Early Injection Research Articles

Hematite U-Pb dating of Snowball Earth meltwater events

The Snowball Earth hypothesis predicts global ice cover; however, previous descriptions of Cryogenian (720-635 Ma) glacial deposits are limited to continental margins and shallow marine basins. The Tavakaiv (Tava) sandstone injectites and ridges in Colorado, USA, preserve a rare terrestrial record of Cryogenian low-latitude glaciation. Injectites, ridges, and chemically weathered crystalline rock display features characteristic of fluidization and pervasive deformation in a subglacial environment due to glacial loading, fluid overpressure, and repeated sand injection during meltwater events. In situ hematite U-Pb geochronology on hematite-quartz veins, which crosscut and are cut by Tava dikes, constrain sand injection at ~690-660 Ma. We attribute early Tava sand injection episodes to basal melting associated with rifting and geothermal heating, and later injections to meltwater generation during ~661 Ma Sturtian deglaciation. A modern analog is provided by the Ross Embayment of Antarctica, where rift-related faults border sediment-filled basins, overpressurized fluids circulate in confined aquifers below ice, and extensive preglacial topography is preserved. Field evidence and geochronology in Colorado further highlight that deep chemical weathering of Proterozoic bedrock and denudation associated with the Great Unconformity predate Cryogenian injection of fluidized sand, consistent with limited glacial erosion.

Research on jet ignition phases and control parameters in an active pre-chamber optical engine under ultra-lean combustion conditions

The active pre-chamber (APC) jet ignition system is one of the primary technologies for achieving ultra-lean combustion and high thermal efficiency in engines. The impact of the jet process within the engine, as well as its control parameters, on emission pollutants (particularly soot particles) remains unclear. This study focuses on examining the effects of various low-flow injection control strategies on engine combustion and emissions by using optical experiments and numerical simulations. It also explores the impact of different ignition advance angles (ignition timings) based on a short pre-chamber mixing interval to observe ignition combustion, flame propagation, and emission characteristics under ultra-lean conditions (λ = 2.0). The main conclusions are as follows. Appropriately increasing the injection mass can enhance engine load. However, further increases in injection mass significantly raise particulate emissions, resulting in an increase in particle number by up to more than 37-fold, especially for small particles in the 5–––10 nm size range. The chemical reaction between the luminous jet flame and the bright incandescent wake jet flame, as captured by high-speed photography, effectively characterizes the various stages of jet ignition. To reduce particulate matter emissions, it is crucial to avoid the foreseeable wake jet flame caused by the enrichment of the jet mixture in the pre-chamber. The low-flow injection timing should neither be too early nor close to the ignition spark timing. The early injection causes fuel to accumulate at the top of the pre-chamber, hindering the jet flame’s propagation into the main combustion chamber. Late low-flow injection leads to fuel enrichment, resulting in uneven mixing and poor atomization and diffusion due to short mixing times. Ignition after a short mixing time interval tends to increase knocking, resulting in intense combustion and an advanced phase, which slightly reduces load and combustion stability. Regarding the heat release ratio, the total heat release from the two combustion stages in the pre-chamber should ideally account for about 5–6 % of the heat release in the main chamber.

CFD unified approach under Eulerian-Lagrangian framework for methanol and gasoline direct injection sprays in evaporative and flash boiling conditions

Innovative synthetic fuels for advanced propulsion systems, such as methanol and ammonia, and synthetic blended fuels (E00, E10, and E30), known for their high volatility, are often injected directly into combustion chambers. It follows that Eulerian-Lagrangian spray models need to accurately capture the spray collapse as a consequence of flash boiling onset and be capable of proficiently handling the preferential evaporation of multi-component fuels in evaporative scenarios.So, we performed the assessment of an Eulerian-Lagrangian CFD code for simulating methanol and E00 gasoline blend sprays in both early and late injection conditions involving flash boiling conditions and preferential evaporation. The adoption of an effervescent breakup model and of a non-equilibrium phase transition model for the discrete phase allows the adoption of a setup that is almost completely free from specific constant tuning, especially for what concerns the breakup model. We validated the simulations using experimental PLV maps of methanol and E00 sprays issued from the ECN Spray M injector. The results highlight a significantly different morphology of the methanol spray compared to the E00 one under late injection conditions. Under stratified combustion, low-volatile fuels are likely to be ignited first, and the flame propagates toward the high-volatile fuels. The spray collapse was also correctly reproduced, inducing the presence of a low-pressure zone and modifying the spray morphology.

Early injection laryngoplasty for acute unilateral vocal fold paralysis after thoracic aortic surgery

ObjectiveUnilateral vocal fold paralysis (UVFP) following open thoracic aortic surgery increases pulmonary complications and hospital stays. An intervention protocol with early injection laryngoplasty (IL) and swallowing maneuvers was developed for acute UVFP following thoracic aortic surgery. This study aimed to compare the incidence of complications and length of medical care between the non-VFP and the IL-UVFP group managed under this protocol. MethodsPatients who underwent open thoracic aortic surgery from March 2020 to February 2023 were included, excluding those with preoperative VFP or postoperative bilateral VFP. Under the protocol, patients with UVFP and incomplete glottic closure received IL and swallowing maneuvers within one week after diagnosis, while those without a glottic gap started a soft diet along with swallowing maneuvers. Postoperative complications, including reintubation, ICU re-transfer, pneumonia, stroke, delirium, wound infection, and bleeding, as well as hospital and ICU stay, were assessed. ResultsOf the 355 patients included in the study, 51 (14.4%) developed postoperative UVFP, while 304 (85.6%) had normal VF function. In the UVFP group, 42 patients underwent IL, while 9 patients without a glottic gap did not undergo IL. The incidence of complications and length of medical care were analyzed in the non-VFP and the IL-UVFP groups. The IL-UVFP group had a longer median hospital stay compared to the non-VFP group (20.5 vs. 16.0 days), though this difference was not statistically significant (P = .0681). ICU stay (P = .5396) and ICU re-transfer rates (P = 1.00) were also comparable between the groups. There was no significant difference in the incidence of pneumonia between the IL-UVFP group (4.8%) and the non-VFP group (9.5%) (P = .4003). Additionally, no significant differences were observed in the incidence of stroke, delirium, wound infection, or bleeding between the groups. No IL-related complications were reported. ConclusionsThe protocol with early IL appears to help reduce complication rates in acute UVFP patients following thoracic aortic surgery to levels comparable to those in patients without VFP. This protocol could serve as a guideline for otolaryngologists in managing UVFP patients. Level of evidence2b/Individual cohort study.

Computational study on the impact of gasoline-ethanol blending on autoignition and soot/NOx emissions under low-load gasoline compression ignition conditions

In the present work, computational fluid dynamics (CFD) simulations of a single-cylinder gasoline compression ignition (GCI) engine are performed to investigate the impact of gasoline-ethanol blending on autoignition, nitrogen oxide (NOx), and soot emissions under low-load conditions. In order to represent the test gasoline (RD5-87), a four-component toluene primary reference fuel (TPRF)+ethanol (ETPRF) surrogate (with 10% ethanol by volume; E10) is employed. A three-dimensional (3D) engine CFD model employing finite-rate chemistry with a skeletal kinetic mechanism (including NOx sub-mechanism), adaptive mesh refinement (AMR), and hybrid method of moments (HMOM) is adopted to capture the in-cylinder combustion phenomena and soot/NOx emissions. The engine CFD model is validated against experimental data for three gasoline-ethanol blends: E10, E30 and E100, with varying ethanol content by volume. Model validation is carried out for a broad range of start-of-injection (SOI) timings (−21, −27, −36, and −45 crank angle degrees (°CA) after top-dead-center (aTDC)) with respect to in-cylinder pressure, heat release rate, combustion phasing, NOx and soot emissions. For relatively later injection timings (−21 and −27 °CA aTDC), E30 yields higher amount of soot than E10; while the trend reverses for early injection cases (−36 and −45 °CA aTDC ). On the other hand, E100 yields the lowest amount of soot among all fuels irrespective of SOI timing. Further, E10 shows a non-monotonic trend in soot emissions with SOI timing: SOI-36>SOI-45>SOI-21>SOI-27, while soot emissions from E30 exhibit monotonic decrease with advancing SOI timing. NOx emissions from various fuels follow a trend of E10>E30>E100. On the other hand, NOx emissions increase as SOI timing is advanced for all fuels, with an anomaly for E10 and E100 where NOx decreases when SOI is advanced beyond −36 °CA aTDC. Detailed analysis of the numerical results is performed to investigate the soot/NOx emission trends and elucidate the impact of chemical composition and physical properties on autoignition and emissions characteristics.

A novel valve strategy for particulate matter reduction in a gasoline direct injection engine operated at cold conditions

In this study, we proposed a novel intake strategy to reduce Particulate matter (PM) emissions from gasoline direct-injection (GDI) engines during cold-start conditions emissions. This strategy is characterized by generating strong intake turbulence and low in-cylinder pressure during fuel injection through delayed intake valve opening, which theoretically promotes fuel atomization and fuel-air mixture, thereby suppressing PM formation during combustion. Experiments were conducted on a single-cylinder GDI research engine, operating at 1500 rpm, 3, 6, and 8 bar IMEP, and stoichiometric air-fuel ratio conditions with low coolant and lubricant temperatures to experimentally demonstrate the effectiveness of the proposed valve strategy in reducing PM emissions. Benchmark tests were performed using an intake camshaft with intake valve opening (IVO) at −13 °aTDC and intake valve closing (IVC) at 227 °aTDC. The novel strategy uses an intake camshaft with very late IVO at 66 °aTDC and IVC at 226 °aTDC. Two injection pressures (Pinj = 100/200 bar) were used to evaluate the pressure requirement for achieving low PM emissions with both strategies. Start of injection was swept and optimized to match the valve strategy. The results showed that the novel valve strategy leads to a 50%–90% reduction in particle number and mass emissions in cold-start conditions, and a lower injection pressure requirement to achieve comparable particle number and mass emissions compared with the normal one. For the novel valve strategy, the fuel impingement with early injection timings is largely mitigated, and thus an early injection timing shortly before the IVO is recommended.

Immediately Injections of Botulinum Toxin A After Surgical Excision for Ear Keloids: A Retrospective Study.

Ear keloids are pathologic scar hyperplasia in the ear region. The most therapeutic approach was surgical shave excision with radiation therapy. However, radiation therapy is easily delivered to healthy surrounding tissues. In the last years, injections with botulinum toxin type A (BTX-A) have been proven to improve surgical scars effectively in clinical trials. This study aimed to evaluate the effect of immediate injections of BTX-A after surgical excision for ear keloids. From January 2020 to January 2023, 33 consecutive patients with ear keloids were enrolled. All patients underwent scar excision and revision at the same time when they needed BTX-A. It was injected into surgical wound closure immediately after surgery. The results of this study were evaluated at follow-up from 7 to 18 months using the Vancouver Scar Scale (VSS) and the Visual Analogue Scale (VAS). From January 2020 to January 2023, 33 patients received concomitant therapy of immediate injections of BTX-A after surgery for ear keloids. The patients were evaluated at follow-ups lasting 7 to 18 months. Only one case recurred within the follow-up period, and no adverse effects were reported. This study demonstrates that significant cosmetic outcomes in ear keloid treatment were achieved after early postsurgical BTX-A injections. The patients reported high satisfaction and few complications.

Investigation of fuel temperature and injection timing effects on ammonia direct injection in an optical engine

This work investigates the effects of fuel temperature and injection timing on ammonia direct injection in an optical engine using a multi-hole injector. Flash-boiling may occur over various engine-relevant conditions due to ammonia’s high vapor pressure. This phenomenon impacts spray characteristics and, in severe cases, facilitates cavitation inside the nozzle. Both fuel temperature and injection timing (i.e., ambient conditions during injection) impact the intensity of flash-boiling during fuel injection. Therefore, this work varies fuel temperature (from 320K to 388K) and injection timing (from −60CADaTDC (crank angle degrees after top dead center) to −6CADaTDC) to assess their impact on injection mass flux, discharge coefficients, and macroscopic spray characteristics using an ammonia injection pressure of 200bar. For this purpose, the injection mass is measured by analyzing exhaust gas compositions during engine operation with ammonia injections but without combustion. In addition, diffuse background illumination (DBI) images capture the liquid phase of the fuel spray to characterize spray behavior. The findings reveal that increasing fuel temperature decreases ammonia’s injection mass by up to 12.8% but has little impact on discharge coefficients for late injection timings and high in-cylinder pressures. However, discharge coefficients decrease by up to 17.4% (from 0.58 to 0.48) for early injection timings if fuel temperatures are high. The individual sprays of the 6-hole GDI injector may collapse into a uniform spray at high-density conditions without flash-boiling or under strongly flash-boiling conditions. The findings clarify the impact of ammonia’s high vapor pressure on injection mass and prove the relevance of different spray collapse mechanisms in ammonia direct injection engines.

Rescue ICSI Improved Cumulative Live Birth Rate for Cycles with Second Polar Body Extrusion Rate

ObjectiveTo determine the indications for early rescue intracytoplasmic sperm injection (ICSI) application. DesignA retrospective cohort study SubjectsThe study included 19,808 patients who underwent conventional in vitro fertilization (IVF) or rescue ICSI for their first cycles between February 2017 and December 2021. ExposureRescue ICSI cycles constituted the study group, where oocytes that had not extruded the second polar body 4-6 hours after insemination were rescued by ICSI. The control group consisted of conventional IVF cycles with no interventions to rescue oocytes without the second polar body. Generalized additive models (GAMs) were constructed to describe the relationship between the second polar body extrusion rate and cumulative live birth rate in conventional IVF and rescue ICSI cycles, respectively. The cutoff value of the second polar body extrusion rate guiding rescue ICSI application was determined from the intersection point of GAMs. Maternal age range applicable to rescue ICSI was further analyzed using the same method. Clinical outcomes were compared between conventional IVF and rescue ICSI cycles across different second polar body extrusion rate and maternal age subgroups. Main outcome measuresThe second polar body extrusion rate and maternal age range for rescue ICSI application, normal fertilization rate, and cumulative live birth rate. ResultsGAMs showed that the cutoff value for the second polar body extrusion rate about rescue ICSI application was 50%. When the rate <50%, normal fertilization rate and cumulative live birth rate (63.7% vs. 46.1%, OR: 1.609, 95% CI: 1.276-2.030) were significantly higher in rescue ICSI cycles than conventional IVF cycles. When the rate ≥50%, rescue ICSI cycles had similar normal fertilization rate and cumulative live birth rate compared to conventional IVF cycles. Further analysis on maternal age in cycles with second polar body extrusion rate <50% released that rescue ICSI cycles showed a higher cumulative live birth rate (67.7% vs. 48.3%, OR: 1.732, 95% CI: 1.361-2.202) than conventional IVF cycles for women aged < 38 years. ConclusionIVF cycles with second polar body extrusion rate <50% in women aged < 38 years was applicable to early rescue ICSI.

Dose-Dependent Effects of Botulinum Toxin Type A on Prevention of Postoperative Scars in Various Regions in the Body: A Prospective, Double-Blind Randomized Controlled Trial.

Botulinum toxin type A (BTXA) can improve wound healing and reduce scar formation; however, the exact dose required to prevent postoperative scarring across various anatomical sites remains unclear. This study aimed to investigate the effectiveness and optimal concentrations of BTXA for preventing postoperative scarring across various common surgical sites throughout the body. In this prospective randomized controlled trial, 46 patients with benign skin tumors received injections of 1, 2.5, or 5U/0.1mL of BTXA or 0.9% saline immediately following surgical tumor excision on both sides of the incisions. Follow-ups were conducted at 7days, 15days, and 1, 3, and 6months postoperatively. Patient-reported adverse events and standardized digital photographs were collected. Scar formation was assessed using the modified Stony Brook Scar Evaluation Scale (mSBSES). All 46 patients completed the trial without severe complications. The mSBSES scores were higher in the experimental groups at all follow-ups. The 5U/0.1mL BTXA dose group demonstrated optimal scar prevention at all high-risk sites for scar hyperplasia. No significant difference was observed between the 2.5U/0.1mL and 5U/0.1mL doses for intermediate-risk sites, while 1U/0.1mL dose was sufficient for low-risk sites. Overall, 86.5% of patients were satisfied with their treatments, with 16.3% being very satisfied. Early postoperative BTXA injection can reduce or prevent hypertrophic scarring, with optimal doses ranging from 1 to 5U/0.1mL depending on the surgical site, supporting broader clinical application of BTXA. The effectiveness of different concentrations of botulinum toxin type A (BTXA) in preventing postoperative scarring was compared, expanding the scope of previous research, which focused only on the head, face, and neck regions, to include the trunk and extremity areas. Different optimal injection strategies were determined based on different surgical sites and their risks of developing hypertrophic scars. The study demonstrates that BTXA not only reduces scar formation but also enhances patient satisfaction and reduces postoperative itching and pain, contributing to overall better postoperative outcomes. By establishing the efficacy and optimal dosing of BTXA for various surgical sites, this research supports the potential for broader clinical application of BTXA in aesthetic and reconstructive surgeries. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

A comparative study of first and second generation biodiesel blends under quaternary injection strategies for enhanced engine performance and reduced emissions

Biodiesel is a promising renewable alternative fuel, offering compatibility with conventional engines without necessitating significant engine modifications. To facilitate the practical integration of biodiesel into engine systems, this study evaluates the performance of two different biodiesel blends (fatty acid methyl ester and hydrogenated catalytic) in a turbocharged inter-cooled diesel engine. The research employs quaternary injection techniques an advanced injection technique, which involve multiple injection events per cycle to enhance engine combustion and emission characterictics of the biodiesel blend fuels and comparing their performance and emission characteristics with those of conventional diesel. Results showed that fatty acid methyl ester biodiesel effectively reduced the CO, UHC, and NOx emissions at lower blend ratios (up to 10 %), with minimal impact on the brake-specific fuel consumption. Conversely, hydrogenated catalytic biodiesel demonstrates notable advantages in reducing fuel consumption with carbon monoxide and particle emissions, particularly for higher blend ratios (20 %), leading to improved indicated thermal efficiency. Additionally, an investigation on higher biodiesel blends under varying early injection timings showed that, optimal fuel efficiency was observed at an early injection timing of −43.6 °CA, accompanied by reductions in total particle number and unburned hydrocarbon emissions albeit with elevated carbon monoxide and nitrogen oxide emissions. These findings suggest that advanced injection strategies combined with sustainable biodiesel blends can significantly improve engine performance and reduce environmental impact, supporting the transition towards cleaner and more efficient transportation fuels.

A comparative analysis of the performances of a syngas port injection plus gasoline direct injection combined-injection spark-ignition engine under lean-homogeneous charge and Lean-Stratified Charge modes

This study conducts a comparative analysis of the performances of a syngas port injection plus gasoline direct injection combined-injection spark-ignition engine operating in Lean-Homogeneous Charge (LHC) and Lean-Stratified Charge (LSC) modes. Results demonstrate that adjusting direct injection timing achieves LHC with early intake stroke injection and LSC with late compression stroke injection. Regarding mixture charge, increasing excess air ratio (λ) or syngas injection proportion (SIP) in LHC mode improves mixture homogeneity, while a higher SIP in LSC mode enhances mixture distribution for ignition. Concerning combustion characteristics, both modes benefit from lower λ and higher SIP with increased peak cylinder pressure, heat release rate, flame speed, and in-cylinder temperature. A higher λ extends CA0-10 and CA10-90, while a higher SIP shortens these durations. Regarding emissions, a higher λ positively affect HC, CO, and NOx emissions, whereas a higher SIP reduces HC, CO and soot but increases NOx emissions. The comparison between LHC and LSC highlights the superior combustion efficiency of LSC, whereas LHC excels in emission control.

Stimulation of tight basalt reservoirs using supercritical carbon dioxide: Implications for large-scale carbon sequestration

Although supercritical carbon dioxide (SC-CO2) fracturing shows tremendous potential for maximizing injection efficiency and enhancing storage volumes, few investigations have been reported on the SC-CO2 fracturing characteristics of tight basalts and the reactions between fractured basalt and SC-CO2. In this study, hydraulic fracturing experiments were conducted on cylindrical basalt specimens using water and SC-CO2 as fracturing fluids. Geometric parameters were proposed to characterize the fracture morphologies based on the three-dimensional (3D) reconstructions of fracture networks. The rock slices with induced fractures after SC-CO2 fracturing were then processed for fluid (deionized water/SC-CO2)-basalt reaction tests. The experimental results demonstrate that SC-CO2 fracturing can induce complex and tortuous fractures with spatially dispersed morphologies. Other fracturing behaviors accompanying the acoustic emission (AE) signals and pump pressure changes show that the AE activity responds almost simultaneously to variation in the pump pressure. The fractured basalt blocks exposed to both SC-CO2 and water exhibit rough and uneven surfaces, along with decreased intensities in the element peaks, indicating that solubility trapping predominantly occurs during the early injection stage. The above findings provide a laboratory research basis for understanding the fracturing and sequestration issues related to effective CO2 utilization.

Development and experimental validation of a novel twin injector concept for a biogas diesel RCCI engine

A bi-fuel RCCI engine that uses a low reactivity renewable fuel like biogas along with diesel can decrease the NOx emissions and at the same time operate with high efficiency. Generally, diesel is injected in pulses, one very early and the other close to TDC. The early injection if done with conventional wide angle diesel injectors leads to wall wetting resulting in high THC, CO and adversely affects the efficiency. In this work a combination of injectors, one with a narrow angle between the sprays and the other with a wide angle between the sprays (NW Injectors) was evaluated for early and near TDC injections respectively in a biogas diesel RCCI engine. Simulations with a validated CFD model were used to determine the suitable injection parameters including the orientation of the spray holes, number of holes of the Narrow angle Injector (NI), fuel split ratio between narrow and wide injectors, injection timing and injection pressure. The studies indicated that the NI sprays have to hit the periphery of the piston bowl for good mixture preparation. The 3-hole NI configuration with the sprays aimed at the periphery of the piston bowl resulted in minimum fuel deposition, highest efficiency, and lowest soot and HC emissions. The NI was subsequently manufactured, installed on the engine and experiments were conducted in the biogas diesel NW RCCI mode for determining the performance and emissions and for comparing the same with the single Wide angle Injector RCCI (WI RCCI) mode in order to bring out its potential.

Effect of injection timings and injection pressure on knock mitigation with a compression stroke injection of hydrous ethanol in spark ignition

Direct injection fuel systems provide precise control over the amount of fuel injected and can enable higher compression ratio operation and earlier combustion phasing under knock-limited operation, particularly for fuels with a high cooling potential like hydrous ethanol, a blend of 92% ethanol and 8% water. Moving a portion of the total fuel mass from an intake stroke injection to a compression stroke injection can provide a knock suppression benefit, which can enable more efficient operation. In this work, the influence of injection pressure on this split injection spark ignition strategy is examined. The effect of injection pressure on two intake stroke injections were characterized, with an injection pressure of 200 bar improving combustion efficiency by ∼3 percentage points and advancing knock-limited CA50 by 1 crank angle degree over an injection pressure of 30 bar. Then, a compression stroke injection was introduced and swept into the compression stroke while maintaining the two intake stroke injections. Direct injections at an injection pressure of 30 bar enabled a small knock intensity reduction of ∼20%, whereas an injection pressure of 200 bar enabled a larger reduction of ∼90% in knock intensity. The spark timing advance permitted by the reduction in knock intensity with a compression stroke injection timing of −80 degrees after top dead center was 0.3 and 2.0 degrees at an injection pressure of 30 and 200 bar, respectively. Then, the second intake stroke injection was varied at 200 bar to evaluate how the stratification profile prior to the compression stroke injection impacted its ability to reduce knock intensity. It was found that compression stroke injections with an early second intake stroke injection was effective at reducing knock intensity throughout the compression stroke. As the second intake stroke injection was retarded, the early compression stroke injections became less effective at suppressing knock.

Research on Gas Injection Limits and Development Methods of CH4/CO2 Synergistic Displacement in Offshore Fractured Condensate Gas Reservoirs

Gas injection for enhanced oil and gas reservoir recovery is a crucial method in offshore Carbon Capture, Utilization, and Storage (CCUS). The B6 buried hill condensate gas reservoir, characterized by high CO2 content, a deficit in natural energy, developed fractures and low-pressure differentials between formation and saturation pressures, requires supplementary formation energy to mitigate retrograde condensation near the wellbore area through gas injection. However, due to the connected fractures, the B6 gas reservoir exhibits strong horizontal and vertical heterogeneity, resulting in severe gas channeling and a futile cycle, which affects the gas injection efficiency at various levels of fracture development. Based on these findings, we conducted gas injection experiments and numerical simulations on fractured cores. A characterization method for oil and gas relative permeability considering dissolution was established. Additionally, the gas injection development boundary for this type of condensate gas reservoir was quantified according to the degree of fracture development, and the gas injection mode of the B6 reservoir was optimized. Research indicates that the presence of fractures leads to the formation of a dominant gas channel; the greater the permeability difference, the poorer the gas injection effect. The permeability gradation (fracture permeability divided by matrix permeability) in the gas injection area should be no higher than 15; gas injection in wells A1 and A2 is likely to achieve a better development effect under the existing well pattern. Moreover, early gas injection timing and pulse gas injection prove beneficial in enhancing the recovery rate of condensate oil. The study offers significant guidance for the development of similar gas reservoirs and for reservoirs with weakly connected fractures; advancing the timing of gas injection can mitigate the retrograde condensation phenomenon, whereas initiating gas injection after depletion may reduce the impact of gas channeling for reservoirs with strongly connected fractures.

Chemical reaction network analysis on N2O emissions control strategies of ammonia/ methanol Co-combustion

As a kind of substitute fuel of hydrocarbon fuel, ammonia has gained increasing attention for its potential to reduce carbon emissions. Blending with carbon-neutral methanol is expected to deal with the slow flame speed of ammonia. Nevertheless, the emission of N2O, a byproduct of ammonia combustion, would undermine the carbon reduction benefits due to its high global warming potential. This study employed Chemkin to construct a Chemical Reaction Network (CRN) model to analyze the reaction kinetics of ammonia combustion when blended with a small amount of methanol. It finds that the increases in the methanol blending ratio, pressure, and temperature can reduce greenhouse gas emissions effectively. Further analysis indicates that pressure and temperature have distinct effects on the emission mechanisms of N2O and NO. Increasing the combustion pressure weakens the chain reactions, thereby reducing the formation of both NO and N2O; the increase in initial temperature raises NO emissions, but also promotes the decomposition of N2O due to the abundance of H in the post-combustion phase. Optimizing post-combustion efficiency and controlling the formation of NO are crucial for N2O emission control. Thus, a staged methanol injection strategy is proposed, where early injection reduces NO emissions and late injection facilitates the decomposition of N2O.

Effectiveness of the use of early secondary sutures and injections of platelet-rich autoplasma in isolated gunshot shrapnel wounds of soft tissues

Effectiveness of the use of early secondary sutures and injections of platelet-rich autoplasma in isolated gunshot shrapnel wounds of soft tissues

Realisation of Low Temperature Combustion in an Unmodified Diesel Engine

Heavy-duty diesel engines are an essential part of road transportation. Since viable alternatives are not expected in the short and medium term, the problematic emission characteristics of compression ignition engines have to be addressed. Low temperature combustion (LTC) is an alternative combustion method for compression ignition engines that allows low particulate matter and nitrogen oxide emissions while improving efficiency. To overcome the difficulties of market introduction, the realization of such alternative combustion methods should come with marginal engine modifications. Thus, this work investigates the possible realization of LTC in an unmodified diesel engine. LTC methods with and without injection strategy modifications were also studied to provide sufficient recommendations for other researchers. It was concluded that techniques requiring early direct injection, such as homogeneous charge compression ignition (HCCI) require a narrow cone angle injector to reduce wall impingement. It was also concluded that modulated kinetics (MK) type LTC can be easily achieved by applying a conventional injection strategy and high amounts of cooled exhaust gas recirculation. The realized MK combustion resulted in an enhanced NOx-PM trade-off and a lower peak pressure rise rate compared to normal operation.

Plasmoid drift and first wall heat deposition during ITER H-mode dual-SPIs in JOREK simulations

The heat flux mitigation during the thermal quench (TQ) by the shattered pellet injection (SPI) is one of the major elements of disruption mitigation strategy for ITER. It’s efficiency greatly depends on the SPI and the target plasma parameters, and is ultimately characterised by the heat deposition on to the plasma facing components. To investigate such heat deposition, JOREK simulations of neon-mixed dual-SPIs into ITER baseline H-mode and a ‘degraded H-mode’ with and without good injector synchronization are performed with focus on the first wall heat flux and its energy impact. It is found that low neon fraction SPIs into the baseline H-mode plasmas exhibit strong major radial plasmoid drift as the fragments arrive at the pedestal, accompanied by edge stochasticity. Significant density expulsion and outgoing heat flux occurs as a result, reducing the mitigation efficiency. Such drift motion could be mitigated by injecting higher neon fraction pellets, or by considering the pre-disruption confinement degradation, thus improving the radiation fraction. The radiation heat flux is found to peak in the vicinity of the fragment injection location in the early injection phase, while it relaxes later on due to parallel impurity transport. The overall radiation asymmetry could be significantly mitigated by good synchronization. Time integration of the local heat flux is carried out to provide its energy impact for wall heat damage assessment. For the baseline H-mode case with full pellet injection, melting of the stainless steel armour of the diagnostic port could occur near the injection port, which is acceptable, without any melting of the first wall tungsten tiles. For the degraded H-mode cases with quarter-pellet SPIs, which have 1/4 total volume of a full pellet, the maximum energy impact approaches the tolerable limit of the stainless steel with un-synchronized SPIs, and stays well below such limit for the perfectly synchronized ones.