Tesis sobre el tema "Wax"
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Nelson, Jac Jeanette. "Wax". PDXScholar, 2016. http://pdxscholar.library.pdx.edu/open_access_etds/3015.
Texto completoJi, Hongyan. "Thermodynamic modelling of wax and integrated wax-hydrate". Thesis, Heriot-Watt University, 2004. http://hdl.handle.net/10399/332.
Texto completoSchwarz, Cara Elsbeth. "The processing of wax and wax additives with supercritical fluids". Thesis, Link to the online version, 2005. http://hdl.handle.net/10019/1195.
Texto completoMarino, Fabien. "Biodegradation of paraffin wax". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0030/MQ50640.pdf.
Texto completoMarino, Fabien. "Biodegradation of paraffin wax". Thesis, McGill University, 1998. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=21312.
Texto completoKinetic studies performed with Rhodococcus IS01 growing on mixtures of n-alkanes showed that the hydrocarbons were degraded in ascending order of chain length: shortest to longest chain. The short lag period between the biodegradation of the different n-alkanes suggested that the growth of Rhodococcus IS01 on mixtures of n-alkanes followed some form of diauxie. Further kinetic studies were conducted growing Rhodococcus IS01 on individual and various mixtures of n-alkanes; these showed that the initial first-order oxidation constant decreased with increasing chain length. This trend is suspected to be due to an enzyme specificity constraint rather than to a mass transfer limitation. In addition, it was also observed that the maximum specific growth rate constant (mumax) increased with increasing n-alkane chain length.
Rhodococcus IS01 was also found to produce a cell-associated biosurfactant.
Starkie, Joanna Rachel. "Wax anti-settling additives". Thesis, University of Cambridge, 2019. https://www.repository.cam.ac.uk/handle/1810/284911.
Texto completoCendrowicz, Aleksander. "The characterisation of wax injection moulding and de-wax processes in investment casting". Thesis, University of Birmingham, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.416512.
Texto completoMahabadian, Mohammadreza Ameri. "Solid-fluid equilibria modelling in wax, hydrate and combined wax-hydrate forming systems". Thesis, Heriot-Watt University, 2016. http://hdl.handle.net/10399/3331.
Texto completoLarsson, Emelie. "Wax-accessory for cross-country skiers : Development of a wax-bench that collect waste". Thesis, Luleå tekniska universitet, Institutionen för ekonomi, teknik och samhälle, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-70833.
Texto completoI den här rapporten kan man följa ett examensarbete för civilingenjörsprogrammet Tek- nisk Design på Luleå Tekniska Universitet. Projektet består av ett utvecklingsarbete där en vallabänk för längdskidåkning har utvecklas. Vallabänken har utvecklats för att underlätta städningen för användaren och för att samla alla vallatillbehör på en och samma plats. I den här rapporten kan man följa hela projektet från start till mål, hur kraven hittades, vem är användaren, vad ska produkten klara av och hur genererades ideer. Det slutgiltiga resultatet är en valla-låda som är vakuumformad och viks ihop på mitten. I lådan finns det justerbara profiler att placera skidan på samt ett justerbart fäste i mitten som fäster i skidans bindning. Lådan fungerar som uppsamlare av skräpet som bildas när man vallar skidor och som förvaring av vallatillbehör när den inte används. Hur valla-tillbehöret ska placeras är ännu inte fastställt men tanken är att det ska utvecklas en specifik väska som passar in perfekt i valla-boxen och som har plats för alla de vanliga tillbehören. Denna väska ska sedan gå att plocka ur när man vallar och placera tillbaka i boxen efter utförd vallning.
Southgate, Jonathan. "Wax removal using pipeline pigs". Thesis, Durham University, 2004. http://etheses.dur.ac.uk/2995/.
Texto completoTaylor, John A. "The lost wax casting technique". Virtual Press, 1993. http://liblink.bsu.edu/uhtbin/catkey/864921.
Texto completoDepartment of Art
ALBAGLI, RAFAEL CAMEL. "WAX DEPOSITION IN TURBULENT FLOW". PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2017. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=29917@1.
Texto completoWax deposition is a phenomenon present in oil production systems (mainly in deep water due to the low temperatures), which consists in the adhesion of solids fractions of hydrocarbon to tubing and lines, reducing the area opened to flow until be completely blocked. The comprehension of the mechanisms that influences in the deposition has not yet been fully achieved. Given the relevance of this kind of system in new fields development and the absence of a theory able to explain the deposit s evolution and characteristics, the production limitation caused by this phenomenon is one of the main issues in flow assurance. Aiming to expand the knowledge about the phenomena that exist in deposition process and identify dominant mechanisms, different mathematical models can be compared with experimental data. The flow regime in production lines is usually turbulent. Thus, in this work, a two equation k-omega turbulence model coupled to the enthalpy-porosity model, where the deposit is a porous media, was developed. From a thermodynamic equilibrium, the species that comes out of solution are determined while their distribution are determined by each molar conservation equation. The conservations equations were solved with the finite volume method, employing the Power-law and implicit Euler schemes to handle the spatial and temporal discretization. Comparisons with experimental data in an annular duct were realized, showing good agreement in the steady state. The deposit thickness, howeve, was overestimated during the transient. The deposit thickness reduction with the Reynold number increase was verified.
Webber, Glenda Vanessa. "Wax characterisation by instrumental analysis". Thesis, Stellenbosch : Stellenbosch University, 2000. http://hdl.handle.net/10019.1/52055.
Texto completoENGLISH ABSTRACT: Various companies produce waxes, which are used extensively in various applications, either as produced or as chemically or physically modified value-added products. They are used in the traditional candle industry and applications including hot melt adhesives, inks, plastics, polishes and emulsions for rust prevention or fruit coating. Insight into the properties of these waxes is required to assist the applications chemist in understanding the role of the wax component in a specific formulation. Analytical techniques such as differential scanning calorimetry (DSC), thermogravimetry (TG), rheometry, gel permeation chromatography (GPC), high temperature gas chromatography (HTGC) and infra-red spectroscopy (IR) were used to characterise Fischer Tropsch, polyethylene, natural and petroleum waxes. Property profiles were formulated by integrating the results from the various techniques. The results of traditional wax analyses (e.g. congealing point, melting point, penetration, density and viscosity) were also correlated to relevant analytical results obtained from the instrumental techniques. Structure-property relationships have been proposed.
AFRIKAANSE OPSOMMING: Verskeie maatskappye vervaardig wasse, wat in menige toepassings gebruik word - of direk, of as chemies- of fisies- veranderde produkte van hoër waarde. Benewens die tradisionele kersbedryf, word die wasse in toepassings soos warmsmeltkleefmiddels, ink, plastiek, roeswerende- en vrugtebedekkings- emulsies en politoere gebruik. Wetenskaplikes betrokke by die formuleering van wasse vir verskillende toepassings sal baat vind by beter inligting van waseienskappe en die rol van waskomponente in formulasies. Tegnieke, bv. differensialeskandeerkalorimetrie (DSC), termogravimetrie (TG), reologie, gelpermeasiechromotografie (GPC), hoëtemperatuurgaschromatografie (HTGC) en infrarooispektroskopie (IR), is gebruik om Fischer Tropsch-, polietileen-, petroleum- en natuurlike wasse te karakteriseer. Profiele van waseienskappe is geformuleer deur die integrasie van die data verkry van die verskillende analitiese tegnieke. Die resultate van tradisionële wasanalises (bv. stolpunt, smeltpunt, penetrasie, digtheid, viskositieit en olie-inhoud) word ook in verband gebring met die resultate van die instrumentele analises. Verbande tussen struktuur en waseienskappe word ook voorgestel.
Liang, Wei-Wan Scott. "Studies of wax ester production and biochemical characterization of jojoba-type wax synthase in Arabidopsis thaliana". Thesis, University of British Columbia, 2011. http://hdl.handle.net/2429/39790.
Texto completoJariwala, Vibhakar G. "Cyclic energy storage in paraffin wax". Thesis, McGill University, 1985. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=63366.
Texto completoVEIGA, HELENA MARIA BORJA. "STUDY OF WAX DEPOSITS IN PIPELINES". PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2017. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=30887@1.
Texto completoO presente trabalho forneceu informações originais para auxiliar o entendimento dos fenômenos básicos que governam a deposição de parafina em dutos. O programa de pesquisa estudou questões relevantes, ainda em aberto na literatura, relacionadas à formação, crescimento e envelhecimento de depósitos de parafina. Com este objetivo, foi desenvolvido um programa experimental seguindo a estratégia de conduzir experimentos simples, empregando seções de teste em escala de laboratório, com condições de contorno e iniciais bem definidas, e empregando fluidos de teste simples e com propriedades conhecidas. As medidas foram realizadas em seções de testes retangular e anular, ambas especialmente projetadas para permitir medidas ópticas da evolução temporal e espacial da espessura dos depósitos. As seções de testes foram equipadas com um sensor de fluxo de calor, sondas de temperatura móveis e janelas para amostragem de depósitos, que permitiram a medição de grandezas importantes como, condutividade térmica do depósito sob condições de escoamento, perfis de temperatura dentro do depósito, evolução da temperatura da interface depósito-líquido, e composição do depósito. A variação espacial e temporal da espessura do depósito foi medida para diferentes valores do número de Reynolds laminar. Excelente concordância foi obtida entre os valores medidos e previsões de um modelo numérico desenvolvido previamente em nosso grupo de pesquisa. Medidas da evolução temporal da temperatura da interface depósito-líquido mostraram que a temperatura da interface evolui de um valor igual à temperatura inicial de aparecimento de cristais da solução, TIAC, até a temperatura de desaparecimento de cristais, TDC, a medida que o depósitos cresce até sua espessura de regime permanente. A sonda de temperatura foi utilizada na medição de perfis transversais de temperatura dentro do depósitos sob condições de escoamento. A comparação destes perfis com soluções teóricas apontaram para a possibilidade de ocorrência de escoamento dentro da matriz porosa do depósitos. As medições da condutividade térmica do depósitos sob condições de escoamento não apresentaram qualquer efeito da taxa de cisalhamento imposta, para a faixa de número de Reynolds investigada. Variações transversais da condutividade térmica do depósitos indicaram a presença de líquido próximo à parede fria. Amostras do depósitos foram obtidas e analisadas por cromatografia gasosa de alta temperatura para a faixa de número de Reynolds laminares investigadas, e para diferentes durações dos experimentos de deposição. As análises indicaram que as distribuições de carbono das amostras de depósitos apresentaram um deslocamento em direção aos maiores números de carbono com o aumento do Reynolds e do tempo de deposição, caracterizando o processo de envelhecimento do depósito. As distribuições do número de carbono apresentaram um comportamento assintótico com o número de Reynolds, para amostras obtidas dos trechos finais dos comprimentos de deposição da seção de testes anular.
The present research provided original information to aid the understanding of the physical mechanisms governing wax deposition in pipelines. The research program addressed a number of relevant open questions in the literature regarding the formation, growth and aging of the wax deposit layer. To this end, an experimental program was devised, following a strategy of conducting simple experiments, employing lab-scale test sections with well-defined boundary and initial conditions, and using simple test uids with known properties. Measurements were performed in a rectangular and in an annular test section, both especially designed to allow for optical measurements of the time evolution of the spatial distribution of the wax deposit thickness. The test sections were equipped with heat ux sensor, temperature traversing probes and deposit sampling ports that allowed the measurement of relevant local information on the deposit, such as, thermal conductivity under owing conditions, temperature profiles within the deposit, deposit-liquid interface temperature, and deposit composition. The temporal and spatial evolution of the deposit layer were measured for different values of the laminar ow Reynolds number. Excellent agreement was obtained between measured values of the deposit thickness and predictions from a numerical model developed previously in our research group. Measurements of the evolution of the deposit-liquid interface temperature have shown that the interface temperature evolves from a value equal to the solution wax appearance temperature, WAT, to the wax disappearance temperature, WDT, as the deposit grows to attain its steady state thickness. The temperature traversing probe was employed to obtain information on the temperature profiles within the wax deposit layer under owing conditions. A comparison of the measured temperature profiles within the deposit with the theoretical solutions, indicated the possibility of convective transport in the deposit. Measurements of the deposit thermal conductivity under owing conditions did not reveal any effects of the imposed shear rate, for the range of Reynolds numbers investigated. Local variations of the thermal conductivity across the deposit layer indicated the presence of liquid close to the cold wall. Deposit samples were obtained and analyzed by high temperature gas chromatography, for the range of the laminar Reynolds numbers tested and for different durations of the deposition experiments. The analyzes revealed that the carbon distributions of the deposit samples presented a shift toward higher carbon numbers both, with increasing deposition time and Reynolds number, characterizing the aging process of the deposit. The carbon number distributions were seen to display an asymptotic behavior with Reynolds number, for samples obtained from the final portion of the longer deposition lengths of the annular test section.
Crause, J. C. (James Christoffel). "Supercritical fluid extraction of paraffin wax". Thesis, Stellenbosch : Stellenbosch University, 2001. http://hdl.handle.net/10019.1/52471.
Texto completoENGLISH ABSTRACT: In this study the deoiling and fractionation of paraffin wax using supercritical fluid extraction (SCFE) has been investigated. SCFE was compared with state-of-the-art processes such as wax crystallisation, static crystallisation and short path distillation. Ethane and carbon dioxide were investigated as supercritical solvents for the supercritical fluid extraction of paraffin wax. Supercritical phase equilibrium data for ethane - n-alkane and CO2 - n-alkane systems close to the mixture critical region were obtained from the literature, and were correlated with several equations of state. Statistical mechanical equations of state failed to correlate the data close to the mixture critical region due to the neglect of density fluctuations which influences phase behaviour close to critical points, or due to inadequate mixing rules. It was found that simple cubic equations of state such as Soave-Redlich-Kwong, Peng-Robinson and Patel-Teja could correlate the data using two interaction parameters. This can be attributed more to their flexibility as correlating tools than to their fundamental accuracy. The Patel-Teja EOS was modified by fitting it to predict low vapour pressure data for long-chain n-alkanes. This modified Patel-Teja EOS was then fitted to the phase equilibria by adjusting two interaction parameters per binary system. The interaction parameters for each solvent (ethane or CO2) system were then fitted to generalised correlations to enable extrapolation to solvent - n-alkane systems for which no equilibrium data were available. The Simplified Perturbed Hardchain theory (SPHC) equation of state was used to correlate lower-pressure solubility data used to model the extract separator. A pilot plant SCFE unit was constructed and used to obtain experimental fractionation data of a low-molecular weight Fischer-Tropsch wax. The experimental results indicate that fractionation of the wax is possible and that the separation efficiency is enhanced by returning some of the extract to the column as reflux. An equilibrium stage model was constructed and used to simulate the extraction experiments. It was possible to obtain good agreement between the experimental results and model predictions. Deoiling of petroleum waxes with a low n-paraffin content (which are not currently deoiled commercially) was investigated. Experimental SCFE and SPD results indicated that selective deoiling is not possible, since the separation is based on differences in molecular weight (or vapour pressure). Simulations of wax crystallisation or solvent extraction and practical tests indicate that deoiling is possible, based on differences in structure and therefore melting point of the components in the wax. Practical problems associated with crystallisation or solvent extraction such as filtration, the use of chlorinated solvents and low yields currently prevent the commercial deoiling of these waxes. During crystallisation of these waxes a soft wax cake is formed which impedes the operation of static crystallisation. A detailed study of the economics of n-paraffin wax deoiling using SCFE was conducted. Flow sheets were proposed to minimise the energy consumption of the SCFE process. Comparison of SPD, static crystallisation and SCFE indicates that a SPD plant will be the cheapest option for deoiling the wax feed investigated. Fractionation of heavier waxes using SPD might not be economically feasible, since the distillation temperature increases dramatically with increasing molecular weight, which leads to higher energy cost. For medium to long chain n-paraffin waxes SCFE should be very competitive, since the capacity of the supercritical solvent can be manipulated to extract longer chain waxes without increasing the extraction temperature. Static crystallisation appears to be the more expensive deoiling option, due primarily to the large initial capital investment cost.
AFRIKAANSE OPSOMMING: Die olieverwydering en fraksionering van paraffienwasse met behulp van superkritiese ekstraksie is in hierdie studie ondersoek. Die modellering van moderne olieverwyderings- en fraksioneringsmetodes soos waskristallisasie, statiese kristallisasie en kortpad distillasie is ook ondersoek. Etaan en koolstofdioksied is ondersoek as superkritiese oplosmiddels vir die superkritiese ekstraksie van paraffienwasse. Literatuurdata van superkritiese fase-ewewigte vir etaan - n-alkaan en CO2 - n-alkaan stelsels naby die mengselkritiese punt is versamel en gekorreleer met verskeie toestandsvergelykings. Statisities-meganiese toestandsvergelykings kon nie data naby mengselkritiese punte korreleer nie, moontlik weens digtheidsvariasies wat afwykings van klassieke gedrag teweegbring, of onakkurate mengreëls. Eenvoudige kubiese toestandsvergelykings soos Soave-Redlich-Kwong, Peng-Robinson en Patel-Teja kon op die ewewigsdata gepas word deur gebruik van twee interaksieparameters. Dit kan eerder toegeskryf word aan hulle buigsaamheid eerder as hulle fundamentele akkuraatheid. Die Patel-Teja toestandsvergelyking is gemodifiseer deur dit te pas op lae dampdruk data van langketting n-alkane. Hierdie gemodifiseerde toestandsvergelyking is gepas op die fase-ewewig data deur twee interaksieparameters te gebruik per binêre sisteem. Die interaksieparameters vir die oplosmiddel stelsels (etaan of CO2) is gekorreleer met algemene vergelykings sodat dit vir ekstrapolasie na oplosmiddel - n-alkaan stelsels gebruik kan word waarvoor ewewigsdata nie beskikbaar is nie. Die "Simplified Perturbed Hardchain" teorie (SPHC) toestandsvergelyking is gebruik om laer druk oplosbaarheidsdata te korreleer vir gebruik in die modellering van die ekstrak skeier. In Superkritiese ekstraksie loodsaanleg is gebou en gebruik om eksperimentele fraksioneringsdata van 'n lae molekulêre massa Fischer- Tropsch was te genereer. Vanaf die eksperimentele resultate blyk fraksionering van was moontlik te wees. Die doeltreffendheid van die skeiding kan verhoog word deur terugvloei van ekstrak na die kolom. 'n Ewewigsmodel is opgestel en gebruik om die ekstraksie eksperimente te modelleer. Deur die ekstraksiedruk en aantal stadia te verander kon goeie ooreenstemming met eksperimentele resultate verkry word. Die verwydering van olie uit petroleumwasse met In lae n-paraffien inhoud (wat nie tans kommersiëel ontolie word nie) is ondersoek. Eksperimentele resultate vir superkritiese ekstraksie en kortpad distillasie dui daarop dat selektiewe olieverwydering nie moontlik is nie, omdat die skeiding gebaseer is op verskille in molekulêre massas en dus (of dampdrukke). Simulasies van waskristallisasie dui op die moontlikheid van olieverwydering gebaseer op verskille in strukture van die komponente in die was. Praktiese probleme geassosieer met kristallisasie of oplosmiddel ekstraksie soos filtrasie, lae opbrengste en gebruik van gechlorineerde koolwaterstowwe as oplosmiddel belemmer die kommersialisering van olieverwydering vir hierdie tipes wasse. 'n Gedetaileerde studie van die ekonomiese lewensvatbaarheid van superkritiese olieverwydering is uitgevoer. Vloeidiagramme is voorgestelom die energieverbruik van die superkritiese ekstraksieproses te minimeer. Vergelyking van kortpad distillasie, statiese kristallisasie en superkritiese ekstraksie dui daarop dat kortpad distillasie die goedkoper opsie vir die olieverwydering van die spesifieke was is. Fraksionering van swaarder wasse met kortpad distillasie sal moontlik nie haalbaar wees nie omdat die distillasietemperatuur drasties toeneem met molekulêre massa. Die skeiding van medium tot langketting wasse met superkritiese ekstraksie behoort meer mededingend te wees, want die kapasiteit van die superkritiese oplosmiddel kan maklik verstel word om langer kettinglengtes wasse te ekstraeer sonder om die temperatuur te verhoog. Statiese kristallisasie blyk die duurder olieverwyderingsopsie te wees hoofsaaklik weens die hoë kapitaalkoste van so 'n aanleg.
Nilsson, Helena. "Occupational exposure to fluorinated ski wax". Doctoral thesis, Örebro universitet, Institutionen för naturvetenskap och teknik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-24289.
Texto completoEl, Mellas Ismail. "Numerical simulation of wax deposition in pipelines". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020.
Buscar texto completoSiljuberg, Morten Kristoffer. "Modelling of Paraffin Wax in Oil Pipelines". Thesis, Norges Teknisk-Naturvitenskaplige Universitet, Institutt for geologi og bergteknikk, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-19383.
Texto completoLEIROZ, ANDREA TEIXEIRA. "STUDY OF WAX DEPOSITION IN PETROLEUM PIPELINES". PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2004. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=5206@1.
Texto completoCENTRO DE PESQUISAS LEOPOLDO AMÉRICO MIGUEZ DE MELLO
Deposição de parafinas de alto peso molecular nas paredes internas de linhas submarinas de produção e transporte é um dos problemas críticos encontrados pela indústria de petróleo. O acúmulo de material depositado pode ocasionar um aumento na potência de bombeamento requerida, diminuição da vazão ou mesmo o bloqueio completo da linha com conseqüente perda de produção e de investimentos. O presente trabalho realizou uma análise detalhada da literatura sobre deposição de parafina onde concluiu-se que não existe evidência experimental suficiente para definir qual o mecanismo básico responsável pela deposição dos cristais de parafina. Baseado no resultado da revisão bibliográfica foram realizados estudos experimentais e simulações numéricas sobre a deposição de parafina no interior de dutos. O trabalho foi direcionado para a condução de estudos de caráter fundamental onde buscou-se, através de experimentos simples, tentar contribuir para o melhor entendimento dos mecanismos de deposição de parafina. Experimentos com deposição em cavidades contendo fluido estagnado e em escoamento laminar produziram resultados para a evolução temporal e espacial da frente de deposição ainda não disponíveis na literatura. O modelo numérico puramente difusivo proposto no presente trabalho para deposição em cavidades com fluido estagnado, subestima os valores de espessura de depósito quando comparados com os valores experimentais observados. As observações realizadas não foram suficientes para corroborar a hipótese que a deposição de parafina é devida somente ao mecanismo de difusão molecular.
Deposition of high molecular weight paraffin on the inner wall of subsea production and transportation pipelines continues to be a critical operational problems faced by the petroleum industry. The accumulation of the deposited material on the inner wall of the lines may lead to increased pumping power, decreased flow rate or even to the total blockage of the line, with loss of production and capital investment. In the present work a critical review of the literature on wax deposition was conducted leading to the conclusion that there is not enough experimental evidence to determine which are the relevant mechanisms responsible for wax deposition. Based on the conclusions of the literature search, experimental studies and numerical simulations were conducted. The focus of the work was on simple, basic studies that were able to contribute to the understanding of the relative importance of the deposition mechanisms. The experiments on deposition cavities containing stagnant fluids and in laminar flow through channels yielded temporal and spatial distributions of paraffin deposits not yet available. A molecular-diffusion-based model developed underestimated the deposit thickness for the stagnant cavity. The results obtained were not sufficient to corroborate the hyphotesis that the wax deposition process is controlled by molecular diffusion.
YUPA, LUIS FERNANDO PALOMINO. "EXPERIMENTAL STUDY WAX DEPOSITION IN TURBULENT FLOW". PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2010. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=17170@1.
Texto completoUm dos principais problemas encontrados na produção de petróleo em águas profundas é a deposição de parafina em linhas de produção e transporte. À medida que o óleo escoa pelos dutos, perde calor para o ambiente marinho mais frio, reduzindo a solubilidade dos hidrocarbonetos mais pesados, podendo levar à deposição destes componentes nas paredes do duto. A deposição de parafina pode causar redução da capacidade de produção e até bloqueio total da linha. A capacidade de previsão da variação temporal destes depósitos, assim como a sua distribuição espacial ao longo do duto, são informações relevantes para o projeto e a operação das linhas. Uma revisão atualizada da literatura revela que os mecanismos responsáveis pela deposição de parafina ainda não são bem compreendidos. O presente trabalho faz parte de um programa de pesquisa em andamento voltado para o estudo dos mecanismos de deposição de parafina em dutos. Foram conduzidos experimentos de laboratório onde soluções de parafina e querosene com propriedades conhecidas escoavam por seção de testes especialmente projetada para permitir a medição da variação espacial e temporal da espessura dos depósitos. As medições foram realizadas para regime de escoamento turbulento utilizando um microscópio óptico. Os resultados obtidos mostraram que a espessura de depósito decresce com o aumento do número de Reynolds, sendo inferior aos valores obtidos para a condição de regime laminar. A boa qualidade das visualizações obtidas permitiu observar a remoção de depósito por cisalhamento. Os resultados obtidos estão disponíveis para validar soluções numéricas e auxiliar no entendimento dos mecanismos básicos responsáveis pela deposição de parafina.
One of the main problems encountered in oil production in deepwaters is the wax deposition in production and transportation lines. As the oil flows in the pipelines, it loses heat to the colder outside environment, reducing its solubility to heavy hydrocarbons, and potentially leading to deposition at the pipe walls. Wax deposition may cause loss of production and even the complete blockage of the line. The ability to predict the spatial and temporal variation of the deposits is relevant to the design and operation of subsea lines. An updated literature review revealed that the mechanisms responsible for wax deposition are still not fully understood. The present work is part of an ongoing research project aimed at studying the mechanisms responsible for wax deposition in pipelines. Laboratory experiments were conducted for turbulent flow of wax and querosene solutions through a specially designed test section that allowed for optical acces. An optical microscope was employed for measuring the wax deposit thicknesses which were shown to decrease with increasing Reynolds number. The deposits measured in the turbulent regime were smaller than those for the laminar regime. The good quality of the visualizations obtained allowed the observation of wax deposit removal by shear effects. The experimental results obtained are available for comparison with numerical solutions, what can contribute to the study of the basic mechanisms responsible for wax deposition.
LIMA, JOAO CLAUDIO BASTOS. "STUDIES ON WAX DEPOSIT FORMATION IN PIPELINES". PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2018. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=36208@1.
Texto completoCOORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
PROGRAMA DE EXCELENCIA ACADEMICA
O entendimento do fenômeno de deposição de parafina em linhas submarinas de produção e transporte de petróleo é importante para a construção de modelos de previsão que auxiliem no projeto e operação destas linhas. No presente trabalho, foram realizados experimentos controlados em escala de laboratório com o objetivo de obter informações sobre alguns aspectos relevantes da deposição de parafina. Para isso, foi utilizada uma seção de testes anular, com condições de contorno bem controladas, operando com um fluido de testes com propriedades bem conhecidas, e apresentando uma distinção marcada entre a composição do solvente e aquela das parafinas. A seção de testes era equipada com uma sonda de temperatura de pequenas dimensões acoplada a um micrômetro, o que permitiu a medição de perfis de temperatura dentro do depósito para condições de escoamento. A sonda também possibilitou a obtenção da temperatura da interface depósito-líquido ao longo da formação do depósito. Os testes incluíram a variação do número de Reynolds do escoamento anular, da temperatura da parede fria, e da taxa de resfriamento da parede. Uma câmera de vídeo de alta taxa de aquisição de imagens acoplada a lentes de aproximação foi utilizada para determinar a posição da sonda de temperatura em relação à interface do depósito. Os resultados mostraram que a temperatura da interface se mantém estável em um valor intermediário entre a TIAC (Temperatura Inicial de Aparecimento de Cristais) e a TDC (Temperatura de Desaparecimento de Cristais), desde quando a deposição de inicia até quando depósito atinge sua espessura de regime permanente. A câmera de vídeo forneceu imagens originais sobre a formação dos depósitos, notadamente sobre uma região acima do depósito em formação onde cristais de parafina são carregados pelo escoamento, sem que um número significativo destes cristais depositasse ou fosse aprisionado no depósito. As imagens revelaram também que estes cristais não são oriundos de cristais arrancados do depósito em posições a montante no início do duto, mas têm origem no seio do fluido adjacente à interface do depósito. A sonda de temperatura foi também utilizada na medição da temperatura nesta região de líquido acima da interface do depósito onde, por um período de tempo, cristais de parafina escoavam.
The proper understanding of the wax deposition phenomena in subsea oil pipelines is relevant to the development of more accurate models to aid in the design and operation of these lines. In the present work, laboratory-scale experiments under well-controlled conditions were conducted to study some relevant aspects of wax deposition. To this end, an annular deposition test section was employed, using a test fluid with known properties, and displaying a marked distinction between the solvent and the wax chemical components. The test section was equipped with a temperature probe of small dimensions, driven by a micrometer head. This probe allowed the measurement of temperature profiles within the wax deposit, under flowing conditions, and also the temperature of the deposit-liquid interface as the deposit was formed. The tests encompassed the variation of the annular flow Reynolds number, the cold wall temperature and the wall cooling rate. A high-frame-rate video camera coupled to magnifying lenses was used to provide images of the temperature probe and of the deposit interface. The results showed that that temperature of the interface remains stable in an intermediate value between the WAT (Wax Appearance Temperature) and the WDT (Wax Disappearance Temperature), since the first moments of the deposition until the deposit reaches its steady state configuration. The video camera captured original images on the deposit formation, especially on a region above the deposit where wax crystals are carried by the flow for a period of time. Only an insignificant number of carried crystals were observed to deposit over the immobile interface, or to be captured at the interface. The images also revealed that the carried crystals do not originate from crystals sloughed from upstream positions in the annular duct. The temperature probe was also employed to measure the temperature of the liquid region above the deposit interface where the crystals existed for a period of time.
Tabatabaei-Nejad, Seyyed Ali Reza. "Phase behaviour modelling of petroleum wax and hydrates". Thesis, Heriot-Watt University, 1999. http://hdl.handle.net/10399/593.
Texto completoButt, Ali Azhar. "Low Temperature Performance of Wax Modified Mastic Asphalt". Thesis, KTH, Väg- och banteknik, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-49694.
Texto completoBotne, Kjetil Kandal. "Modeling wax thickness in single-phase turbulent flow". Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for petroleumsteknologi og anvendt geofysikk, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-19307.
Texto completoQi, Chuan. "NCF/Wax nano composites inspired by plant cuticles". Thesis, KTH, Skolan för kemivetenskap (CHE), 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-146034.
Texto completoGalta, Tore. "Bypass Pigging of Subsea Pipelines Suffering Wax Deposition". Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for produksjons- og kvalitetsteknikk, 2014. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-26676.
Texto completoCABANILLAS, JOSE LUIS PLASENCIA. "WAX DEPOSITION IN LAMINAR FLOW WITH SUSPENDED CRYSTALS". PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2006. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=8715@1.
Texto completoA tendência da produção offshore do petróleo é crescente. O transporte do óleo nestes ambientes frios (águas profundas) ocasiona a perda de solubilidade e precipitação das parafinas de alto peso molecular. A deposição de parafinas nas paredes internas das linhas é um problema crítico para o transporte do óleo, causando o bloqueio parcial ou total da linha, um incremento da potência de bombeamento e elevados custos de manutenção que são proporcionais ao aumento da lâmina de água. A pesquisa bibliográfica realizada neste trabalho revela que ainda existem discordâncias entre os pesquisadores sobre a relevância de cada um dos mecanismos de deposição de parafina conhecidos. O melhor entendimento dos mesmos resultaria em previsões mais acuradas das taxas de deposição que seriam muito importantes para orientar programas de manutenção e o projeto de novas linhas. A filosofia do presente trabalho é realizar experimentos simples, com propriedades de fluido conhecidas e condições de contorno bem controladas procurando um melhor entendimento da importância e relevância de cada um dos mecanismos de deposição. Para este fim, foram realizadas experiências de visualização do fenômeno de deposição para uma mistura de óleo-parafina escoando em regime laminar, submetida a diferentes condições de temperatura. Experiências feitas com cristais de parafina precipitados em suspensão mostraram que é necessário um fluxo de calor negativo para produzir deposição. Para fluxos de calor zero e positivo não foi visualizada deposição alguma. Adicionalmente, para condições de fluxo de calor negativo, foram realizadas medições da evolução temporal da espessura da camada depositada tendo como variáveis, diferentes números de Reynolds e gradientes de temperatura. Os perfis de deposição obtidos das experiências realizadas são informação importante e original que podem ser utilizadas para validação de modelos de simulação numérica.
Offshore crude oil production is steadily growing. Oil transport in these cold environments (deep water) causes the precipitation of the heavy organic crude oil components like waxes. Wax deposition at the inner wall of pipelines is a serious problem in crude oil transportation causing the partial or total plugging of pipelines, increase in pumping energy and a high cost of maintenance that is proportionally greater as development depth increases. A literature research conducted in the present work leads to the conclusion that the relative importance of the wax deposition mechanisms is still misunderstood. The importance of this knowledge will result in more accurate prediction of paraffin deposition rates that would be very important to sub sea pipelines maintenance and design. The philosophy of this work is to make simple experiments with known fluid properties and well controllable conditions trying to understand the importance and relevance of each known fouling mechanism. Hence, wax deposition experiments were performed in laminar flow for different temperature conditions with a single-phase paraffin-oil mixture, having the particle migration visualization in mind. Experiments with oil mixture injection temperature below the Wax Appearance Point (with wax crystals flowing) have shown that it is necessary a negative heat flux to produce significant deposition. For positive and zero heat fluxes there was no deposition visualized. Also, the unsteady fouling state for negative heat flux was followed and their temporal deposition profiles measured for different Reynolds and temperature conditions. Those temporal and dimensional deposition profiles are original important information to be compared with numerical simulation.
CRUZ, SAMUEL RODRIGUES. "WAX DEPOSITION STUDY IN A MULTIPHASE PIPE FLOW". PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2011. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=18475@1.
Texto completoCrude oil is formed by several hydrocarbons. At the reservoir, due to high pressures and temperatures, it is found in the liquid form. As the oil flows, its pressure drops as well as its temperature, due to a heat loss to the ambient, causing liberation of the gas dissolved in the oil and it becomes a two-phase flow. Further, if the temperature drops below the initial crystallization temperature, crystals precipitation occurs, forming a solid phase deposit at the inner pipeline walls. Wax deposition is one of the most critical operational problems regarding oil flow through subsea pipelines. This work, wax deposition in a multiphase flow is numerically predicted. The influence of a water phase and pipe inclination angle in the deposition rate is investigated. The Drift Flux Model was employed to predict the multiphase flow and the wax deposition was determined based on a Molecular Diffusion Model. The methodology was validated by investigating the flow in a short pipe, reproducing laboratory experimental conditions. The wax deposit thickness presented a excellent agreement with the experimental data and against results of commercial code OLGA. An existing oil production well in Campos Basin was modeled, and the impact in pressure drop due to cross section area reduction caused by progressive wax deposition on the pipe wall. The results obtained in this study demonstrated good physical consistency and a reasonable agreement with the compared experimental database.
PIMENTEL, DANIEL MONTEIRO. "EXPERIMENTAL STUDY OF WAX DEPOSITION ON COATED SURFACES". PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2012. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=22080@1.
Texto completoWax deposition is a relevant flow assurance issue for the petroleum industry. Besides the well-known prevention and mitigation techniques for wax deposition, non-stick internal coatings have been proposed as an alternative solution to this problem. A literature review has been carried out and revealed that the available results, based on either field experience and laboratory experiments, are often contradictory. The present work aims at developing a laboratory apparatus to evaluate the influence of coated surfaces on wax deposition. The experiments were carried out at constant heat flux conditions to eliminate the insulation effects that are associated with the different coating. The tests conducted were aimed at establishing a relationship between wax deposition thickness,, surface roughness and surface energy. The experiments consisted of a closed loop circuit for the wax solution, employing a transparent test section where plates with different surface coatings were tested. Continuous monitoring of the heat flux removed and fluid and plate temperatures allowed total control of the deposition process. Wax layer thicknesses were measured optically with the aid of a digital camera. Five different surfaces were tested, namely, 316L stainless steel (rough and polished), Teflon, Nylon 11 and amorphous carbon. A key finding of these experiments is that the lower the surface energy or the smoother the surface, the lower the wax deposit thickness. However, the wax deposit reduction was seen to be highly dependent on flow conditions. As a side result of the experiments, the indirect determination of wax thickness based on heat flux measurements was shown to be a viable technique. Although the thermal conductivity of the wax deposit, a necessary information for the implementation of the technique, seemed to depend on the flow Reynolds number.
SOUZA, LUCIANA BOHER E. "WAX DEPOSITION IN PIPELINES: NUMERICAL AND EXPERIMENTAL STUDY". PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2014. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=24627@1.
Texto completoCONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
Parafinas de alto peso molecular presentes no petróleo escoando em ambientes de baixa temperatura cristalizam-se e depositam-se nas paredes internas dos dutos, ocasionando a redução da taxa de escoamento e o aumento do custo de produção, podendo levar até mesmo ao bloqueio das linhas de transporte. O processo de deposição é complexo e envolve conhecimento multidisciplinar, de modo que diferentes abordagens têm sido propostas para a sua modelagem. O principal objetivo deste trabalho foi investigar o fenômeno de deposição de parafina em uma geometria simples, com condições bem controladas, utilizando uma abordagem numérica e experimental, com foco no melhor entendimento dos mecanismos que induzem a deposição, a formação dos depósitos e seu envelhecimento. Experimentalmente, foram conduzidos testes com fluidos de laboratório que permitiam a visualização e a medição da evolução espacial e temporal de depósitos de parafina formados sob escoamentos laminar e turbulento. Numericamente, foi desenvolvido um modelo multicomponente para escoamento laminar, chamado de entalpia-porosidade. Tanto a espessura quanto a composição do depósito foram determinadas através de um modelo termodinâmico acoplado às equações de conservação de massa, de quantidade de movimento linear, de energia e de espécies. Os resultados indicaram que o efeito Soret não influencia a deposição de parafina. A espessura do depósito foi bem avaliada numericamente para regime permanente, apresentando diferenças na sua evolução temporal. O modelo composicional desenvolvido fornece importantes dados além da espessura depositada, como a temperatura inicial de aparecimento de cristais (TIAC) e o número de carbono crítico (NCC) do sistema, ampliando a previsão do processo de deposição com informações sobre a composição e o envelhecimento do depósito. As investigações numéricas mostraram que maiores taxas de cisalhamento e temperaturas da parede resultam em depósitos menos espessos. Mostrou-se também que maiores taxas de cisalhamento resultam em depósitos mais densos, e que maiores temperaturas da parede tendem a aumentar a saturação de sólido na região intermediária do depósito.
High molecular weight paraffins crystallize and deposit on the inner walls of production lines and oil pipelines operating in cold environments, causing reductions in flow rate, increase of the production cost, or even the total blockage of the transport lines. Wax deposition is a complex process involving multidisciplinary knowledge, so that different approaches have been proposed for its modeling. The primary purpose of this work was to investigate the wax deposition process in a simple geometry under well-controlled conditions, using a numerical and experimental approach, focusing on a better understanding of the phenomena controlling the wax deposition, the formation of the deposit and its aging. Controlled experiments were conducted using laboratory solutions which allowed visualization and measurement of the spatial and temporal evolution of wax deposits under laminar and turbulent flows. A multicomponent model for laminar flow, called enthalpy-porosity, was developed. The thickness and composition of the deposit were determined by a thermodynamic model coupled with conservation equations of mass, linear momentum, energy and species. The results indicated that the Soret effect does not contribute to wax deposition. The thickness of the deposit was well predicted by the numerical model for steady state, presenting, however, differences in its temporal evolution. The multicomponent model developed provides valuable information in addition to the deposited thickness, such as the wax appearance temperature (WAT) and the critical carbon number (CCN) of the wax-oil system. These are relevant information for the prediction of the deposit composition and the aging process. The numerical results demonstrated that higher flow rates and wall temperatures lead to thinner deposits. It was also shown that the deposit wax content is higher for higher shear rates, while higher wall temperatures lead to higher solid content in the intermediate region of the deposit.
Beri, Akash. "Wax based emulsions for use in lipstick application". Thesis, University of Birmingham, 2015. http://etheses.bham.ac.uk//id/eprint/5673/.
Texto completoKang, Johan y Mattias Bygge. "Geiser : A wax heater in the ski trail". Thesis, KTH, Maskinkonstruktion (Inst.), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-189528.
Texto completoCross country skiing is a popular winter sport in the Nordic countries and ski waxing is a vital part of the sport. But ski waxing comes with logistical problems and it needs equipment that is either heavy and cumbersome or needs electricity to function. Today there are few solutions to expedite ski waxing in the trail, this is most likely due to the problems that come with portability; the ski wax can be too cold for application or the ground can be too uneven to allow ski waxing. The purpose of this project is to produce a concept that will fill this vacuum in the ski wax market. The project is based on the demands and expectations that skilled waxers and skiiers would put on portable ski wax and what is expected of such a product today. These were formed through interviews with professional ski waxers in stores around Stockholm and by investigating what products today facilitate portable ski waxing. During the course of the project several concept propositions were formed through different idea generating techniques and brainstorming. These came in two rounds; first three koncept propositions that were named 1. Det Stavstabiliserande Vallastället, 2. Hängselstället and 3. Klistervärmaren that were put through an elimination. The concept proposition that got the most points was 3. Klistervärmaren which function is to heat up ski wax, foremost kick wax, for easier application. Three new concept ideas were furtherly developed from the winning concept proposition; 3.1 Termos, 3.2 Klädseln and 3.3 Kombo. These were evaluated until a final concept was chosen. The winning concept was 3.3 Kombo. Kombo was developed further and its appearance and properties were defined through design, choice of material and energy source aswell as heat generation. The result was GEISER which is a portable, battery powered wax heater and container that is to be used as a complement to existing ski gear such as drink belts and packs. GEISER keeps the ski wax isolated from the cold by having several different layers of cloth with unique, isolating attributes and it heats the ski wax through a heating wire woven into the inner fabric of the cloth layers. This wire is connected to a battery pack that is situated on top of the cylindrical wax container in a pouch. A circuit breaker is integrated in the outermost layer on the upper side of GEISER for easy on- and off switching.
Taher, Salam Ghafour. "Synthesis of myobacterial wax esters and related compounds". Thesis, Bangor University, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.664599.
Texto completoAli, Abdualbaset Ahmed. "Altering Wax Appearance Temperature Using Shear and Pressure". University of Toledo / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1575992511410478.
Texto completoSaunders, Heath G. "Wax distribution quantification using digital image analysis techniques". Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-11102009-020230/.
Texto completoRibas, Garriga Mariona. "Evaluation of natural wax for green packaging applications". Thesis, Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-74848.
Texto completoKing, Andrew Stewart. "The Folk-Song Society wax cylinder recordings in the English Folk Dance and Song Society wax cylinder collection : context, history, and reappraisal". Thesis, University of Sussex, 2016. http://sro.sussex.ac.uk/id/eprint/61113/.
Texto completoBabalola, Olamide Akanbi. "Utilities optimization in a wax process plant / O.A. Babalola". Thesis, North-West University, 2007. http://hdl.handle.net/10394/1790.
Texto completoWang, Qian. "Characterization of xtcl mutant with reduced cuticular wax accumulation". Thesis, University of British Columbia, 2007. http://hdl.handle.net/2429/352.
Texto completoFLEMING, FELIPE PEREIRA. "FUNDAMENTAL STUDY OF WAX DEPOSITION UNDER REAL FLOW CONDITIONS". PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2018. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=34612@1.
Texto completoDesde o início dos anos 1980, esforços foram direcionados para modelar o fenômeno de deposição de parafinas. Ao longo dos anos, a avaliação crítica dos mecanismos da deposição de parafinas vem cedendo espaço ao desenvolvimento de correlações flexíveis capazes de acomodar diferentes situações testadas no laboratório. Numa tentativa de investigar o fenômeno em uma abordagem fundamental, o presente trabalho propôs uma estratégia de pesquisa que envolve avaliar cada pedaço do fenômeno de deposição de parafinas e garantir seus resultados ótimos. Para alcançar tal objetivo, uma nova estratégia para se avaliar modelos termodinâmicos de equilíbrio de fases sólido-líquido foi desenvolvida. Os resultados mostram que o modelo utilizado é robusto e preciso o suficiente para descrever tais fenômenos para misturas assimétricas em pressões ordinárias e altas, assim como descrever o comportamento de misturas complexas como amostras de óleo Diesel. Para garantir uma base física sólida dos resultados, a condutividade térmica de n-alcanos pesados foram medidos na fase líquida e na fase sólida e reportados na literatura pela primeira vez. Por fim, um modelo de escoamento de sólido-líquido foi proposto. Acoplado a um modelo termodinâmico capaz de gerar dados de equilíbrio de fases sólido-líquido e propriedades dessas fases, assim como combiná-las em propriedades da mistura, o modelo foi utilizado para descrever os resultados disponíveis na literatura. O mecanismo de deposição de parafinas avaliado se baseia no aumento da viscosidade com a temperatura e concentração de sólidos. Os resultados mostraram que embora houvesse um acordo qualitativo entre os resultados experimentais e os simulados, o modelo subestimou a espessura do depósito de parafinas. Por outro lado, o modelo foi capaz de descrever a condutividade térmica do depósito de acordo com os dados medidos experimentalmente para um depósito similar. Tal fato reforça as conclusões finais e indica que a deposição de parafinas parece não ser um fenômeno regido apenas por um mecanismo.
Since the early 1980 s, efforts have been directed towards modeling the complex wax deposition phenomenon. Over the years, the critical evaluation of the wax deposition mechanisms proposed initially through a solid physical background start to make room to flexible codes that could be tuned to different experiment scenarios. In an attempt to investigate the phenomenon in a fundamental way, the current work proposed a research strategy that would evaluate every single part of the complex wax deposition model under well-controlled optimal conditions. To achieve such a goal, a new strategy to evaluate solid-liquid thermodynamic models was developed. Results showed that the model used was robust enough to precisely describe the solid-liquid phase behavior of asymmetric model mixtures at both ordinary and high pressures, as well as to describe the behavior of complex mixture like Diesel fuel samples. To assure the solid physical basis of the models being employed in this work, the thermal conductivity measurement of heavy n-alkanes in both liquid and solid phases was carried out and reported for the first time in the literature. At last, a drift flux solid-liquid CFD model was proposed. Coupled with a thermodynamic model to supply the model with phase equilibria and properties data, the model was used to investigate the experimental results available in the literature. The wax deposition mechanism evaluated was based on the viscosity increase due to the appearance of solids. The results showed that although a qualitative agreement between the model and experimental results were obtained, the model underestimated the thickness of the deposit. On the other hand, the thermal conductivity of the deposit matched the recently available experimental data on the thermal conductivity of such a deposit measured under flowing conditions. This fact strengthens the presented conclusions that wax deposition is not a single mechanism phenomenon after all.
Depuis le début des années 1980, des efforts ont été déployés pour modéliser le phénomène complexe de dépôt de cire. Au fil des années, l évaluation critique des mécanismes de formation de dépôts de cire limités initialement à la cristallisation des paraffines, a commencé à faire place à des algorithmes flexibles qui peuvent être adaptés à différents scénarios expérimentaux. Dans une tentative d étudier le phénomène de manière fondamentale, le travail actuel a consisté à proposer une stratégie globale de recherche qui permet d évaluer les différentes mécanismes impliqués dans la formation de dépôts de cire. Pour atteindre cet objectif, une nouvelle stratégie a tout d abord été proposée pour ajuster les modèles thermodynamiques utilisés pour décrire le comportement de phase solide-liquide. Les résultats de comparaison avec l expérience ont montré que la démarche proposée était suffisamment robuste pour décrire précisément le comportement de phase solide-liquide des mélanges synthétiques asymétriques aux pressions ordinaires ou très élevées, ainsi que pour représenter le comportement de mélanges complexes réels comme par exemple des carburants pour moteur Diesel. Dans un second temps, des mesures de conductivité thermique dans des n-alcanes lourds à l état liquide mais aussi solide ont été réalisées et rapportée pour la première fois ici afin d assurer une base physique solide dans les modèles utilisés dans ce travail. Enfin, un modèle CFD solide-liquide a été proposé. Couplé au modèle thermodynamique utilisé pour décrire les équilibres de phase et les propriétés thermophysiques, ce modèle a été utilisé pour étudier les résultats expérimentaux disponibles dans la littérature. Le mécanisme de dépôt de cire évalué était basé sur l augmentation de la viscosité devenue de l apparition des solides. Les résultats ont montré un accord qualitatif entre les prédictions du modèle et les observations expérimentales malgré une sous-estimation de l épaisseur du dépôt formé. D autre part, la conductivité thermique du dépôt estimée correspondait parfaitement à la conductivité thermique mesurée récemment dans des conditions d écoulement réelles.
Azevedo, Pedro Mapurunga. "Determinants of the sale price of carnauba wax benefited". Universidade Federal do CearÃ, 2009. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=4870.
Texto completoAt this article, it was analyzed the real capacity of some valuation in a sales price of composition in a Carnauba Wax and it was tried to preview this price, the linear model that has been used was Least Quarters. Despite of ad hoc, the studied model and chosen variables have showed satisfactory results, it has been chosen macroeconomics variables, weathers variables (dummy) and specifics variables. The final results confirmed some empiric affirmations however it showed some results that business men from its market used to say the other way round.
Nesta dissertaÃÃo foi analisada a influÃncia de algumas variÃveis explicativas na capacidade de composiÃÃo de preÃo de venda da Cera de CarnaÃba beneficiada, e a tentativa de prevÃ-la, o modelo linear utilizado foi o de MÃnimos Quadrados OrdinÃrios (MQO). Apesar de ad hoc, o modelo e as variÃveis escolhidas mostraram resultados bastante satisfatÃrios, onde foram escolhidas variÃveis macroeconÃmicas, variÃveis climÃticas (dummy) e variÃveis setoriais. O resultado final do estudo confirmou algumas afirmaÃÃes que eram feitas de forma empÃrica, mas tambÃm demonstrou resultados que foram contra ao que especialistas do assunto julgavam como verdades absolutas.
Pereira, Fleming Felipe. "Fundamental study of wax deposition under real flow conditions". Thesis, Pau, 2018. http://www.theses.fr/2018PAUU3009/document.
Texto completoSince the early 1980’s, efforts have been directed towards modeling the complex wax depositionphenomenon. Over the years, the critical evaluation of the wax deposition mechanisms proposedinitially through a solid physical background start to make room to flexible codes that could be tunedto different experiment scenarios. In an attempt to investigate the phenomenon in a fundamental way, the current work proposed a research strategy that would evaluate every single part of thecomplex wax deposition model under well-controlled optimal conditions. To achieve such a goal, anew strategy to evaluate solid-liquid thermodynamic models was developed. Results showed thatthe model used was robust enough to precisely describe the solid-liquid phase behavior ofasymmetric model mixtures at both ordinary and high pressures, as well as to describe the behaviorof complex mixture like Diesel fuel samples. To assure the solid physical basis of the models beingemployed in this work, the thermal conductivity measurement of heavy n-alkanes in both liquid andsolid phases was carried out and reported for the first time in the literature. At last, a drift flux solidliquidCFD model was proposed. Coupled with a thermodynamic model to supply the model withphase equilibria and properties data, the model was used to investigate the experimental resultsavailable. The wax deposition mechanism evaluated was the one proposed by Merino-Garcia. Theresults showed that although a qualitative agreement between the model and experimental resultswere obtained, the model underestimated the thickness of the deposit. On the other hand, thethermal conductivity of the deposit matched the recently available experimental data on the thermalconductivity of such a deposit measured under flowing conditions. This fact strengthens thepresented conclusions that wax deposition is not a single mechanism phenomenon after all
Desde o início dos anos 1980, esforços foram direcionados para modelar o fenômeno de deposiçãode parafinas. Ao longo dos anos, a avaliação crítica dos mecanismos da deposição de parafinas vemcedendo espaço ao desenvolvimento de correlações flexíveis capazes de acomodar diferentessituações testadas no laboratório. Numa tentativa de investigar o fenômeno em uma abordagemfundamental, o presente trabalho propôs uma estratégia de pesquisa que envolve avaliar cadapedaço do fenômeno de deposição de parafinas e garantir seus resultados ótimos. Para alcançar talobjetivo, uma nova estratégia para se avaliar modelos termodinâmicos de equilíbrio de fases sólidolíquidofoi desenvolvida. Os resultados mostram que o modelo utilizado é robusto e preciso osuficiente para descrever tais fenômenos para misturas assimétricas em pressões ordinárias e altas,assim como descrever o comportamento de misturas complexas como amostras de óleo Diesel. Paragarantir uma base física sólida dos resultados, a condutividade térmica de n-alcanos pesados forammedidos na fase líquida e na fase sólida e reportados na literatura pela primeira vez. Por fim, ummodelo de escoamento de escorregamento sólido-líquido foi proposto. Acoplado a um modelotermodinâmico capaz de gerar dados de equilíbrio de fases sólido-líquido e propriedades dessasfases, assim como combiná-las em propriedades da mistura, o modelo foi utilizado para descrever osresultados disponíveis. O mecanismo de deposição de parafinas avaliado foi o proposto por Merino-Garcia. Os resultados mostraram que embora houvesse um acordo qualitativo entre os resultadosexperimentais e os simulados, o modelo subestimou a espessura do depósito de parafinas. Por outrolado, o modelo foi capaz de descrever a condutividade térmica do depósito de acordo com os dadosmedidos experimentalmente para um depósito similar. Tal fato reforça as conclusões finais e indicaque a deposição de parafinas parece não ser um fenômeno regido apenas por um mecanismo
Wax, Andreas [Verfasser]. "Internationales Sportrecht. : Unter besonderer Berücksichtigung des Sportvölkerrechts. / Andreas Wax". Berlin : Duncker & Humblot, 2009. http://d-nb.info/1238360572/34.
Texto completoLamperti, Riccardo. "Rheological and energetic characterization of wax-modified asphalt binders". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2012. http://amslaurea.unibo.it/4260/.
Texto completoHegebarth, Daniela. "Cuticular wax analyses with high spatial and temporal resolution lead to the identification and characterization of novel wax biosynthesis genes in Arabidopsis thaliana". Thesis, University of British Columbia, 2016. http://hdl.handle.net/2429/58833.
Texto completoScience, Faculty of
Botany, Department of
Graduate
Jose, Sarah Bryallen. "Investigating the link between cuticular wax biosynthesis and stomatal development". Thesis, University of Bristol, 2016. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.715839.
Texto completoMoore, Jacob Madison. "Qinae the wax and gold of the Ethiopian Orthodox Church /". Theological Research Exchange Network (TREN), 2005. http://www.tren.com/search.cfm?p062-0271.
Texto completoMariageraldrajan, Natarajansoundarapandian. "Novel carbopol-wax blends for controlled release oral dosage forms". View the abstract Download the full-text PDF version, 2007. http://etd.utmem.edu/ABSTRACTS/2007-011-Rajan-index.html.
Texto completoTitle from title page screen (viewed on July 17, 2008). Research advisor: Atul J. Shukla, Ph.D. Document formatted into pages (ix, 146 p. : ill.). Vita. Abstract. Includes bibliographical references (p. 137-146).