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The necessity to focus and work with renewable energy for value-added product generation has gained interest in recent years, which has led to the development of mathematical models that allow a better understanding and optimization of these processes. In this work an extension of the anaerobic digestion model (ADM No. 1) with H 2 and CO external gas injection was proposed. Therefore, the modification of the volumetric mass transfer coefficient in terms of gas injection and the use of CO as a substrate of the process were proposed. Then, a model reduction was performed applying the principal process analysis (PPA) methodology with two threshold values δ=0.05 and δ=0.1. The R 2 , AIC c criterium, and Global Relative Error (%Error) were used to compare the model and reductions performance. The threshold value δ=0.05 presented the best results with an R 2 > 0.99 and AIC c criterium of-114 compared to the experimental process. For the %Error, values of 2.32%, 1.38%, and 2.18% were achieved for H 2 , CH 4 , and CO outlet gas flowrates when the reduction δ=0.05 is compared with the complete model. This reduction also allowed to decrease the simulation time from 1.94s to 0.82s. Thus, concluding that a first reduced model approximation is possible for the biomethanation process.

To achieve future emission targets for internal combustion engines, the use of hydrogen gas generated by renewable energy sources (known as “green” hydrogen) instead of fossil fuels plays a key role in the development of new combustion-based engine concepts. For new hydrogen engine generations, there are different challenges concerning the injector layout and functionality. Especially when talking about direct hydrogen injection, the key challenge is to ensure a proper mixing between hydrogen and the combustion air—the mixing of gas with a gas is not trivial as shown in this article. In terms of injector functionality, it must be ensured that the requested amount of hydrogen gas needs to be provided in time and, on the other hand, accurately metered to provide an appropriate mixing formation quality inside the combustion chamber. This contribution discusses deep injector analysis techniques with pneumatic and optical approaches for an improved overall understanding of functionality and effects caused by operation with a gaseous fuel. A metering technique for gas flow characterization and, for test simplification, a comparison of hydrogen with helium and nitrogen as possible surrogate gases indicate that helium and nitrogen can act as a substitute for hydrogen in functional testing. Furthermore, this contribution focuses on the usability of helium instead of hydrogen for the determination of spray properties. This is shown by the comparison of spray propagation images that were observed with the Schlieren technique in a pressure vessel proving comparable spray properties. In a next step, the usage of spray-guiding devices to improve the global gas distribution during the injection period is discussed. Here, it turns out that the volume increase does obviously not depend on the nozzle design. Thus, the advantage of multi-hole guiding-devices is based on its flexible gas-jet orientation.

This work presents the potential for using pulsed gas injection to produce amorphous carbon films. In this experiment, the frequency of injecting small amounts of gas was used to control the pressure amplitudes, thus achieving the conditions of plasma generation from stationary, through quasi-stationary, to pulsed oscillations of pressure. In addition, we used various gases and their mixtures, an alternative to argon. In the experiment, we studied the energy state of the plasma. The films were examined for phase and chemical composition, surface morphology, and optical and mechanical properties. We determined low-frequency pulsed gas injections to be conditions favorable for C(sp3)−C(sp3) bond formation. The plasma generated by gas injections is better ionized than that generated by static pressure. Pulsed conditions favor the plasma species to retain their kinetic energy, limiting the probability of intermolecular collision events. Since helium has a relatively high ionization energy, it is a practical addition to sputtering gas because of the increasing sp3 content in the films. The electrons created by helium ionization improve the plasma’s ionization degree.

Combustion noise is relevant to current aviation, rocket, and ground-based gas turbine engines, as it contributes to environmental noise pollution and can trigger thermoacoustic instabilities. These consequences are particularly prevalent in lean, premixed, prevaporised combustors, which are designed to reduce nitrous oxide (NOx) emissions. As a result, there is a need to better understand the mechanisms that drive sound generation in such systems. There are two components to combustion noise: direct noise – generated by the unsteady heat release of a flame – and indirect noise – produced by the acceleration of entropic, vortical, or compositional inhomogeneities. Separation of the respective contributions has proven to be complex to achieve in real engines – for this purpose, model experiments have been developed. These are non-reacting experiments that use unsteady, synthetic perturbations to emulate the fundamental physics of combustion acoustics processes and provide clear data for comparison with theory. Indirect noise models have been theorised for compositional perturbations and experimental validation has been provided via the measurement of acoustic waves (i.e. the output), while assuming a constant compositional perturbation (i.e. the input). This thesis follows on from such experiments by simultaneously measuring both acoustic and compositional waves in a model setup, making use of numerical, analytical, and experimental studies. It first builds upon a previous model experiment through a numerical investigation on the generation, mixing, and convection of entropic and compositional waves generated by heat addition and gas injection. The computed temperature and mass fraction fields are compared with experimental results and inform the design of a new model setup – the Canonical Wave Rig (CWR). The CWR is then used to study direct and indirect noise under simplified, well-controlled conditions. Subsonic and sonic (choked) conditions are investigated for a convergent-divergent nozzle. Acoustic, entropic, and compositional perturbations are generated via the co-flow injection of air or methane into a low Mach number mean flow of air. Spontaneous Raman spectroscopy (1.5 kHz) is employed for the time-resolved measurement of the local concentration upstream of the nozzle. Single pulse experiments in the infra-sound range are used to validate the derived analytical model for direct noise due to co-flow injection. The measurement of non-reverberated indirect noise is made for the first time and is contrasted with results obtained via dereverberation (i.e. removing the effect of pressure build up due to acoustic reflections). Indirect noise transfer functions are calculated using the acoustic and compositional measurements, and issues pertaining to the methods applied are highlighted. Lastly, the pulse burst injection of methane at frequencies up to 250 Hz is presented. The goal of these experiments is to provide data at more realistic frequencies and amplitudes., Engineering and Physical Sciences Research Council (EPSRC), the School of Technology (Qualcomm Scholarship), and Rolls-Royce.

Hydrogen is the energy vector that will lead us toward a more sustainable future. It could be the fuel of both fuel cells and internal combustion engines. Internal combustion engines are today the only motors characterized by high reliability, duration and specific power, and low cost per power unit. The most immediate solution for the near future could be the application of hydrogen as a fuel in modern internal combustion engines. This solution has advantages and disadvantages: specific physical, chemical and operational properties of hydrogen require attention. Hydrogen is the only fuel that could potentially produce no carbon, carbon monoxide and carbon dioxide emissions. It also allows high engine efficiency and low nitrogen oxide emissions. Hydrogen has wide flammability limits and a high flame propagation rate, which provide a stable combustion process for lean and very lean mixtures. Near the stoichiometric air–fuel ratio, hydrogen-fueled engines exhibit abnormal combustions (backfire, pre-ignition, detonation), the suppression of which has proven to be quite challenging. Pre-ignition due to hot spots in or around the spark plug can be avoided by adopting a cooled or unconventional ignition system (such as corona discharge): the latter also ensures the ignition of highly diluted hydrogen–air mixtures. It is worth noting that to correctly reproduce the hydrogen ignition and combustion processes in an ICE with the risks related to abnormal combustion, 3D CFD simulations can be of great help. It is necessary to model the injection process correctly, and then the formation of the mixture, and therefore, the combustion process. It is very complex to model hydrogen gas injection due to the high velocity of the gas in such jets. Experimental tests on hydrogen gas injection are many but never conclusive. It is necessary to have a deep knowledge of the gas injection phenomenon to correctly design the right injector for a specific engine. Furthermore, correlations are needed in the CFD code to predict the laminar flame velocity of hydrogen–air mixtures and the autoignition time. In the literature, experimental data are scarce on air–hydrogen mixtures, particularly for engine-type conditions, because they are complicated by flame instability at pressures similar to those of an engine. The flame velocity exhibits a non-monotonous behavior with respect to the equivalence ratio, increases with a higher unburnt gas temperature and decreases at high pressures. This makes it difficult to develop the correlation required for robust and predictive CFD models. In this work, the authors briefly describe the research path and the main challenges listed above.

The objective of this research was to develop a technological architecture proposal that allows for the supervision and control of the operational parameters of gas injection (flow, temperature, and pressure) in a cluster of a high-pressure gas injection plant. The proposal provides a supervision and control system for the HPGIP I high-pressure gas injection plant that includes instrumentation equipment (transmitters and actuators), a remote terminal unit (RTU) as a control device, and the creation of a control logic as the basis for the development of the SCADA GALBA®, through which the operational variables involved in the process of the gas injection plant can be visualized and controlled, allowing the automatic regulation of the flow of gas that enters the deposits. Automatization of the process allows for the elimination of the average error differential that increases from 2 to 5% when the control valve is opened manually. Currently, the MUC-67 and MUC-68 wells that make up cluster 5 require a control valve opening of 20% and 5%, respectively, and this percentage is directly affected by the average valve opening error when performed manually. In addition, there is a savings of around 40 min in the response time by the operators for the adjustment of the opening or closing parameters of the control valve manually. The proposal allows for the different control actions on the variables or parameters of gas injection present in the clump to be carried out from a control room.

Gas and downhole water sink-assisted gravity drainage (GDWS-AGD) is a new process of enhanced oil recovery (EOR) in oil reservoirs underlain by large bottom aquifers. The process is capital intensive as it requires the construction of dual-completed wells for oil production and water drainage and additional multiple vertical gas-injection wells. The costs could be substantially reduced by eliminating the gas-injection wells and using triple-completed multi-functional wells. These wells are dubbed triple-completion-GDWS-AGD (TC-GDWS-AGD). In this work, we design and optimize the TC-GDWS-AGD oil recovery process in a fictitious oil reservoir (Punq-S3) that emulates a real North Sea oil field. The design aims at maximum oil recovery using a minimum number of triple-completed wells with a gas-injection completion in the vertical section of the well, and two horizontal well sections—the upper section for producing oil (from above the oil/water contact) and the lower section for draining water below the oil/water contact. The three well completions are isolated with hydraulic packers and water is drained from below the oil–water contact using the electric submersible pump. Well placement is optimized using the particle swarm optimization (PSO) technique by considering only 1 or 2 TC-GDWS-AGD wells to maximize a 12-year oil recovery with a minimum volume of produced water. The best well placement was found by considering hundreds of possible well locations throughout the reservoir for the single-well and two-well scenarios. The results show 58% oil recovery and 0.28 water cut for the single-well scenario and 63.5% oil recovery and 0.45 water cut for the two-well scenario. Interestingly, the base-case scenario using two wells without the TC-GDWS-AGD process would give the smallest oil recovery of 55.5% and the largest 70% water cut. The study indicates that the TC-GDWS-AGD process could be more productive by reducing the number of wells and increasing recovery with less water production.

Gas injection in the tundish has been considered as an alternative to optimizing inclusion removal from steels. In the present study, physical and mathematical modeling were used to investigate the effect of gas injection in the tundish on the inclusion removal efficiency. The physical model is a 1/3 reduced scale of an industrial two-strand tundish of 40 tons. The inclusion removal efficiency was quantified using the APS III probe, which counts particles leaving the tundish during the test. Different locations for the gas injection plug were evaluated. Additionally, a mathematical model was developed using commercial CFD software CFX. The predictions of the mathematical model were validated by the physical model results, comparing the efficiency of inclusion removal. The proposed model includes a new boundary condition to describe the behavior of the particles at the free surface, implemented by a special subroutine. The model enabled the identification of appropriate conditions: plugs located at 0.56 or 0.84m from the tundish inlet with gas injection with the flow rate of 3NL/min.

The change regulations of the smelting parameters in a gas-injection blast furnace are investigated using theoretical calculations. The results show that when the volume of gas injected, the oxygen enrichment rate and the theoretical combustion temperature of tuyere are 600 m3/tHM, 10% and 1950~2200∘C, respectively, the conditions meet the smelting requirements of a blast furnace. With the increase of the oxygen enrichment rate, the required air volume decreases, the contents of CO and H2 in the top gas increase, and the content of CO2 first increases and then decreases.With an increase of the volume of gas injected, the coke rate decreases. In addition, when the oxygen enrichment rate and the volume of gas injected are 10% and 600 m3/tHM, respectively, the CO content of the top gas constantly increases with the increase of the coke rate, while the H2 and CO2 contents both decrease. With the increase of the H2 content in the gas, the direct reduction degree of iron gradually decreases and the volume shrinkage burden increases. Apparently, injecting gas into the blast furnace can prevent the theoretical combustion temperature from being too high and solve the contradiction between the upper cooling and lower heating of the blast furnace.

Experimental work has been conducted to study the influence of gas injection on the phase inversion between oil and water flowing in a vertical pipe. A vertical transparent pipe test section line of 40 mm ID and 50 cm length was used. The test fluids used were synthetic oil and filtered tap water. Measurements were taken for mixture velocity, superficial water velocity, superficial gas velocity, and input superficial oil velocity ranging from 0.4 to 3 m/s, 0.18 to 2 m/s, 0 to 0.9 m/s, and 0 to 1.1 m/s. Most of the experiments were conducted more than two times, and the reproducibility of the experiments was quite good. Special attention was given to the effect of oil and water concentration where phase inversion took place with and without gas injection. The results showed that the phase inversion point was close to water fraction of ~ 30%, for both water friction direction changes (from water to oil or from oil to water) and that the effective viscosity increases once the mixture velocity increases. On the other hand, the results with gas injection showed that gas injection had no effect on the oil or water concentration where phase inversion occurred. Furthermore, the study investigated the effect of gas–oil–water superficial velocity on the total pressure gradient in the vertical pipe. It was found that the total pressure gradient was fast and increased at high superficial gas velocity but was slow at low superficial gas velocity. When the superficial oil velocity increased, the total pressure gradient approached the pressure gradient of an oil–water two-phase flow. The obtained results were compared with few correlations found in the literature, and the comparison showed that the uncertainty of the flow pattern transition peak in this study is very low.

Underwater plasma has been long recognized as a "green" alternative to conventional chemicals in the wastewater treatment processes. However, practical application of underwater plasma is still challenging due to insufficient treatment performance. Recently, we proposed a novel process named ACAP utilizing acoustic cavitation in order to stabilize the plasma generation and to enlarge the plasma processing region. This work continues our investigation regarding the ACAP treatment process focusing on effects of gas injection. Experiments were performed using an ultrasonic installation equipped with a specially designed sonotrode (Diam. 48 mm) operated at a frequency of 20 kHz and acoustic power of 120 W. The results revealed that the degradation efficiency of Rhodamine B, which was used as a model wastewater pollutant, remains almost unchangeable in the case of air injection, but it is doubled when argon is injected into the ACAP reactor. It was found that the argon injection enhances the degradation efficiency significantly even without ultrasound irradiation. Results of additional measurements suggest that the effect of argon is attributed to its ability to yield high temperature during cavitation, comparatively good solubility in water and a better ability to reduce the breakdown voltage in water compared to the air case.

Closed-cell solid aluminium alloy foams should ideally contain small and equally sized cells for the sake of better and more predictable mechanical properties, but real foams generated by injection of gas into melts usually exhibit a broad distribution of cell sizes and shapes. Here we investigate how gas bubbles in an aluminium alloy melt containing stabilizing SiC particles can be created in a controlled way by letting the injector move on a circular orbit through the melt at different velocities and adapting the gas flow. The structures of the resulting solidified foams are characterized by X-ray tomography. We identify conditions that allow us to obtain near-monodisperse foams with cell sizes below 1 mm and are able to reduce the content of SiC particles from the usual 20 vol% to 8 vol%.

Pneumatic vitreolysis with C3F8 gas is effective in releasing focal vitreomacular traction in a high percentage of eyes with few adverse events, especially with limited vitreomacular traction (within 1 disk area), lack of thick cellophane membranes, no diabetes mellitus, younger age (mean age of 69.1 years vs. 78.1 years), better baseline best spectacle–corrected visual acuity (mean of 20/50 vs. 20/66), small Stage 2 macular hole, and female gender., Purpose: To evaluate the outcome of perfluoropropane (C3F8) gas injection for symptomatic vitreomacular traction (VMT) with or without Stage 2 macular hole (MH). Methods: A retrospective review of eyes with VMT treated with 0.3 mL of C3F8 gas was performed. Patients avoided the supine position until gas resolution. Patients with small MH maintained partial face-down positioning. Results: Forty-nine consecutive patients (50 eyes) with symptomatic VMT underwent pneumatic vitreolysis between 2010 and 2016. A posterior vitreous detachment developed in 43 eyes (86.0%) after a single gas injection, at a median of 3.0 weeks. Twenty-eight of 35 eyes (80.0%) with VMT only and all 15 eyes (100%) with a small Stage 2 MH developed a posterior vitreous detachment, with MH closure in 10 of 15 eyes (66.7%). Median baseline and last best spectacle–corrected visual acuities were 20/50 and 20/40, respectively (P < 0.001). Mean follow-up time was 11.1 ± 9.9 months. Rate of posterior vitreous detachment was reduced with presence of diabetes mellitus (25%) and with thick cellophane membrane (50%). Univariate analysis showed increased VMT release for eyes with VMT extent within 1 disk area (χ2 = 13.1, P = 0.002), eyes with absence of diabetes mellitus (χ2 = 8.8, P = 0.007), and eyes with Stage 2 MH (χ2 = 5.47, P = 0.019); there was a trend between success and lack of thick cellophane membrane (χ2 = 3.32, P = 0.068). Results using logistic regression also showed younger age (P = 0.012), followed by better baseline best spectacle–corrected visual acuity (P = 0.044), lack of diabetes mellitus (P = 0.077), and female gender (P = 0.045) to be predictors of increased VMT release. One VMT-only eye formed a MH and another VMT-only eye developed a retinal detachment. Both eyes responded to vitrectomy. Conclusion: Pneumatic vitreolysis with limited face-down position is a viable option for treating VMT with few adverse events. More studies are needed to elucidate its indications, benefits, and risks.

En el Campo Colombia en paz se visualiza la oportunidad de incrementar productividad mediante la implementacion de metodos de recobro secundario. El proyecto apunta a las arenas basales debido a que la calidad de su fluido es mejor en comparacion con las arenas superiores (30 ° API vs 20 ° API, de forma respectiva). El objetivo principal es evaluar el efecto de la reinyeccion de gas en la produccion de petroleo.En la actualidad el campo dispone de una red de gas para levantamiento artificial (Gas Lift) con una presion disponible de 1,200 psi. Esta red se usaria para la implementacion del proceso, tanto de manera ciclica como continua, con tasas de flujo entre 100 y 1,000 kscfpd (kilo standard cubic feet per day). Se espera que la produccion de petroleo se incremente debido a la presurizacion en el area de drenaje del pozo e incremento de la movilidad por solubilidad parcial del gas en el crudo.En el Centro de Innovacion y Tecnologia - Instituto Colombiano del Petroleo se midio el recobro de crudo por la inyeccion de gas de produccion. Para ello, se siguio el instructivo tecnico de ensayo GTN-I-009 para realizar evaluaciones con gas de produccion. Los ensayos se realizaron a temperatura de yacimiento de 138 ° F, Gas Oil Ratio (GOR) de 440 scf/STB y crudo con agua y sedimentos Basic Sediments and Water (BS&W) menor que 1 %, tal como lo exigen los protocolos experimentales.En laboratorio, la eficiencia de desplazamiento de crudo con gas de produccion fue del 18 % a la presion maxima de operacion del sistema Gas Lift de 1,600 psi. La Minima Presion de Miscibilidad se estimo en 8,407 psi mediante extrapolacion lineal debido a que se tomaron datos a dos presiones en el equipo Slim Tube.Palabras claves: Inyeccion de gas, Slim Tube, Minima Presion de Miscibilidad.

The permanent aim of the automotive industry is the further improvement of the engine efficiency and the simultaneous pollutant emissions reduction. In order to optimize the small internal combustion engines, it is necessary to further improve the basic knowledge of the thermo-fluid dynamic phenomena occurring during the combustion process. In this context, the application of optical diagnostic techniques permits a deep insight into the fundamental processes such as flow development, fuel injection, and combustion process. The aim of this study was the optimization of the compressed natural gas direct injection by means of the analysis of the injection phase and combustion process. This analysis allowed the improvement of the engine efficiency in lean-burn operation condition too. The investigation was carried out in an optically accessible small direct injection spark ignition single-cylinder engine. Two different injectors were tested. The first one was the injector designed according to the results of model simulation, and the second one was a modified prototype obtained using the findings of the optical analysis carried out in the combustion chamber. The characteristic parameters of the gaseous fuel jet were evaluated through an image processing procedure. The fuel rail was modified in order to allow the injection of seeding particles into the gaseous fuel. The gas jet was analyzed using a white light source coupled with a high spatial and temporal resolution fast camera. The combustion process development was investigated for same engine operative condition performing a cycle-resolved visualization of the flame. Moreover, this methodology permitted the evaluation of motion field and turbulence during the injection process directly into the combustion chamber. The results of investigation evidenced that the modification of the injector, designed according to the optical analysis made in the optically accessible engine, allowed an optimization of compressed natural gas direct injection resulting in improved combustion and emissions reduction

The paper considers numerical simulation of a non-machine energy separation device with a porous inner tube. The results obtained show that with a flow rate variation up to 30% of general rate the channel efficiency of gas-dynamic non-machine device for energy separation falls by 3-5%. Hence, a heat efficiency loss due to the colder air injection prevails over the increase of heat flow resulting from a recovery factor decrease when the temperature difference between supersonic and subsonic flows rises. So, the use of gas injection (porous inner tube) to improve the efficiency of the non-machine device for energy separation is beside the purpose.The effect when the temperature changes its sign in the non-machine device for energy separation and supersonic flow becomes cooler while a subsonic one is heated has been also simulated. This effect was previously obtained experimentally.The numerical simulation has shown good coincidence with analytical solution in case of the laminar flow regime. The research has shown that with the laminar flow the efficiency of the non-machine device for energy separation can be significantly higher than with the turbulent flow, but its implementation is quite difficult.

Tuz Golu (Salt Lake) Underground Gas Storage (UGS) Project in Turkey is being implemented. In some of salt caverns, natural gas is currently stored. While analyzing the data of Tuz Golu UGS project, it was observed that this location is appropriate for safe underground natural gas storage due to its rock salt with high purity and very low permeability. In this study, many numerical simulations for a salt cavern in Tuz Golu UGS project at different gas withdrawal and injection rates were conducted by using TOUGH+RealGasBrine simulator. According to the results of these numerical simulations, the temperature inside salt cavern reduced below 0 degrees C from 53 degrees C within 20days at a rate of gas withdrawal of 3.33 million standard m(3)/day due to Joule-Thomson effect. The temperature inside salt cavern reduced below 0 degrees C within 25days, 40days, and 60days at a rate of gas withdrawal of 2.5, 1.67, and 0.833 million standard m(3), respectively. In order to avoid fracture around the walls of salt cavern, the temperature change inside salt cavern should not be higher than 30 degrees C. In the numerical simulations, there is no gas seepages from the salt cavern to other neighbor salt caverns, which are 600m away owing to very low permeability of salt rock in the study area. The implication of this study is that gas withdrawal and gas injection profiles are quite important to keep the temperature inside salt caverns at an optimum range for safe natural gas storage.

В статье рассматривается возможность увеличения добычи жидких углеводородов (нефти и ретроградного конденсата) из истощенной нефтегазоконденсатной залежи на примере Вуктыльского НГКМ. Увеличения добычи можно достичь путем закачки в продуктивный пласт смеси пропан-бутановой фракции и пластового или сухого газа. Приведены результаты оценки объемов добычи жидкой углеводородной фазы за счет ее испарения в паровую фазу при прокачке «сухого» и пластового газа, как в чистом виде, так и при обогащении пропанбутановой фракцией в различных концентрациях. Рассчитано давление смесимости с пластовой жидкой фазой при закачке «сухого» газа, обогащенного пропан-бутановой фракцией., The article considers the possibility of increasing the production of liquid hydrocarbons (oil and retrograde condensate) from a depleted oil-gas-condensate deposit on the example of Vuktylskoye oil-gas-condensate field. Increased production can be achieved by injection of a mixture of propane-butane fraction and reservoir gas or dry gas. The results of estimating production volumes of liquid hydrocarbons due to evaporation into the vapor phase during injection of dry gas and reservoir gas, both pure or enriched with propane-butane fraction in various concentrations, are presented. The minimum miscibility pressure is calculated for injection of dry gas enriched with the propanebutane fraction.

Hydroxyapatite nanorods were synthesized with a new strategy by mixing hydrogen (15%) and argon (85%) gas injected into hydrothermal autoclave. Calcium nitrate tetrahydrate and diammonium hydrogen phosphate solutions were used as precursors. These materials were mixed together to maintain Ca/P ratio of 1.67. The final solution pH was adjusted with ammonia solution and transferred to the autoclave for hydrothermal process. The temperature and pH were set to 180 o C and 11 respectively. Powder synthesis was carried out once without gas injection, which was 10 h. The powders synthesized at 5, 10, and 15 h by injecting the gas mixture. The synthesized powders were characterized with Fourier transform infrared spectroscopy, Field emission scanning electron microscopy, X-ray diffraction, High-resolution transmission electron microscopy, and Raman spectroscopy. The results showed that use of injected gas increased crystallinity and crystallite size. Also, the use of gas injection has increased the hardness and elastic modulus.

Air layer drag reduction has been shown to be a feasible drag reducing technique at the laboratory and at full ship scales. In most studies, the air layers have been generated via gas injection from two-dimensional spanwise slots. However, given ship's structural considerations, it would be preferable to use discrete holes. The present study expands on the work on single orifice gas injection to multi-hole injection. When compared with slot injection, multi-point injection lead to a reduced range of gas fluxes that formed an air layer. Gas injected from a series of discrete holes can exhibit complex flow patterns, including roll-up into the core of liquid vortices that form as part of the process of injecting gas into the liquid boundary layer. The finite span and length of the model utilized for the present experiments was modest. It remains to be shown if a larger model with similar scaled up geometry (and with more beanwise holes) would enable the formation of a stable air layer with a gas flux per unit span that is similar to that required for slot injection. Nevertheless, the results presented here illustrate the complexity associated with gas injection through multiple perforations in a hull.

Gas injection into liquids is common in many applications. Nozzles with simple geometries are used for injecting gases, this lead to some turbulence and thus different rates of mixing and residence times. In this paper we present a study on gas injection using convergent-divergent nozzles. Gas flow through nozzles with different diameter ratios has been studied. It was found that changes in diameter ratios have a definitive effect on the performance of these nozzles as the gas is injected into a liquid. Pressure measurements of the gas during injection were conducted so momentum transfer could be estimated; additionally high speed video allowed us to see the differences in the gas plumes as the different nozzles were used.

In secondary steelmaking, the refining operation is typically carried out in a metallurgical ladle that is commonly furnished with gas injection facilities. Since gas injection plays an intrinsic role in determining the efficiency of secondary steelmaking and thus the quality of final products, a great volume of work has been conducted mostly utilizing air-water systems at room temperature. Despite a portion of the air-water correlations have been adopted in the literature, their applicability to the real argon-metal system is still questionable. The main motivation behind this paper is to present a simple mathematical model for plume hydrodynamics of metallurgical ladles based on the characteristic phenomena and underlying mechanisms of a buoyant plume, where bubble breakup and coalescence occur simultaneously. The main assumptions/simplifications and governing equations are firstly introduced. After that, the accuracy of the model is demonstrated by comparing predicted plume velocities with the ones measured in an industrial ladle.

Gas injections into liquid are prevalent in the natural environment and are essential in industrial applications, they can lead to complex flow. The flow structure and processes are essentially unsteady and turbulent. In this study, a set of experiments were carried out to investigate the behavior of horizontal round noncondensing gas jets that discharge in a stagnant water ambient, considering subsonic and sonic jet exit conditions. A flow visualization technique using a CCD camera, which allowed simultaneous measurements, was used to investigate such flows. This technique provided a direct measurement of the interfacial behavior between the gas jet and the liquid ambient. Two different methods, the summation and the statistical one were used to obtain and analyze the experimental results, and we have found that both methods yield almost identical results. The results showed that the injector diameter and the Froude number play an important role in dictating both the jet pinch-off and the jet interface unsteadiness. The maximum location before the jet pinchoff is shown to have a logarithmic relation with the Froude number for all the jet diameters. The jet penetration length was measured in the momentum and buoyant regimes respectively and it was found to be strongly influenced by the nozzle diameter and the Froude number as well as by the mass and momentum flow rates of the injected jet. Jet spreading which is indicative of liquid entrainment is also shown to increase with the Froude number and the injector diameters. Also it was found that the Froude number plays an important role in dictating the expansion jet angle and the jet half-width. These magnitudes were obtained from recorded time-averaged images and finally empirical correlations have been developed to predict these parameters., The authors of this paper are indebted to the National of I+D Projects REMODERN ENE2010-21368-CO2-01/CON and ENE 2010-21368-CO2-02/CON.

With the wide promotion of energy saving and environmental protection, the improvement of heating capacity especially at low ambient temperature condition and the working efficiency of room air conditioner become more and more important. Firstly, the purpose of this paper was introduced. Then, the relative techniques like DC inverter, variable volume and gas injection were simply analyzed. Thirdly, a new coupling compressor with these three techniques to satisfy both heating capacity and efficiency demands was indicated. Moreover, the detail design of the coupling compressor was described. At last, the prototype compressor was designed and assembled to validate the effect of this coupling compressor on RAC system. According to the test result, this coupling compressor has significant effect as we expectation when using in RAC system. The maximum heating capacity increasing up to 185% by compare to the base system at -15℃ ambient temperature condition which makes half time consumption at the same room temperature rising. Furthermore, the APF efficiency of the system increased by about 6%.

Purpose: To report the outcomes of pneumatic retinopexy (PR) performed as a primary surgical procedure for rhegmatogenous retinal detachment (RRD) or as a secondary procedure for recurrent RRD. Methods: We retrospectively analyzed case records of 54 patients (54 eyes) who underwent PR for RRD by injecting 0.3 ml of perfluoropropane (C3F8) in the vitreous cavity and cryopexy to break in the same sitting, followed by positioning. Results: A total 54 eyes of 54 patients aged between 17 and 84 years (mean - 51.3, median - 53 years) were included in the study. Except five eyes, all had breaks in the superior quadrants. The RRD ranged from 1 quadrant to 4 quadrants. Twenty-eight eyes (51.8%) were phakic and 26 (48.1%) were pseudophakic. The follow-up ranged from 6 to 144 months. In 25 eyes (46.2%), PR was the primary intervention and was successful in 15 (60%) eyes with a significant visual improvement (P = 0.023). Twenty-nine eyes (52.7%) with failed scleral buckle or failed pars plana vitrectomy underwent PR with a success rate of 65.5% and significant visual improvement (P = 0.0017). Progression of proliferative vitreoretinopathy changes (40%) was the most common cause of failure. The success rate was higher in phakic eyes, eyes with attached macula, superior breaks, superior RRD, and RRD limited to 3 quadrants or less. Conclusion: PR remains a minimally invasive procedure which can be used primarily or as a salvage procedure in failed surgery with moderately good success rate and minimal complications. One-step procedure reduces patient visits and ensures adequate treatment of the break.

Global energy consumption is increasing and hence the need for fossil fuels such as oil. Yet, conventional oil production from known reservoirs is about to reach its peak. So, more needs to be done to meet the demand in the near future. Enhanced oil recovery (EOR) among others is one of the ways to add to global oil production. Gas injection is considered one of the largely utilized EOR methods. Especially, gas supported gravity drainage process has great potential for production from dipping fractured reservoirs to assist the displacing fluid for producing more oil. This thesis presents an experimental investigation that evaluates the optimum performance of three-phase flow of gravity drainage under different miscibility conditions. In the experiments, glass bead models were used as the porous medium and analog fluids (a quaternary three-phase system of H2O, n-butyl alcohol “NBA”, hexadecane “C16¬” and NaCl) were used instead of actual water, oil and gas. An analogy between these fluids and reservoir fluids was constructed based on similar behaviours of the interfacial tensions of both systems. Simulated injection schemes include the continuous gas injection “CGI”, water alternating gas “WAG” and simultaneous water and gas injection “SWAG”. Various fracture patterns and injection rates were also used in the experiments in order to investigate their impacts. In addition, upward WAG injection under near-miscible condition in fractured glass beads model was investigated and its efficiency is compared to the downward near-miscible WAG flooding. The CGI scheme versus WAG and SWAG injection schemes under different conditions using the NBA-rich “oleic” phase indicates that CGI in the vertical injection gives a better performance than the WAG and SWAG injections. However, the CGI consumes more gas injection than the SWAG and WAG schemes, respectively. This implies that WAG injection seems to be more stable and feasible. For injection direction of displacing fluid, an upward injection has lower recovery and injection efficiency factors than downward injection of displacing fluid due to early gas breakthrough, which is related to the density difference between displacing and displaced fluids. The comparison between different miscibility experiments shows that the oil recovery is gradually increased under near-miscible and miscible conditions. The immiscible flood has a slightly sharp breakthrough compared to other two floods which leaves behind a higher residual oil. In addition, decreasing oil recovery and injection efficiency are noticed with reducing the miscibility between gas and oil-phase in the fracture model. This is believed to be a result of interfacial tension and capillary pressure effect, which could dominate the mass transfer between the matrix and fracture. In addition, the oil recovery in miscible flooding is lower than the near-miscible flooding since the gas phase is completely miscible and the oil phase which can pass easily through the fracture. Accordingly, the gas phase breakthrough occurs early in the miscible flooding. The comparison between intermediate and high flow rate of 1:1 WAG ratio and 0.2 PV slug size injections under immiscible condition in the conductive vertical fracture model is studied in this thesis. In contrast, intermediate flow of displacing fluid has a lower oil recovery than the high injection rate. This might have happened due to increasing possibility of mass transfer between the matrix and fracture. On the other hand, different injection rates (from the low to the high flow rate) under near-miscible condition in isolated vertical fracture model are investigated. Those lead to that the oil recovery slightly increases with reducing flow rate since the low injection rate has more stability of the diffusion and dispersion between the displacing and displaced fluids. Several fracture shapes (Isolated, double and conductive vertical fracture models) have been investigated. It is clearly shown that the conductive vertical fracture model has a lower oil recovery than other models and its gas breakthrough occurs early. The isolated vertical fracture model has a high oil recovery because it has two media, which are before and after the fracture. These sections can delay gas breakthrough and thereby increase oil production. Furthermore, the oil recovery factor is inversely proportional with the length of the fracture inside the model. The flow regions of all experiments are investigated using scaling laws reported by Zhou et al. (1994). The calculated scaling law numbers indicate that the optimum oil recovery and injection efficiency occur in the gravity-dominated region, which is represented by the low injection rate and near-miscible fluids.

Gas injection technology is often used in cold regions to solve heat pump’s low heating capacity and high discharge temperature at low ambient temperature. Injecting gas into port opened at specific position of compressor could increase mass flow rate of compressor and total heating capacity of heat pump. Gas injection also changes compression ratio of compressor and decreases discharge temperature. An optimal gas injection pressure is got when the coefficient of performance reached to peak value at a certain working condition. It’s a feasible way to increase performance of heat pump at cold regions. High temperature heat pump could provide higher temperature water for industrial usage regions but there still existed some problems on its usage. Total heating capacity decreased and discharge temperature increased with the raise of condensation temperature. Refrigerant temperature before throttling valve was high and may exceed working temperature range of electrical expansion valve. Gas injection technology with an economizer was adopted to solve these problems. A new high temperature heat pump cycle was designed based on gas injection and outlets water temperature of the prototype manufactured was reached to 90?. Temperature before throttling valve was well controlled by the usage of economizer. Heating capacity, discharge temperature, compressor power consumption of the heat pump system at different amount of injected gas was conducted by theoretical and experimental research in this paper. This study showed the function of gas injection technology which used in high temperature heat pump.

In the phase of declining oilfields and at a time when recovering hydrocarbons has becoming more difficult, effective techniques are the key to extract more oil from mature fields. The difficulty of developing effective techniques is often the real obstacle when dealing with heterogeneous formations such as naturally fractured reservoirs, which are among the most challenging class of hydrocarbon formations. Because of the large degree of heterogeneity, in terms of reservoir properties, the production methods from naturally fractured reservoirs differ from the production methods from conventional reservoirs. To identify an efficient and optimum strategy for oil production from naturally fractured reservoirs, fluid displacement mechanisms at reservoir conditions need to be understood. Gas injection into the conventional reservoirs has been already common practice for years. However, gas injection into naturally fractured reservoirs is still controversial. This is mainly due to the existence of highly permeable fracture systems in fractured reservoirs. These highly permeable and interconnected fracture networks offer easy-flow pathways to the injected gas. As a result, the injected gas is usually produced without sufficient contact with the oil in the matrix, which is left behind and unproduced. Therefore, it is of practical importance to examine the efficiency of a gas injection process in naturally fractured reservoirs to achieve a reliable and effective production process. This thesis is a collection of experimental and theoretical work on the efficiency of gas-oil gravity drainage process in naturally fractured reservoirs. Gas injection experiments were performed using a modified experimental set-up to simulate the gravity-drainage process in naturally fractured reservoirs. In this thesis, the possibilities and limitations of improved oil recovery from fractured reservoirs by gas injection are investigated.

Gas injection is used in several metal smelting and refining operations to increase mixing in the melt and as a carrier for particle addition. Some of the fluid dynamical phenomena that occur in liquid baths when injected with gas are discussed. Mathematical models for simulating three of these phenomena are described: a two-fluid model for simulating bath circulation is compared with data obtained in air-water experiments; a technique that allows the swelling of the bath surface to be simulated is illustrated; and a mathematical model for the prediction of wave motion in gas-agitated baths is summarized.

Rich Zagros basin of hydrocarbon bearing structures in the Middle East has led to a number of oil and gas reservoirs in Iran are shared with neighboring countries. The reservoirs are integrated in geology, and in terms of property are communal. Border competition between neighboring countries has caused the shared reservoirs be in the top attention. In addition, Iran's largest oil and gas reservoirs are located in political boundaries. Therefore, a better understanding of the reservoir makes better use of them. In this article classified EOR methods base on lithology of the reservoirs and investigated the frequent EOR method (gas injection) in the carbonate reservoir that is the most reservoir lithology in Iran, gas has low viscosity and due to this property we need some complementary methods like foam flooding to overcome this disadvantage.Keywords: lithology; carbonate; gas injection; foam flooding.

NIO1 (Negative Ion Optimization 1) is a versatile ion source designed to study the physics of production and acceleration of H- beams up to 60 keV. In ion sources, the gas is steadily injected in the plasma source to sustain the discharge, while high vacuum is maintained by a dedicated pumping system located in the vessel. In this paper, the three dimensional gas flow in NIO1 is studied in the molecular flow regime by the Avocado code. The analysis of the gas density profile along the accelerator considers the influence of effective gas temperature in the source, of the gas temperature accommodation by collisions at walls, and of the gas particle mass. The calculated source and vessel pressures are compared with experimental measurements in NIO1 during steady gas injection.

In this work injection of air into a water physical model of an industrial steel ladle was mathematically simulated. Calculations were developed based on a multiphase Eulerian fluid flow model involving principles of conservation of mass, momentum and chemical species on both phases in order to predict turbulent flow patterns and mixing times in both centric and eccentric injections. Mixing phenomena was addressed by injecting a tracer and it was analyzed the effect of the gas flow rate, injector position, number of injectors and geometry of the ladle on the mixing time. It was concluded that the optimum injection conditions is using a single injector at 2/3 of the radius with high gas flow rates. It is shown that incrementing the number of injectors is detrimental on mixing. Finally, quantitative correlations of mixing time as a function of gas flow rate, position of the injector, number of injectors, geometry of the ladle and mass of liquid were obtained. En este trabajo se simuló, matemáticamente, la inyección de aire en agua en modelo físico de una cuchara de acero industrial. Los cálculos se hicieron con la modelación de flujos bifásicos Euleriana, empleando principios de conservación de la cantidad de movimiento y de materia en ambas fases, para simular patrones de flujo turbulento y mezclado en inyecciones por el centro del reactor (céntricas) y fuera del centro (excéntricas). Se estudió el fenómeno de mezclado de un trazador y se analizó el efecto que tienen el flujo de gas, la posición del inyector, el número de inyectores y la geometría de la cuchara sobre el tiempo de mezclado. Se concluyó que la mejor manera de disminuir el tiempo de mezclado es inyectar el gas con un solo tapón colocado a 2/3 del radio con flujos altos de gas. Se demostró que incrementar el número de inyectores perjudica al mezclado. Además, se obtuvieron correlaciones cuantitativas del tiempo de mezclado en función del flujo de gas, número de tapones, posición del tapón, geometría del reactor y masa de líquido.

Bu çalışma, 21-26 Eylül 2003 tarihinde San Antonio[ABD]'de düzenlenen 13. International Conference on Surface Modification of Materials by Ion Beams'da bildiri olarak sunulmuştur. Tool life can be long and productive, or short and disastrous. Understanding the basic forces in the metal-cutting process that contribute to tool wear or failure will help you use today's tool technologies to ensure that your cutting tools will have a long and productive life [CNC Mach. 5 (2001)]. Thin films, deposited by plasma vapor deposition (PVD) or chemical vapor deposition (CVD), are commonly used techniques to ensure long tool life on cutting inserts and tools as compared with ion implantation. This paper compares the wear behavior of PVD TiCN-coated cutting inserts with the nitrogen ion implanted PVD TiCN-coated ones. These inserts are used in dry turning of steel AISI-SAE 1050 under three different cutting speeds. Cutting forces are measured during cutting by using a piezoelectric dynamometer, charge amplifiers and a PC-based data acquisition system. Results of the turning tests are discussed in terms of tool life, flank wear and cutting forces. SW Res Inst

Studies on the self-leveling behavior of debris bed are crucial in the assessment of core disruptive accident (CDA) that could occur in sodium-cooled fast reactors (SFR). To clarify the mechanisms underlying this behavior, several series of experiments were elaborately designed and conducted within a variety of conditions in recent years, under the close collaboration between Japan Atomic Energy Agency (JAEA) and Kyushu University (Japan). The current contribution, including knowledge from both experimental analyses and empirical model development, is focused on a recently developed comparatively larger-scale experimental facility using gas-injection to simulate the coolant boiling. Compared to the previous investigations, this facility can achieve a much wider range of gas velocities (presently up to a flow rate of around 300 L/min). Based on the experimental observation and quantitative data obtained, influence of various experimental parameters, including gas flow rate (～ 300 L/min), water depth (180 mm and 400 mm), bed volume (3 ～ 7 L), particle size (1 ～ 6 mm), particle density (beads of alumina, zirconia and stainless steel) along with particle shape (spherical and non-spherical) on the leveling is checked and compared. As for the empirical model development, aside from a base model which is restricted to predictions of spherical particles, the status of potential considerations on how to cover more realistic conditions (esp. debris beds formed with non-spherical particles), is also presented and discussed. This work, which gives a large palette of favorable data for a better understanding and an improved estimation of CDAs in SFRs, is expected to benefit future analyses and verifications of computer models developed in advanced fast reactor safety analysis codes.

We perform a quantitative characterization of a microbubble injector in conditions relevant to microgravity. The injector pregenerates a slug flow by using a capillary T-junction, whose operation is robust to changes in gravity level. We address questions regarding the performance under different injection conditions. In particular we focus on the variation of both gas and liquid flow rates. The injection performance is characterized by measuring bubble injection frequency and bubble sizes. We obtain two distinct working regimes of the injector and identify the optimal performance as the crossover region between them.