Determination of bubble point pressure of two live oils with injected nitrogen by quartz crystal resonator

ACLInternational audienceAn experimental investigation of bubble pressure determination of two live oils with injected nitrogen is presented in this work. Conventional bubble point measurement is done with the aid of a constant expansion test. In such method the bubble point is characterized by an inflection in the PV curve as the oil becomes saturated. For some oils the PV curve is smoothed and it becomes difficult or impossible to accurately determine the bubble point. This work demonstrates that in such cases, the use of quartz crystal resonator technique makes it possible. This technique is successfully applied to determine the bubble point pressure of two live oils in which nitrogen is injected up to 40 mol%

Finite elements simulations of thin copper sheets blanking : study of blanking paramaters on sheared edge quality

The capabilities of finite elements codes allow now accurate simulations of blanking processes when appropriate materials modelling are used. Over the last decade, numerous numerical studies have focused on the influence of process parameters such as punch-die clearance, tools geometry and friction on blanking force and blank profile (sheared edge). The proposed study focuses on the finite elements simulations of a blanking process using a new viscoplastic model for the evolution of the flow stress coupled with a new damage model. The commercial finite elements code ABAQUS/Explicit has been chosen to simulate the blanking process. The finite elements predictions have been compared with experimental results. Then the finite elements simulations have been used to assess the influence of punch-die clearance as well as the influence of tool wear and friction on sheared edge quality

A physically-based and fully coupled model of elasto-plasticity and damage for dynamic failure in ductile metals

It is well established that spall fracture and other rapid failures in ductile materials are often dominated by nucleation and growth ofmicro-voids. In the present work, a mechanistic model for failure by cumulative nucleation and growth of voids is fully coupled with the thermoelastoplasticconstitutive equations of the Mechanical Threshold Stress (MTS) which is used to model the evolution of the flow stress. Thedamage modeling includes both ductile and brittle mechanisms. It accounts for the effects of inertia, rate sensitivity, fracture surface energy, andnucleation frequency. The MTS model used for plasticity includes the superposition of different thermal activation barriers for dislocationmotion. Results obtained in the case of uncoupled and coupled model of plasticity and damage from the simulations of the planar impact withcylindrical target, are presented and compared with the experimental results for OFHC copper. This comparison shows the model capabilities inpredicting the experimentally measured free surface velocity profile as well as the observed spall and other damage patterns in the material underimpact loading. These results are obtained using the finite element code Abaqus/Explicit

Influence of Dissipated Energy on Shear Band Spacing in HY100 Steel

International audienceTo analyze the formation of multiple shear bands in HY-100 steel, we consider an infinitely extended layer of finite thickness subjected to shear loading. The perturbation approach, associated with numerical methods, is used to determine the instability modes. The criteria of Wright-Ockendon and Molinari are used to determine the shear band spacing. The hypothesis consisting in considering the proportion of plastic work dissipated as heat (quantified by the Taylor-Quinney coefficient B) as independent of the loading path is now recognized as highly simplistic. The present work attempts to provide a systematic approach to the inelastic heat fraction evolution for a general loading within the framework of thermoviscoplastic standard modeling including a number of material parameters as strain hardening, strain rate sensitivity, thermal softening. The effect of each material parameter on the shear band spacing is determined by using a power law constitutive relation. The Johnson Cook and power law models are used to illustrate the influence of the constitutive relation on the results for the adiabatic shear band spacing, by studying the response of HY-100 steel. We have compared our results with available experimental results in the literature over a very wide range of strain rate (103 -105 s-1) . In this study, we show that the variation of the Taylor-Quinney parameter, B(y), as a function of shear strain is an important parameter that plays a significant role in the calculation of the shear band spacing

Flow optimization study of a batch microfluidics PET tracer synthesizing device.

We present numerical modeling and experimental studies of flow optimization inside a batch microfluidic micro-reactor used for synthesis of human-scale doses of Positron Emission Tomography (PET) tracers. Novel techniques are used for mixing within, and eluting liquid out of, the coin-shaped reaction chamber. Numerical solutions of the general incompressible Navier Stokes equations along with time-dependent elution scalar field equation for the three dimensional coin-shaped geometry were obtained and validated using fluorescence imaging analysis techniques. Utilizing the approach presented in this work, we were able to identify optimized geometrical and operational conditions for the micro-reactor in the absence of radioactive material commonly used in PET related tracer production platforms as well as evaluate the designed and fabricated micro-reactor using numerical and experimental validations

Simulation of the Taylor impact test and analysis of damage evolution using a nucleation and growth based approach

International audienceComputational modeling of the Taylor impact test, using OFHC copper rods are carried out for two impact velocities (260 m/s and 365 m/s). The aim of this work is to demonstrate the efficiency of the recently proposed material model for dynamic plasticity and failure for metals. This model combines the use of a damage approach based on void nucleation and growth, with the Mechanical Threshold Stress (MTS) model for the evolution of the flow stress in isotropic plasticity. The proposed approach is implemented in the finite element code ABAQUS/Explicit via a user material subroutine and the symmetric Taylor impact test, using copper rods, is simulated. The predicted results are compared to the experimental results reported in the open literature and good agreement is found for both shape change and damage distribution

Caractérisation des bruts lourds en présence de solvant

La croissance de la demande en produits pétroliers (essence et gazole), en particulier dans les pays développés, et la nature limitée des ressources pétrolières conduisent l industrie pétrolière à s intéresser de plus en plus à l exploitation et la transformation des huiles lourdes et extra-lourdes. Leurs propriétés non conventionnelles du fait de leur forte composition en asphaltènes (particules définies comme l'ensemble de constituants insolubles dans le n-heptane et solubles dans le toluène) nécessitent la mise en oeuvre de procédés de plus en plus sophistiqués à toutes les étapes de leur exploitation et de leur production. Ces bruts, situés principalement au Canada et au Venezuela, sont caractérisés par leur forte viscosité de 1 à 55 Pa.s (1 000 cP à 55 000 cP), qui rend leur transport en surface impossible dans leur état naturel. Le développement de solutions technologiques nouvelles repose sur une meilleure connaissance des propriétés thermo- physiques et du comportement colloïdal de ces produits.Les méthodes de caractérisation expérimentale et de modélisation utilisées pour les bruts conventionnels sont inadaptées pour les bruts lourds et extra lourds. La caractérisation PVT des bruts lourds fait l objet de nombreux travaux à l heure actuelle. Les propriétés à déterminer sont les équilibres de phase et les propriétés thermo physiques des phases en équilibre. Dans ce contexte, cette thèse a pour objectifs principaux le développement de méthodes expérimentales et de modèles adaptés aux bruts lourds et aux procédés de récupération envisagés pour ces bruts (production froide, injection de solvant VAPEX, injection de vapeur SAGD, etc...).Due to increasing demand for fuel, in particular for developed countries, and the limited nature of reserves, petroleum industry is, and will, growing concerned by the heavy and and extra-heavy oil processing. The non-conventional properties of these oils (due to a high asphaltene composition) require specific engineering solutions during the different steps of their processing. These crudes, mainly localized in Canada and Venezuela, are characterized by their strong viscosity, from 1 up to 55 Pa.s, which makes their transport to earth surface impossible. The development of new technological solutions is based on a better knowledge of the thermophysical properties and the colloidal behavior of these products. The methods of experimental characterization and modelling used for the conventional crudes are unsuited for both heavy and extra heavy crudes. To date, characterization PVT of heavy crudes is the subject of numerous studies. The properties to be determined are balances of phase and thermophysical properties of the equilibrium cycles. In this context, the main objectives of this thesis are not only the development of experimental methods and models suitable for heavy crudes, but also the recovery processes envisaged for these crudes (cold production, VAPEX process, SAGD process, etc ).PAU-BU Sciences (644452103) / SudocSudocFranceF

On a multiscale strategy and its optimization for the simulation of combined delamination and buckling

This paper investigates a computational strategy for studying the interactions between multiple through-the-width delaminations and global or local buckling in composite laminates taking into account possible contact between the delaminated surfaces. In order to achieve an accurate prediction of the quasi-static response, a very refined discretization of the structure is required, leading to the resolution of very large and highly nonlinear numerical problems. In this paper, a nonlinear finite element formulation along with a parallel iterative scheme based on a multiscale domain decomposition are used for the computation of 3D mesoscale models. Previous works by the authors already dealt with the simulation of multiscale delamination assuming small perturbations. This paper presents the formulation used to include geometric nonlinearities into this existing multiscale framework and discusses the adaptations that need to be made to the iterative process in order to ensure the rapid convergence and the scalability of the method in the presence of buckling and delamination. These various adaptations are illustrated by simulations involving large numbers of DOFs

CO2 and temperature effects on the asphaltene phase envelope as determined by a quartz crystal resonator

Knowledge of the asphaltene phase envelope (APE) is crucial for oil companies, especially when enhanced oil recovery is applied. An innovative quartz crystal resonator (QCR) technique was employed to assess the phase behavior of asphaltene under reservoir conditions. The effect of CO2 injection coupled to temperature changes on the APE of a recombined oil with a very low asphaltene content (0.235% w/w of C7 asphaltene in dead oil) are reported. It has been shown that QCR is an appropriate and highly sensitive nondestructive experimental technique for detecting asphaltene flocculation. Pressure onsets were found to be dependent on the depressurization rate.Knowledge of the asphaltene phase envelope (APE) is crucial for oil companies, especially when enhanced oil recovery is applied. 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Caractérisation thermophysique des biodiesels (vitesse du son, densité, compressibilité)

Dans le cadre de la lutte pour la réduction des émissions de gaz à effet de serre, les biocarburants présentent un potentiel intéressant, en raison notamment de leur bilan CO2 "du puits à la roue" souvent très bon. Ainsi de nombreux programmes sont mis en œuvre, notamment en Europe, pour le développement de nouveaux carburants, et de moteurs automobiles adaptés à ces derniers. La conception de ces derniers nécessite une bonne maîtrise du système d injection qui doit être aussi parfait que possible. Une meilleure connaissance du comportement et des propriétés sous haute pression de ces biocarburants revêt un caractère important. Le projet français NADIABIO rentre dans ce cadre et a pour principal objectif une meilleure maîtrise de l'injection (de la propagation d'onde dans la ligne HP à l'auto inflammation et la combustion) et de l'impact des biodiesels via une analyse fine à la fois numérique et expérimentale. En effet, dans le domaine des hautes pressions, la détermination des propriétés thermophysiques comme la densité ou les coefficients de compressibilité, présente souvent des difficultés contrairement à la vitesse du son qui peut se mesurer d une manière simple et directe. Des dispositifs expérimentaux permettant d effectuer des mesures de vitesses ultrasonores et de densité ont été mis au point pendant ce travail de thèse. Ils ont permis de fournir des données expérimentales de vitesses ultrasonores (pour des pressions et températures allant respectivement de 0,1 à 250 MPa et de 263,15 à 423,15K) et de densité (pour des pressions et températures allant respectivement de 0,1 - 100 MPa et de 283,15 à 393,15K). La campagne de mesure a été effectuée sur 12 biodiesels et sur un ensemble de 7 corps purs (EMHV, EEHV) représentatifs des mélanges étudiés. Cependant, pour des raisons de confidentialité, seuls les résultats relatifs aux corps purs et au Normafluid sont accessibles dans ce mémoire. Parallèlement, dans le but de proposer des méthodes de calcul prédictifs, nous nous somme intéressés à une procédure de type predictor corrector , à une méthode de contribution de groupes moléculaires ainsi qu à la théorie des états correspondants. Ces techniques de modélisation ont permis de déduire d autres propriétés thermophysiques comme les coefficients de compressibilité, sous le même domaine de pression et de température.Within the politic changes for the reduction of greenhouse gas emissions, biofuels present an interesting potential because of their very well CO2 balance sheet. Numerous projects were engaged in Europe, for the development of new fuels and for the design of automobile engines adapted to these carburant. The conception of new engine requires specific systems of injection which must be perfectly designed. With this aim in mind thermophysical properties such as density and compressibility must be known with accuracy. The French project NADIABIO goes into this industrial issue and its main objective consist in a better control of the injection (wave distribution in the High Pressure line, during the automobile inflammation and combustion process) and the impact of biodiesels (FAME and synthetic materials) on the environment through fine numerical and experimental analyses. The direct measurement of the density or the coefficients of compressibility often presents difficulties under high pressure. It is therefore easier to determine it indirectly from the velocity of sound, which can be measured in a simple and direct way with a good accuracy. Therefore, experimental devices allowing to make measurements of ultrasound speeds and density were finalized during this work. Experimental data of ultrasound speeds (from 0,1 to 250 MPa and from 263,15 to 423,15 K) and of density (0,1 to 100 MPa and 283,15 to 403,15K) have been determined with good precision on 19 biodiesels (mixtures and synthetic products (FAME, FAEE)). However, for reasons of confidentiality, only the results relative to the synthetic products and to Normafluid appear in this report. At the same time, with the aim of proposing predictive methods, we are interested in the procedure like predictor-corrector , in the method contribution of molecular groups and to the theory of the corresponding states which allowed deducting the other thermophysical properties like the coefficients of compressibility as a function of temperature and pressure.PAU-BU Sciences (644452103) / SudocSudocFranceF