Добірка наукової літератури з теми "Fluidi multifase"

Un sensor basado en la permitividad eléctrica del fluido fue usado para análisis de las tomografías enlos diferentes patrones que se presentan en flujo multifase aceite y agua(Liquido-Liquido). El estudio experimental fue realizado en un tubo de vidrio borosilicatode 25,4 [mm]de diámetro interno y12 [m]de longitud. El sensor está formado por una malla de alambre condos planos de 8 x 8 hilos,llamado sensor de malla de alambre (WMS). Los experimentos fueron efectuadoscon dos viscosidades diferentes de aceite,una con 200[cP]yotra de60[cP]a 860 [kg / m3]de densidadcon el tubo posicionado en la horizontal y levemente inclinado a + 5 grados, para variar la viscosidaddel aceite fue usado un intercambiador de calor. El patrón de flujo multifase analizado fue anular, estratificado y disperso. Las tomografíasobtenidaspor la WMS fueron comparadas con una cámara de altavelocidad para la validación cualitativa de los resultados. Se usaron doce modelos de permitividad eléctricapara el estudiodel régimen del fluido presente

Konsep dinamika fluida sering diaplikasikan dalam penyelesaian masalah di kehidupan sehari-hari, salah satunya gerakan sloshing pada kontainer yang berisi cairan. Penelitian ini bertujuan untuk menyusun sebuah code simulasi sloshing pada kontainer segi empat dengan menggunakan persamaan Navier-Stokes dua dimensi. Persamaan Navier-Stokes digridesaikan dengan ACM (Artificial Compressibility Method) dan metode beda hingga berbasis staggered grid. ACM digunakan untuk memperoleh nilai dari komponen kecepatan dan tekanan sedangkan metode beda hingga digunakan dalam proses diskritisasi untuk melakukan pendekatan secara numerik. Karena dalam kasus ini melibatkan aliran multifase, maka metode lain seperti VOF (Volume of Fluid) juga digunakan untuk menentukan permukaan bebas fluida. Hasil penelitian ini divalidasi dengan simulasi pembanding menggunakan Ansys, dan menunjukkan kesesuaian yang cukup baik secara kuantitatif maupun kualitatif. Secara kuantitatif, nilai RMSE (Root Mean Square Error) relatif sangat kecil dengan RMSE maksimum adalah 0,235 dan RMSE minimum adalah 0,030. Sedangkan secara kualitatif, fase gerak antara kedua simulasi menunjukkan kesamaan. Dengan mengubah beberapa parameter simulasi, diketahui bahwa RMSE paling minimum diperoleh saat nilai dx=0,08 dan dy=0,0143.

Human serum albumin (HSA) is the most abundant protein in plasma, contributing actively to oncotic pressure maintenance and fluid distribution between body compartments. HSA acts as the main carrier of fatty acids, recognizes metal ions, affects pharmacokinetics of many drugs, provides the metabolic modification of some ligands, renders potential toxins harmless, accounts for most of the anti-oxidant capacity of human plasma, and displays esterase, enolase, glucuronidase, and peroxidase (pseudo)-enzymatic activities. HSA-based catalysis is physiologically relevant, affecting the metabolism of endogenous and exogenous compounds including proteins, lipids, cholesterol, reactive oxygen species (ROS), and drugs. Catalytic properties of HSA are modulated by allosteric effectors, competitive inhibitors, chemical modifications, pathological conditions, and aging. HSA displays anti-oxidant properties and is critical for plasma detoxification from toxic agents and for pro-drugs activation. The enzymatic properties of HSA can be also exploited by chemical industries as a scaffold to produce libraries of catalysts with improved proficiency and stereoselectivity for water decontamination from poisonous agents and environmental contaminants, in the so called “green chemistry” field. Here, an overview of the intrinsic and metal dependent (pseudo-)enzymatic properties of HSA is reported to highlight the roles played by this multifaced protein.

Performa centrifugal submersible pump (ESP) terganggu ketika menangani fluida viscous. Efeknya dicirikan oleh kenaikan horsepower, menurunnya head, efisiensi dan penurunan kapasitas. Rumusan masalah adalah pengaruh viskositas terhadap performa ESP yaitu penurunan efisiensi head pompa, perbandingan performa ESP fluida air dengan minyak berat. Analisis dilakukan pada Sumur X-1, Sumur X-2 dan Sumur X-3 yang mempunyai API gravity 15,6o, 17,5o dan 16,9o. Metode analisis adalah menghitung dan membandingkan Total Dynamic Head kedua fluida tersebut pada sensitivitas laju alir dan water cut (wc) menggunakan perangkat lunak. Live oil viscosity dengan korelasi Ng dan Egbogah, gas terlarut didekati korelasi Standing dan aliran multifasa menggunakan Hagedorn Brown. Dari analisis ketiga sumur, Sumur X-1 memberikan head factor 96,82 % dan 98,38% pada water cut 80% dan 94% dengan produksi 1800 bpd. Sumur X-2 head factor 94,07% (wc=82%) dan 98,07% (wc=97%) produksi 3000 bpd, Sumur X-3 head factor 98,04% (wc=82%) dan 99,22% (wc=97%) produksi 1300 bpd

Keberadaan pasir dalam fluida produksi di industri perminyakan merupakan hal yang tak dapat dihindari. Pada kecepatan fluida tertentu, pasir berpotensi menimbulkan erosi pada dinding perpipaan yang apabila proses tersebut terjadi secara terus menerus maka dapat menyebabkan penipisan dinding pipa, mengurangi tekanan kerja maksimum fluida yang diijinkan, kegagalan pipa dan akhirnya fluida hidrokarbon keluar dari sistem tertutup pipa. Kondisi ini berpotensi menimbulkan kerugian dalam hal keselamatan kerja, kehilangan finansial dan isu lingkungan. Kompleksitas mekanisme erosi akibat fluida berpasir didalam perpipaan memerlukan bantuan perangkat lunak untuk menghitung besaran dan profil erosi didalam pipa. Makalah ini memprediksi laju erosi aliran multifasa cair-gas-padat pada belokan pipa yang didominasi fasa cair dengan CFD menggunakan ANSYS Fluent 18.2 dengan validasi berdasarkan eksperimen yang dilakukan peneliti lain yang sudah dipublikasi. Dari hasil simulasi, laju erosi dengan model Oka lebih mendekati hasil eksperimen dibandingkan model Finnie dan McLaury. Hal ini dimungkinkan karena kondisi eksperimen lebih sesuai dengan model erosi yang dibangun oleh Oka. Hasil simulasi lanjutan menunjukkan bahwa laju erosi pada pipa meningkat dengan kenaikan laju alir dari minyak mentah dan gas, ukuran partikel dan laju alir partikel. Laju erosi menurun dengan meningkatnya diameter pipa.

Tear film is a thin layer of non-newtonian fluid covering and protecting cornea and conjunctiva epithelia. The multifaced functions of tears are reflected by their complex structure and advances in proteomics/metabolomics/lipidomics technologies have greatly deepened the knowledge of the chemical composition of tears. The purpose of this article is to survey recent advances in proteomic analysis of human tears and to summarise the most relevant proteins proposed as biomarkers in dry eye. Besides, the potential clinical application of these biomarkers is discussed.

Separator siklon silinder vertikal (Gas Liquid Cylindrical Cyclones) merupakan alat pemisahan aliran multifase yang umum dipergunakan dalam industri perminyakan. Penelitian ini bertujuan untuk mengevaluasi unjuk kerja dan perilaku hidrodinamika fluida separator GLCC metering loop pada pemisahan aliran campuran udara dan air. Eksperimen dilakukan dengan membuat separator skala uji laboratorium menggunakan pipa acrylic plexyglass diameter 6,25 cm, tinggi 140 cm dengan sistem inlet tangensial pada sudut inklinasi 30o, serta dilengkapi 5 variasi posisi saluran keluaran. Percobaan dilakukan dengan memvariasikan debit udara dan efek posisi saluran keluaran (recombination point). Beberapa aspek penting seperti kecepatan superficial gas (Vsg), kecepatan superficial cairan (Vsl), level cairan kesetimbangan (Leq), liquid carry over (LCO) dan gas carry under (GCU) menjadi perhatian selama percobaan. Hasil penelitian menunjukkan bahwa empat regim aliran yaitu aliran gelembung (bubble flow), aliran gelembung paket (packed bubble flow), aliran kantung gas atau sumbat cair (slug flow) dan aliran acak (churn flow) dipengaruhi oleh konfigurasi rasio aliran gas-cairan dan posisi rekombinasinya. Rasio kecepatan superfisial antara udara dan cairan memainkan peran penting terhadap terbentuknya regim aliran dan ketinggian level cairan kesetimbangan.

This paper uses lived experiences to critically examine the orientation of international graduate students at research-intensive Canadian universities. We, five co-authors, embody diverse ethnic, racial, sexual, religious, national, and gender identities, yet are all (or have been) international graduate students in Canada. Through collaborative autoethnography, we destabilize the notion of “orientation.” We argue that international student orientation should be understood as a fluid, ongoing process rather than one with rigid boundaries and timelines. Furthermore, orientation programming should more deeply consider the intersecting identities and positionalities of international students as multifaced individuals, as well as the implicit expectations of one-way “integration” into settler-colonial Canadian society. We suggest a different approach to orientation and offer a conceptual framework to guide future practice, highlighting the role universities play in not only supporting students academically but also in (im)migrant settlement.

Nel campo dell’industria ceramica, il trasporto dell’atomizzato di barbottina è attualmente effettuato mediante nastri trasportatori, che prelevano il materiale all’uscita dell’atomizzatore e lo trasportano fino ai silos di stoccaggio, coprendo lunghe distanze all’interno dello stabilimento produttivo. Questa tipologia di sistemi di trasporto disperde nell’ambiente di lavoro polveri sottili contenenti silice libera cristallina, che compromettono la salubrità dell’aria ed espongono i lavoratori dell’industria ceramica al rischio di silicosi, una malattia invalidante dell’apparato respiratorio. In questo elaborato è stata analizzata una soluzione alternativa ai nastri trasportatori, che prevede l’utilizzo di un sistema pneumatico per la movimentazione dell’atomizzato di barbottina. Grazie a questa soluzione, in cui il trasporto avviene in un sistema chiuso e completamente confinato, è possibile risolvere in maniera definitiva il problema dell’inquinamento da polveri sottili. Tuttavia, affinché i sistemi di trasporto pneumatici possano essere applicati con successo su scala industriale devono essere in grado di movimentare portate di atomizzato paragonabili a quelle dei nastri trasportatori, preservando l’integrità del prodotto ed evitando una sua eccessiva essiccazione o umidificazione. Numerosi test di trasporto sono stati effettuati su di un impianto sperimentale, appositamente progettato e realizzato per il trasporto pneumatico in fase densa dell’atomizzato di barbottina. Grazie a questo impianto è stato possibile determinare i parametri caratteristici del materiale solido ed individuare le condizioni operative ottimali. Con l’ausilio del software simulativo TPSim Win è stato infine progettato un impianto su scala industriale, definendo il lay-out impiantistico, il diametro delle tubazioni ed il rapporto di miscela ottimali.
Atomized slip conveying in the ceramics industry is currently carried out by conveyor belts, that pick up the material from the spray dryer bottom and transport it to the storage silos, covering long distances inside the production plant. This kind of transport spread out fine particles containing crystalline silica, which compromise the salubrity of the working environment and generate a risk for worker’s health due to silicosis, a disabling disease of the respiratory system. In this thesis, an alternative solution to the conveyor belts was analyzed, based on a pneumatic system for atomized slip handling. This transport system, completely closed and confined, fully solves dust pollution problem. However, in order to be successfully applied on an industrial scale, pneumatic conveyor systems must be able to handle atomized slip flow rates comparable to those of conveyor belts, preserving the integrity of the material and avoiding its excessive drying or humidification. Numerous transport tests have been carried out on an experimental plant, specially designed and built for the pneumatic transport in dense phase of the atomized slip. Thanks to this plant, it was possible to determine the characteristic parameters of the solid material and identify the best operating conditions. Finally, using TPSim Win simulation software, an industrial scale system was designed, defining the plant layout, the diameter of the pipes and the optimal value of solid loading ratio.

This dissertation is a contribution to the development of a unified model of continuum mechanics, describing both fluids and elastic solids as a general continua, with a simple material parameter choice being the distinction between inviscid or viscous fluid, or elastic solids or visco-elasto-plastic media. Additional physical effects such as surface tension, rate-dependent material failure and fatigue can be, and have been, included in the same formalism. The model extends a hyperelastic formulation of solid mechanics in Eulerian coordinates to fluid flows by means of stiff algebraic relaxation source terms. The governing equations are then solved by means of high order ADER Discontinuous Galerkin and Finite Volume schemes on fixed Cartesian meshes and on moving unstructured polygonal meshes with adaptive connectivity, the latter constructed and moved by means of a in- house Fortran library for the generation of high quality Delaunay and Voronoi meshes. Further, the thesis introduces a new family of exponential-type and semi- analytical time-integration methods for the stiff source terms governing friction and pressure relaxation in Baer-Nunziato compressible multiphase flows, as well as for relaxation in the unified model of continuum mechanics, associated with viscosity and plasticity, and heat conduction effects. Theoretical consideration about the model are also given, from the solution of weak hyperbolicity issues affecting some special cases of the governing equations, to the computation of accurate eigenvalue estimates, to the discussion of the geometrical structure of the equations and involution constraints of curl type, then enforced both via a GLM curl cleaning method, and by means of special involution-preserving discrete differential operators, implemented in a semi-implicit framework. Concerning applications to real-world problems, this thesis includes simulation ranging from low-Mach viscous two-phase flow, to shockwaves in compressible viscous flow on unstructured moving grids, to diffuse interface crack formation in solids.

El objetivo principal de este trabajo es predecir la dispersión de un flujo bifásico en el lecho de un reactor de hidrodesulfuración. Se consideran propiedades físicas constantes, sin incluir reacciones químicas ni procesos de transferencia de calor ni materia. Dos herramientas de simulación diferentes se han utilizado en este estudio. Una de ellas es el software comercial Fluent, ampliamente utilizado en el campo de la Computación en Dinámica de Fluidos, en el que se han introducido nuevos modelos de arrastre y capilaridad no incluidos en la versión comercial del software. La segunda herramienta utilizada es el código doméstico Multiphase Flow Solver, escrito en lenguaje de programación Fortran, que ha sido desarrollado durante esta tesis doctoral, constituyendo un importante objetivo de la misma. Este código incorpora los modelos necesarios para describir los procesos físicos que describen el comportamiento de este tipo de flujos multifásicos y su dispersión en medios porosos.
The main objective of this work is to predict the two-phase flow dispersion in the bed of a hydrodesulfurization reactor. Physical properties are considered to remain constant, without including chemical reactions nor heat and mass transfer processes. Two different simulation tools have been used in this study. One of them is the commercial software Fluent, widely used in the field of Computational Fluid Dynamics, in which new drag and capillarity models not included in the commercial version of the software have been implemented. The second tool used is the domestic code Multiphase Flow Solver, written in Fortran programming language, which has been developed during this doctoral thesis, being one important goal of it. This code includes the models needed to describe the physical processes which describe the behavior of this type of multiphase flows and their dispersion in porous media.

Orientador: Milton Mori
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica
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Resumo: A presente pesquisa apresenta a modelagem matemática e a simulação de uma operação de fluidização rápida em um longo duto cilíndrico vertical, operação importante em vários processos industriais, sendo que sua principal aplicação está vinculada ao craqueamento catalítico do petróleo para a conversão em gasolina. Tem como objetivos a obtenção de uma compreensão contínua e o conhecimento do desenvolvimento do escoamento gás-sólido, bem como a soma de experiências às pesquisas em escala industrial motivados pela possível predição do desempenho deste tipo de escoamento. O modelo tridimensional, turbulento e bifásico usado para a predição do escoamento gás-sólido, consiste num conjunto de equações de conservação da massa e momento para cada uma das fases, formuladas seguindo a aproximação Euleriana-Euleriana. As variáveis fluidodinâmicas foram estimadas pela solução do modelo, com o emprego de correlações empíricas da literatura e disponibilizadas pelo código computacional de CFD, para garantir o fechamento do modelo e sua solução numérica. Desde de que a predição da dinâmica do escoamento complexo, em dutos com alto fluxo ascendente de sólidos não é possível por meio somente de equações fundamentais, a maioria dos modelos requerem entradas empíricas, as quais somente são adquiridas com a experimentação. Estes dados foram obtidos dos estudos de PÄRSSINEN e ZHU (2001). A geometria e a malha numérica estrutural do duto vertical foram geradas pelo software (CAD) ICEM, subdividido em DDN (geometria) e Hexa (malha). A adaptação do modelo matemático para a geração do modelo numérico foi alcançada com o uso do simulador comercial CFX 5.7. Os resultados obtidos foram avaliados com respeito à teoria apresentada ao longo da dissertação, sendo finalmente feita uma comparação entre as predições numéricas com o modelo e dados experimentais da literatura
Abstract: The present research presents the mathematical modeling and the simulation of an operation of fast fluidization in a long vertical cylindrical duct line, which is an important operation in many industrial processes, where its main application is tied with the catalytic cracking of oil for gasoline synthesis. It has as objective the attainment of a continuous understanding and knowledge of the development of the gas-solid flow, as well as adding of experiences to research of industrial scale equipments motivated by the possibility of prediction of the performance of this type of flow. The three-dimensional, turbulent and two-phase model used for the prediction of the gas-solid flow, consists of a set of conservation equations of mass and momentum for each phase, which was formulated following the Eulerian-Eulerian approach. The fluid dynamics variables was estimated by the solution of the model with the use of correlations found in the literature and available in the computational CFD code, in order to guarantee the closure of the model and its numerical solution. Since the prediction of the dynamics of the complex flow in ducts with high ascending solid flow is not possible by solely using the basic equations, the majority of the models require the setting empirical, parameters which are acquired only with experimentation. These data were obtained from the studies of PÄRSSINEN and ZHU (2001). The geometry and the structural numerical mesh of the vertical duct was generated by the software (CAD) ICEM, subdivided in DDN (geometry) and Hexa (meshing). The adaptation of the mathematical model for the numerical model generation was reached with the use of the commercial simulator CFX 5.7. The results were evaluated with respect to the theory presented along this dissertation, where comparisons between the numerical predictions with the model and experimental data from the literature were performed.
Mestrado
Desenvolvimento de Processos Químicos
Mestre em Engenharia Química

Orientador: Milton Mori
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica
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Resumo: Apresenta-se nesta pesquisa uma análise experimental e numérica do comportamento da fase dispersa em um jato circular bifásico confinado e uma comparação com jato circular bifásico livre. Nas análises experimentais, uma câmara pentagonal em acrílico foi utilizada como sistema de confinamento para a obtenção de perfis axiais e radiais de velocidade média, flutuação de velocidade (RMS) e intensidade de turbulência. Estes dados foram analisados a fim de desenvolver uma análise completa da região desenvolvida do jato. Três diferentes jatos foram utilizados para a alimentação da fase gás no topo da câmara, mas apenas o jato central foi carregado com partículas entre 60 e 90µm de diâmetro. Os outros dois foram utilizados para proporcionar uma maior interação entre as fases no interior da câmara. A técnica óptica Phase Doppler Anemometry (PDA), foi empregada na medição da velocidade instantânea da fase sólida e do diâmetro das partículas nas diferentes posições axiais a partir do bico do jato. Nove casos de estudo distintos são investigados individualmente e, em seguida, comparados entre si. Estes casos fornecem informações importantes sobre o comportamento e o efeito do confinamento dos jatos sobre o transporte macrocóspico e turbulento das partículas entre o centro e as regiões de contorno do jato. As análises numéricas tratam da modelagem matemática tridimensional, turbulenta e transiente do escoamento no jato bifásico confinado. O modelo trata as fases gás e sólida a partir de uma abordagem Euleriana. O fechamento das equações de transporte foi realizado utilizando o modelo de turbulência de duas equações k-e para a fase gás e modelos de turbulência de zero-equação para a fase sólida, e ainda em alguns casos esta última apenas sofreu efeitos turbulentos advindos da fase contínua. A acurácia das previsões do modelo em um jato de partículas confinadas com as características médias no tempo, assim como os coeficientes da correlação de turbulência foram avaliados. Perfis radiais de velocidade média e fração volumétrica das partículas foram capturados em quarenta e dois níveis, subdivididos em nove casos e comparados aos dados experimentais adquiridos. O diâmetro médio das partículas utilizado nas simulações foi de 75µm e as velocidades iniciais utilizadas variam entre 3 e 11m/s no jato central. O modelo matemático previu um escoamento desenvolvido semelhante ao que foi encontrado experimentalmente.
Abstract: It is presented in this research an experimental and numerical analisys of the dispersed phase behavior in a circular confined two-phase jet and a comparison with circular free two-phase jet. In the experimental analysis, a pentagonal plexiglass chamber was used as confined system for the axial and radial profiles investigation of mean velocity, fluctuation velocity known as RMS velocity and turbulence intensity. These data were analyzed in order to develop a complete analysis in the developed region of the jet. Three different nozzles were used to feed the gas phase at the top of the chamber, but just the central nozzle was loaded with particles between 60 and 90µm of diameter. The other two were used to increase the interaction between the phases in the chamber. An optical technique known as Phase Doppler Anemometry was used to measure the instantaneous velocity of the solid phase and particle diameter in different axial positions of the jet nozzle. Nine different cases of study are investigated individually and then compared among each other. These cases provide important information about the jets behavior and the confinement effect on the macrocospic and turbulent transport of particles between the jet center and the jet contour regions. The numerical analysis deals with three-dimensional, turbulent and transient mathematical modeling of a confined two-phase jet flow. The model treats the gas and the solid phases from an Eulerian approach. The closure of the transport equations have been accomplished by using the k-e turbulence model for the gas phase and the zero-equation turbulence model for the solid phase, and in some cases the latter suffered turbulent effects occuring only from the continuos phase. The accuracy of the model predictions in a particle-laden confined jet with the characteristics as well as turbulence correlation coefficients have been evaluated. Radial mean velocity profiles for the solid phase were computed on forty two axial levels, subdivided in nine cases and compared to the obtained experimental data. The mean particle diameter used in the simulations was 75µm and the initial velocities used vary between 3 and 11m/s. The mathematical model predicted a flow development similar to that found experimentally.
Doutorado
Desenvolvimento de Processos Químicos
Mestre em Engenharia Química

The thesis presents the definition and development of standardized design procedures of three type of hydraulic turbines for small hydraulic power plants: Pelton, Francis and Kaplan. In order to properly define the design parameter of each type of turbine, a technical-economical criterion was first applied to the flow duration curves of the turbine installation sites. Then, the critical aspects of the design procedure of each type of turbine were analyzed. As regards the Pelton turbines, a numerical investigation of the interaction between the jet and the bucket is presented. Unsteady numerical analyses were carried out on a single jet Pelton Turbine installed in the north of Italy. A two-phase inhomogeneous model was used. Two different jet configurations were analyzed and compared. In the first configuration the interaction between the runner and an axial-symmetric jet characterized by a given velocity jet profile was investigated, whereas in the second configuration the runner was coupled with the needle nozzle and the final part of the penstock and the interaction between the jet and the bucket was analyzed. A detailed analysis of the torque highlighted the influence of the shape of the water jet on the turbine losses and the influence of the stator on the efficiency of this type of hydraulic machines was shown. The numerical results was compared with the experimental data derived from the installation test of the turbine in order to validate the numerical analysis. As regards the Francis turbines, the analysis was focused on the design procedure of the statorical part. Numerical analyses, carried out on an installed and working machine, highlighted problems on the prediction of the operating conditions due to the distributor design procedure. To overcome these problems, an alternative distributor design procedure was presented and validated by numerical analysis. Finally, for the Kaplan turbines a new design methodology of the blade profiles is presented. Moreover, in order to overcome the prediction problems highlighted for the Francis turbines, a prediction criterion of the flow deflection obtainable from the distributor is also proposed.
La tesi presenta procedure di progettazione standardizzata sviluppate per tre tipologie di turbine idrauliche impiegate in centrali idroelettriche di piccola potenza: turbine Pelton, Francis e Kaplan. In primo luogo, per definire in modo appropriato e razionale i parametri progettuali delle turbine, le curve di durata delle portate dei siti di installazione sono state analizzate mediante un criterio sviluppato sulla base di parametri sia tecnici che economici. Si sono poi analizzati in dettaglio gli aspetti critici della procedura di progettazione delle varie tipologie di turbine. Per quanto riguarda le turbine Pelton, oggetto dell'indagine è stata l'interazione tra il getto e la pala a doppio cucchiaio. Analisi numeriche non-stazionarie multifase sono state condotte su di una turbina Pelton a singolo getto installata nel Nord Italia della quale si sono prese in considerazione due diverse configurazioni. Nella prima si è analizzata l'interazione tra la girante e un getto ideale assial-simmetrico a cui è stato assegnato un definito profilo di velocità, mentre nella seconda configurazione la girante è stata accoppiata con l'ugello e la parte finale della condotta forzata per analizzare l'interazione tra la girante e un getto dalle caratteristiche più vicine alla realtà. Un'analisi dettagliata della coppia all'albero ha consentito di valutare l'influenza della forma del getto e dell'elemento statorico sulle perdite e l'efficienza di questa tipologia di macchine idrauliche. I risultati numerici sono stati quindi confrontati con i dati sperimentali dei test di installazione della turbina allo scopo di valutare l'accuratezza dell'analisi numerica. Per quanto riguarda invece la turbine Francis, analisi numeriche condotte su di una macchina installata e funzionante, hanno evidenziato problemi di predizione della condizione di funzionamento dovuti alle procedure di progettazione dell'organo statorico. Per ovviare a questi problemi, si è sviluppata una procedura alternativa per il dimensionamento del distributore che consentisse di prevedere la condizione di funzionamento della macchina in modo più accurato. Tale procedura è stata convalidata tramite analisi numerica. Per quanto attiene le turbi ne Kaplan, è stata sviluppata una metodologia standardizzata di calcolo dei profili palari. Inoltre per ovviare ai problemi di predizione riscontrati anche per questa tipologia di turbine si è sviluppato un criterio di predizione della deviazione all'uscita dell'organo statorico, verificato per via numerica.

Abstract Equations of state and transport property models for hydrogen and hydrogen mixed with natural gas components relevant for pipeline transport have been evaluated by comparing to experimental data and reference equations of state. The evaluated properties are density, speed of sound, Joule-Thompson coefficient, the isobaric and isochoric heat capacity, viscosity, and thermal conductivity. A temperature span of −10 to 50 °C and a pressure span of 1-300 bara has been set as the target range for pipeline transport. Viscosity and thermal conductivity models have been evaluated for binaries where experimental data are available. The goal of this work was to determine if models already available in commercial simulators can predict fluid properties accurate enough for engineering purposes. The classical cubic equations of state of Soave-Redich-Kwong (SRK) and Peng-Robinson (PR) with van der Waals mixing rules have been tested with parameters extracted from the common commercial simulations tools Hysys, Unisim, PVTsim Nova and Multifash. In general, the different parameter sets give similar performance. One exception is the H2-CH4 binary, where both Unisim and Multifash use a non-optimal kij interaction parameter. Neither the SRK, nor PR can describe the Joule-Thompson coefficient of hydrogen, and the error lies in the range 50%-100%. The Joule-Thompson coefficient is however small, and the effect of this misprediction on pipeline simulations might not be significant. For viscosity and thermal conductivity predictions, the SuperTRAPP model in REFPROP 10 as well as simpler viscosity models LGE, LBC and a corresponding-state-principle model of PVTsim Nova have been evaluated. The SuperTRAPP model in REFPROP 10 was found to predict viscosity and thermal conductivity within a reasonable accuracy for pure hydrogen. The simpler viscosity models LGE and LBC overestimate the viscosity of hydrogen by 65% to 90% in the transport domain of interest. For the hydrogen binary systems studied, the SuperTRAPP model for the thermal conductivity and viscosity had errors around 20% at high pressures. Comparing corresponding-state-principle viscosity models with the SuperTRAPP model gave relative deviations in the range 3.9% to 13%. The SRK equation of state is found to perform better than the PR equation of state, with a relative density error below 1% for hydrogen rich systems. A TIBCO Spotfire® visualization dashboard has been developed for easy access to the evaluation results of the large amount of data and thermodynamic models. A steady-state thermohydraulic analysis for Europipe (Norway to Europe) has been performed to evaluate the effect that using different equations of state and viscosity models have on the thermohydraulic estimations. After a review of the thermodynamic model's performance, clear guidance on model selection for hydrogen transportation is provided.

This study examined the thermodynamic synergistic inhibition effects of MEG considering in case of produced water breakthrough, which includes high concentration of salts solution mixed with hydrocarbon fluids during natural gas production. First, we proposed the modified model based on Soave-Redlich-Kwong equation of state for expressing the vapor phase and van der Waals and Platteuw theory to predict the hydrate equilibrium conditions in the presence of both MEG and NaCl. The proposed model adopt the change of fugacity of gas component in aqueous MEG and NaCl solution using ENRTL-RK model in Aspen plus v8.6. The activity of water was determined by Margules equation for MEG, Pitzer equation for NaCl and temperature effect. The hydrate equilibrium conditions of solutions containing both MEG and NaCl with high salinity (∼ 20 wt%) was measured as well. The results showed that the hydrate formation condition was shifted toward lower temperature and higher pressure in accordance with the increased NaCl concentration. The proposed model was acceptably correspond with experimental data. For MEG and NaCl mixed solutions, the average deviation of hydrate formation pressures (AADP) of the proposed model had the lowest value of 5.37% compared to 17.52% of CSMGem and 13.77% of Multiflash.