Engineering Commons^™

Investigation Of Solid Polymeric Hollow Fiber Heat Exchange Devices For Use In Thermally-Driven Desalination Processes, Saskia Christian

Theses

The heat exchange between hot brine (4 wt% NaCl) and cold water as well as between condensing steam and cold water without direct fluid-fluid contact using modules made out of solid polymeric hollow fibers of polypropylene (PP) and polyetheretherketone (PEEK) has been studied. The solid hollow fiber dimensions were 425μm/575μm (ID/OD) for PP and 420μm/570μm (ID/OD) for PEEK. Extensive heat transfer measurements have been performed and the experimentally-determined overall heat transfer coefficients utilized to isolate the wall heat transfer coefficient, the inside heat transfer coefficient and the outside heat transfer coefficient. The heat exchange between hot brine and cold water …

Synthesis And Characterization Of Polymer Nanocomposites, Nirav S. Patel

Theses

Polymer nanocomposites were produced by solution mixing of a commercial flexible acrylic polymer paint, with nanofillers of different size, shape, aspect ratio and purity such as hydrotalcite (HT), sodium montmorillonite (MMT), single wall carbon nanotubes (SWNT) and fullerenes (FUL), at 5 and 10 wt% loading. Structural characteristics and mechanical, thermal and barrier properties of the nanocomposites were characterized by different techniques and compared to those of the unfilled polymer.

The presence of partially exfoliated and intercalated nanoplatelets in the polymer resulted in increased 2% secant tensile modulus, and decreased tensile strength and elongation at break, to different extents. While the …

Optimization Of Sequential Purification Of Beta-Glucosidase From Tricoderma Reesei In Aqueous Two-Phase System, Shalini Gautam

Dissertations

A novel sequential technique was developed for the purification of a valuable enzyme, beta-glucosidase, from microorganism Tricoderma reesei. The fungus T. reesei produces cellulose degrading enzymes, called cellulases: beta-glucosidase, endo-glucanase and exo-glucanase and low molecular weight proteins. For specific applications, the enzyme must be separated from other contaminants. The sequential technique, that included affinity precipitation with chitosan followed by separation with an aqueous two-phase system (ATPS), was implemented for the purification of beta-glucosidase from the culture filtrate of T. reesei.

The cultivation medium (nutrient) was optimized for the production of betaglucosidase from T. reesei cell culture. Treatment of the …

Fluid-Phase Thermodynamics From Molecular-Level Properties And Interactions Based In Quantum Theory, Steven G. Arturo

Dissertations

A methodology to predict the thermodynamics of macroscopic fluid systems from quantum chemistry and statistical thermodynamics has been developed. This work extends the group-contribution concepts most utilized in chemical engineering. Computational chemistry software is used to define the geometries and electron density profiles of target molecules. Atoms in Molecules theory and associated software packages are used to calculate rigorous properties of the functional groups within molecules of interest. These properties are incorporated into an intermolecular potential energy function which describes interactions between entire molecules as a set of interactions between functional groups. This information is applied to a lattice-fluid model …

Evaluation Of Unifac Group Interaction Parameters Usijng Properties Based On Quantum Mechanical Calculations, Hansan Kim

Theses

Current group-contribution methods such as ASOG and UNIFAC are widely used for approximate estimation of mixture behavior but unable to distinguish between isomers. Atoms in Molecules (AIM) theory can solve these problems by using quantum mechanics and computational chemistry to compute atomic contributions to molecular properties and to intermolecular interactions. Rigorously defined properties available through AIM theory and new functional group definitions are used for the UNIFAC model to predict the behavior of various mixtures. Results are presented for various mixtures with nine regressed global parameters to optimize model's predictive capability. The results are also compared to analogous results for …

Evaluation Of Knox Group Contribution Parameters Using Quantum Based Molecular And Group Properties, Myriam Carrillo

Theses

Thermodynamic property prediction through the group contribution methods has been improving. However, the approaches considered in the past present not only limitations on the physical basis but often have restrictions as to certain substances, such as isomers. A new group contribution method is proposed that uses AIM theory, which is based on computational chemistry and quantum mechanics, to overcome these limitations by treating each molecule individually. An evaluation of this method as applied to the Knox model is proposed and analyzed for Vapor Liquid Equilibrium (VLE) of mixtures with the help of nine global parameters that are obtained by correlation. …

Crystalization Studies In Hollow Fiber Devices, Dimitrios Zarkadas

Dissertations

Crystallization was examined under a new perspective and in a flow environment much different from that available in currently used industrial devices. Three crystallization techniques were tested in the unique flow environment offered by hollow fiber devices. In addition, a new type of heat exchanger based on hollow fibers was tested as well as the potential use of porous hollow fiber devices as mixing devices. Hollow fiber devices are compact, extremely efficient on a volumetric basis, easy to scale up and control and their inherent characteristics promote the creation of homogeneous temperature and concentration conditions on a scale considerably smaller …