Injection Tube Research Articles

Experimental study of implementing nano thermal insulation coating on the steam injection tubes in enhanced oil recovery operation for reducing heat loss

Thermal recovery in oil fields is an effective conventional method for extracting heavy oil. Steam injection is one of the main techniques in thermal recovery. Temperature reduction of the injected steam due to heat transfer from tubes to the reservoir environment is one of the essential problems in this method. Increasing the steam temperature or injection rate to overcome this energy loss and to provide the required temperature at the tube outlet considerably enhances the steam generation costs. Furthermore, increasing the injection temperature enhances the thermal stress to injection tubes that in turn brings irreparable damages to production units like casing breakage. In this study, an experimental setup used to simulate steam injection operation in order to decrease the heat transfer coefficient and reduce heat loss to conserve the injected steam temperature. This aim ascertained by using nano coatings as thermal insulator. Two types of thermal insulators including nano silica-based and nano ceramic-based insulators used in this study. Temperature, pressure, and injection rate of steam, and type and thickness of nano thermal insulators were the operating variables. Results show that increasing the injection temperature from 119 °C to 145 °C improves the heat transfer coefficient about twofold that in turn, causes rapid reduction of temperature in injection process. It was also shown that increasing the injection rate from 2.1 g/l to 6.3 g/l inside the bare tube improves the heat transfer coefficient up to 2.5-folds. Therefore, increasing the temperature or injection rate of steam could not be the suitable solution for compensating steam heat loss. The experimental results showed that using ceramic-based and silica-based nano insulation with 5 mm thickness reduces the heat loss up to 45% and 33% for injected steam at 145 °C, respectively.

Micron-sized double emulsions and nematic shells generated via tip streaming

Here we show that the so called Confined Selective Withdrawal technique [1] can be used to produce compound drops whose radii and thicknesses can be easily decreased down to length scales of the order of 5 µ m, and even smaller. This method is based on the generation of a highly stretched thin coaxial jet of two immiscible fluids that flow inside a third bulk co-flowing fluid under creeping flow conditions. The subsequent capillary breakup of such coaxial jet produces, in a single step, compound droplets at rates that can be easily modulated to values of the order of 10 KHz. Using algebraic equations deduced using slender body theory, we report that the production frequency, the diameter and the shell thickness follow well defined scaling laws, enabling us to generate, from milimeter-sized injection tubes, and in a highly controlled way, uniformly-sized double emulsions with the smallest diameters reported up to date. We illustrate our results by producing micron-sized nematic shells with radii below 5 microns and show that the radius of curvature of the surface and the shell thickness can be fixed independently.

Effects of Swirl on the Stabilization of Non-Premixed Oxygen-Enriched Flames Above Coaxial Injectors

Abstract An experimental study is carried out to analyze the effects of swirl on the structure and stabilization of methane non-premixed oxygen-enriched flames above a coaxial injector in which the two streams are eventually swirled. The mean position of the flame and the liftoff height above the injector lips are investigated with OH* chemiluminescence images. The oxygen enrichment, the momentum flux ratio between the two coflows, the swirl level inside the central jet, and the swirl level in the annular jet are varied over a large range of operating conditions. It is found that, in the absence of swirl in the central stream, the flame is always attached to the lips of the internal injection tube. As the inner swirl level increases, the flame front located at the lips of the internal injection tube disappears. When the annular swirl level is high enough to create a central recirculating bubble, the flame detaches from the nozzle rim and remains lifted at a finite distance above the injector. Increasing the oxygen concentration shifts this transition to smaller momentum flux ratios and smaller annular swirl levels. The liftoff distance can be finely tuned and depends on the inner and outer swirl levels, and on the momentum flux ratio between the two coaxial streams. It is shown that this feature depends neither on the confinement of the injector nor on the thermal stress exerted by the hot burnt gases on the injector back plane. About 1000 configurations were investigated that could be classified into only four distinct stabilization modes, in which the flame structure was shown to follow a similar pathway when the momentum flux ratio between the two streams, the swirl level in the central and external streams, and the quarl angle of the annular stream are varied. It is finally shown how these limits are altered when the oxygen concentration in the annular oxidizer stream is varied from air to oxygen-enriched operation.

Operational Control of Mixing Enhancement and Far-Field Jet Noise Suppression Using Downstream Fluidic Injection

Abstract A novel fluid injection scheme is analyzed for its ability to suppress the far-field jet noise using multiple radial microjets placed downstream from the nozzle exhaust. Contrary to other previous research studies, which injected fluid either inside the nozzle or just at the nozzle exhaust, this injection scheme uses a coaxial injector tube to inject multiple equally spaced microjets perpendicular to the jet axis at an axial location downstream from the nozzle exhaust. Microjet injection closer to the jet axis leads to the formation of a counter rotating vortex pair (CVP) close to the injection location which subsequently breaks down into streamwise vortices as the microjet bends and follows the flow direction. Microjet injection pressure and angle of injection play a crucial role in determining the jet trajectory, penetration, and the strength of the CVP formed. The effect of these parameters on the far-field acoustic radiation is evaluated in this study. Detailed large eddy simulations are performed for a nozzle–injector setup operating at Mach 0.9 jet with Reynolds number ≈106 to help understand the aerodynamic and acoustic features of the interaction of this fluid injection scheme with the main jet.

Research on airflow uniformity of marine selective catalytic reduction reverse blow system

In order to improve the working performance of the ceramic catalyst filter, a model of nozzle blowback was designed to change the nozzle diameter. The blowback tube blowback model with variable diameter and the blowback blowback model with equal diameter were used for backflush simulation analysis. Also the influence of the sum of the injection tube inlet velocity, nozzle length, and nozzle cross-sectional area on the uniformity of backflush was studied. Through simulation analysis, it can be obtained that the outlet flow of nozzles with equal diameters and blowback models increases gradually from front to back; the variable-diameter blowback model can make the nozzle outlet flow uniform, but the nozzles at both ends still deviate from the average flow; continuing to change the nozzle diameter. The nozzle outlet flow can continue to be uniform; different boundary conditions and sizes can affect the uniformity of the backflush: the smaller the inlet velocity of the injection tube, the larger the nozzle length, the smaller the sum of the nozzle areas, and the more uniform the nozzle outlet flow.

Computational modeling of resin infusion process applied to small vessel hulls

Polymeric composite materials are largely used for small vessels hull fabrication. They have many desired advantages like low weight, good mechanical performance and good resistance to marine environments. Resin infusion is one of the most common manufacture processes used for this kind of application. In this process, injection tubes are positioned above reinforced media inside mold cavity and resin is forced to flow, first, through these tubes. Tube correct positioning is crucial for a fast and free of imperfections (air bubbles or other filling problems) hull fabrication; however, usually, it is not easy to determine best location for them. In this work, a numerical modeling of the resin injection into a small hull vessel was performed using OpenFOAM software. Besides main solver, other three applications were used in current work. Blender was used to build the tree-dimensional hull geometry, Gmsh used to discretize the geometry, creating a regular mesh formed with hexahedra elements and ParaView used in results post-processing. Finite volume formulation combined with the volume of fluid method was used to solve the multi-phase (air + resin) fluid flow. Four sequential simulations were necessary to determine optimized injection procedure. Each simulation represents an enhancement to the previous one correcting problems like void formation. At the end, some theoretical recommendations are proposed and discussed for an optimized injection procedure for small vessels fabrication.

Study of combined flow control strategies based on a quantitative analysis in a high-load compressor cascade

Micro-vortex generator and a jet flow control technique are combined to improve the flow performance of a high-load compressor cascade, and the injection position is further investigated. The calculated results showed that the reverse flow region of baseline grows with the increment of incidence, and an unstable flow phenomenon rapidly occurs near the leading edge when the incidence rises to +7.9°. Meanwhile, two critical points occur on the end-wall, that is considered to be the main reason for occurring stall. When an injection tube is applied to remove the low energy fluid, the total pressure loss appears drastic reduction, and the occurrence of stall shows a slight delay from +7.9° to +8.7° incidence compared with the baseline. With the micro-vortex generator is introduced in the baseline, the occurrence of stall is delayed from +7.9° to +10.0° incidence due to the mixture of low energy fluid and main flow. The combined application shows an excellent effect in delaying the occurrence of stall and reducing the total pressure loss, and the sudden deterioration of the cascade performance occurs at +9.8° incidence. A quantitative analysis of total pressure loss shows that the secondary flow loss and wake loss contribute to the reduction of total pressure loss, the former is reduced by 31.0% and the latter is decreased by 24.1% at the near stall condition. Moreover, the spanwise injection position can affect both the total pressure loss and stall incidence, and the wider operating range is accompanied by the increment of total pressure loss.

Flow field characteristics of a supersonic jet influenced by downstream microjet fluidic injection

Mixing characteristics of a supersonic jet influenced by a Downstream Microjet Fluidic Injection (DMFI) system are numerically investigated. The DMFI system is built on the observation of a previous experimental study that utilized transverse fluidic injection from four equally spaced injection ports placed on an injection tube at a distance downstream of a 1.5 Mach number nozzle. The measurements from these previous experiments demonstrated thickening and mixing enhancement of the jet shear layer as a result of fluidic injection. The current numerical study examines the underlying physics of the flow field, as well as the effectiveness of the DMFI system at smaller mass flow rate ratios compared to those utilized in the previous experiments. Results indicate good agreement with the trend observed by the experimental study, and considerable improvement in enhancement of the jet mixing is observed. The observed mixing enhancement is attributed to the presence of the microjet tube and fluidic injection and the consequent generation of streamwise vortices, as well as the natural separating bow shock due to the transverse flow injection. DMFI system is shown to enhance the early mixing, resulting in attenuation of the downstream turbulence production. Furthermore, the DMFI system is demonstrated to be an effective method of mixing enhancement for supersonic jets with a potential for reducing the jet noise radiation.

The Microneurosurgical Training Model for Intrinsic and Extrinsic Brain Tumor Surgery Using Polyurethane Foam and Fresh Cadaveric Cow Brain: An Experimental Study

ObjectiveTo evaluate the feasibility of an experimentally designed brain tumor model consisting of polyurethane foam and fresh cadaveric cow brain for the surgical training of the technique for tumor ablation.MethodsA laboratory-training model was created for microneurosurgical intervention of intrinsic brain tumor ablation covering microdissection of the brain tissue and opening of the pia mater, dissection and separation of the sulcal and cisternal structures, and dissection and removal of the tumor tissue. The left front parietal lobe was used as the area of interest for this experimental study. One-centimeter cube polyurethane foam was injected 2-cm deep inside the brain tissue using a plastic injection tube. After 5 minutes, the model was ready to use under the operating microscope for dissection, separation, and removal of the tumor tissue. The compatibility of the training model also was evaluated as poor, acceptable, and perfect.ResultsTen stripped fresh cadaveric cow brains were used in this experimental feasibility study. The compatibility of the model was evaluated as poor, acceptable, and perfect in 1, 6, and 3 subjects, respectively.ConclusionsIn intrinsic brain tumor ablation, surgical manipulations of sulcal, cisternal, and fissural dissection must be undertaken while preserving vital neural and vascular structures. We believe that our model holds promise in developing the technical skills of neurosurgeons in training.

Seawater Desalination with Light Energy Incorporating Artificial Transpiration Stream Using Gas Injection Tube

Abstract Transpiration is a function of plants to evaporate water from their leaf stomata, which enables plants to take up ground water from their roots to their leaves through the xylem. This water flux function is called the transpiration stream. This paper shows the application of the concept of a transpiration stream to seawater desalination using sunlight as a single energy source. This approach uses a simple mimic of plants using a glass gas injection tube, where its inside channel, porous glass part and small pores of the porous part are paralleled with xylem, leaf and stomata of plants, respectively. Aqueous solutions of a dye (methylene blue) absorbing visible light were evaporated from the porous part under visible light irradiation and upward pumping of a dye solution was observed in the channel. When the porous part of the glass gas injection tube was modified with solvent black 5 as non-water-soluble dye, the vaporization and the upward pumping of water in the tube were observed. Recovered vaporized water from artificial seawater was successfully desalinated. Using the mechanism of a transpiration stream, desalination and automatic supply of seawater were achieved only using sunlight.

Development of a nonintrusive pressure sensor for polymer tubes based on dielectric elastomer membranes

In this work, a nonintrusive pressure sensor for contrast fluid injection in medical applications is developed, based on a dielectric elastomer (DE) membrane transducer. A DE is essentially a highly deformable capacitor, consisting of a thin elastomer membrane coated with compliant electrodes. A novel solution is proposed to perform a nonintrusive pressure measurement, in which a DE membrane is wrapped around the injection tube (patient line). While pressure is applied to the tube it expands, leading to an extension of the sensor and therefore to a significant increase in DE capacitance.First, a test rig is designed in order to measure the expansion of the polymer tube during pressure application. Multiple experiments are then performed to evaluate the tube deformation at different pressure levels. Subsequently, analytical models are developed for both fabric-reinforced injection tube and DE sensor, in order to predict the resulting capacitive change of the DE as well as to approximate the mechanical properties of the tube. Based on model predictions and tube characterization results, membrane DEs with different sensor geometries are developed, manufactured, and characterized. The sensor performance is finally assessed by means of several experiments, showing remarkable performance for pressures up to 62 bar.

Mathematical Simulation of the Thermodynamic Processes Associated with the Vapour-Injected Scroll Compressor

Both the major energetic crisis and the global warming, which influence the worldwide economy and the future of the society, determine the development of energetic and ecological performances of both the refrigeration equipment and air conditioning systems. Thus, there is a worldwide supported effort made in order to decrease the carbon dioxide emissions resulted from the burning of fossil fuels and the other greenhouse effect gas emissions. This article presents a refrigeration system design model using a vapour injection scroll compressor and tube in tube evaporators working with refrigerant R407C. The refrigerant circuit comprises of a main evaporator, a secondary evaporator (for the injection process), scroll compressor, condenser and five expansion valves. Furthermore it uses R407C as refrigerant. The secondary refrigerant for both the main and the secondary evaporator is a 50% concentration solution of propylene-glycol and water. Secondary circuit comprises of a pump, an electric boiler, an expansion vessel and a by-pass circuit made of many stop valves. The condenser is cooled with mains water.

Experimental characterization of RDE combustor flowfield using linear channel

An experimental study was conducted to characterize fundamental behavior of detonation waves propagating across an array of reactant jets inside a narrow channel, which simulated an unwrapped rotating detonation engine (RDE) configuration. Several key flow features in an ethylene-oxygen combustor were explored by sending detonation waves across reactant jets entering into cold bounding gas as well as hot combustion products. In this setup, ethylene and oxygen were injected separately into each recessed injector tube, while a total of 15 injectors were used to establish a partially premixed reactant jet array. The results revealed various details of transient flowfield, including a complex detonation wave front leading a curved oblique shock wave, the unsteady production of transverse waves at the edge of the reactant jets, and the onset of suppressed reactant jets re-entering the combustor following a detonation wave passage. The visualization images showed a complex, multidimensional, and highly irregular detonation wave front. It appeared non-uniform mixing of reactant jets lead to dynamic transverse wave structure. The refreshed reactant jets evolving in the wake of the detonation wave were severely distorted, indicating the effect of dynamic flowfield and rapid pressure change. The results suggest that the mixing between the fuel and oxidizer, as well as the mixing between the fresh reactants and the background products, should affect the stability of the RDE combustor processes.

Ozone Propagation in Sterile Waste Piles From Uranium Mining: Modeling and Experimental Validation

Acid mine drainage is generated when sulfide minerals are exposed to air and water through the porous subsurface, and it is significantly accelerated by the action of oxidizing autotrophic bacteria. This is a serious problem in the extraction of most minerals. The use of ozone, which has powerful antimicrobial properties, for microbiological inactivation of sterile waste is a possible solution to mitigate the generation of acid mine drainage. However, ozone generates oxygen as a by-product which can produce short-term oxidation of exposed minerals as well as the potentialization of the leaching of metals and sulfides. This would require early intervention strategies for removal of these substances. In this study, a propagation prediction model of ozone in sterile waste piles from uranium mining was developed on an experimental basis. Such piles can be considered as porous medium consisting of a porous matrix and a pure gas phase for the flow of ozone. A kinetic coefficient of interaction between ozone and sterile waste of the order of 10−3 s−1 was obtained through bench-scale experiments conducted using waste columns. Another pilot-scale experiment was conducted on the pile using experimental parameters of a waste column to evaluate the propagation of ozone in the pile. A three-dimensional axisymmetric numerical simulation showed that ozone tends to rise near the injection site. The propagation of ozone was observed at approximately 1 m from the injection tube, showing an ozone concentration of the order of 10−4 mol m−3 in the porous subsurface.

Droplet-based microfluidic method for robust preparation of gold nanoparticles in axisymmetric flow focusing device

A novel microfluidic mixing strategy was developed and used to prepare polyvinylpyrrolidone (PVP) capped gold nanoparticles (AuNPs). In this process, 1 mM tetrachloroauric acid (HAuCl4) stream containing 1% (w/v) PVP was injected through the inner capillary tube and mixed with 20 mM L-ascorbic acid solution delivered co-currently through the outer coaxial capillary. The reaction mixture was hydrodynamically flow focused by the environmentally friendly oil Miglyol 840 delivered from the opposite side of the outer capillary, which resulted in the generation of reaction droplets in a tapered collection tube. The reactants were rapidly mixed within droplets by internal circulating flows induced by hydrodynamic interactions of fluids inside the droplets with the carrier oil. The size of the prepared AuNPs was measured by both dynamic light scattering and transmission electron microscopy and was found to decrease with decreasing the droplet size and increasing the difference in velocity between the two reactant streams, which improved mixing efficiency within droplets. The smallest nanoparticles were obtained when the outlet section of the injection tube was positioned at the entry section of the collection tube due to the highest shear at the liquid interface. The carrier oil formed a hydrophobic barrier between the droplets and the reactor walls preventing deposition of the synthesised particles. As a result, the size of the AuNPs was smaller than in the co-flow mixer operated with two continuous reactant streams.

Investigation on optical path of laser detection of multiple thermal fluids and suppression of high-temperature stray radiation interference

The on-line detection of the component content of multiple thermal fluids (MTFs) has a crucial impact on heavy oil recovery. A long absorption path-length is an indispensable condition for on-line laser detection system (MTFs-OLDS). Therefore, an open-path reflectarray gas cell was presented based on multi-reflection absorption spectroscopy model. The off-axis optical receiver with extinction threads and spherical filter cavity was designed to suppress the thermal radiation emitted from high temperature injection tube internal wall. The effect of detecting deviations on receiving efficiency and the effectiveness of stray radiation suppression structure were analyzed by Monte Carlo ray tracing method. The results show that the proposed absorption path-length is enhanced 22 times, when the optical window material is fused silica and the reflector mirror coating is silver. The increases of beam divergence angle and alignment error have a reduction role of receiving efficiency. Extinction ratio of extinction threads is improved with base length and hemline length decrease. After adding the filter cavity in the dewar baffle, the point source transmittance (PST) of off-axis optical receiver can be reduced to 1.21 × 10−7 at the off-field angle 5° of incident stray light. The conclusion indicates the PST of the optical receiver of MTFs-OLDS is less than the maximum allowable value, and the level of stray radiation suppression is dramatically improved.

Flame lift-off height control by a combined vane-plasma swirler

In this study, a swirler combining the vane swirler and the plasma swirler is designed to control the flame lift-off height. The plasma swirler is located near the rim of the injector and the vane swirler is placed upstream of the plasma swirler. The vane swirler is employed to form a divergent flow to sustain the detached flame and the plasma swirler is adopted to control the flame lift-off height. The ionic wind clinging to the inner wall of the injector tube does not penetrate into the center, leaving the main stream flow in the central region largely undisturbed. Characteristics of the flow field are analyzed from the results of laser Doppler anemometry (LDA) measurement and mechanism of the flame lift-off control by the combined vane-plasma swirler is revealed. The flame lift-off locations calculated from the LDA measurement are consistent with those from direct observation. The dielectric barrier discharge (DBD) voltage influences the height of the flame lift-off with a linear relationship observed, which means the flame lift-off height can be controlled precisely by the DBD voltage without any mechanical movement or changing the mass flow rate. The combined vane-plasma swirler has the potential to improve the fuel flexibility, increase flame stability and attenuate the injector overheating.Highlights1. A combined vane-plasma swirler is designed to control the flame lift-off height.2. Flame lift-off height can be adjusted by changing the voltage of the dielectric barrier discharge.3. A linear relationship between flame lift-off height and the dielectric barrier discharge voltage is observed.4. Flame lift-off control by the combined vane-plasma swirler is mainly associated with the aerodynamic effect.5. The swirler can improve fuel flexibility, increase flame stability and attenuate injector overheating.

Numerical modelling of char formation during glucose gasification in supercritical water

Supercritical water gasification is an efficient thermochemical conversion process to convert wet biomass into a high grade fuel. However, char formation during the conversion might influence the process efficiency and operational stability. Providing insight into char formation behavior during the gasification process will facilitate the utilization of this technology. Computational fluid dynamic modelling is used to study the supercritical water gasification of glucose in a tubular helical reactor, which includes an injector tube to mix glucose feed with pre-heated water to provide fast heating. Validation against experimental data confirms that the developed model performs well. An average discrepancy of 4% is obtained for the total feed conversion whereas the gas yield at high temperature is computed with 15% difference. The char yield trend is also captured well. Sensitivity analysis reveals that the presence of low temperature zone at the injection point plays a significant role in char formation.

Characterization of Bubble Size Distributions within a Bubble Column

The current study experimentally examines bubble size distribution (BSD) within a bubble column and the associated characteristic length scales. Air was injected into a column of water via a single injection tube. The column diameter (63–102 mm), injection tube diameter (0.8–1.6 mm) and superficial gas velocity (1.4–55 mm/s) were varied. Large samples (up to 54,000 bubbles) of bubble sizes measured via 2D imaging were used to produce probability density functions (PDFs). The PDFs were used to identify an alternative length scale termed the most frequent bubble size (dmf) and defined as the peak in the PDF. This length scale as well as the traditional Sauter mean diameter were used to assess the sensitivity of the BSD to gas injection rate, injector tube diameter, injection tube angle and column diameter. The dmf was relatively insensitive to most variation, which indicates these bubbles are produced by the turbulent wakes. In addition, the current work examines higher order statistics (standard deviation, skewness and kurtosis) and notes that there is evidence in support of using these statistics to quantify the influence of specific parameters on the flow-field as well as a potential indicator of regime transitions.

Mechanical behavior and fracture spatial propagation of coal injected with liquid nitrogen under triaxial stress applied for coalbed methane recovery

Fracturing technology through liquid nitrogen (LN2) injection alters the physical properties of coal and rock masses because of the thermal and pressure effects. In order to investigate heat transfer and fracture propagation behaviors under in situ geological condition with LN2 injections, experimental work was conducted to study the LN2 induced rock/coal failures under true triaxial stress conditions. During the experiments, the temperature, ultrasonic waves, and acoustic emission location detection were monitored to determine the intensity and complexity of specimen failure under singular or cyclic LN2 injections. The results show that a single LN2 injection mainly transfers heat through the solid skeleton and only damages areas adjacent to the injection tube. However, cyclic injections formed a propagated fracture network and the heat can sequentially transfer further along the induced fractures. Moreover, plastic deformation occurred in the entire volume of the sample and the main fractures coalesced until the sample failed. Based on the spatial locations of the acoustic emission sources, the dynamic fracturing within the sample progressed after LN2 injection was clarified. The experimental results can provide evidences for the proposed crack propagation model for the coal masses. The research revealed that high-pressure nitrogen gas transferring liquid water to the tips of new fractures is essential for cyclic LN2 injection to form effective frost-heaving forces and fracturing. Therefore, the fracturing efficiency of the cyclic LN2 injection is far higher than that of singular LN2 injections.