To test the applicability, over a wide range of temperatures, pressures, and gas physical properties, of the mass transfer correlation presented earlier, 0.5-in. naphthalene Berl saddles were vaporized into air, carbon dioxide, and Freon-12 in a 4.0-in. column. Temperatures from 15" to 73°C. and pressures from 0.26 to 1 atm. were covered.The correlation was found to represent all the experimental data when the surface temperature of the naphthalene was used to evaluate the correct driving force.This correlation, when combined with effective interfacial areas presented previously, makes it possible to estimate the volumetric mass transfer coefficient, &a, for any gasliquid-solute system. I n the first three papers (10, 11, 1g) of this series devoted to packed columns, a method was proposed for predicting over-all mass transfer coefficients KGu from gas-and liquid-phase coefficients kG and kL and the effective interfacial area a. The correlation presented for estimating kG was based on data obtained with air as the inert gas a t atmospheric pressure and room temperatures. although this equation correlated the data of several previous investigators, obtained under similar conditions, thrre were no data to provide a suitable check on the ability of the equation to predict kG over the wide range of temperatures, pressures and gas physical properties that may be encountered in design problems.The object of this work is to study the effect of gas physical properties, temperature, and pressure on gas-phase mass transfer coefficients and the usefulness of Equation (1) for predicting coefficients under a variety of conditions.An examination of the terms in Equation (1) indicates that kG should be almost indcprndent of temperature, being approximatcly proportional to To 11. The methods for estimating effective interf:icial areas a prcsentcd previously Decreases in kGa with increasing temperature for ammonia absorption work have been reported by Kowalke, Hougen, and Watson (7), Dodge and Dwyer (S), and Molstad, McKinney, and Abbey (Q), these decreases ranging from 0.2 to 0.8 %/"C. based on the outlet water temperature. These data cannot be used for predicting the effect of temperature or checking Equation (1) because the gas temperatures were not varied over a wide range and the water temperature variations are peculiar to the conditions under which the columns were operated. I n ammonia absorption it is possible to obtain a rise in water temperature when the ammonia dissolves and a fall in water temperature if the air used is not saturated. I t should be pointed out that the effect of tempcrature on kG should be determined by employing varying gasphase tcmprratures rather than temperatures based on conditions in the liquid phase.For low concentrations of the solute in the carrier gas, Equation (1) predicts that kc should be inversely proportional to total pressure. This has been found to hold for absorption in packed columns over the range of 1 t o 14 atm. by Zabban and Dodge (14). Goodman's (4) unpublished data for the va...
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