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Nelson, Jac Jeanette. "Wax." PDXScholar, 2016. http://pdxscholar.library.pdx.edu/open_access_etds/3015.
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In content, concept, and form, my collection of poems is composed of a number of thematic obsessions. These are: music, sound, and hearing; recording and surveillance; play and participation as described by Hans-Georg Gadamer in Truth & Method; the angel of history as described by Walter Benjamin; situation, inheritance, influence; aggression, antagonism, manipulation, control; fixity and mutability; eros, desire, and sex; conversation, the dialectic relationship of wholes and parts. You might see that all of these themes relate, that they each appear as one another. WAX speaks and performs all of these themes from that point where self and other--and where identity and universality--collapse; that single point of fear, violence, loss, union, obliteration, feeling, responsibility; that single point of possibility where we might discover a revised I, a new answer for "how to write we."
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Ji, Hongyan. "Thermodynamic modelling of wax and integrated wax-hydrate." Thesis, Heriot-Watt University, 2004. http://hdl.handle.net/10399/332.
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Schwarz, 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.
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Marino, 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.
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Marino, Fabien. "Biodegradation of paraffin wax." Thesis, McGill University, 1998. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=21312.
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Nineteen bacteria were tested for growth on paraffin wax as the sole source of carbon. Paraffin wax is a solid mixture of hydrocarbons including n-alkanes ranging from C18H38 to C37H 76. Of the nineteen bacteria tested, four bacteria (Arthrobacter paraffineus ATCC 19558, Mycobacterium OFS, Pseudomonas fluorescens Texaco and Rhodococcus IS01) grew well on paraffin wax. However, only one, Rhodococcus IS01, was found to rapidly and completely degrade a mixture of paraffin wax liquefied with hexadecane using the Self-Cycling Fermentation (SCF) technology. This strain was able to degrade n-alkanes ranging from dodecane to heptatriacontane as well as highly branched hydrocarbons such as pristane and hepta-methyl-nonane.Kinetic 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.
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Starkie, Joanna Rachel. "Wax anti-settling additives." Thesis, University of Cambridge, 2019. https://www.repository.cam.ac.uk/handle/1810/284911.
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Wax anti-settling additives (WASA) are used to mitigate against the problems caused by the settling of n-alkane wax crystals, which crystallise from petroleum diesel. This can result in the blocking of fuel filters and hence vehicle failure. However, the mode of action for such additives is not currently known and two mechanisms have been proposed: they reduce the wax crystal size to such an extent that they settle very slowly; or they induce gelation in the wax suspension. This project aims to elucidate the mechanism of WASA within the diesel system. A room temperature crystallising model diesel (10 wt% n-alkanes in dodecane) has been developed. This model system has given a good response to the additives, with the wax crystals reduced in size, and is hence suitable for mechanistic studies. Differential scanning calorimetry and infra-red spectroscopy both suggest that the WASA is incorporated in or onto the wax crystal. DSC shows that small amounts of WASA suppress the wax crystallisation temperature and change the shape of the heat flow curve. FT-IR shows the WASA amide stretch present within filtered and dried wax crystals. Intriguingly, electrophoresis experiments show that the WASA imparts a positive charge to the wax crystals, suggesting an electrostatic role in the WASA action. Rheological experiments show the presence of a weak gel in the WASA doped model diesel. However, the gel strength is not altered by the presence of an organic salt and thus cannot be purely electrostatic in origin. Small angle neutron scattering has been conducted to help locate the WASA in the system. It has shown that in solution WASA shows a collapsed polymer coil structure with a single molecule occupying a 28 Å diameter sphere and multiple WASA molecules forming a 2400 Å diameter sphere. In the presence of the wax the WASA scatter does not significantly change suggesting that the WASA is on the surface of the wax crystal. By combining these results, a mechanism of WASA action is proposed as WASA cations interactions bridging between the wax crystals causing a weak bridging flocculation gel with electrostatic and steric effects contributing to stabilisation. The WASA charges are partially dissociated thus giving the electrophoretic effect and the long chains on the cations can contribute to stability via steric stabilisation.
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Cendrowicz, 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.
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The wax injection moulding and de-wax processes in investment casting were investigated; by measuring the relevant material properties of two commercially available pattern waxes; performing experimentation on industrial equipment; and using analytical and numerical techniques to solve some of the fluid mechanics, heat transfer and solid mechanics equations associated with each process. The rheological behaviour of the molten pattern waxes was found to be Newtonian at higher temperatures and shear-thinning at lower temperatures. The viscosity was also found to depend on shear and thermal history. Samples pre-sheared by both "screw" and "tank" type injection moulding machines were found to give lower vi~cosities than freshly melted pellets. The extensional viscosity was higher at lower temperatures and lower shear rates than that expected for a Newtonian liquid. The pressureflowrate- time relationship for the flow through a tube of a power-law fluid with exponential dependency with temperature was obtained by solving the coupled dimensionless heattransfer and fluid mechanics equations. The method was used to correct capillary viscometry results for viscous heating. Predictions of the pressure-drop through cold cylindrical running systems during injection moulding were found to agree qualitatively with experimentally measured values, although quantitative agreement was limited by the constitutive model that was used. The formation of surface defects during the injection of patterns was investigated by using flow-visualisation and computational fluid dynamics. It was found that substantial flow-lines occur when the flow-front velocity is below 10 mm.s-l, and significant air entrapment occurs at flow-front velocities above 1 m.s-1 A model was developed to predict the freezing time of running systems during the holding stage of the injection moulding cycle and the subsequent shrinkage behaviour of the pattern, which were found to be influenced most by the wax temperature, hold pressure, hold time, and runner diameter for thick unrestrained pattern geometries. The gas-assisted injection moulding process was adapted for wax pattern production, and was observed to reduce shrinkage by a factor of two. A onedimensional dynamic model was developed to calculate the stress in a cylindrical investment shell during de-waxing. The relevant physical properties of un-sintered ceramic shells were measured, including the pore size distribution, wax permeability, thermal expansion and hot & wet stress-strain behaviour. It was shown how the geometry, material properties and operating conditions can affect the frequency of shell cracking during the de-wax process.
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Mahabadian, 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.
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Waxes and hydrates formation are two major flow assurance challenges, imposing considerable costs for prevention and, in worst case scenario, pipeline blockage removal and deferred production. Employing remediation and prevention schemes for hydrate and wax related problems necessitates knowledge of their formation conditions as well as their amount. The main focus of this work is thermodynamic modelling of phase equilibria in systems prone to waxes, hydrates and combined wax−hydrate formation. Study of these complex mixtures requires the development of a robust multiphase flash calculation algorithm capable of identifying the correct number and nature of the phases in equilibrium. Such an algorithm is devised in this work based on the Gibbs free energy minimization concept. The algorithm is first applied to complex hydrate forming systems and then extended to combined wax-hydrate forming mixtures, enabling investigation of the mutual interactions between hydrates and waxes from the thermodynamics viewpoint. The new algorithm is fast and is capable of showing complex behaviours in hydrate and wax forming systems including stability of several wax phases or more than one hydrate structure at equilibrium conditions. In this work, an integrated thermodynamic model coupling three highly accurate schemes, i.e., the cubic plus association equation of state, UNIQUAC activity coefficient model and van der Waals and Platteeuw approach−to describe the non-idealities of the fluids, paraffinic solids (waxes) and hydrates, respectively−is implemented. Furthermore, the formation of waxes in high-pressure condition is thoroughly investigated, especially for highly asymmetric condensate-like systems. Accordingly, a modified thermodynamic model is presented for wax formation in high-pressure systems. Comparing with experimental solid-fluid equilibrium data of synthetic mixtures, the integrated model presents excellent agreement which demonstrates the reliability of the approach. Finally, the method available for the extension of the integrated model−which was based on synthetic mixtures−to real oil systems and especially for wax formation, are evaluated. Based on the analysis presented the best model is chosen and used for illustrating the combined wax-hydrate precipitation in a real crude oil.
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Larsson, 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.
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This is a master thesis report for MSc in Industrial Design Engineering at Luleå University of Technology. It is a development project where a wax-bench for cross-country skiing has been developed. The wax-bench have been developed to facilitate the clean-up for the user and to gather all wax-accessories at one place. In this report the entire project can be followed from start to finish, how the requirements were found, who is the user, what should the product handle and how was the ideas ge- nerated. The final result is a wax- box that is vacuum formed and folded in the middle. In the box there are adjustable profiles to place the ski on and an adjustable attachment part in the center that attaches to the skis binding. The box acts as a collector of the waste that is produced when waxing skis, and as storage of waxing accessories when not in use. How to install the accessory in the box is not yet determined, but the idea is to develop a specific bag that fits perfectly in the wax-box and includes all the usual accessories. This bag should then be taken out when you wax and put back in the box after complete the waxing.I 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.
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Southgate, Jonathan. "Wax removal using pipeline pigs." Thesis, Durham University, 2004. http://etheses.dur.ac.uk/2995/.
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The deposition of paraffin wax solids in pipelines and risers represents a continuing challenge to flow assurance in offshore installations. Wax deposits reduce product throughput, requiring increased energy expenditure to re-establish flow levels. In severe cases, wax deposits can completely block a pipeline. Preventative solutions to the problem such as pipeline insulation, active heating of pipes or chemical dosing with wax inhibitors are not always economically viable, so mechanical removal using a device known as a 'pig' remains an economical solution to the problem of wax removal. A pig is a cylindrical tool that is driven through the pipe by the flow of product, scraping deposits from the pipe wall as it travels. Despite the importance of pipeline pigging to the oil and gas industry, the effectiveness of pigs in removing wax is poorly understood and it is this problem that is addressed by this thesis. One of the first necessities in undertaking this work has been to define the mechanical properties of wax deposits. This has required critical analysis of published material on the subject of wax deposition along with practical experimentation to create representative models of wax deposits that require mechanical removal from pipelines. Previously, studies of wax removal using pigs have assumed the mechanics of the process to be adequately represented by uniaxial compression or simple shear load models. In this work wax removal is analysed using the orthogonal cutting model. This provides a more accurate description of the process as it includes the effect of material after yielding (the chip) on the net wax removal force. Experiments were designed to allow testing of the validity of the orthogonal cutting theory to the pigging process under a variety of conditions. An original contribution from this work is through experimental and theoretical results that are given context through comparison with established metal cutting theory. Through experimentation a specific cutting energy is obtained for wax removal. The results of the wax cutting experiments have identified particular differences between wax cutting and metal cutting regarding the homogeneity of chip formation. These observations have important implications in predicting wax removal forces using mechanical removal tools. Although the affect of removed wax chips on pigging forces has been neglected in theory, it is well known in practice. The fluid used to drive cleaning pigs is often used to produce a jet radiating centrally from the front of the pig intended to blast wax chips away from the pig body, avoiding formation of a 'plug' of wax ahead of the pig. In this study a novel variation of this process in the form of an annular bypass jet is experimentally studied. A semi-empirical model of wax removal using an annular bypass jet has been developed and empirical constants obtained to allow prediction of removal rates for different waxes under various conditions. The new model introduced here allows balancing of pig velocity with wax removal velocity so that a non-contacting wax removal system is obtainable. The bypass-jetting model has been validated using a full-scale trial of the process by industrial sponsors.
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Taylor, John A. "The lost wax casting technique." Virtual Press, 1993. http://liblink.bsu.edu/uhtbin/catkey/864921.
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The primary objective of this creative project was to fully explore and analyze the centuries old technique of lost wax casting.The secondary objective was to produce a body of work combining my creative inspirations from nature and my African culture.This body of work employed a variety of traditional metalsmithing techniques combining raised/constructed hollow ware, in a variety of metals, with cast metal forms.Department of Art
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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.
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A deposição de parafina é um fenômeno presente nos sistemas de produção de petróleo (principalmente em águas profundas devido às baixas temperaturas), consistindo na aderência de frações sólidas de hidrocarbonetos nas colunas e linhas, conduzindo à redução da área aberta ao fluxo até o eventual bloqueio. A compreensão dos mecanismos que influenciam na deposição ainda não foi totalmente alcançada. Dada a relevância deste tipo de sistema para o desenvolvimento de novos campos e a ausência de uma teoria consolidada que seja capaz de explicar a evolução e as características do depósito, a limitação de produção por este fenômeno é um dos principais problemas de garantia de escoamento. Visando a aumentar o conhecimento acerca dos fenômenos existentes no processo de deposição, e identificar os mecanismos dominantes, diferentes modelos matemáticos podem ser confrontados com dados experimentais. Geralmente, os escoamentos encontrados ao longo das linhas de produção encontram-se no regime turbulento. Dessa forma, no presente trabalho, desenvolveu-se um modelo de turbulência de duas equações k–omega, acoplado com o modelo entalpia-porosidade, no qual o depósito é considerado um meio poroso. A partir de um equilíbrio termodinâmico determinam-se as espécies que saem de solução e a sua distribuição é determinada pela equação de conservação molar. As equações de conservação foram resolvidas pelo método de volumes finitos, utilizando o esquema Power-law e Euler implícito para as discretizações espacial e temporal. Comparações com dados experimentais em um duto anular foram realizadas, apresentando boa concordância para o regime permanente, mas superestimando a espessura do depósito durante o regime transiente. Constatou-se redução de espessura do depósito com o aumento do número de Reynolds.Wax 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.
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Webber, Glenda Vanessa. "Wax characterisation by instrumental analysis." Thesis, Stellenbosch : Stellenbosch University, 2000. http://hdl.handle.net/10019.1/52055.
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Thesis (MSc)--Stellenbosch University, 2000.ENGLISH 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.
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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.
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Wax esters are components of surface lipids, serving as surface protectants for both terrestrial plants and animals. Wax esters are also specialized energy storage reserves for the organisms living in extreme environments, such as marine animals in Arctic and Antarctic oceans, the jojoba plant in the desert, and Acinetobacter species in the soil. Wax esters are also important substrates for industrial applications, such as the production of biodiesel, lubricants, cosmetics and polishes. Our current sources and production methods of wax esters from living organisms are not sufficient to meet market demands, so alternative sources including engineered oil crops that can generate sufficient amounts of wax esters are being sought. For my MSc project, I 1) investigated the feasibility of producing high levels of wax esters in the seed of Arabidopsis thaliana; 2) attempted to biochemically characterize new wax ester synthases that share amino acid similarity to the jojoba wax ester synthase; and 3) studied the promoter activity of the wax ester synthase encoded by the At5g55330 gene in Arabidopsis thaliana by a GUS assay. The first objective has been achieved, and the jojoba-type wax esters accumulated when the jojoba wax ester biosynthetic pathway was introduced in the seeds of Arabidopsis. I found that the enzyme encoded by the At5g55330 gene has wax ester synthase activity, but I was unable to characterize its substrate specificity. The third objective is still in progress, but my preliminary results to date indicate that the At5g55330 gene is transcribed in specific tissues of flowers, leaves, stem, and siliques.
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Jariwala, 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.
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VEIGA, 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.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROO 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.
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Crause, J. C. (James Christoffel). "Supercritical fluid extraction of paraffin wax." Thesis, Stellenbosch : Stellenbosch University, 2001. http://hdl.handle.net/10019.1/52471.
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Thesis (PhD)--University of Stellenbosch, 2001.ENGLISH 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.
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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.
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Per- and polyfluorinated substances (PFAS) are used in the production of ski wax to reduce the friction between the snow and the ski. In this occupational study of ski wax technicians’ exposure to PFAS and particulate aerosol we have collected whole blood (wb) (n =94), air (n =84) and aerosol (n =159) samples at World Cup events from 2007-2011. We have analysed the blood, air and aerosol with respect to 13 perfluorocarboxylic acids (PFCAs), 4 perfluorosulfonic acids (PFSAs), 3 fluorotelomer alcohols (FTOHs), 3 fluorotelomer acids (FTCAs) and 3 unsaturated fluorotelomer acids (FTUCAs). Further, we assessed the exposure to 3 particulate aerosol fractions (inhalable, respirable and total aerosol) in air. In comparison to a general population, several of the PFCA blood levels are elevated in the technicians’, primarily erfluorooctanoate (PFOA) and perfluorononate (PFNA) with concentrations up to 628 and 163 ng/mL wb, respectively. Further, we detected FTUCAs and FTCAs in the blood, suggesting biotransformation of FTOHs to PFCAs. The metabolites 5:3 and 7:3 FTCA were detected in all blood samples at levels up to 6.1 and 3.9 ng/mL wb. Levels of perfluorohexadecanoic acid PFHxDA) and perfluorooctadecanoic acid (PFOcDA) were detected in the technician’s blood at mean concentration up to 4.22 ng/mL wb and 4.25 ng/mL wb. The FTOH levels in air of the wax cabin during work ranged up to 997 000 ng/m3 (average=114 000 ng/m3 ) and PFOA up to 4 890 ng/m3 (average= 526 ng/m3 . FTOHs were not detected in aerosols but PFOA showed average levels of 12 000 ng/m3 (range=1 230- 46 900 ng/m3 ). The occupational exposure limit (OEL) of 2 mg/m3 was exceeded in 37% of the personal measurements with aerosol concentrations up to 15 mg/m3 . Keywords : Perfluorinated, polyfluorinated, FIS, occupational exposure, ski wax, iotransformation, metabolism, fluorotelomer alcohol, fluorotelomer acid, aerosol, dust, UPLC/MS-MS, GC/MS-MS
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El, Mellas Ismail. "Numerical simulation of wax deposition in pipelines." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020.
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Crude oils are complex mixtures of hydrocarbons. Among these components, high molecular weight paraffin (waxes) and asphaltenes may cause severe flow assurance issues in production and transportation subsea pipeline systems. Wax molecules are dissolved in the crude oil, when the temperature decreases, the solubility of high molecular weight paraffins decreases rapidly, and this results in the formation of gels of complex morphology, that deposit on the cold walls of the subsea pipelines during the flow of waxy crude oils, and this is a big problem for the subsea pipelines. The cost of wax management is enormous and rapidly increasing because of increased oil production in deep-sea areas. In this work, is presented a new numerical model for predicting wax deposition in oil pipes. While the almost part of the models existing in the literature are based on a separated two-fluid description of the oil/wax-oil flow, the model proposed is based on a mixture description, where wax is considered as a suspended phase surrounded by crude oil. When wax separates in the crude oil, the mixture becomes a gel-like fluid, and this mechanism is incorporated in the flow model by a specific rheological model where the mixture viscosity depends on both the local wax concentration and its “age”. In order to simultaneously model moving regions of different “ages”, our model solves a transport equation for the ageing time. Deposition is modelled by solving wax mass balance, dissolved asphaltenes mass balance, and energy. Wax generation and asphaltenes removal are modelled as a first-order reaction coupling mass balance between the species, where the local equilibrium saturation is given as a function of the mixture temperature. In this work, is present the implementation of the model in the open-source C++ library OpenFOAM and validation of the model between some similar works. Besides a discussion of the results for wax deposition and a parametric study about the critical parameters.
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Siljuberg, 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.
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As warm oil or condensate from the reservoir flow through a pipeline on the cold sea bottom, wax often precipitate and deposit on the wall. To predict the rate of the deposition, wax modeling is important. The main mechanism contributing to deposition, molecular diffusion, is driven by a radial concentration gradient. The concentration gradient is driven by the radial temperature gradient. When precipitation of wax crystallites occurs in the bulk of the flow, it affects the concentration gradient, which again affects the rate of deposition. The current thesis gives an elucidation of this particularity. Fundamental heat and mass transport equations are solved numerically in Matlab and the result shows that the concentration profiles become slighter as the precipitation become larger. This decreases the mass flux due to molecular diffusion. A term “shear dispersion” was introduced in 1980’s to describe particle deposition of wax. The term has been used in several wax deposition models, but the mechanisms behind are not well explained in the literature. An elucidation of both a shear induced lift force and shear induced diffusion are investigated.
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LEIROZ, 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.
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CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOCENTRO 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.
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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.
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CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOUm 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.
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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.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCOORDENAÇÃO 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.
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Tabatabaei-Nejad, Seyyed Ali Reza. "Phase behaviour modelling of petroleum wax and hydrates." Thesis, Heriot-Watt University, 1999. http://hdl.handle.net/10399/593.
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Butt, 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.
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The current interest in energy saving asphalt production techniques is great and several new processes have been developed to reduce the mixing and compaction temperatures for hot mix asphalt. In particular, mastic asphalt products (Gussasphalt) require high working temperatures, and harder requirements concerning bitumen fumes and carbon dioxide emissions have been introduced for such products. Consequently, the need of a new means of producing and placing mastic asphalt at lower temperatures is particularly large. One way of reducing asphalt mixture temperature is by using special flow improving additives like wax. This technique has successively been tried in several studies for polymer modified mastic asphalt used for bridge decks and parking areas in Sweden. However, there still are uncertainties about possible negative impact on crack susceptibility at lower temperatures due to the addition of wax. In this study, 4% montan wax (Asphaltan A) was used for one particular polymer modified mastic asphalt product. Type and amount of wax additive was selected based on results from earlier studies. The impact on binder, binder/filler mixtures and mastic asphalt from production was tested in the laboratory, focusing on low temperature performance. The bending beam rheometer (BBR) was used for determining low temperature creep compliance and the tensile stress restrained specimen test (TSRST) for determining fracture temperatures. Binder properties were determined using dynamic mechanical analysis (DMA), Fourier transform infrared (FTIR) spectroscopy and conventional tests (softening point, penetration, elastic recovery, Fraass breaking point, viscosity and storage stability). Aging was performed using the rolling thin film oven test (RTFOT) at 200°C. As expected, the addition of wax to the polymer modified binder showed a viscosity reduction at higher temperatures, corresponding to a similar positive effect of more than 10°C on production and laying temperature for the mastic asphalt. DMA and BBR results showed some increase in stiffness and a more elastic response of the wax modified binder at medium and low temperatures. The TSRST fracture temperature was 5 °C higher for the mastic asphalt containing 4% wax, indicating however no dramatic negative impact on crack susceptibility.
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Botne, 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.
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Oil and gas transport is today a vital part of the industry. Oil cooled during transport in pipelines may precipitate paraffin wax. Precipitated wax may deposit on pipe walls and cause flow restrictions. Deposition models are used to understand and predict deposition of solids. A deposition model can help predict wax problems before a pipe line is set into operation. If the amount of deposited wax is predicted it can help operators to develop removal plans and strategies. A total of 21 wax deposition experiments performed by others were digitized and evaluated. The logarithmic deposition-release model showed a good match with 18 of the experiments. The experiments tested the effect of varying flow rate, temperature or both. Most experiments behaved as expected when flow rate and temperature were varied. The deposition-release model consists of two coefficients, k1 and k2. Both coefficients were evaluated against wall shear stress for the varying rate experiments. The coefficients in the varying temperature series were evaluated against the temperature driving force. Linear trends between most coefficients and physical parameters were found. These linear trends lead to the development of four models that predict wax deposition. The models use either wall shear stress, the temperature driving force or both as an input. All models produce similar results. Each model was based on an experimental series. A study of a real pipeline with wax deposition was also investigated. Temperature and viscosity calculations matched well with values used in the study. The study reported calculated wax thickness based on measurements of pressure drop. The pressure drop method was evaluated and explained. The method does not consider an altered pressure drop due to increased pipe roughness and non-evenly distribution of deposits. Both of these effects will increase the pressure drop. It was found that neglecting these will cause the calculated thickness to be overestimated. Because of the overestimation of thickness it was hard to get an accurate match with models.
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Qi, 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.
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Plant cuticles are extracellular membranes covering aerial organs of plants, whose main functions rely on the protection against water loss, mechanical injury from the environment, attack of microorganism, and also regulation of gas exchange. Among the several constituents of plant cuticles, waxes are those that play an important role in their barrier properties. In order to enhance the mechanical properties of wax, NFC was applied in. In the project, mainly two kinds of methods were used to prepare wax-NFC composites. One way was wax and NFC were dissolved in toluene and casted to be a film, another way was to prepare NFC aerogel firstly, and then, impregnated the aerogel into wax liquid. After pressing it the structure was more compact. In order to characterize the properties of samples, SEM, XRD, TGA, DSC, Contact angle testing, tensile test and oxygen permeability methods were applied in.
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Galta, 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.
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Which criteria to pay attention to is important when finding the optimal pigging frequency. This thesis illustrates the forces acting on a bypass pig in operation. Expressions for both the frictional force and wax removal force have been presented. Results presented in this thesis show that the frictional forces are much higher than the forces for wax removal. The most important factor for the contact forces for a cleaning pig seems to be due to the oversize of the discs. However, it is difficult to obtain accurate values for the friction force without experimental data. The insulating effect of wax deposition on the overall heat transfer has been confirmed by analytical calculation. Results do also show that the simulation software Hysys do not account for wax deposition when estimation the U-value. Pressure drop calculations for a pipe with wax deposition have been done. Results show that the roughness of wax has a large influence on the pressure drop in a pipeline. Ageing of wax leads to higher wax removal forces and may decrease the removal efficiency for a cleaning pig. Pigging operations should happen at a given frequency to prevent wax from hardening. It would be beneficial to have more knowledge about wall adhesion and ageing for the given composition when estimation the wax removal forces
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CABANILLAS, 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.
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COORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIORA 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.
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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.
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O Petróleo é formado por um conjunto de hidrocarbonetos. No reservatório, devido à altas pressões e temperaturas, encontra-se na forma de líquido. Conforme o petróleo escoa, a pressão cai assim como a temperatura, devido a perda de calor para o ambiente marinho, causando a liberação do gás dissolvido no petróleo tornando o escoamento bifásico. Adicionalmente, caso a temperatura caia abaixo da temperatura inicial de cristalização (TIAC), ocorre precipitação dos cristais, formando uma fase sólida que se deposita na parede interna das tubulações. Deposição de parafinas é um dos mais críticos problemas operacionais na produção e transporte de petróleo em linhas submarinas. O presente trabalho analisa numericamente a deposição de parafina em escoamento multifásico no interior de dutos para diversos padrões de fluxo. Investiga-se ainda a influência da presença da água e dos ângulos de inclinação da tubulação com a horizontal nas taxas de deposição. Para prever o escoamento multifásico utilizou-se o modelo de deslizamento e a deposição da parafina foi determinada baseada no modelo de difusão molecular. A modelagem desenvolvida foi validada com a simulação do escoamento ao longo de um duto curto, reproduzindo condições experimentais de laboratório. Os resultados obtidos para a espessura do depósito apresentaram excelente concordância com os dados experimentais e com os dados obtidos com o simulador comercial OLGA. Analisou-se o escoamento entre um poço produtor e uma plataforma na Bacia de Campos, onde determinou-se o impacto na perda de carga devido a diminuição do diâmetro interno da tubulação causada pelo aumento da espessura dos depósitos. Os resultados obtidos destes estudos apresentaram boa coerência física e razoável concordância com relação aos dados experimentais.Crude 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.
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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.
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A deposição de parafinas em dutos de produção e coleta é um dos principais
problemas de garantia de escoamento na indústria do petróleo. Além das técnicas
de prevenção e mitigação tradicionais, o uso de revestimentos internos
antiaderentes é uma alternativa ainda em desenvolvimento. Uma extensiva revisão
bibliográfica mostrou que muitas das informações disponíveis sobre este assunto
baseiam-se em conhecimento de campo e os experimentos desenvolvidos em
laboratório apresentam resultados contraditórios. A contribuição deste trabalho foi
desenvolver um experimento em laboratório para avaliar a eficiência de
superfícies revestidas com relação à prevenção da deposição de parafinas,
eliminando o efeito de isolante térmico do mesmo e buscando correlacionar os
resultados com as características da superfície como rugosidade, energia crítica e
de superfície. O experimento desenvolvido consistia de um loop fechado contendo
uma seção de teste em acrílico, com controle de temperatura dos fluidos, medição
contínua de fluxo de calor e medição da espessura de depósito através de
visualização com câmera. Neste trabalho foram avaliadas as superfícies de aço
inox 316L (rugosa e polida), Teflon, Nylon 11 e carbono amorfo sob a forma de
placas retangulares que eram acopladas à seção de teste. Os resultados parecem
corroborar as conclusões de alguns estudos da literatura, mostrando que a
espessura de depósito de parafina pode ser reduzida pela redução da rugosidade e
pela redução da energia crítica e de superfície. A utilização da medida de fluxo de
calor como medida indireta da espessura de deposição se mostrou promissora,
porém a variação da condutividade térmica do depósito em função do número de
Reynolds dificulta sua utilização devido à necessidade de calibração para cada
vazão de escoamento.Wax 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.
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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.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCONSELHO 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.
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Beri, Akash. "Wax based emulsions for use in lipstick application." Thesis, University of Birmingham, 2015. http://etheses.bham.ac.uk//id/eprint/5673/.
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Water-in-oil emulsions have the potential to eradicate drying of the lips caused by constant lipstick application by improving moisturising properties and delivering hydrophilic molecules to the lips. To conduct this research, a food microstructure approach was utilised developing emulsion structures’ using either a batch or continuous process and monitoring the affect these structures had on physical and material properties. The lubricating properties of emulsions structures were then compared to a trained sensory panel. Finally the release behaviour of a moisturising agent was investigated. It was shown that the ingredients used to produce the microstructure are pivotal in indicating the melting profile, droplet size and material properties of the final structure. Specifically, when an aqueous phase is incorporated within a hard shell the elastic modulus increases as the aqueous phase become part of the wax network. The effect of lubrication showed that friction coefficient of a solid emulsion could be related to how smooth a lipstick would be perceived based on the Kokani Model. Finally, it was shown that the release of a moisturising agent is governed by the droplet size and the amount of destruction caused to the wax network.
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Kang, Johan, and 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.
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Längdskidåkning är en populär vintersport i Norden och vallning är ett viktigt moment i sporten. Skidvallning medför dock logistiska utmaningar och det krävs utrustning som oftast är tung och otymplig eller kräver tillgång till elektricitet för att fungera. Idag finns det få lösningar som underlättar vallning av längdskidor i spåret, detta på grund av de utmaningar som portabilitet för med sig; vallan kan vara för kall för applicering eller underlaget kan vara för instabilt och ojämnt för vallning. Syftet med detta projekt är att ta fram ett koncept som ska fylla detta vakuum i vallningsmarknaden. Projektet utgår från de krav och önskemål som vallningskunniga skulle ställa på portabel skidvallning och vad som förväntas av en sådan produkt idag. Dessa togs fram genom intervjuer med vallabodar runt om i Stockholm och genom att undersöka vilka produkter som idag underlättar portabel skidvallning. Under projektets gång har flera delkoncept tagits fram genom olika idégenereringsmetoder som brainstorming. Dessa kom i två omgångar; först tre delkoncept som namngavs till 1. Det stavstabiliserade vallastället, 2. Hängselstället och 3. Klistervärmaren som fick genomgå en elimineringsprocess. Det delkoncept som vann var koncept 3. Klistervärmaren vars funktion är att värma fästvalla, framförallt klistervalla, för att göra den applicerbar. Sedan utvecklades ytterligare tre delkoncept från det valda konceptet; 3.1 Termos, 3.2 Klädseln och 3.3 Kombo, som utvärderades tills ett slutgiltigt koncept valdes ut. Den som vann var koncept 3.3 Kombo. Kombo vidareutvecklades och dess utseende och egenskaper definierades genom formgivning, materialval och val av energikälla samt värmegenerering. Resultatet blev GEISER som är en portabel, batteridriven vallavärmare som ska användas som ett komplement på till exempel drickabältet under skidåkningen. GEISER håller vallan isolerad från kylan genom flera olika lager tyg med unika, isolerande egenskaper och den värmer vallan genom en värmeslinga invävd i ett av de inre lagren. Denna värmeslinga är kopplad till ett batteripack som sitter ovanpå den cylindriska vallabehållaren i en tygficka. En strömbrytare är integrerad på ovansidan av GEISER i tyget för lätt på- och avslagning.Cross 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.
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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.
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Mycobacteria are present in a wide range of environments. They contain characteristic complex mixtures of mycolic acids in the cell wall together with other lipids. The high resistance of mycobacteria to the majority of antibiotics, therapeutic agents and disinfectants is thought to be related to the unique structure of the mycobacterial cell wall. Mycolic acids are high molecular weight a-alkyl-branched B-hydroxy long chain fatty acids (60-90 carbon atoms). Different species of Mycobacteria may produce different classes of mycolic acids including a-, methoxy, keto, and wax ester mycolic acids, each present as mixtures of homologues. These may contain different functional groups such as ester, keto, methoxy, hydroxyl, and alkene. The most reported lipids present in the cell wall are sugar esters, e.g mycolyl trehalose esters. These mycolic acids and mycolyl trehalose esters show very interesting toxic and immunological properties; these offer considerable potential for application in the detection, control, and treatment of mycobacterial infection, and also in developing sensors for detection of disease. This study will seek to explore these potentials. This project involved the synthesis of several mycolic acids, wax esters and trehalose esters. The biological activities of these synthetic compounds would be studied, particularly their suitability as specific antigens to detect mycobacterial infections in serodiagnostic assays. The objectives of the project are discussed in four parts. The first part of this project involved the first synthesis of wax ester (A) and its corresponding ω-carboxymycolic acid (B), one component of the complex mixture isolated from Mycobacterium avium. Once the synthesis had been optimised, synthesis of the wax ester (C) and its corresponding ω-carboxymycolic acid (D) were also achieved, the latter compounds being isolated from Mycobacterium gordonae. In addition the wax ester (E) was also prepared introducing longer chain lengths than the natural wax ester. This was to study whether or not the chain length has any effect on the biological activities.
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Ali, Abdualbaset Ahmed. "Altering Wax Appearance Temperature Using Shear and Pressure." University of Toledo / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1575992511410478.
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Saunders, 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/.
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Ribas, 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.
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Society has become more aware of the negative environmental impact of the petroleum-based packaging materials (e.g. plastics) used in the food industry. Therefore, cleaner and more sustainable packaging with ecological zero-impact is in demand. One of the solutions for this problem could be the use of natural wax-impregnated paper. It has been recently demonstrated that wax obtained from arctic berries may be a good candidate for this application. This project is intended to define the properties of this wax which are essential for the food-packaging application and evaluate if berry wax can fulfil those requirements. For this reason, physical characterization of different natural waxes has been conducted and compared. On the one hand, it has been concluded that pure arctic berry wax presents similar thermal parameters to commercially available natural waxes. In addition, mechanical testing and barrier properties of paper substrates coated with beeswax and lingonberry have been successfully carried out. During the testing, wax-coated samples showed interesting results in terms of good barrier properties, which is the key factor to be a promising alternative for food packaging applications. Nevertheless, further research should be conducted in order to study other barrier properties and mechanical performance of these natural wax-impregnated papers. In addition, it would be of great interest to investigate more precise coating procedures in order to obtain the optimum way for coating paper substrates with natural waxes.
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King, 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/.
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Babalola, Olamide Akanbi. "Utilities optimization in a wax process plant / O.A. Babalola." Thesis, North-West University, 2007. http://hdl.handle.net/10394/1790.
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Wang, Qian. "Characterization of xtcl mutant with reduced cuticular wax accumulation." Thesis, University of British Columbia, 2007. http://hdl.handle.net/2429/352.
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Cuticular wax is a component of the plant cuticle, the lipid barrier which covers the surface of above ground primary plant organs and plays important protective roles. The isolation of wax deficient mutants from Arabidopsis and other plants resulted in identification and isolation of genes required for wax deposition, and broadened our knowledge of this process in plants. To identify additional components involved in cuticular wax production, I investigated the role of the XTC1 gene, defective in the xtcl (extra cotyledon 1) mutant. This mutant was reported to have reduced levels of cuticular wax on its inflorescence stems and accumulate a large number of oil bodies in the primordia of its extra cotyledons.
Stem wax extraction and gas chromatography analysis showed that the total xtcl stem wax is decreased 3-fold in comparison to the wild type, and that all wax components were reduced to a similar extent. Compositional analyses of leaf and seed fatty acids demonstrated that saturated fatty acid content was decreased by around 55%, and unsaturated fatty acid content was approximately 20% lower in xtcl mutants. A detailed examination of xtcl seeds revealed seed deformities, altered seed coat permeability and defective seed mucilage extrusion. Positional cloning of the XTC1 gene resulted in the discovery that it is identical to FATB, an already characterized gene known to encode the fatty acid thioesterase B. The FATB enzyme releases saturated free fatty acids (C16:0and C18:0) from ACP in the plastid and allows their export across the plastid envelope. Analysis of FATB gene expression pattern showed that FATB is transcribed ubiquitously in all tissues and in different development stages. It is therefore not surprising that FATB disruption results in multiple lipid associated phenotypes, including decreased cuticular wax amounts and altered fatty acid compositions of leaves and seeds. Additional phenotypes caused by mutations in FATB that affect embryo and seed development and lead to appearance of extra cotyledons, altered permeability of the seed coat and defective seed mucilage extrusion are difficult to explain at present.
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FLEMING, 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.
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PETRÓLEO BRASILEIRO S. A.Desde 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.
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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.
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nÃo hÃAt 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.
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Pereira, Fleming Felipe. "Fundamental study of wax deposition under real flow conditions." Thesis, Pau, 2018. http://www.theses.fr/2018PAUU3009/document.
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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 dépôt de cire proposés initialement à travers un solide contexte physique commence à faire place à des algorithmes flexibles qui pourraient être adaptés à différents scénarios expérimentales. Dans une tentative d'étudier le phénomène de manière fondamentale, le travail actuel a proposé une stratégie de recherche qui permettrait d'évaluer chaque partie du modèle complexe de dépôt de cire et de garantir leur démarche dans des conditions optimales. Pour atteindre ce objectif, une nouvelle stratégie d'évaluation des modèles thermodynamiques des équilibre des phases solide-liquide a été développée. Les résultats ont montré que le modèle utilisé était suffisamment robuste pour décrire précisément le comportement de phase solide-liquide des mélanges des mélanges asymétriques aux pressions ordinaires et élevées, ainsi que pour décrire le comportement d’une mélange complexe comme les échantillons de Diesel. Pour assurer la base physique solide des modèles utilisés dans ce travail, la mesure de la conductivité thermique des n-alcanes lourds dans les phases liquides et solides a été réalisée et rapportée pour la première fois. Enfin, un modèle CFD drift flux solide-liquide a été proposé. Couplé à un modèle thermodynamique pour fournir des données sur les équilibres de phase et les propriétés, le modèle a été utilisé pour étudier les résultats expérimentaux disponibles.Le mécanisme de dépôt de cire évalué était celui proposé par Merino-Garcia. Les résultats ont montré un accord qualitatif entre le modèle et les résultats expérimentaux, mais le modèle sous estimait la largeur du dépôt. D'autre part, la conductivité thermique du dépôt correspond à la conductivité thermique expérimentale récemment disponible d'un tel dépôt mesurée dans des conditions d'écoulement réelles. Ce fait renforce les conclusions présentées que le dépôt de cire n'est pas un phénomène de mécanisme unique après toutSince 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
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Wax, Andreas [Verfasser]. "Internationales Sportrecht. : Unter besonderer Berücksichtigung des Sportvölkerrechts. / Andreas Wax." Berlin : Duncker & Humblot, 2009. http://d-nb.info/1238360572/34.
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Lamperti, 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/.
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Hegebarth, 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.
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Plant cuticles seal above-ground organs against non-stomatal water loss, and therefore are vital for survival on land. Besides providing a transpiration barrier, cuticles have important secondary functions, for example to protect from harmful UV radiation, and to provide a self-cleaning mechanism and mechanical support. Cuticles consist of aliphatic very-long-chain wax compounds (C₂₄ to C₃₈) and a cutin polymer. The diversity of cuticular wax compositions across the plant kingdom but also between different organs and ontogenetic stages is remarkable, yet the regulating mechanisms and function of those chemical differences are largely unknown. In the study presented here, a new approach was used, increasing temporal and spatial resolution and integration of chemical wax analyses with analyses of gene expression patterns of wax biosynthesis genes, using Arabidopsis thaliana as a model organism. The aims of the study were to, first, monitor wax composition and gene expression as a function of leaf development as well as different epidermal cell types and, second, to use this information to identify new wax biosynthesis genes.
In the second chapter, high temporal resolution was used to follow the dynamics of wax chemistry and gene expression during development of Arabidopsis thaliana leaves, and I was able to link changes in wax chemistry to differential expression of the elongation enzyme KCS6/CER6.
In the third chapter, wax analyses and gene expression data with high spatial resolution were acquired, and I identified differences between Arabidopsis epidermal cell types in wax composition and gene expression. Trichomes had a higher abundance of longer chain waxes (C₃₂ to C₃₈) compared to pavement cells, and the KCS5, KCS8 and KCS16 elongation enzymes were identified as candidates for the elongation of C₃₄₊ waxes. In the fourth chapter, I characterized the Arabidopsis condensing enzyme KCS16 and was able to show that it is functioning on the wax elongation pathway, elongating C₃₄ to C₃₈ acyl-CoA wax precursors, mainly in trichomes but also in pavement cells.Science, Faculty of
Botany, Department of
Graduate
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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.
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Moore, 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.
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Mariageraldrajan, 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.
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Thesis (Ph.D.)--University of Tennessee Health Science Center, 2007.Title 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).