Heat Transfer With Change Of Phase 521
FIG. 5-9 Chart for determining film coefficient hm for film-type condensation of pure vapor, based on Eqs. 5-88 and 5-93. For vertical tubes multiply hm by 1.2. If 4r pf exceeds 2100, use is in U.S. customary units to convert feet to meters, multiply by 0.3048 to convert inches to centimeters, multiply by 2.54 and to convert British thermal units per hour-square foot-degrees Fahrenheit to watts per square meter-kelvins, multiply by 5.6780. FIG. 5-9 Chart for determining film coefficient hm for...
P 525o
T Use with log mean concentration difference. Based on end of extraction column. No continuous phase resistance. kL,d,osc in cm s, v, _ drop velocity relative to continuous phase. Q. Single liquid drop in immiscible liquid, range rigid to fully circulating Rigid drops 104 lt NPec lt 106 N-hc,rigid _ K _ 2.43 0.774N 5Nsc33 Circulating drops 10 lt NRe lt 1200, 190 lt N-c lt 241,000, 103 lt NPe,c lt 106 N-h,c,fully circular _ 5 jNP' c N-k,c- N ,rigid _ 1 exp 4.18 X 10-3 NPe42 E Allows for slight...
Info Yyx
T,S Use arithmetic mole fraction difference. Fits some, but not all, data. Low mass transfer rate. Md mean molecular weight of dispersed phase tf formation time of drop. Ld mean dispersed liquid phase M.T. coefficient kmole s m2 mole fraction . E Use arithmetic mole fraction difference. Based on 23 data points for 3 systems. Average absolute deviation 26 . Use with surface area of drop after detachment occurs. u0 velocity through nozzle a interfacial tension. T Use arithmetic mole fraction...
Info Tmq
13.3 x 10-8 T147 HB10' -a791 V 71 n II -0.27 - 0.38 m -0.05 0.1 m Pr References are listed on pages 5-7 and 5-8. References are listed on pages 5-7 and 5-8. Random comparisons of predictions with 2.26 versus 2.6 show no consistent advantage for either value, however. It has been suggested to replace the exponent of 0.6 with 0.7 and to use an association factor of 0.7 for systems containing aromatic hydrocarbons. These modifications, however, are not recommended by Umesi and Danner. Lees and...
824
For laminar flow in vertical tubes a series of charts developed by Pigford Chem. Eng. Prog. Symp. Ser. 17, 51, 79 1955 may be used to predict values of ham. Annuli Approximate heat-transfer coefficients for laminar flow in annuli may be predicted by the equation of Chen, Hawkins, and Solberg Trans. Am. Soc. Mech. Eng., 68, 99 1946 Limiting Nusselt numbers for slug-flow annuli may be predicted for constant heat flux from Trefethen General Discussions on Heat Transfer, London, ASME, New York,...
L
Critical surface tensions, Oc 61 ceramic , 75 steel , 33 polyethylene , 40 PVC , 56 carbon dynes cm. Graphical comparison with data in Ref. 126. E From experiments on desorption of sparingly soluble gases from water. Graphs Ref. 146 , p. 606. Equation is dimensional. A typical value of n is 0.3 Ref. 91 p. 633 has constants in kg, m, and s units for use in 5-28-A and B with 0g in kgmole s m2 and 0l in kgmole s m2 kgmole m3 . Constants for other packings are given by Refs. 121 p. 187 and 161, p....
Nature Of Thermal Radiation
Consider a pencil of radiation, defined as all the rays passing through each of two small widely separated areas dA1 and dA2. The rays at dA1 will have a solid angle of divergence dQ.i equal to the apparent area of dA2 viewed from dAi, divided by the square of the separating distance. Let the normal to dA1 make the angle 01 with the pencil. The flux density q energy per time-area normal to the beam and per unit solid angle of its divergence is called the intensity I, and the flux dQ1 energy per...
1 Wke
where D B diffusivity based on molarity rather than normality of dilute salt A in solvent B, cm2 s. The previous definitions can be interpreted in terms of ionic-species diffusivities and conductivities. The latter are easily measured and depend on temperature and composition. For example, the equivalent conductance A is commonly tabulated in chemistry handbooks as the limiting infinite dilution conductance Ao and at standard concentrations, typically at 25 C. A 1000 KJC X Ao f C , cm2 ohm...
Na
vJa Ca x nvi mJa xa x n ' In each case, the term containing the summation accounts for conveyance, which is the amount of component A carried by the net flow in the direction of diffusion. Its impact on the total flux can be as much as 10 percent. In most cases it is much less, and it is frequently ignored. Some people refer to this as the convective term, but that conflicts with the other sense of convection which is promoted by flow perpendicular to the direction of flux. Mutual Diffusivity,...
K K
Effective interfacial mass transfer area per unit volume Cross-sectional area of vessel Constant see Table 5-28-I See a Concentration P RT for an ideal gas Concentration of component i XiC at gas-liquid interface Self-diffusivity Da at Xa 1 Mutual diffusivity Mutual diffusivity at infinite dilution of A in B Effective diffusivity within a porous solid pD T Knudson diffusivity for gases in small pores Activation energy for surface diffusion Molar gas-phase mass flux Heat transfer coefficient...