George Thodos

Vapor—liquid equilibrium measurements for the n-pentane—methanol system at 372.7, 397.7 and 422.6 K

Abstract P-x-y measurements have been obtained for the n-pentane—methanol system along the 372.7, 397.7 and 422.6 K isotherms. For these isotherms, this system exhibited maximum pressure azeotropic behavior. No other isothermal vapor—liquid equilibrium information exists in the literature for this sytem. The experimental data were correlated with the four-suffix Margules equation. The temperature dependence of the three parameters of this Margules equation was established for temperatures ranging from 372.7 to 422.6 K. However, attempts to extrapolate these relationships to lower temperatures, using excess enthalpy data available in the literature, proved inadequate for the prediction of the isobaric vapor—liquid equilibrium measurements of Tenn and Missen (1963) . Auxiliary expressions have been developed relating azeotropic pressure and composition to temperature. These expressions are valid for temperatures ranging from 303.25 to 422.6 K.

Mass transfer in gas-fluidized beds: measurement of actual driving forces

Abstract Concentration profiles of naphthalene vapors were measured in the flow of air through fluidized beds of naphthalene spheres. Seven different sizes of spheres were used in this study and ranged from 0.02480 to 0.2000 cm. To avoid saturation conditions in the air leaving the bed, the naphthalene spheres were diluted in a matrix of inert beads (styrene divinylbenzene copolymer) of the same size and density as the naphthalene spheres. The established concentration profiles were graphically integrated to produce from them actual mass transfer coefficients. These transfer coefficients were then used to calculate j d , mass transfer factors, for this fluidized bed system and also the product j d Re f which has been found to depend on Re mf , the corresponding Reynolds number at minimum fluidization conditions. Actual driving forces, (Δ p ) a were normalized with the corresponding log-mean values, (Δ p ) m , to produce the driving force factor, F = (Δ p ) a /(Δ p ) m . This factor has been correlated with the parameters of the system and can be predicted with a certainty of 10.5%.

Analogy between mass and heat transfer in beds of spheres: Contributions due to end effects

Mass- and heat-transfer data obtained by the vaporization of water from porous spheres were used to calculate j-factors. Strict adiabatic conditions were employed for the attainment of solely fluid to particle transfer. Fixed beds of several void fractions were constructed using short lengths of fine rigid wire to hold the spheres in regular geometrical orientations. In addition, the entrance and exit effects were eliminated by extending the ends of each bed with layers of inactive solid plastic spheres. The resulting mass- and heat-transfer factors possessed a good correspondence indicating the existence of an analogy for these transfer processes. It was found that for the same Reynolds number the transfer factor,j, increased with the elimination of entrance and exit effects. The j-factors and the void fractions of the several beds, for which end effects were eliminated, produced with the Reynolds number the relationship, e1.19j = 0.539Re0.437 in the range 185 < Re < 8500. This relationship is somewhat higher than that resulting from the data of Gamson, Thodos and Hougen and definitely lower than that proposed in 1963 by Sen Gupta and Thodos. Explanations for these differences are advanced.

(Vapor + liquid) equilibrium behavior of (n-pentane + ethanol) at 372.7, 397.7, and 422.6 K

Abstract Isothermal (vapor + liquid) equilibrium measurements for (n-pentane + ethanol) have been made at 372.7, 397.7, and 422.6 K. Maximum-pressure azeotropic behavior was observed over the temperature range examined. The experimental results were correlated using the four-suffix Margules equation to represent the excess molar Gibbs free energy of the liquid phase. The three parameters of this model were established at each temperature using Barkers method. The results of this study have been combined with the limited information at atmospheric pressure available in the literature to develop empirical relations for the dependence of azeotropic composition and azeotropic pressure on temperature. These relations extend to the critical locus reported by McCracken et al. (J. Chem. Eng. Data1960, 5, 130). Dew- and bubble-pressures measured by McCracken et al. have been compared with corresponding values resulting from the present study in the temperature range 391 to 422.6 K. In these comparisons, deviations in pressure between the two investigations ranged from 1.2 to 33.2 per cent.

Vapor—liquid equilibrium measurements for the methanol—acetone system at 372.8, 397.7 and 422.6 K

Abstract A static high pressure equilibrium facility has been used to obtain P − x − y measurements for the methanol—acetone binary for the three isotherms 372.8, 397.7 and 422.6 K. These measurements show that maximum pressure azeotropic behaviour exists at each of these temperatures. The data obtained have been correlated satisfactorily using the three suffix Margules equation. A comparison has been made between the information resulting from this study and the high pressure data of Griswold and Wong. Parameters of the three suffix Margules equation have been correlated with temperature over the range 285–425 K using additional vapor—liquid equilibrium and excess enthalpy data available in the literature. These correlations have been used to predict isobaric behavior. Auxiliary expressions have been developed which relate azeotropic pressure and composition to temperature.

Thermal Conductivity of Argon in the Dense Gaseous and Liquid Regions

Thermal conductivities for argon in the dense gaseous state were determined at 6.2°, 20.7°, 25.0°, and 48.8°C for pressures up to 10 340 psia, using a coaxial cylindrical cell. These values were found to be in good agreement with thermal conductivities reported by others and when expressed as residual quantities, k—k*, unique relationships resulted with ρR and the (∂PR/∂TR)ρR. These relationships were independent of temperature and pressure and included both the dense gaseous and liquid states.The Enskog equation for the effect of pressure on thermal conductivity, k/k*=bρ[(1/bρχ)+(6/5)+0.7574bρχ],, has been applied to the data of this study and of others for the dense gaseous and liquid regions, to obtain values of b. These values were found to be independent of pressure and to depend upon temperature as follows: bρc=1.06/TR23. For these calculations, bρχ values were established from PVT data for argon. The experimental values obtained in this study were used to determine (k/ρ)min for each temperature, wh...

Mass-transfer factors from actual driving forces for the flow of gases through packed beds (0.1 < Re < 100)

Concentration profiles of naphthalene vapor were measured in the flow of air through packed beds of naphthalene spheres dispersed in a matrix of inert beads of styrene divinylbenzene copolymer. These profiles permitted the establishment of average actual driving forces, (Δp)α, used to obtain corresponding actual mass-transfer coefficients. Six different particle sizes ranging from 0.02480 to 0.2000 cm in diameter were used in a single reactor, 6.59 cm (2.59 in) in diameter. A plot of Jd-factor vs Reynolds number obtained from the data of this study was found to be linear on log-log coordinates which can be expressed in equation form as, Jd = 1.33/Re0.40 in the range investigated (0.1 < Re < 100). This relationship, which includes axial and radial dispersion contributions, differs from that of earlier studies in which the log-mean driving force, (Δp)m, was assumed to apply. The information of this study has been applied to the tank-in-series model to produce the dependence of Peclet number of Reynolds number, needed for the establishment of the actual mixing factor, defined as F = (Δ ρp)α(Δ ρp)m.

Thermal conductivity of mixtures in the dense gaseous state: The methane-carbon tetrafluoride system

Abstract Using a coaxial cylindrical cell, thermal conductivities were measured for gaseous methane, carbon tetrafluoride, and three of their mixtures. The nominal temperatures used were 60, 100, 130, and 160°C and pressures from approximately 3 atm up to 680 atm. The experimental values when correlated as residual thermal conductivities, k − k∗, against density showed a slight temperature dependence which decreased with increasing methane concentrations. When this temperature dependence was accounted for, the thermal conductivities of methane, carbon tetrafluoride, and their three mixtures were found to be consistent with the method outlined in the literature which relates (k − k∗)λz5c with ϱR. The experimental values obtained in this study for the methane-carbon tetrafluoride system produced with reduced density a unique relationship which reproduces 215 experimental values with an average deviation of 2.55%.

Ion exchange kinetics: the removal of oxalic acid from glycol solutions

Abstract The kinetics for the removal of oxalic acid from glycol solutions through the use of the ion exchange resin, Permutit SKB, has been studied. The mechanism was found to be controlled by the combined resistances of both the liquid and resin phases. The equilibrium relationship of the system was determined experimentally and the results were found to fit a Freundlich type of equation. Liquid film mass transfer coefficients were established and correlated with the variables of this system. Simple experimental procedures together with the diffusion equation enabled the determination of the diffusion coefficient for the resin phase. This information in conjunction with the proper mathematical developments has made possible the prediction of the break-through curve which has been found to be in agreement with experimental results.

Thermal Conductivity of Mixtures in the Dense Gaseous State: The Methane–Carbon Dioxide System

Experimental thermal conductivities were established for the methane–carbon dioxide system using a coaxial cylindrical cell. These measurements were carried out on pure methane, carbon dioxide, and three binary mixtures containing 0.755, 0.464, and 0.243 mole fraction of methane. The temperatures of this study ranged from approximately 60° to 160°C and pressures extended up to 10 000 psi. The resulting thermal conductivities k for the dense gaseous state and the corresponding thermal conductivities of the dilute gas at atmospheric pressure, k*, for this binary system were used to produce the unique relationship for this system, (k − k*)λzc5 = 3.075 × 10−8[exp(1.203ρR) − exp(− 4.359ρR2)], where the thermal conductivity parameter, λ = M1/2Tc1/6 / Pc2/3. For the mixtures of this system, pseudocritical constants were used. This relationship was applied for the calculation of thermal conductivities which, when compared with corresponding experimental values, produced an average deviation of 2.24% for 220 exper...