles up to about 8mm in diameter. The equations proposed by Vazquez and Calvelo, based on the Chilton-Colburn j-factor model, suggest rather higher coefficients of fhe order of 300-400for the fluidization of particles up to 20mm in diameter at gas velocities reasonably in excess of those required for minimum fluidization. 

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)... 

In some kinds of equipment, data only on mass transfer rates may be known. From these, on the basis of the Chilton-Colburn analogy, corresponding values of heat transfer rates can be estimated. 

This method takes advantage of the rough proportionality between heat and mass transfer coefficients according to the Chilton-Colburn analogy, and employs only heat transfer coefficients for the process of condensation from a mixture. The sensible heat of the vapor is transferred through the gas film... 

To characterize the mass transport, Wilson and Geankopolis (1966) used the /-factor according to Chilton-Colburn (Bird et al., 2003) which is defined as follows... 

The heat transfer coefficient can be calculated from the mass transfer coefficient by means of the Chilton-Colburn analogy, also called the factor analogy. The factors are defined as ... 

In case of perfect Chilton-Colburn analogy, both factors are equal ... 

The two major modelling approaches based on either boundary layer approximations or well developed laminar flow have also been applied to the barrel reactor. Dittman (11) used a Chilton-Colburn analogy for flow over a flat plate to predict Si growth... 

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