Digital Commons Network^™

The Modeling And Control Of Freeze Dryers, Martin James Millman

Doctoral Dissertations

"Two models of the freeze drying process were constructed and used to study various operational policies in order to determine the policy that would provide the shortest drying times.

The sublimation model which accounts only for the removal of frozen water, is found to predict shorter times for the free water removal phase than the sorption-sublimation model which properly accounts for the removal of frozen and bound water.

This study shows that the policy which produces the shortest free water removal phase, also produces the shortest overall drying time. This policy, predicted by both models, holds the chamber pressure at …

Thermogravimetric And Electrical Conductivity Studies Of Mg-Doped Lacro₃ And La-Doped Srtio₃, Brian Keith Flandermeyer

Doctoral Dissertations

"Mg-doped LaCrO₃ and La-doped SrTiO₃ are perovskite compounds that display electrical conductivity which is a function of partial pressure of oxygen (po2). It has been proposed that acceptor-doped LaCrO₃ becomes highly resistive at low po2's due to ionic compensation of the acceptor-dopant present by oxygen vacancies. SrTiO₃ has been thought to absorb O₂ into a crystallographic shear structure and exsolve strontium vacancies which can then ionically compensate the La present and give a high resistance at high po2's.

Given these models, relationships between weight loss and conductivity vs. po₂ are developed for both these …

Applications Of Finite And Wave Envelope Element Approximations To Acoustic Radiation From Turbofan Engine Inlets In Flight, A. V. Parrett

Doctoral Dissertations

"The problem of acoustic radiation from turbofan engine inlets in flow has not lent itself fully to analysis by numerical means because of the large domains and high frequencies involved. This project has extended the use of finite elements and wave envelope elements, elements which simulate decay and wavelike behaviour in their interpolation functions, from the no-flow case in which they have been proven, to cases incorporating mean flow. By employing an irrotational mean flow assumption, the acoustics problem has been posed in an axisymmetric formulation in terms of acoustic velocity potential, thus minimising computer solution storage requirements. The wave …

Fixed Bed Sorption With Recycle, John Thomas Casey

Doctoral Dissertations

"A mathematical model that describes single and multicomponent recycle-sorption systems is constructed. The model accounts for the generation of species by chemical reactions occurring in a single perfectly mixed tank, in the bulk fluid of the sorbent bed, and in the pores of the adsorbent particles.

Results are shown for single zeroth, first and second order reversible reactions as well as a network consisting of two first or second order reactions which may occur in series or parallel. For systems in which a single reaction occurs, both linear and non-linear equilibrium adsorption isotherms are considered. If multiple reactions occur, then …