A lumped kinetic model of a pulsed corona discharge reactor, where the high-voltage dischargeinduced electron density fluctuation and hence the electron collision rate fluctuation are approximated with a uniform electron distribution and a new Arrhenius-type rate model, is found to capture the effect of power input, NO x composition, and residence time. An N atom and N 2 (A) are found to control the conversion of nitrogen oxides and the evolution of byproducts; the N atom controls the NO conversion, N 2 (A) controls the N 2 O conversion, and the N atom and N 2 (A) control the NO 2 conversion.

A heat-and mass-transfer model was deueloped to Jimulule micr-owaue and spoutedbed combined (MWSB) drying

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The problem of diffusion and dispersion in porous media is considered in the absence of either adsorption or chemical reaction. For this situation, local volume averaging has been used to obtain both a convection‐dispersion equation and a method of closure that provides for a direct theoretical prediction of the dispersion tensor. This approach is associated with three length scales, lβ, the pore diameter, ro, the radius of the averaging volume, and L the macroscopic length scale, and makes use of a representative unit cell to determine the dispersion tensor. Previous work suggests that extremely complex unit cells must be used to capture the observed dispersion phenomena, and complex unit cells naturally introduce another length scale, i.e., the length scale associated with the local heterogeneities. To deal with this problem, we propose the use of large‐scale averaging to account for the influence of the local heterogeneities. This leads to a large‐scale convection‐dispersion equation that contains additional terms involving time derivatives which arise as a result of the presence of heterogeneities and which do not appear in the conventional local volume average convection‐dispersion equation. The first new term contains the second derivative with respect to time and is likely to be unimportant for time scales appropriate for groundwater transport processes; however, it may be important for small‐scale laboratory experiments. The second new term contains a mixed space‐time derivative which may be important for many cases of practical interest. A closure scheme is presented that allows for the theoretical determination of all the coefficients that appear in the large‐scale convective‐convection‐dispersion equation.

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An experimental study has been conducted to provide a data base for drying packed beds of granular, nonhygroscopic materials. Experimental results for drying rate, saturation distribution, temperature distribution, and surface saturation are reported for drying glass beads under carefully documented drying conditions. Capillary pressure for both imbibition and drainage was measured for the glass beads, whose size ranged from 65 μm to 450 μm. The drying results demonstrate that, contrary to available model predictions, porous materials do not necessarily exhibit saturation gradients that always increase with distance from the drying surface. Under certain conditions the capillary potential is sufficient to create an internal drying front. The measurements of surface saturation are the first to be reported. They are utilized to speculate on the reasons for the failure of drying models to compare well with experiment without adjusting the convective heat or mass transfer coefficients.

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