Thesis (MScIng)--University of Stellenbosch, 2006. / Bibliography. Also availabe via the Internet.

Orientador: Paulo Roberto de Aguiar / Co-orientador: Eduardo Carlos Bianchi / Banca: Carlos Alberto Fortulan / Banca: Marcos Tadeu Tibúrcio Gonçalves / Banca: Amauri Hassui / Banca: Jaime Gilberto Duduch / O Programa de Pós-Graduação em Ciência e Tecnologia de Materiais, PosMat, tem caráter institucional e integra as atividades de pesquisa em materiais de diversos campi da Unesp / Resumo: É analisada a influência das técnicas de mínima quantidade de lubrificante (MQL), refrigeração otimizada e refrigeração convencional, com diferentes vazões e velocidade de aplicação do fluido de corte, na qualidade das peças produzidas (acabamento, erros de forma, trincas, queima, perda da dureza) com aços endurecidos, no processo de retificação cilíndrica externa de mergulho com a utilização de rebolos superabrasivos com baixa concentração de CBN. Utilizou-se fluidos de corte de origem vegetal, que representam menos riscos à saúde e ao meio. A análise da qualidade das peças foi realizada através da avaliação das variáveis de saída do processo como o comportamento da força tangencial de corte, energia específica de retificação, rugosidade, desvio de circularidade, emissão acústica, tensão residual, análise de microscopias eletrônicas de varredura e microdureza. Com a análise das formas de aplicação e das várias vazões e velocidades do fluido de corte utilizadas encontraram-se condições de lubri-refrigeração que propiciam a diminuição do volume de fluido de corte, diminuição do tempo de usinagem sem prejudicar os parâmetros geométicos, dimensionais, o acabamento superficial e a integridade superficial dos componentes. Em relação as diferentes formas de aplicação do fluido de corte notou-se o melhor desempenho da aplicação otimizada para maiores velocidades mostrando a eficiência de um novo conceito de bocal utilizado. O processo otimizado e o processo MQL foram capazes de manter a dureza superficial e a integridade superficial das peças produzidas. Exceção somente para a condição MQL com vazão de fluido de corte de 40ml/h que produziu trincas e retêmpera superficial. O desvio de circularidade e a rugosidade proporcionada pelos métodos estão dentro de valores recomendados para a retificação sendo que a técnica otimizada... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The influences on surface integrity of the parts (finishing, geometrical errors, cracks, burn, microhardness) and grinding wheel (wear) have been analyzed in this research by employing the minimum quantity of lubrication (MQL), optimized and conventional cooling for hardened parts of steel and superabrasives grinding wheel in the cylindrical plunge grinding process. This study was carried out through the assessment of the process output variables such as the behavior of the tangential cutting force, specific energy, surface roughness, circularity errors, acoustic emission, residual stress, scanning electronic microscopy (SEM) and microhardness. The cutting fluid derived from vegetal oil has been utilized in order to comply with the environmental requirements and thus offering less risk to the health. It could be observed from the analysis on different ways of cutting fluid applications that there are cooling conditions which facilitate the decrease in cutting fluid volume, decrease in grinding time without impairing the geometrical and dimensional parameters, the surface finish and surface integrity of the parts. It could be noted the optimized application for higher velocities has presented the best performance regarding the different applications of cutting fluids. The optimized and MQL processes were able to maintain the hardness and surface integrity of the ground parts. Exception occurend only for MQL condition with flow rate of 40ml/h, which led to cracks and quench on the workpiece surface. Roundness errors and surface roughness are within recommended valus for grinding with the best results obtained for the optimized method (2'mü' for roundness error and 0.5'mü'm for surface roughness) compared with the MQL technique (6.8'mü'm for roundness error and 1.2'mü'm for surface roughness). The process of minimum quantity of lubrication, however, has showed possible... (Complete abstract click electronic access below) / Doutor

The study introduces and demonstrates the viability of the continuous flow reactor (CFR) system for the production of bio-crude oil (BCO) from wet microalgae. Preliminary experiments conducted in the CFR system in hot compressed water (HCW) were successful in converting wet microalgae into liquid BCO. However, the synthesis and aggregation of high boiling point (HBP) components of BCO and the accumulation of char in the tubular piping of CFR system were identified as the limiting factor to the viability of the system. The aggregation of HBP components and the accumulation of char result to system blockage which prevents the continuous flow of the liquefaction product mixture in the CFR system. Inhibiting the reactions leading to the formation of HBP components and char will improve the performance of the CFR system. Therefore, the study seeks to incorporate co-solvents in the liquefaction reaction media in an attempt to inhibit or minimize the prevalence of HBP components of BCO. As such, different co-solvents were screened for their influence on improving the quality of BCO with respect to its boiling point profile (BPP), initial and final boiling point, as well as the amount of char recovered from each experiment. Only one co-solvent was chosen for further exploration in the CFR system. Batch liquefaction reactor’s (BLR) made up of stainless steel were used to carry out the co-solvent screening experiments. These experiments were carried out at a constant temperature (280 °C), pressure (75 bar), and co-solvent concentration (10 wt.%), at varying residence times. Solvent extraction with dichloromethane (DCM) was performed on the liquefaction product mixture to separate the products, viz. BCO, char and water soluble components. The extracted BCO was analysed through simulated distillation (SimDis) to obtain the BPP. The BPP properties of the BCO samples, from different liquefaction media, and the amount of char recovered were highly influenced by the addition of a co-solvent. The final boiling point (FBP) of tetralin, heptane, and n-octanol BCO products were significantly reduced to below 500 °C for all tested residence times except at 20 minutes. The residence time also proved to be influential in the processing of wet microalgae. n-Octanol was selected as the optimal performing co-solvent and was used for the continuous liquefaction of wet microalgae in the CFR system. The CFR system was modified by adding a co-solvent feed line into the continuous system since n-octanol was insoluble in water. The n-octanol pump was set at different flow rates, 0.2, 0.3, and 0.4 g/min, which resulted in a concentration of about 10 wt.% in the reactor feed. The concentration of n-octanol had a significant influence on the BPP of BCO components. The FBP’s were reduced with an increase in n-octanol concentration. The initial boiling point (IBP) of n-octanol BCO was increased to just above 100 °C which was required for the stability of the BCO product. The components of BCO were identified by GCMS. n-Octanol also proved to affect the composition of the BCO with respect to its components. HCW BCO components were significantly different from those identified from n-octanol BCO. A second co-solvent (tetralin) was used to prove whether the difference on the components of BCO was affected by n-octanol. The results proved that indeed the addition of different solvents in liquefaction reaction media favours the formation of different components. The amount of char formed was also reduced when using a co-solvent. A decrease in the oxygen/nitrogen compounds was also observed in the presence of a co-solvent, thus improving BCO properties.

Made available in DSpace on 2014-06-11T19:35:11Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-07-21Bitstream added on 2014-06-13T21:07:28Z : No. of bitstreams: 1 barreto_cs_dr_botfmvz.pdf: 336891 bytes, checksum: 2ec6600a65ab0775c0d9c612d2474e34 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / O feto prematuro não sobrevive à vida extra-uterina devido a imaturidade de órgãos vitais como os pulmões e rins. O objetivo desse trabalho foi avaliar a maturidade renal através da identificação de proteínas de baixa massa molecular; pulmonar através da citologia com azul de Nilo (0,1%), teste de Clements modificado e densidade óptica dos fluidos; alfa-fetoproteína através da eletroforese em SDS-PAGE (12%) e concentração de cortisol nos líquidos fetais por radioimunoensaio. Foram obtidas 40 amostras de líquido amniótico e alantoideano de 16 cadelas gestantes pela cesariana. Ajustes no teste de Clements favorecem a análise de fluidos caninos promovendo resultados confiáveis (p<0,05) para as diluições. Células morfologicamente diferentes e com porcentagem de células orangeofílicas e cianofílicas refletem a maturidade pulmonar sugerindo feto em estágio de pós-maturidade. Na densidade óptica (DO) dos líquidos fetais encontramos 220l0,190 para os líquidos amniótico e 0,250l0,02 para o alantoideano sendo indicativo de maturidade (= 0,150). A concentração proteica nos fluidos estudados reflete a fisiologia fetal (p<0,05). A dosagem de cortisol indica a exposição do feto no ambiente uterino (p<0,05). A IOD da banda protéica de 66kDa foi de 15,94 para o líquido amniótico e 13,3 para o alantoideano. Cinco bandas proteicas presentes nos dois fluidos podem espelhar a maturidade renal (32; 30; 28; 20 e 12). Com base nestes dados conclui-se que a obtenção de informações básicas sobre a maturidade e viabilidade do feto canino podem ser avaliada com os testes propostos. / The premature fetus is unable to survive in extra-uterine environment due to immaturity of its vital organs as the lungs and kidneys. The objective of this work was to evaluate the renal maturity through the identification of low molecular mass proteins; pulmonary maturity through the cytology with Nile blue (0,1%), modified Clements test and optic density of fluids; moreover, the alpha-fetoprotein was evaluated through electrophoresis using SDS-PAGE (12%); and the cortisol concentration from fetal liquids was determinated by radioimunoassay. Forty amniotic and allantoic liquid samples from 16 pregnant bitches were colleted by punction during cesarean section. The Clements test was adapted to canine fluid analysis to promote true results (p<0,05) for the diluitions. Cells morphologically and with percentage of different orangeo and cyanophilia cells reflect the maturity. The optic density (DO) of the fetal fluids liquids were 220l0,190 and 0,250l0,02 to the amniotic and allantoic liquid, respectively, indicating maturity (= 0,150). The protein concentractions reflect the fetal physiology (p<0,05) in evaluated fluids. The cortisol concentration indicates the fetal exposition in the uterine environment (p<0,05). The IOD of 66 kDa protein band was 15,94 to amniotic and 13,30 to allantoic liquid. Five protein band in two fluids can reflect the renal maturity (32; 30; 28; 20 e 12). Based in these results we conclude that the tests considered in the study can evaluate the maturity and viability of canine fetus.

Made available in DSpace on 2014-06-11T19:35:12Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-06-30Bitstream added on 2014-06-13T20:26:17Z : No. of bitstreams: 1 zanella_lf_dr_botfmvz.pdf: 531665 bytes, checksum: c547ec20928912c591261203344c53d9 (MD5) / Universidade Estadual Paulista (UNESP) / Os líquidos fetais possuem diversas funções que são vitais para o feto. Para a espécie eqüina até o presente momento, não está totalmente definida a composição bioquímica do líquido amniótico no decorrer da gestação. O presente trabalho teve como objetivo verificar a composição bioquímica do liquido amniótico e alantoideano das éguas em diferentes fases da gestação. Para isso analisou-se 60 amostras de fluidos fetais, empregando-se kits comerciais para se determinar a concentração bioquímica da Fosfatase Alcalina, Glicose, Proteínas Totais, Uréia, Creatinina, Cálcio, Cloreto, Sódio e Potássio durante a gestação. A concentração da alfa-fetoproteína foi avaliada empregando-se a eletroforese em gel de poliacrilamida. A concentração da Fosfatase Alcalina no liquido amniótico foi maior quando comparada ao liquido alantoideano nas três fases da gestação (p < 0,05). Para a glicose o valor médio entre os dois fluidos não apresentou variações (p < 0,05). Para a Proteína total o valor médio do liquido amniótico foi maior que o alantoideano (p < 0,05). A Uréia sofreu variações na concentração entre as fases, mas não há diferenças dos valores médios (p > 0,05) entre os fluidos. Para a Creatinina os valores presentes no liquido alantoideano são mais altos que os valores do liquido amniótico (p < 0,05). As concentrações dos íons Cloreto e Sódio apresentaram–se mais elevados (p < 0,05) no liquido amniótico. As concentrações dos íons Cálcio e Potássio foram mais elevadas nos líquidos alantoideanos (p<0,05). A eletroforese identificou duas bandas protéicas que podem ser a alfa-fetoproteína, ela parece aumentar a concentração durante o período gestacional. Porém, faltam estudos na espécie eqüina para a comparação dos resultados do presente trabalho. / Fetal fluids play a vital role in the development of the fetus. The biochemical composition of the amniotic fluid along pregnancy in horses had not been described until this present study. Sixty samples of fetal fluids were collected and the concentrations of Alkaline Phosphatase (FA), Glucose, Total Proteins (PT), Urea, Creatinin, Calcium (Ca), Chloride (Cl), Sodium (Na) and Potassium (K) along pregnancy were determined using commercially available kits. The levels of alpha-fetoprotein (AFT) were measured by polyacrylamide gel electrophoresis. During the three stages of pregnancy the concentrations of FA in the amniotic fluid were higher than those determined in the allantoic fluid (p < 0,05). The glucose levels did not differ between the fluids (p < 0,05). The mean values for the concentrations of PT were higher in the amniotic fluid than in the allantoic (p < 0,05). The urea levels differ among the pregnancy stages, but there were no differences in the mean values of urea (p > 0,05) between the two fluids. The concentrations of creatinin obtained in the allantoic fluid were higher than those obtained in the amniotic fluid (p < 0,05). The concentrations of Cl and Na were elevated (p < 0,05) in the amniotic fluid. The levels of the ions Ca e K were higher in the allantoic fluid (p<0,05). Polyacrylamide gel electrophoresis identified two protein bands that could be alpha-fetoprotein, which appears to have its concentration increased during pregnancy. There is a need for more studies in the biochemical composition of fetal fluids in horses to compare the results obtained in this study.

Thesis (MTech (Civil Engineering))--Cape Technikon, Cape Town, 1999 / Pipe roughness is known to greatly increase the turbulent flow friction factor for Newtonian fluids. The well-known Moody diagram shows that an order of magnitude increase in the friction is possible due to the effect of pipe roughness. However, since the classical work of Nikuradse (1926 -1933), very little has been done in this area. In particular, the effects that pipe roughness might have on non-Newtonian turbulent flow head loss, has been all but totally ignored. This thesis is directed at helping to alleviate this problem. An experimental investigation has been implemented in order to quantify the effect that pipe roughness has on non-Newtonian turbulent flow head loss predictions. The Balanced Beam Tube Viscometer (BBTV), developed at the University of Cape Town, has been rebuilt and refined at the Cape Technikon and is being used for research in this field. The BBTV has been fitted with pipes of varying roughness. The roughness of smooth P\'C pipes was artificially altered using methods similar to those of Nikuradse. This has enabled the accumulation of flow data in laminar and turbulent flow in pipes that are both hydraulically smooth and rough Newtonian and non-Newtonian fluids have been used for the tests. The data have been subjected to analysis using various theories and scaling laws. The strengths and problems associated with each approach are discussed and It is concluded that roughness does have a significant effect on Newtonian as well as non-Newtonlan flow.

Master of Technology: Civil Engineering In the Faculty of Engineering At the Cape Peninsula University of Technology 2014 / Notches, particularly rectangular and V shaped are the cheapest and most common devices used to measure the flow rate of water in open channels. However, they have not been used to measure the flow rate of non-Newtonian fluids. These viscous fluids behave differently from water. It is difficult to predict the flow rate of such fluids during transportation in open channels due to their complex viscous properties. The aim of this work was to explore the possibility of extending the application of especially rectangular and V-shaped notches to non-Newtonian fluids. The tests reported in this document were carried out in the Flow Process and Rheology Centre laboratory. Notches fitted to the entrance of a 10 m flume and an in-line tube viscometer were calibrated using water. The in-line tube viscometer with 13 and 28 mm diameter tubes was used to determine the fluid rheology. Flow depth was determined using digital depth gauges and flow rate measurements using magnetic flow meters. Three different non-Newtonian fluids, namely, aqueous solutions of Carboxymethyl Cellulose (CMC) and water-based suspensions of kaolin and bentonite were used as model non-Newtonian test fluids. From these the coefficient of discharge (Cd) values and appropriate non-Newtonian Reynolds numbers for each fluid and concentration were calculated. The experimental values of the coefficient of discharge (Cd) were plotted against three different definitions of the Reynolds number. Under laminar flow conditions, the discharge coefficient exhibited a typical dependence on the Reynolds number with slopes of ~0.43-0.44 for rectangular and V notches respectively. The discharge coefficient was nearly constant in the turbulent flow regime. Single composite power-law functions were used to correlate the Cd-Re relationship for each of the two notch shapes used. Using these correlations, the Cd values could be predicted to within ±5% for the rectangular and V notches. This is the first time that such a prediction has been done for a range of non-Newtonian fluids through sharp crested notches. The research will benefit the mining and food processing industries where high concentrations of non-Newtonian fluids are transported to either disposal sites or during processing.

Thesis (MTech (Chemical Engineering))--Cape Technikon, Cape Town,1996 / The handling of solid-liquid suspensions is an important concern within the chemical and processing industries and many theoretical models have been proposed to try and explain and predict turbulent flow behaviour. However, the prediction of turbulent flow from only the viscous properties of non-Newtonian suspensions has over the years been questioned by researchers. This thesis considers theoretical models well established in the literature and the Slatter model, which uses both the rheology of the suspension and the particle size distribution of the solids. These models are used to analyze the experimental data and the effect that particle size and the particle size distribution has on turbulent flow behaviour. The literature concerning the rheological fundamentals relevant to fluid flow in pipes has been examined. The Newtonian turbulent flow model as well as the non-Newtonian models of Dodge & Metzner, Torrance, Kemblowski & Kolodziejski, Wilson & Thomas and Slatter have been reviewed. Test work was conducted at the University of Cape Town's Hydrotransport Research Laboratory using a pumped recirculating pipe test rig. The test apparatus has been fully described and calibration and test procedures to enable collecting of accurate pipeline data have been presented. Three slurries were used in test work namely kaolin clay, mixture I (kaolin clay and rock flour) and mixture 2 (kaolin clay, rock flour and sand) with ad,s particle size ranging from 24/Lm to 170/Lm. The yield pseudoplastic model has been used to model and predict the laminar flow of the suspensions that were tested and the meth9J adopted by Neill (1988) has been used to determine the rheological constants. The pipeline test results have been presented as pseudoshear diagrams together with the theoretical model lines providing a visual appraisal of the performance of each model. The Slatter model predicts the test data best with the other theoretical models that were considered tending to under predict the head loss. The reason the Slatter model performs better than the other theoretical models is because this model can account for the wall roughness and particle roughness effect. Evidence to support this statement has been presented. This thesis highlights the fact that the particle size distribution is a vitally important property of the suspension and that it does influence turbulent flow behaviour. It shows that turbulence modelling using the particle roughness effect (eg Slatter, 1994) is valid and can be adopted for non-Newtonian slurries. It is concluded that the particle size distribution must be used to determine the particle roughness effect and this effect must be incorporated in the turbulent flow analysis of non-Newtonian slurries.

Thesis (MTech (Chemical Engineering))--Cape Peninsula University of Technology, 2010. Includes bibliographical references (leaves 132-137).

Dissertation submitted in fulfilment of requirements for the degree Master Technology: Chemical Engineering in the FACULTY OF ENGINEERING at the CAPE PENINSULA UNIVERSITY OF TECHNOLOGY, 2009 / The prediction of the energy losses when designing pipeline and pumping systems requires accurate loss coefficient data. But the loss coefficient data found in the open literature was not adequate for predicting the loss coefficient for Saunders straight-through diaphragm valves. As more accurate loss coefficient data to enable more efficient pipeline designs are scarce in the open literature, it is problematic to predict the head loss due to the pipeline fittings, and particularly for diaphragm valves. Most of the data given in the literature are for turbulent flow based on water. Due to water shortages mining operations are forced to increase their solids concentrations and to operate in laminar flow (Slatter, 2002). Consequently there is a need to determine loss coefficient data in laminar flow for valves used in these industries to ensure energy efficient designs (Pienaar et al., 2001; 2004) or if needed, to derive a new correlation to predict losses through Saunders diaphragm valves. However, a systematic study of various sizes of diaphragm valves of different manufacturers to ascertain, if the same loss coefficient can be applied, has never been done. Therefore a comparison will be made between the data produced in this work and the existing correlations. The objective of this research was to determine loss coefficient data in laminar, transitional and turbulent flow for the Saunders type straight-through diaphragm valves ranging from 40 mm to 100 mm in the fully open, 75 %, 50 % and 25 % open positions, using a range of Newtonian and non-Newtonian fluids. The test work was conducted on the valve test rig in the Flow Process Research Centre at the Cape Peninsula University of Technology. This work investigated only Newtonian and time independent homogeneous non-Newtonian fluids or slurries flowing through Saunders straight-through diaphragm valves in the turbulent, transitional and laminar regimes. Weir-type Saunders valves and time-dependent fluid behaviour were not investigated in this study. Preamble Non-Newtonian Loss Coefficients for Saunders Diaphragm Valves A Mume Kabwe The results for each test are presented in the form of valve loss coefficient (kvalve) against Reynolds number (Re). This thesis adds new loss coefficient data to the open literature, and a new correlation, which will be useful for designing pipelines in industries, as well as contributing to the academic debate in this discipline.