The light intensity distribution in a perfectly mixed photoreactor has been studied experimentally and analytically. Experimental measurements of intensities within the reactor were made with a specially designed light probe. These data were then used to test the validity of a model which treats the ultraviolet lamp as a linear source radiating in all directions. I t was found that this model, which seems appropriate and allows reasonable computations, is somewhat in error owing to the neglect of the finite size of the lamp and the existence of reflection and refraction effects within the reactor. An empirical correction function was determined for use with the model which then yields predictions in close agreement with experimental data when the reactor is filled with a light absarbing liquid.

No abstract

Starting with the Stefan-Maxwell equations, general expressions for the ionic flux rates for binary exchange in ionsxchange resins have been developed. These equations have been shown to reduce to the Nernst-Planck equations exactly only as the concentration of either exchanging ion approaches unity. Furthermore, the single-ion diffusion coefficients used in the Nernst-Planck equations are shown to be certain combinations of the Stefan-Maxwell interaction coefficients. Most importantly, these combinations of the Stefan-Maxwell interaction coefficients are shown to reduce to the tracer diffusion coefficient of each exchanging ion, measured in ion-exchange resin completely in the competing ion form. As these limiting tracer ion diffusion coefficients may be very different from the usual pure selfdiffusion coefficients, this result may explain existing anomalies resulting from the use of the Nernst-Planck equations to describe diffusion in ion-exchange resins and related ion-exchange systems.The Stefan-Maxwell relations were used to analyze the ion exchange of Na' and Cs' in Dowex 50-X8. Tracer diffusion coefficients for both ions were measured as a function of composition. This allowed certain combinations of the Stefan-Maxwell interaction coefficients to be determined which in turn allowed limiting single ion tracer coefficients (Na' diffusing in Cs' form resin only and Cs' diffusing in Na' form resin only) to be estimated. Resultsshow that use of these limiting tracer coefficients in the Nernst-Planck equations gives much improved prediction of ion exchange than does the use of usual selfdiffusion coefficients. The improved results are attributed to the fact that the Stefan-Maxwell relations take into account important ion-ion interactions.

A new experimental technique for determining the pumping capacity of impellers in stirred tanks i s described. Data for marine propellers operoted in a well-baffled tank ore presented. I t i s shown that the pumping capacity of propellers is proportional to the product of propeller speed and the cube of propeller diameter. I Abstract: This paper presents some recent measurements on the rate of transport of sodium chloride in turbulent axisymmetric jets of water. Only mean values for velocity and concentration are considered and these are evaluated using classical transport theory.As measured by the half-concentration radius, material is seen to spread linearly with distonce downstream of the orifice beyond about ten orifice diameters. In this region for all practical purposes, both the velocity and the concentration profiles are affine. A value of 0.67 is obtained for the turbulent Schmidt number. Abstract: Protrusion of perforations* in sieve-troy construction for liquid-gas contacting results in a decrease in dry pressure drop and entrainment dilution of liquid on a tray. For 3/16-in. diam. perforations with the protrusion geometry of 0.4-in. hip diam. and 0.1 -in. protrusion above the tray, dry pressure drop over a wide range of vapor flow was reduced 50% and entrainment, from 50 to 80%, below that of o conventional sieve tray. Tray efficiency for the protruded tray remained essentially constant for 0.7

As a part of a fundamental study of the kinetics of rapid smelting reduction of iron