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At present, diesel injection systems are desirable due to their advanced technology and balance between performance and consumption. However, there are still some problems that this technology is not yet able to overcome. One of these is corrosion. In the Common Rail Injection (CRI) system, one important component subject to corrosion attack is the nozzle. This part of the injector is the only component that is directly subject to high thermal load and chemical or electrochemical reactions with its surroundings in the combustion chamber. However, the main task of the injector nozzle is to properly inject high-pressure fuel into the combustion chamber while withstanding outside effects such as high temperature, high pressure, cavitation, and corrosion, among others. The aim of this study is to investigate the corrosion behaviors of nozzles with different runtimes, temperatures, and fuel types. In addition, corrosion behaviors are investigated on different sides of the nozzle. As a result, the relationships between corrosion and runtime, temperature, and different fuel types are described. All interpretations are derived from statistical results based on the experimental data.

A parametric study of the effects of binary interaction parameter and real-gas equations of state on the high pressure vapor-liquid equilibrium of nitrogen-n-dodecane system was carried out. Different values of the binary interaction parameter reported in literature, including one which depends on temperature, were employed in different equations of state to predict the vapor-liquid equilibrium as a function of ambient pressure and temperature. The findings were compared against the available experimental values reported in literature. Constant values of binary interaction parameter, estimated based on temperature dependent values, are demonstrated to predict the experimentally observed vapor-liquid equilibrium values accurately. The Peng-Robinson equation of state and an average binary interaction parameter were demonstrated to predict the vapor-liquid equilibrium over a wide range of temperature and pressures for nitrogen-n-dodecane binary system.

[EN] The present study gives a general outline for the fluid-dynamical calculation of flows at high pressure conditions. The main idea is to present a mathematical description of high pressure processes in liquids at compressible conditions, quantifying the effect of density variations on the flow pattern due to those pressure variations. The improved mathematical approach is coupled to a Large Eddy Simulation (LES) solver. The main code was developed by OpenSource Ltd. for OpenFOAM, and the authors have introduced the additional expressions in order to calculate particular variables. For validating the code improvement, the LES solver is applied to a modern common-rail nozzle injector used in diesel engines. Results have been compared against other calculations that assumed constant properties and simultaneously validated with experimental data. © 2010 Elsevier Ltd., This work has been funded by MINISTERIO DE CIENCIA E INNOVACION from Spain, in the framework of the project “ESTUDIO TEORICO EXPERIMENTAL DE LA INFLUENCIA DEL COMBUSTIBLE SOBRE LA CAVITACION Y EL DESARROLLO DEL CHORRO EVAPORATIVO”, Reference No. TRA2010-17564. The authors would like to thank Universidad de Valencia for the computer resources, technical expertise, the assistance provided and for allowing the use of the supercomputer Tirant.

Regulated and unregulated gaseous emissions with high pressure and low pressure EGR (exhaust gas recirculation) system were tested in a 4-cylinder, light-duty diesel EURO IV engine typically used in European vehicles. Four different engine calibrations with the low pressure EGR system were studied. Regulated emissions of NOX, CO, HC and CO2 were measured for each configuration. Unburned Hydrocarbon Speciation, HCHO (formaldehyde), HCOOH (formic acid) and N2O (nitrous oxide) were also measured in order to determine the MIR (maximum incremental reactivity) of the gaseous emissions. Pollutants were measured without the DOC (diesel oxidation catalyst) to gather data about raw emissions. When the low pressure EGR system was used, decreases in NOX, N2O and fuel consumption were observed and significant increases HC, CO and unregulated emissions; this is the result of a lower intake manifold temperature, which provides a higher gas density which modifies the combustion process. The potential of tropospheric ozone production was higher in all cases when the low pressure EGR was used. © 2011 Elsevier Ltd.

International audience; The aim of this study is to assess the conversion of a natural gas combined cycle power plant (NGCC) using an advanced gas turbine (GE9H) for CO2 pre-combustion capture. The natural gas is reformed in an auto-thermal reformer (ATR) either with pure oxygen or with air. After water-shift conversion of CO into CO2 and physical CO2 recovery, the synthesis gas contains a high fraction of H2. It is diluted with N2 and steam to lower its low heating value (LHV) for NOX emission control. Oxygen purity and reforming pressure have little impact on the performances. High-pressure reforming is preferred to reduce the process size. Air reforming results in a slightly higher efficiency but in a bigger process too. The CO2 recovery rate has a big impact on the power plant efficiency since a lot of steam is required to lower the heating value (LHV) of the synthesis gas leaving the recovery process. Two values of LHV have been assessed. Steam consumption for natural gas reforming and synthesis gas dilution are the main con- suming elements.

Dry reforming of methane has been studied over Pt/ZrO2 catalysts promoted with Ce for different temperatures and feed compositions. The influence of the impregnation strategy and the cerium amount on the activity and stability of the catalysts were investigated. The results have shown that introduction of 1 wt.% Ce to the Pt/ZrO2 catalyst via coimpregnation method led to the highest catalytic activity and stability. 1 wt.%Ce-1 wt.%Pt/ZrO2 catalyst prepared by sequential impregnation displayed inferior CH4 and CO2 conversion performances with lowest H-2/CO production ratios. 1 wt.%Ce-1 wt.%Pt/ZrO2 catalyst prepared by coimpregnation showed the highest activity even for the feed with high CH4/CO2 ratio. The reason for high activity was explained by the intensive interaction between Pt and Ce phases for coimpregnated sample, which had been verified by X-ray photoelectron spectroscopy and Energy Dispersive X-Ray analyses. Strong and extensive Pt-Ce surface interaction results in an increase in the number of Ce3+ sites and enhances the dispersion of Pt. (C) 2009 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.

PRES 2006. 9th Conference of Process Integration, Modelling and Optimisation for Energy Saving and Pollution Reduction - PRES 2006 -- PRES 2006; International audience; This study is devoted to technical evaluation of a carbon dioxide removal in an existing Integrated Gasification Combined Cycle (IGCC) plant. This IGCC case is based on an oxygen blown entrained flow gasifier operating at 27 bar, the removal of acid gas (H2S) is performed with MDEA unit, the efficiency of this IGCC is 43% based on the low heating value (LHV) of coal. A carbon dioxide separation unit conveniently integrated in a pre-combustion separation process is chosen, in order to take advantage of the high pressure of the gas. The methanol process for carbon dioxide removal is integrated downstream the existing desulfuration unit, and after a CO shift conversion unit. In this study, the integration of the CO2 capture process to the IGCC is simulated as realistically as possible. The design parameters of both the gas turbine (the turbine inlet temperature, compressor pressure ratio, reduced flow rate) and the steam turbine (Stodola parameter) are taken into account. Maintenance of low NOx production in the combustion chamber is also considered. The production of NOx is supposed to be influenced by the low heating value of the gas which is maintained as low as for case of the synthesis gas without CO2 capture. Thus the choice is made to feed the gas turbine of the combined cycle with a diluted synthesis gas, having similar low heating value than the one produced without the CO2 capture. Plant performances for different conversion and capture rates are compared. A final optimized integration is given for 92 mol% CO conversion rate and 95 mol% CO2 absorption rates, a comparison with former studies is proposed.

Mixture preparation is a crucial aspect for the correct operation of modern direct injection (DI) Diesel engines as it greatly influences and alters the combustion process and, therefore, the exhaust emissions. The complete comprehension of the spray impingement phenomenon is a quite complete task and a mixed numerical-experimental approach has to be considered. On the modeling side, several studies can be found in the scientific literature but only in the last years complete multidimensional modeling has been developed and applied to engine simulations. Among the models available in literature, in this paper the models by Bai and Gosman (Bai, C., and Gosman, A. D., 1995, SAE Technical Paper No. 950283) and by Lee et al. (Lee, S., and Ryou, H., 2000, Proceedings of the Eighth International Conference on Liquid Atomization and Spray Systems, Pasadena, CA, pp. 586-593; Lee, S., Ko, G. H., Ryas, H., and Hong, K. B., 2001, KSME Int. J., 15(7), pp. 951-961) have been selected and implemented in the KIVA-3V code. On the experimental side, the behavior of a Diesel impinging spray emerging from a common rail injection system (injection pressures of 80 and 120 MPa) has been analyzed. The impinging spray has been lightened by a pulsed laser sheet generated from the second harmonic of a Nd-yttrium-aluminum-garnet laser. The images have been acquired by a charge coupled device camera at different times from the start of injection. Digital image processing software has enabled to extract the characteristic parameters of the impinging spray with respect to different operating conditions. The comparison of numerical and experimental data shows that both models should be modified in order to allow a proper simulation of the splash phenomena in modern Diesel engines. Then the numerical data in terms of radial growth, height and shape of the splash cloud, as predicted by modified versions of the models are compared to the experimental ones. Differences among the models are highlighted and discussed. Copyright © 2007 by ASME.

The effect of partial substitution of transition elements (M=V, Cr, and Al) in ZrMnFe0.5Ni0.5 and ZrMnFe0.5Co0.5 systems on the lattice parameter, hydrogen storage properties such as plateau pressure, plateau slope and thermodynamic of dissolved hydrogen have been studied. The powder X-ray diffractograms of ZrMnFe0.45Co0.45Ni0.1, ZrMnFe0.5Co0.25Ni0.25, ZrMn0.95V0.05Fe0.5Ni0.5, ZrMn0.9V0.1Fe0.5Ni0.5, ZrMn0.7V0.15Cr0.15Fe0.5Ni0.5, ZrMn0.95V0.05Fe0.5Co0.5, ZrMn0.5Cr0.5Fe0.5Co0.5, ZrMn0.45Cr0.45V0.1Fe0.5Co0.5, ZrMn0.5Cr0.5Fe0.45Co0.45V0.1, ZrMn0.55Cr0.3V0.15Fe0.5Co0.5, ZrMn0.5Cr0.25V0.25Fe0.5Co0.5, ZrMn0.25Cr0.5V0.25Fe0.5Co0.5 and ZrMn0.25Cr0.25V0.25Al0.25Fe0.5Co0.5 alloys show the formation of C14 single phase and the lattice constants and the unit cell volume of these alloys are found to increase with substitution of V and Cr at the Mn site in ZrMnFe0.5Ni0.5 and ZrMnFe0.5Co0.5. The hydrogen absorption isotherms of these alloys using high pressure hydrogen absorption/desorption setup in the temperature and pressure ranges 30⩽T (° C )⩽100 and 0.001⩽P ( bar )⩽30 have been obtained. The maximum hydrogen intake capacity is around 3.5 hydrogen atoms per formula unit at room temperature in ZrMn0.5Cr0.25V0.25Fe0.5Co0.5. The plateau pressure, at any particular investigated temperature, decreases with increase of V content. The plateau slope increases when the ordered structure is disturbed by the substitution of other chosen elements at the B site. The plateau pressures in these alloy-hydrides at the temperature investigated depend mainly on their unit cell volume. The dependence of the thermodynamics of dissolved hydrogen in these alloy-hydrides on the hydrogen concentration shows the different phase regions α, α+β and β as seen in the hydrogen absorption isotherms. The chemical potential of dissolved hydrogen (ΔμH) decreases with the substitution of V and Cr at Mn site in ZrMnFe0.5Ni0.5 and ZrMnFe0.5Co0.5, which is attributed to the increase in the volume of the unit cell of the alloys. The desorption isotherms of ZrMn0.5Cr0.25V0.25Fe0.5Co0.5 show a free energy loss per cycle of about 0.89 kJ mol −1 H at 50°C. The powder X-ray diffractograms of the hydrides of ZrMn0.95V0.05Fe0.5Ni0.5 and ZrMn0.25Cr0.5V0.25Fe0.5Co0.5 show the different phases exists in the isotherms with out any structural change with the inclusion of hydrogen in the interstitial sites with a volume expansion of about 19%. The kinetics of hydrogen absorption at 30°C, 50°C and 75°C have been studied for ZrMn0.95V0.05Fe0.5Co0.5. The different phases identified by both kinetic and thermodynamic studies confirm those seen in the hydrogen absorption isotherms. The average activation energies Ea obtained from kinetics of hydrogen absorption in α+β and β phase are 205±6 and 540±10 meV , respectively. The diffusion coefficient in β phase at 30°C in ZrMn0.95V0.05Fe0.5Co0.5-H is about 6.9×10 −11 cm 2 s −1 .

In this paper, a finite element formulation based on first-order shear deformation theory (FSDT) is used to study the thermal buckling behavior of functionally graded material (FGM) hemispherical shells with a cut-out at apex in a high temperature environment. A Fourier series expansion for the displacement variable in the circumferential direction is used to model the FGM hemispherical shell. The material properties of FGM hemispherical shells are functionally graded in the thickness direction according to a volume fraction power law distribution. Temperature-dependent material properties are considered to carry out a linear thermal buckling analysis. The hemispherical shell is assumed to be clamped-clamped and has a high temperature specified on the inner surface while the outer surface is at ambient temperature. The one-dimensional heat conduction equation is applied along the thickness of the shell to determine the temperature distribution and thereby material properties. Converged critical buckling temperatures are computed for two cases of thermal loads, namely, under uniform temperature rise and temperature gradient across the thickness. Numerical studies include the influence of, power law index, base to radius ratios, and different cut-out angles at the apex on the magnitude of thermal buckling temperature. ? World Scientific Publishing Company.

Contactless fluid level detection in process equipment is an important challenge for the process automation industry, especially under high-pressure conditions. In this study, a method is presented, which permits the contactless measurement of liquid levels in thin opaque capillaries at high pressures. The method is based on the mass dependence of the flexural resonance frequencies of a finite section of a tube. These resonance frequencies are determined from the complex electrical impedance of a slitted toroid coil exciting a magnet attached to the tube. The system has been theoretically described using a set of two Bernoulli-Euler beams, resulting in an analytical solution for the equation of motion. To validate the model, experiments have been performed on a thick-walled stainless steel capillary partly filled with mercury. The model is in good agreement with the experimental data. Moreover, the sensitivity of the method appears to be adequate as a fluid level indicator for control purposes in industrial applications.

Contactless fluid level detection in process equipment is an important challenge for the process automation industry, especially under high-pressure conditions. In this study, a method is presented, which permits the contactless measurement of liquid levels in thin opaque capillaries at high pressures. The method is based on the mass dependence of the flexural resonance frequencies of a finite section of a tube. These resonance frequencies are determined from the complex electrical impedance of a slitted toroid coil exciting a magnet attached to the tube. The system has been theoretically described using a set of two Bernoulli-Euler beams, resulting in an analytical solution for the equation of motion. To validate the model, experiments have been performed on a thick-walled stainless steel capillary partly filled with mercury. The model is in good agreement with the experimental data. Moreover, the sensitivity of the method appears to be adequate as a fluid level indicator for control purposes in industrial applications.

Hydrogen absorption isotherms have been obtained for the C14-type hexagonal-structured alloys ZrMnFe1-xCox (x = 0.2, 0.4, 0.5 and 0.6) in the temperature and pressure ranges 30 � T/�C � 100 and 0.1 � P/bar � 40 using a high-pressure unit based on the pressure reduction method. The powder x-ray diffractograms show that the lattice constants and the unit-cell volume for ZrMnFe1-xCox (x = 0.2, 0.4, 0.5 and 0.6) alloys decrease with increase of XCo. The hydrogen absorption isotherms show the presence of a single plateau region (� + ?) in the temperature and pressure ranges studied and it is found that the plateau pressure and plateau slope at any given temperature increase with increase of the XCo-Content, except in the case of ZrMnFe0.5Co0.5 wherein the hydrogen absorption plateau slope is found to be smaller due to the ordering of the alloy. The dependence of the thermodynamics of the dissolved hydrogen in ZrMnFe1-xCox-H (x = 0.2, 0.4, 0.5 and 0.6) systems in the temperature range 30-50 �C on the hydrogen concentration shows the different phase regions (�, � + ?, ?) seen in the hydrogen absorption isotherms. The powder x-ray diffractograms of the hydrides of ZrMnFe0.8Co0.2 show that the formation of different phases is manifested in the isotherms without there being any structural change and the inclusion of hydrogen in the interstitial sites expands the unit-cell volume by about 21%. Comparison of the hydrogen absorption kinetics of ZrMnFe1-xCox with that of the corresponding Ni alloys in similar experimental conditions shows that the kinetics is slow in the ZrMnFe1-xCox alloys.

We perform high-pressure Raman-scattering measurements on different In xGa1-xN/Si(111) epilayers (0.19 < x < 0.45). We find that the experimental pressure coefficient of the A 1(LO) mode measured in these samples is larger than that expected from the linear interpolation between the corresponding values of GaN and InN. Similar measurements in InGaN epilayers grown on GaN/sapphire templates yield much lower values, below the linearly interpolated pressure coefficients. We conclude that the phonon pressure coefficients measured in InGaN are mainly determined by the different compressibility of the substrate and epilayer material. Neglecting substrate effects may yield highly inaccurate phonon pressure coefficients and mode Grüneisen parameters., The work was supported by the Spanish Ministry of Economy and Competitiveness (MINECO) under project MAT2010-16116.

Stress analysis and determination of eigen pairs of a typical turbocharger compressor impeller have been carried out using the concept of cyclic symmetry. A simplified model treating the blade and the hub as isolated members has also been attempted. The limitations of the simplified model have been brought out. The results of the finite element model using the cyclic symmetric approach have been discussed. ? 1995.

Gas mixture and pressure modify the spectral characteristics of diver's speech. Additionally, constraints imposed on jaw movements by wearing a facial mask affect the speech production process. The auditory feedback loop is equally concerned. Furthermore, underwater adverse working conditions are characterised by noise from different sources. As a result, divers' speech is poorly intelligible and communications between divers and surface control need to be enhanced. To this end, "voice unscramblers" are being used. However, the technological state of commercially available equipment is dated and the quality of speech remains insufficient. To help with the design, testing and qualification (NORM) of new communication devices, a bilingual (French-English) Data-base is currently being set up. It consists of phonetically balanced lists of 200 words read by 17 divers under sea and in chambers at operational levels from the surface to -300 m. These recordings will be edited, labelled and stored for further distribution on a CD-ROM.

A partir du modèle classique d'équation d'état des solides, de la forme de Mie-Gruneïsen, nous introduisons une isotherme à 0 K et une contribution électronique redonnant les résultats Thomas Fermi corrigés à forte compression. De plus nous tenons compte, comme l'a fait Grover d'une transition solide-liquide suivant la loi de Lindemann ; en détente nous employons pour le fluide une formulation de type Van der Waals. L'équation ainsi obtenue se prête bien à l'emploi dans les codes de calcul. Enfin, nous présentons deux applications numériques de notre modèle au cas du cuivre et de l'aluminium ; les comportements de ces métaux sous choc sont correctement restitués.

Metal matrix composites composed of high-purity aluminum and Du Pont PRD-166 continuous zirconia-stabilized polycrystalline alumina fibers are fabricated by liquid metal infiltration using three different casting procedures. The microstructure of the composites is analyzed using optical and electron microscopy, including analytical electron microscopy. It is found that discrete faceted particles of ZrAl3 form at the interface and grow into the matrix of samples processed above the melting point of the matrix for 13 minutes or more. The formation of this compound is in agreement with thermodynamic stability calculations. It is also found that there is a reaction between solid aluminum and the fibers at 913 K, yielding a reaction product which has the same morphology as that observed with molten aluminum. When the fibers are infiltrated with an initial preform temperature below the metal melting point and a solidification time below 1 minute, no reaction products were visible in the composite using the scanning electron microscope (SEM). This leads to the conclusion that aluminum matrix composites can be cast with no apparent interfacial reaction product using these fibers provided that adequate processing parameters are chosen.