Chilton-Colburn analogies

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... 

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... 

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... 

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... 

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... 

Another concept sometimes used as a basis for comparison and correlation of mass transfer data in columns is the Chilton-Colburn analogy (35). This semi-empirical relationship was developed for correlating mass- and heat-transfer data in pipes and is based on the turbulent boundary layer model... 

Vb /(1 — x )> to be taken at liquid feed temperature yB/yB = saturation of solvent in feed gas ff0G ffG q the height of a gas phase heat transfer unit. (The FfOGs are computed from equation 54 the individual heights of a transfer unit for the solvent and for heat may be estimated from HGA and fiLA using the Chilton-Colburn analogy. The m in equation 54 is to be evaluated at the temperature of the liquid feed.) Reprinted by permission (45). 

FIGURE 14-47 When the friction or heat transfer coefficient is known, the mass transfer coefficient can be determiued directly from the Chilton-Colburn analogy. 

The Chilton-Colburn analogy has been obserx ed to hold quite well in laminar or turbulent flow over plane surfaces. But this is not always the case for internal flow and flow over irregular geometries, and in such cases specific relations developed should be used. When dealing with flow over blunt bodies, it is important to note that/in these relations is the skin friction coefficient, not the total drag coefficient, which also includes tlie pressure drag. 

Assumptions 1 The low mass flux conditions exist so that the Chilton-Colburn analogy between heat and mass transfer is applicable (v/ill be verified). 2 Both air and naphthalene vapor are ideal gases. 

Analysis Utilizing the Chilton-Colburn analogy, the surface temperature of the drink can be determined from Eq. 14-92,... 

SOLUTION Spray paint cans are temperature tested by submerging them in an uncovered hot water bath. The rates of heat loss from the top surface of the bath by radiation, natural convection, and evaporation are to be determined. Assumptions 1 The low mass flux conditions exist so that the Chilton-Colburn analogy between heat and mass transfer Is applicable since the mass fraction of vapor in the air is low (about 2 percent for saturated air at 300 K). 2 Both air and water vapor at specified conditions are ideal gases (the error involved in this assumption is less than 1 percent). 3 Water is maintained at a uniform temperature of 50°C. 

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