Hydrophobization of Cellulose-Based Fibers for Packaging Applications with Alkyl Ketene Dimers (AKD) and Food-Grade Waxes via Supercritical Impregnation with Carbon Dioxide – Experimental and Thermodynamic Modeling Approaches

This modified material has applications in food packaging, where frequently water-repellant surfaces are required. This method is preferable to traditional coating methods because it sizes across the entire thickness of the substrate rather than just the surface and can be used for non-planar surfaces; uses significantly less material than traditional methods and will be an excellent technique for multilayered and intelligent coating

An investigation of cavitation cooling effect in converging-diverging nozzles

Master of ScienceDepartment of Mechanical and Nuclear EngineeringMohammad H. HosniA traditional cooling/refrigeration cycle has four main system components which are an evaporator, a compressor, a condenser, and an expansion valve. This type of cycle requires use of refrigerants which have been found to be harmful to the environment, including causing damage to the atmospheric ozone layer. The main objective of the project was to investigate a water-based non-vapor compression cooling system. Water as a working fluid has the advantages of being inexpensive and environmentally safe for use, as compared to commercially available chemical refrigerants. The water-based cooling system investigated employed cavitation phenomena in converging-diverging glass nozzles. Cavitation is an important phenomenon in fluids, and is common occurring in many devices such as pumps, refrigeration expansion valves, and capillary tubes. It occurs when the static pressure of the fluid falls below the vapor pressure, into a metastable liquid state. Cavitation can be in the form of traveling bubble cavitation, vortex cavitation, cloud cavitation, or attached wall cavitation. In this thesis, the focus was first on visualizing cavitation for water flowing through converging- diverging glass nozzles. These nozzles had throat diameters between 2 mm and 4 mm. Two systems were used: (1) a continuous flow system, where water was driven by a centrifugal pump, and (2) a transient blow down system, where water flow was initiated using a suction pump. A high-speed camera was used to record videos and images of the associated cavitation phenomena. A thermal infrared camera was used in an attempt to measure temperature drop in the nozzle while the system was running The second part of this thesis focused on the understanding of the fundamental thermodynamics phenomena and on the development of practical knowledge relevant to the cavitation process. Two equations of state were used in the analysis, the van der walls equation of state, and the Peng Robinson equation of state. Equations of state were used to predict the transition from vapor to liquid. At a given temperature, the equations were solved for a pressure value corresponding to saturated liquid and saturated vapor specific volume values. Then, the equations were used to determine the spinodal liquid and vapor lines, which represent the metastabillity limits for the liquid and vapor. The characteristic equations of state, combined with implementation of the Law of Corresponding States and thermodynamic theory, were used to estimate the temperature reduction available for refrigeration

Modelling of gas clathrate hydrate equilibria using the electrolyte non-random two-liquid (eNRTL) model

International audienceA thermodynamic framework for modelling clathrate hydrate equilibria involving electrolytes is presented. In this framework, the gas phase is described by using the Soave-Redlich-Kwong equation of state, while the gas solubility in the liquid phase is estimated by means of a Henry's law approach. The liquid phase non-idealities are accounted for by using the semi-empirical electrolyte non-random two-liquid (eNRTL) excess Gibbs energy model. The van der Waals and Platteeuw model is used for the hydrate phase. This three-phase equilibrium model has been implemented in a new Java-based in-house programme. The main focus of the present work is the influence of the electrolytes on the incipient hydrate forming conditions. Therefore, the most recent version of the eNRTL model is thoroughly discussed. The model equations are presented in detail to facilitate future implementation and further development of this model, since the eNRTL modelling approach is quite new in the context of gas hydrate calculations. The correctness of the programme implementation is rigorously studied and verified by comparing the results with results of selected examples in the literature. At last, calculations are performed on solid-aqueous liquid-gas phase equilibria of selected systems of the type {water + salt + gas}, {water + salt1 + salt2 + gas}, {water + salt + CH4 + CO2} and {water + salt1 + salt2 + CH4 + CO2} with salt = NaCl, KCl, CaCl2 and gas = CH4, CO2) comprising a gas clathrate hydrate phase. The results are in good agreement with experimental p-T-hydrate-liquid-gas phase equilibrium data found in the literature, with average absolute relative deviations between experimental and calculated pressures ranging from 1% to 15%

A More Comprehensive Evaluation of Equation of State Influences On Compressor Performance Determination

Lectur

Brushless doubly-fed reluctance machine modeling, desing and optimization

Tese (doutorado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia Elétrica, Florianópolis, 2015.Esta tese aborda a modelagem, o projeto e a otimização, com validação experimental, de máquinas de relutância duplamente alimentadas sem escovas (BDFRM) para sistemas de geração de energia eólica. O objetivo principal dela é de contribuir para o domínio de técnicas de projeto otimizado para a BDFRM através da proposição de uma metodologia baseada em diferentes níveis de modelagem e em otimização. Discute-se como técnicas de otimização podem ser aplicadas em todas as fases de desenvolvimento com objetivos distintos. Especificamente, a metodologia proposta se concentra na definição e na solução iterativa de problemas de otimização com restrições nas saídas utilizando um algoritmo determinístico acoplado a modelos semi-analíticos de diferentes níveis. Como conclusão geral, pode-se afirmar que a BDFRM é potencialmente uma boa candidata para ser utilizada em sistemas de geração de energia eólica. Contudo, aspectos técnicos e econômicos sobre essa escolha devem ainda ser avaliados, comparando-se as diferentes topologias existentes sob o mesmo enfoque metodológico.Abstract : This thesis addresses the modeling, design and optimization with experimental validation of the Brushless Doubly-Fed Reluctance Machine (BDFRM) for wind power systems. Its main goal is to contribute on mastering the BDFRM optimized design by proposing a methodological approach based on different modeling levels and on optimization. More precisely, it draws its attention on setting the optimization problem and on the iterative solution of a constrained inputs/outputs problem by using a deterministic algorithm. As a general conclusion, the results show that the BDFRM is potentially a good candidate to be used in wind power systems. However, the technical and economic aspects on this choice must be still assessed, analyzing and comparing the overall system solution of distinct topologies within the same framework

Estudo de diagramas de fase líquido-vapor e destilação

Dissertação (mestrado)—Universidade de Brasília, Instituto de Química, Programa de Pós-Graduação em Química, 2019.A destilação é muito utilizada industrialmente para purificação de substâncias e os diagramas de equilíbrio de misturas são de extrema importância para tal processo. Através do uso das equações do modelo regular, foi feito um estudo para que se pudesse obter os diagramas de quatro sistemas e, a partir destes e do método de McCabe-Thiele, obter informações relevantes sobre o número de estágios de equilíbrio no processo de separação desses sistemas. Os resultados obtidos mostraram que o modelo regular se adequa muito bem às soluções ideais, mas possui limitações quanto às azeotrópicas relacionadas ao cálculo de β. A partir dos mesmos foi possível ter uma melhor compreensão do comportamento dessas misturas e, consequentemente, visar uma melhora no processo de separação.Distillation is widely used industrially for purification of substances and the equilibrium diagrams of mixtures are of extreme importance for such process. Through the use of the equations of the regular model, a study was made to obtain the diagrams of four systems and, from these and the McCabe-Thiele method, to obtain relevant information on the number of equilibrium stages in the separation process of these systems. The results obtained showed that the regular model fits the ideal solutions very well, but it has limitations on the azeotropics related to the calculation of β. From these, it was possible to have a better understanding of the behavior of these mixtures and, consequently, to improve the separation process

Research and development of enhanced, integrated and accessible flow metering software for industry.

This project was an investigation to find improvements required in the delivery of software for the flow metering industry. The project has resulted in the repackaging of existing software using appropriate technologies. This included developing software that is accessible via the web and extending functionality whereby a user can import and export information in a variety of data formats. The software was successfully revised and is now commercially accessible to the flow metering industry. The project was performed in the context of a KTP (Knowledge Transfer Partnership) programme with academic supervision provided by TUV NEL (the academic partner) on the premises of KELTON® (the commercial partner) who provided day-to-day project management supervision. The project was in collaboration between the two organisations with the joint aims of facilitating knowledge transfer between the organisations and enhancing the market performance of the commercial partner. The main objective of the study was to gain a full understanding of the needs of the flow metering industry in terms of software and delivery via web or standalone application. Web based applications are new to KELTON® so it was necessary to investigate the methods of delivery. The work concentrated on investigating techniques to modularise code, allowing flexible access to data between applications and on data presentation. iv At an early stage of the project an online market survey program was developed and appropriate questions were used to get customer feedback. The results were analysed and used to prioritise work. Following the review, the current software architecture was found to be unsuitable so new approaches were investigated. The software was created using an n-tier architecture which is a method of splitting common code into separate components. Web based applications were found to be slower than standalone applications. However, web applications benefited from not having to fully install software on individual user PCs therefore allowing access from anywhere that users have access to the network

Beyond the noise : high fidelity MR signal processing

This thesis describes a variety of methods developed to increase the sensitivity and resolution of liquid state nuclear magnetic resonance (NMR) experiments. NMR is known as one of the most versatile non-invasive analytical techniques yet often suffers from low sensitivity. The main contribution to this low sensitivity issue is a presence of noise and level of noise in the spectrum is expressed numerically as “signal-to-noise ratio”. NMR signal processing involves sensitivity and resolution enhancement achieved by noise reduction using mathematical algorithms. A singular value decomposition based reduced rank matrix method, composite property mapping, in particular is studied extensively in this thesis to present its advantages, limitations, and applications. In theory, when the sum of k noiseless sinusoidal decays is formatted into a specific matrix form (i.e., Toeplitz), the matrix is known to possess k linearly independent columns. This information becomes apparent only after a singular value decomposition of the matrix. Singular value decomposition factorises the large matrix into three smaller submatrices: right and left singular vector matrices, and one diagonal matrix containing singular values. Were k noiseless sinusoidal decays involved, there would be only k nonzero singular values appearing in the diagonal matrix in descending order providing the information of the amplitude of each sinusoidal decay. The number of non-zero singular values or the number of linearly independent columns is known as the rank of the matrix. With real NMR data none of the singular values equals zero and the matrix has full rank. The reduction of the rank of the matrix and thus the noise in the reconstructed NMR data can be achieved by replacing all the singular values except the first k values with zeroes. This noise reduction process becomes difficult when biomolecular NMR data is to be processed due to the number of resonances being unknown and the presence of a large solvent peak