The principal aim of this study was the use and evaluation of dynamic modeling techniques to identify mathematical models for cereal drying rates and quality changes that best describe thin-layer malt drying data. Seven thin-layer malt drying experiments were performed at the Great Western Malting pilot facilities, Vancouver, WA. Malt moisture content, temperature, β-amylase activity, endo-barley-β-glucanase activity, and color were all monitored as the malt was dried with air at various temperature and relative humidity values. A constrained direct search optimization method was used to fit available drying, enzyme deactivation, and color formation models to the data obtained by minimizing the error between predicted and experimental values. Because the deactivation of β- amylase observed during the kiln experiments was less than the error involved in β-amylase measurement, β-amylase modeling efforts were dropped from the study. The end result is a computer simulation of the malt kilning process that can predict malt drying rates, color formation, and endo-barley-β-glucanase deactivation based on the drying air temperature, relative humidity, and time spent in the kiln. Further research is suggested towards modeling malt drying rates at high moisture contents, (above 40%) analysis of drying model applicability when drying conditions fall outside those encountered in this study, and development of assay procedures and models so that the fate of other important malt quality indicators during kiln drying can be predicted. / Graduation date: 1993

Typescript. / Thesis (Ph. D.)--University of Hawaii at Manoa, 1985. / Bibliography: leaves 101-106. / Microfilm. / xxiv, 193 leaves, bound ill. 29 cm

A comprehensive microscale model of transport phenomena in paper drying was developed. The model includes five species (free water, sorbed water, air, water vapor, fibers) in three phases: humid air, liquid, solid. AlI relevant transport mechanisms were treated: capillary transport of free water, diffusion of sorbed water, convective-diffusive transport of water vapor. Effects on drying from the hygroscopic nature of paper were included: the reduced vapor pressure and extra evaporation energy for bound water and the changes in porosity and thickness because of sorbed water removal. / Un modèle détaillé des phénomènes de transport à petite échelle a été développé pour le séchage du papier. Le modèle inclut cinq espèces (eau libre, eau sorbée, air, vapeur d'eau et fibres) et trois phases: air humide, liquide et solide. Tous les mécanismes de transport pertinents du séchage ont été traités: le transport par capillarité de l'eau libre, la diffusion de l'eau sorbée ainsi que le transport de la vapeur d'eau par convectiondiffusion. Plusieurs effets sur le séchage de la nature hygroscopique du papier ont été inclus: l'énergie supplémentaire nécessaire à l'évaporation de l'eau liée, la réduction de la pression de vapeur de l'eau liée et les changements de porosité et d'épaisseur provenant de l'enlèvement de l'eau sorbée. fr

No description available.

Call number: LD2668 .T4 1978 C5 / Master of Science

Call number: LD2668 .T4 1986 C44 / Master of Science / Chemical Engineering

Typescript. / Digitized by Kansas Correctional Industries

Separation of liquid from solids is a necessary step in the ultimate disposal of wastewater sludges. Most commonly, sludges are dewatered by pressure-filtration methods. Mathematical models of the physics of the sludge dewatering process would provide the ability to predict dewatering performance and optimize the design and operation of dewatering facilities.

A study is made of the simultaneous heat and mass transfer processes which occur within a finite wood cylinder of circular cross-section when it is convectively dried. Governing transport equations are developed allowing for the functional dependence of both thermal and moisture diffusivities on moisture content and temperature. Derivative type boundary conditions are included in the analysis. The equations are formulated using a cylindrical coordinate system because it is well suited to modelling wood's anisotropy. In the case considered, the axial coordinate direction is aligned with the wood-grain. Due to the coupling and non-linearity present in the transport and boundary equations, an implicit finite-difference solution scheme is formulated. The three-time-level scheme uses an equation splitting technique to simplify its solution on the computer. A mathematical wood-model, as available in the literature, is refined and used to determine moisture and thermal diffusivities, and mass transfer boundary conditions. Results from this wood-model apply to softwoods below the fiber-saturation moisture content. Combined diffusivities of liquid and vapour are calculated for the radial and axial directions and results for the radial direction are compared to those found from diffusion experiments. Desorptional isotherms are used in the mass transfer boundary condition equations to relate surface humidity and moisture content. The wood-model is used in the mass transfer equation to determine wood drying behaviour under isothermal conditions. Initial moisture contents are uniform and equal to the fiber-saturation value. Solutions are presented to give local and average moisture content as a function of time as well as moisture content profiles. The effect of drying temperature was investigated for one case of wood density and shrinkage. / Applied Science, Faculty of / Mechanical Engineering, Department of / Graduate

Call number: LD2668 .T4 1978 K34 / Master of Science