Multiple Injection Points Research Articles

CFD Study of Thermal Stratification in a Scaled-Down, Toroidal Suppression Pool of Fukushima Daiichi Type BWR

During the 2011 nuclear catastrophe at Fukushima Daiichi, Unit 3 had a sharper increase in containment pressure than Unit 2, with thermal stratification of the suppression pool cited as one of the contributing factors. In the present work, the buoyancy-induced circulation consequent to steam condensation in a large, toroidal pool of water is studied using computational fluid dynamics (CFD) simulations with a view to understanding the role of important design parameters of the suppression pool system. The tunnelling phenomenon observed in the development of the thermal stratification process is delineated in terms of the establishment of a thermocline. The effects of the number of steam injection points and the cross-section of the pool on thermal stratification characteristics have been investigated through a number of case studies. In all the cases, the surface temperature, which is responsible for over-pressurization of the containment, is found to be significantly higher than the bulk pool temperature. Multiple injection points with the same overall steam flow rate are found to lead to higher surface temperatures due to a shortened circulation path. For the same volume of pool water, the simulations show that a deeper and narrower pool gives rise to significantly higher temperatures than a wider and shallower pool. This is attributed to the relatively deeper penetration of the buoyancy-induced circulation into the pool.

Experimental investigations on aviation kerosene Multi-jets in high temperature and low pressure air crossflow

There are the key factors affecting the combustion performance of the burner, including the jet trajectory, fragmentation and evaporation process of fuel jet in air crossflow and the uniform characteristics of fuel-gas mixing. In our experimental investigation, we studied the effects of liquid/air momentum flux ratio, the number of radial and axial injection points on jet trajectory, penetration depth and Sauter mean diameter (SMD) distribution of aviation kerosene injected into high temperature and low pressure air crossflow. Specifically, the pressure of air crossflow was set to 0.06–0.09Mpa, the speed 0.1 Ma, and the temperature 500 K. The jet trajectories of aviation kerosene were captured using a triggered image sensor (CCD) camera; the SMD of the aviation kerosene along the flow direction was measured using a Malvern laser particle sizer. The main observation results are: (1) The liquid/air momentum flux ratio is still the main factor affecting the penetration depth of liquid jet, fitting the dimensionless formula of jet trajectories of aviation kerosene injected into high temperature and low pressure lateral airflow. The fitting formula of single injection point and multiple injection points is y/d=0.4357q0.8384x/d0.4797 and y/d=0.513q0.8869x/d0.3661 respectively. (2) When the air crossflow pressure goes down, it will reduce the aerodynamic Weber number and increase the penetration depth, while it will reduce the Reynolds number of jet liquid and increase the average droplet size. For every 0.01Mpa decrease in air crossflow pressure, the aviation kerosene particle size SMD increases by 5–20 µm. (3) When the number of radial jet points goes up, it will enhance the interaction between CVP (Counter Rotating Vortex Pairs) and complex vortex system between multiple jets, which leads to rising growth rate of jet liquid column surface wave and the premature break-up, reducing the penetration depth by 15–25 mm; Compared with the single injection point, the influence of liquid/air momentum flux ratio on the jet trajectory and penetration depth of the multi-injection point becomes smaller, and the difference is more obvious under the condition of high liquid/air momentum flux ratio.

Toward Generalizable Trajectory Planning for Human Intracerebral Trials and Therapy

Introduction: Stereotactic neurosurgical techniques are increasingly used to deliver biologics, such as cells and viruses, although standardized procedures are necessary to ensure consistency and reproducibility. Objective: We provide an instructional guide to help plan for complex image-guided trajectories; this may be of particular benefit to surgeons new to biologic trials and companies planning such trials. Methods: We show how nuclei can be segmented and multiple trajectories with multiple injection points can be created through a single or multiple burr hole(s) based on preoperative images. Screenshots similar to those shown in this article can be used for planning purposes and for quality control in clinical trials. Results: This method enables the precise definition of 3-D target structures, such as the putamen, and efficient planning trajectories for biologic injections. The technique is generalizable and largely independent of procedural format, and thus can be integrated with frame-based or frameless platforms to streamline reproducible therapeutic delivery. Conclusions: We describe an easy-to-use and generalizable protocol for intracerebral trajectory planning for stereotactic delivery of biologics. Although we highlight intracerebral stem cell delivery to the putamen using a frame-based stereotactic delivery system, similar strategies may be employed for different brain nuclei using different platforms. We anticipate this will inform future advanced and fully automated neurosurgical procedures to help unify the field and decrease inherent variability seen with manual trajectory planning.

An experimental study on the effect of gas injection configuration on flow characteristics in high viscosity oil columns

AbstractGas‐viscous liquid bubbly and slug flow are very common in petroleum, chemical, bioengineering, polymer, and food processing. However, there is a major knowledge gap in two‐phase flow research in the design of gas injectors/distributers in very high viscosity oil systems. The present study investigates the effect of gas injection methods in columns containing very high viscosity oils (i.e., realistic liquids), and more specifically using 360 Pa · s viscosity oil in a 240‐mm diameter column. The effects that the radial positioning, number of gas nozzles, and their distance from each other have on the structure of the flow in viscous liquids are presented in detail. Electrical capacitance tomography (ECT) is used to extract experimental data. Void fraction, bubble velocity, frequency, liquid film thickness, and bubble length were measured and analyzed at different radial gas injection positions. It has been observed that bubble length increases significantly by 0.3 m when the injection nozzle is located next to the wall of the pipe. Bubble velocity and length also increase by 0.217 m/s and 3.6 m, respectively, with increasing gas flowrate when multiple injection points are used. Increasing the distance between the gas injection points increased bubbles' length by 1.2 m. Bubbles' velocity and frequency (at higher gas flow rate) were also increased.

Investigation of the Multi-Point Injection of Green Hydrogen from Curtailed Renewable Power into a Gas Network

Renewable electricity can be converted into hydrogen via electrolysis also known as power-to-H2 (P2H), which, when injected in the gas network pipelines provides a potential solution for the storage and transport of this green energy. Because of the variable renewable electricity production, the electricity end-user’s demand for “power when required”, distribution, and transmission power grid constrains the availability of renewable energy for P2H can be difficult to predict. The evaluation of any potential P2H investment while taking into account this consideration, should also examine the effects of incorporating the produced green hydrogen in the gas network. Parameters, including pipeline pressure drop, flowrate, velocity, and, most importantly, composition and calorific content, are crucial for gas network management. A simplified representation of the Irish gas transmission network is created and used as a case study to investigate the impact on gas network operation, of hydrogen generated from curtailed wind power. The variability in wind speed and gas network demands that occur over a 24 h period and with network location are all incorporated into a case study to determine how the inclusion of green hydrogen will affect gas network parameters. This work demonstrates that when using only curtailed renewable electricity during a period with excess renewable power generation, despite using multiple injection points, significant variation in gas quality can occur in the gas network. Hydrogen concentrations of up to 15.8% occur, which exceed the recommended permitted limits for the blending of hydrogen in a natural gas network. These results highlight the importance of modelling both the gas and electricity systems when investigating any potential P2H installation. It is concluded that, for gas networks that decarbonise through the inclusion of blended hydrogen, active management of gas quality is required for all but the smallest of installations.

Lateral magma migration through interconnected sills: Evidence from analogue modeling

We explore the capability of interconnected sills to transport magma in the shallow crust, as well as the effect of simultaneous and temporally separated multiple magma emplacement on deformation pattern. We analyze this process through analogue models run with synchronous or diachronous magma injection from different, aligned inlets. Experimental results show that the position and activation in time of multiple injection points strongly influence model evolution. In case of synchronous injection at different inlets, intrusions and associated surface deformation are elongated. Forced folds and annular bounding reverse faults are quite elliptical, with the main axis trending sub-parallel to the magma input alignment. Diachronous injection from different sources would instead favor the lateral migration of magma rather than the vertical growth of intrusions. This evolution promotes the development of interconnected intrusions, and suggests that the deformation observed at surface does not necessarily reflect the location and activation timing of their feeders. Overall, our observations have significant implications for the kinematic evolution of sill complexes, timing of intrusion and associated deformation, raising the possibility that interconnected sills may act as channels for long-range lateral magma transport through a succession of sill-fed emplacement events. Model results also suggest that caution should be taken when trying to infer the feeding areas on the basis of the deformation features observed at the surface or in seismic profiles.

Bilateral erector spinae plane block for scoliosis surgery: Case series

Spinal correction surgery is a very invasive surgical procedure and results in severe postoperative pain. We report six cases in which Bilateral Erector Spinae Plane Block was performed for scoliosis surgery. Our aim was to provide an effective perioperative pain management and to achieve intraoperative hemodynamic stability with no interference on neuromonitoring. The technical challenges are also highlighted. An ultrasound guided scout scan is necessarry to identify the bony prominences and determine the possible multiple injection points. Erector Spinae Plane Block in scoliosis surgery is an easier and safer technique compared to epidural anesthesia and can use instrumented complex spinal surgery. This block seems to have a role in perioperative pain pathway complementing the multimodal analgesic regimen and not have interference with evocated potentials in adults. However the diffusion mechanism of the this block is not well known hence it should be awake regarding local anesthetic toxicity.

Case report of a drug-related death following the use of cathinone derivatives (MPHP and 4-MEAP)

The consumption of new psychoactive substances (NPS), such as cathinones, has been on the rise over the last few years, with adverse effects ranging from agitation, anxiety and hallucinations to convulsions, severe cardiac, hepatic and renal failures [1] . This work aims to report and discuss a fatal case related to the concomitant use of two cathinone derivatives (CDs). A 39-year-old man, known for drug addiction history, was found dead in his caravan. Multiple injection points were observed. The medical examiners concluded to a non-specific asphyxia syndrome combined with pulmonary and pericerebral edema and multivisceral congestion. Hence, the hypothesis of a death related to drug abuse was retained. Blood and urine samples were collected for NPS identification and quantification using LC-HRMS. A metabolic study using human liver microsomes was also conducted to identify human metabolites compared to published studies in animals. Ethanol concentrations were determined using GC-FID and toxicological screenings were performed using LC-UVDAD, LC-MS/MS and GC-MS. Various analyses detected the presence of two CDs, 4′methyl-α-pyrrolidinohexanophenone (MPHP) and N-ethyl-4′methylnorpentedrone (4-MEAP), as well as tetrahydrocannabinol [(THC): 1.4 μg/L and (THC-COOH): 6.6 μg/L] and ethanol (0.5 g/L in cardiac blood). The concentrations of MPHP/4-MEAP in the femoral blood, cardiac blood and urine were 47/1.6, 97/3.5 and 2380/49,700 μg/L, respectively. The in vitro metabolic study allowed us to identify five metabolites for MPHP and three for 4-MEAP, but only two metabolites were detected at low levels in biological samples. One metabolite of MPHP, the 4′-carboxy-PHP, was detected in all biological samples, with higher chromatographic signals than those of MPHP. Regarding the growing phenomenon of CD abuse, analytical toxicologists must have: – efficient tools to detect such NPS focusing on relevant biomarkers; – interpretation data (toxic and fatal blood levels) on CD. In this study, the CD concentrations found appeared to be of the same order of magnitude as the only two reports found in the literature, one concerning a case of death due to MPHP with a plasma (supernatant of heart blood) concentration of 32.9 μg/L [2] and another one on two cases of 4-MEAP intoxication with a positive outcome showing urine concentrations of 7676 and 4554 μg/L, respectively [3] . It is very likely that an additive or synergistic effect between both CDs might have precipitated the fatal outcome.

Evaluation of CO2 gas supply of large open algae ponds

In this study it is evaluated how large open algae ponds can be supplied with sufficient CO2. Therefore, a 2.2 acre and a 10 acre pond are simulated over a one-year operating period. The ponds are operated with two different kinds of algae that achieve a yearly yield of 8 gm2d and 25 gm2d. The algae consume CO2, which is fed into the ponds as CO2 gas injected into sumps.The algae ponds have such long channels that the CO2 has to be injected at multiple points along the channel to keep the pH value in the pond within a specified operating range. The necessary number of injection points is determined for different operating pH ranges. Furthermore, the influence of multiple injection points on algae showing a pH dependent growth is evaluated.The investigations show that it is possible to supply such large ponds with sufficient CO2 by injecting CO2 gas whose volume flow is controlled by a proportional control algorithm. Large ponds that have long channels require more than one injection point along the channel. In some scenarios, even a high number of injection points cannot prevent the pH value from violating the lower limit of the operating range.

Fundamental Understanding of Water Movement in Gas Diffusion Layer under Different Arrangements Using Combination of Direct Modeling and Experimental Visualization

In this paper, direct-modeling-based Lattice Boltzmann Method (LBM) combined with in-situ flow visualization, is used to explore fundamentally the transport of liquid-water inside the gas-diffusion layers (GDLs) used in polymer electrolyte fuel cells. Studies of the water evolution, water saturation, and breakthrough pressure inside a GDL with single and multiple injection points under land and channel geometries are explored. The model and experiment demonstrate good agreement between geometries of GDLs provided in this study which were obtained by a three-dimensional (3-D), reconstructed micro-structure from micro X-ray computed tomography (CT). The overall predictions of water evolution within the GDL agree well with the data visualized from the X-ray CT experiment for all cases studied. It also reveals that the liquid-water saturation profiles inside the GDL and breakthrough pressure are different when the location of the water injection point is altered, thereby providing analysis as to the impact of microporous layers or catalyst-layer functioning. Moreover, the uncompressed GDL undergoes a significantly different mechanism of water transport than that of the compressed GDL. Furthermore, the predictions show that the wettability variation is one of the key factors of the saturation characteristics.

A proposal for SO2 abatement in existing power plants using rich in calcium lignite

Under current European legislation for the abatement of SO2 emissions and the strict ELV after 2016, existing power plants need to apply flue gas desulphurization technologies. For the majority of the units operating in Northern Greece and elsewhere in the Balkans, wet FGD is not the desired option due to the high capital investment involved and the limited service life of the units (less than 20 years).The answer to the dilemma (opt out or new investment) seems to be a solution that comes from the rich calcium lignite of the region. Although local lignite is of low calorific value and loaded with mineral matter and high moisture, it carries a high calcium oxide content part of which is in the form of limestone. The calcareous fly ash is rich in free lime and under certain conditions full desulphurization of the flue gas is already achievable. The desulphurization efficiency of the flue gas due to calcium in lignite is at an average of 80% and it only needs to be boosted to 96% in order to achieve SO2 emission levels below 200 mg/Nm3 (dry, 6% reference oxygen).The scope of this research work is an effort to study the effect of the so called “natural desulphurization” and have its efficiency characterized in terms of certain lignite physical parameters. Under proper mixing and homogenization of the lignite feed to the power plants, the peak SO2 emissions can be smoothed out. Further desulphurization of the flue gas can be achieved by several dry FGD techniques already investigated in Greece and elsewhere [1]. Dry FGD is reported to have an efficiency limitation of 80% in the cool side of the combustion process (after LUVO). SO2 emission concentrations in the vicinity of 1.000 mg/Nm3 can by cooped with low investment dry FGD installation (with multiple injection points if required). Actual operation data show a clear relation between power load and flue gas velocities in the ducts as well as SO2 emission concentrations. A feasibility study carried out for a dry FGD installation is compared to wet FGD technology. It turns out that if lignite feed homogenization is employed, power plants can afford a compromising solution with power load losses in case of peak SO2 emissions and dry FGD installations instead of the classic and expensive wet FGD solution.

(Invited) Comparison of Slurry Film Distribution between a Novel Slurry Injection System and Conventional Slurry Application Method

In this study, slurry film distribution on an embossed Politex pad was compared between a novel slurry injection system (SIS) and conventional slurry application method. The slurry injector was placed on top of the pad surface and it injected slurry in a thin layer at the device trailing edge using multiple injection points. Slurry was also applied to the pad center area using the conventional slurry application method. A fluorescent dye (4-methyl-umbelliferone) was added to the slurry. The slurry fluoresced under UV light and the fluorescent light was captured by a high resolution charged coupled device camera. Results showed that SIS provided a much more uniform slurry distribution to the pad-wafer interface than the conventional slurry application method.

(Invited) Performance Analysis of a Novel Slurry Injection System for Oxide Chemical Mechanical Planarization

In this study, a novel slurry injection system (SIS) was installed on an Ebara F-REX200® polisher and its performance was analyzed for oxide chemical mechanical planarization process. The slurry injector contacts the pad with a light load and applies slurry in a thin layer at the device trailing edge using single or multiple injection points. Used slurry, rinse water and pad debris are then removed from the pad by the injector leading edge. Blanket 200-mm oxide wafers were polished using Cabot Microelectronics Corporation Semi-Sperse™ 25 slurry at different flow rates (100, 150 and 200 ml/min) on Dow IC1000™ k-groove and XY-perforated pads. The results show that at each flow rate, the oxide removal rate is enhanced sufficiently over the rate from the standard slurry applicator that the flow rate can be reduced by about 35% on the XY-perforated pad and 50% on the k-groove pad without sacrificing removal rate.

Investigation of low emission combustors using hydrogen lean direct injection

One of the key technology challenges for the use of hydrogen in gas turbine engines is the performance of the combustion system, in particular the fuel injectors. Tests were conducted to measure the nitrogen oxide (NOx) emissions and combustion performance at inlet conditions of 588 to 811 K, 0.4 to 1.4 MPa, and equivalence ratios up to 0.48. All the injectors were based on Lean Direct Injection (LDI) technology with multiple injection points and quick mixing. One challenge to hydrogen-based premixing combustion systems is flashback since hydrogen has a reaction rate over 7 times that of Jet-A.

Injection System for Multi-Well Injection Using a Single Pump.

Many hydrological and geochemical studies rely on data resulting from injection of tracers and chemicals into groundwater wells. The even distribution of liquids to multiple injection points can be challenging or expensive, especially when using multiple pumps. An injection system was designed using one chemical metering pump to evenly distribute the desired influent simultaneously to 15 individual injection points through an injection manifold. The system was constructed with only one metal part contacting the fluid due to the low pH of the injection solutions. The injection manifold system was used during a three-month pilot scale injection experiment at the Vineland Chemical Company Superfund site. During the two injection phases of the experiment (Phase I = 0.27 L/min total flow, Phase II = 0.56 L/min total flow), flow measurements were made 20 times over three months; an even distribution of flow to each injection well was maintained (RSD <4%). This durable system is expandable to at least 16 injection points and should be adaptable to other injection experiments that require distribution of air-stable liquids to multiple injection points with a single pump.

Inference of the structure of karst conduits using quantitative tracer tests and geological information: example of the Swiss Jura

Karst aquifers are known for being particularly heterogeneous with highly transmissive conduits embedded in low permeability volumes of rock matrix. Artificial tracer experiments have been carried out in a complex karst aquifer of the folded Jura Mountains in Switzerland with the aim of deciphering the conduit organisation. It is shown that tracer experiments with multiple injection points under different flow conditions can lead to useful information on the conduits’ structure. This information has been combined with data from structural geology, spring hydrology, and speleological observations. A conceptual model of the conduit network shows that a detailed inference of the conduit organisation can be reached: geology controls conduit location and orientation; spring hydrology, including temporary springs, constrains conduit elevations and relative hydraulic heads in the aquifer subsystems; and tracer tests identify major flow paths and outlets of the system and dilution caused by non-traced tributaries, as well as the presence of secondary flow routes. This understanding of the Aubonne aquifer structure has important implications for the future management of the groundwater resource. Similar approaches coupling geological information, spring hydrology, and multi-tracer tests under various flow conditions may help to characterise the structure of the conduit network in karst aquifers.

Nonequilibrium Thermodynamics: Transport and Rate Processes in Physical and Biological Systems

Equilibrium thermodynamics: basic definitions reversible and irreversible processes equilibrium thermodynamic laws entropy and entropy production the Gibbs equation equations of state thermodynamic potentials. Transport and rate processes: nonequilibrium systems kinetic approach transport phenomena The Maxwell-Stefan equations transport coefficients electric charge flow the relaxation theory chemical reactions coupled processes. linear nonequilibrium thermodynamics: local thermodynamic equilibrum second law of thermodynamics phenomenological equations Curie-Prigogine principle dissipation function variation of entropy production. Balance equations and entropy generation: entropy generation equation. Entropy and exergy: Entropy exergy. Using the second law of thermodynamics: second law analysis heat and fluid flow heat and mass transfer chemical reactions and reacting flows separation. Thermoeconomics thermodynamic analysis thermodynamic optimum availability exergy destruction number equipartition and optimization. Diffusion: Maxwell-Stefan diffusivity diffusion in nonelectrolyte systems diffusion in electrolyte systems irreversible processes in electrolyte systems. Heat and mass transfer: heat and mass transfer heat of transport degree of coupling coupling in liquid mixtures. Chemical reactions: dissipation for chemical reactions coupled chemical reactions. Membrane transport: passive transport facilitated transport active transport. Thermodynamics and biological systems: mitochondria bioenergetics in mitochondria oxidative phosphorylation proper pathways multiple injection points coupling in mitochondria thermodynamic regulation in bioenergetics facilitated transport active transport molecular evolution molecular machines evolutionary criterium. Other thermodynamic approaches: network thermodynamics with bond graph mosaic in nonequilibrium thermodynamics rational thermodynamics. Extended nonequilibrium thermodynamics: stability ordering in physical structures ordering in biological structures bifurcation extended nonequilibrium thermodynamics.