Effects Of Injection Strategies Research Articles

The Effect of Injection Strategy on the Mixture Formation and Combustion in a Direct Injection Hydrogen Engine

The Effect of Injection Strategy on the Mixture Formation and Combustion in a Direct Injection Hydrogen Engine

A numerical model for evaluating the long-term migration and phase transition behavior of foam-assisted injection of CO2 in saline aquifers

Geological Carbon Storage (GCS) is a rapidly developing technology with the potential to mitigate the environmental impact of excessive greenhouse gas emissions. Foam-assisted injection of CO2 can effectively alter fluid rheological properties, thereby enhancing sweep efficiency. In this paper, a numerical model to evaluate the long-term migration behavior of foam-assisted injected CO2 in saline aquifers is developed. It is found that foam-assisted injection improves storage efficiency and reduces the plume migration distance compared to direct CO2 injection. This creates higher demands on the injection pressure but minimizes the risk of leakage. The effects of injection strategy, volume fraction of foam, and reservoir heterogeneity were investigated. Modeling results show that the injection strategy with a high foam volume fraction enhances the sweep efficiency and improves the transition rate of injected CO2 to the dissolved state. This can effectively enhance the long-term security of the sequestration. Simulations of layered formations indicates that foams can potentially inhibit the rapid migration of plumes along high-permeability zones. Our study provides insights for foam-assisted injection to enhance reservoir storage efficiency and long-term safety for GCS.

Numerical study on the effect of injection strategy on combustion and NO emission from different sources in a diesel/ammonia RCCI engine

Diesel/ammonia operation is one of the ways to efficiently utilize ammonia and reduce carbon emissions, however, the increase in fuel NO introduces serious emission problems. To explore the mechanisms of fuel NO and oxidant source NO generation, a multi-component diesel/ammonia chemical reaction mechanism was constructed in this study, and based on 3D CFD simulation and N-element tracking method, the combustion and different source NO emission characteristics of diesel/ammonia reactivity controlled compression ignition (RCCI) engine at low loads were investigated by pilot injection timing (SOI1) and pilot injection ratio (PIR). In addition, the effect of different first injection spray angle (SA1) and double injection spray angle (SAtotal) on the engine operation was investigated. The results showed that high PIR and delayed SOI1 enhanced the engine IMEP but led to high PRRmax. At a PIR of 15%, total NO emissions increased as SOI1 advanced, and the trend was reversed when the PIR was higher than 15%. Fuel NO was produced earlier than the oxidant source N*O. In terms of 1 spatial distribution, high concentrations of both NO and N*O were distributed in and around the secondary diesel fuel ignition location, and fuel NO began to be reduced where the oxidant source N*O was rapidly formed. The reduction mechanism of NO in the cylinder was a multi-path reduction mechanism incorporating Thermal DeNOx, NO Reburning, and inverse reaction pathways for NO formation from the oxidant source. Appropriate reduction of the SAtotal can significantly reduce the total NO emission while maintaining no significant reduction in IMEP. When SAtotal was 82°, the total NO emission was only 16.3% of the original spray angle and PRRmax was further reduced. After optimization, when a narrow SAtotal of 82°, SOI1 of -15° CA, and PIR of 35% were used, the IMEP of the engine increased by 5.9%, and the total NO emission was reduced by 86%, while PRRmax did not exceed the PRR upper limit.

Effectiveness of Injection Strategies on Patients With Patellar Tendonitis (Jumpers' Knee): A Network Meta-analysis of Randomized Controlled Trials.

Patellar tendonitis (PT) is a common degenerative disease of the patellar tendon that seriously affects the sports careers of elite athletes and activities of daily living of sports enthusiasts. Injection therapy is a prevalent invasive treatment for PT. This work comprehensively analyzes various injection treatments for PT that consider agent type and characteristics, frequency, and assessment timepoints by meta-analysis. PubMed, Embase, and the Cochrane Library were sources of data. Randomized controlled trials (RCTs) analyzing the effect of various injection strategies on the treatment of patients with PT were considered. Systematic review and meta-analysis. Level 2. First author, year of publication, research location, registration information, patient type, sample size, age, sex, intervention, control treatment, and follow-up period in each study were extracted. Nineteen RCTs were included in the analysis. In the network meta-analysis of Victorian Institute of Sports Assessment-Patellar (VISA-P) outcomes, polidocanol (standardized mean difference (SMD), 6.52; 95% CI 4.75, 8.30; P < 0.01), tenocyte-like cells (SMD, 4.08; 95% CI 2.92, 5.25; P < 0.01), and leukocyte-poor platelet-rich plasma (LP-PRP) plus high-volume image-guided injection (HVIGI) (SMD, 1.56; 95% CI 0.62, 2.50; P < 0.01) were significantly superior to noninjection conservative treatment, mainly at the 6-month follow-up timepoint. For visual analog scale results, multiple dry needling (DN) (SMD, -1.78; 95% CI -2.56, -1.00; P < 0.01), LP-PRP (SMD, -0.71; 95% CI -1.31, -0.12; P = 0.02), and LP-PRP plus HVIGI (SMD, -1.31; 95% CI -2.22, -0.39; P < 0.01) were significantly superior to blank, which was also mainly at the 6-month timepoint. Injection-related treatments: polidocanol, tenocyte-like cells, LP-PRP, and multiple DN showed potential short (1-3 months) or medium (6 months)-term treatment benefits. There is still no evidence for injection interventions with long-term therapeutic benefit.

Effect of injection strategy on the hydrogen mixture distribution and combustion of the hydrogen-fueled engine with passive pre-chamber ignition under lean burn condition

Turbulent jet ignition (TJI) effectively achieves lean and stable combustion in hydrogen engines. However, research on injection strategies for TJI hydrogen engines is still lacking. In this study, experimental methods investigated the effects of single and split injection strategies on the combustion and emissions of TJI hydrogen engines under medium loads. The numerical simulation reveals the operational characteristics of fuel distribution, ignition capability, and energy conversion in the pre-chamber at different injection times in a single injection strategy. This work is conducted at 1600 rpm with a manifold absolute pressure of 70 kPa. The experimental results indicate that the delay of the start of injection (SOI) can enhance the performance of the TJI hydrogen engine. However, as SOI approaches TDC, emissions worsen, and combustion stability decreases. When SOI is 90°CA BTDC, the brake mean effective pressure (BMEP) and brake thermal efficiency (BTE) can achieve 3.1 bar and 32.9 %, with the coefficient of variation of the IMEP (COVIMEP) of 1.6 % and lower emissions. For the split injection strategy, delaying the secondary end of injection (SEOI) can increase BMEP and BTE. As SEOI gradually delays the TDC, emissions deteriorate sharply. Under the split injection strategy, COVIMEP is higher, which is unfavorable for hydrogen engine applications.

Study on the effect of injection strategy on the combustion and emission characteristics of direct injection spark ignition bio-butanol engine

Owing to its physicochemical similarities with gasoline and renewable nature, n-butanol (bio-butanol) has garnered significant researcher interest. However, the lower atomization and volatility of n-butanol pose challenges when implemented in direct-injection spark-ignition (DISI) engines, leading to inhomogeneous air-fuel mixtures which subsequently results in a deterioration of combustion performance and an uptick in pollutant emissions. This study uses numerical simulations to examine the effects of injection pressure and timing on mixture formation, combustion, and emission characteristics in n-butanol DISI engines. The results indicate that for n-butanol, characterized by its reduced volatility and atomization capabilities, enhancing injection pressure from 10 MPa to 20 MPa effectively improves combustion and emission performance. However, the benefits taper off with subsequent increases in pressure. At injection pressure of 20 MPa, optimizing injection timing offers better combustion and emission results than merely increasing injection pressure. An early injection, represented by −300°CA start of injection, provides extended evaporation and mixture diffusion, significantly improving mixture quality and resulting in better combustion and emission outcomes. At −260°CA start of injection, while peak in-cylinder pressures can be achieved more favorably, the resultant inhomogeneous in mixture distribution results in increased emissions of CO, soot, and HC.

Combustion of liquid ammonia and diesel in a compression ignition engine operated in high-pressure dual fuel mode

This study investigates the characteristics of a compression ignition engine fuelled by ammonia and diesel in high-pressure dual fuel mode. The study focuses on the effect of injection strategies on engine performance and important emissions like NH3, NO/NO2 and N2O. The engine was operated with fixed intake air conditions and at an engine speed of 1500 rpm for all operating points, and liquid ammonia was directly injected at 180 bar using a GDI injector. The ammonia energy shares tested were 40 %, 50 % and 60 %. Various combustion modes were achieved by fixing the diesel injection timing at −15 CAD aTDC and varying the ammonia injection timing between -80 and 2.5 CAD aTDC. Injecting ammonia early (-80/-60 CAD aTDC) led to premixed-type combustion with very high ammonia slip (65 %). Delaying the ammonia injection to -30 CAD aTDC, i.e. 15 CAD before the diesel injection, yielded a very long ignition delay due to the strong influence of the ammonia injection on the diesel injection, resulting in premixed combustion of ammonia and diesel. Injecting ammonia simultaneously or after diesel did not affect the diesel ignition, yielding stable combustion where the ammonia burned during the mixing-controlled phase. Temporally overlapping injections of ammonia and diesel resulted in the highest combustion efficiency, lowest ammonia slip, highest NOx emissions, and lowest N2O emissions, i.e., the optimal cases found. For temporally overlapping ammonia and diesel injections, extending the ammonia injection to after the end of diesel injection was found to increase ammonia slip compared to injecting ammonia before diesel, due to the limited time for liquid ammonia to vaporise, mix and combust in the expansion stroke. The NOx and N2O emissions were found to have opposite trends, where the highest NOx and lowest N2O concentrations were achieved for the operating points with the highest combustion efficiency. Delaying the combustion phasing improved the combustion efficiency for the 40 % and 50 % ammonia energy share cases, while for the 60 % cases, it deteriorated, which can be explained by the injection of ammonia after the end of diesel injection for the 60 % ammonia energy share cases.

Experimental study on the effect of injection strategies on the combustion and emissions characteristic of gasoline/methanol dual-fuel turbocharged engine under high load

This study aims to investigate the impact of methanol direct injection strategy on the combustion and emission characteristics of a dual-fuel turbocharged engine running under high load of 1500 rpm. Five methanol injection timings ranging from −330° CA (crank angle) to −60° CA ATDC (after top dead center) were tested under four different methanol energy substation ratios. Based on the experimental results, a suitable injection timing was selected to study the effect of methanol energy substation ratio. The results showed that different injection timings had varying effects on engine combustion and emission characteristics. End of injection timing of methanol (EOI) at −180° CA ATDC resulted in fuller atomization of methanol, which delayed combustion and reduced the combustion rate, with the lowest knock intensity and highest indicated mean effective pressure. However, this timing also had the highest emissions of NOx. Further experiments were conducted at EOI = −180° CA ATDC under eight different energy substation ratios. The results demonstrated that adjusting the injection strategy of methanol can effectively change the engine's performance. The optimal injection strategy was found to be EOI = −180° CA ATDC and an energy substation ratio range of 4.6%–8.9%. This research provides valuable insights into the use of methanol as a fuel and its impact on engine characteristics.

Effect of injection strategy on an air-assisted direct injection aviation kerosene two-stroke engine

In small aviation piston engines, the atomization and combustion of aviation kerosene have attracted much attention. Due to the low volatility and high viscosity of aviation kerosene, high-pressure injection or air-assisted injection is used to improve the fuel atomization quality. Considering the weight, cost and power consumption, air-assisted injection is more appropriate for compact, small aviation piston engines. In the paper, computational fluid dynamics (CFD) software was used to simulate the air-assisted spray and spark ignition combustion of aviation kerosene in a heavy-fuel direct injection spark ignition (DISI) two-stroke engine based on air-assisted direct injection (AADI) technology. The effects of injection pressure, single and double injection on formation and combustion characteristics of the aviation kerosene/air mixture were analyzed. The results show that increasing the air-assisted injection pressure can promote air flow in the cylinder and accelerate fuel evaporation, but also increase the film mass on the combustion chamber wall. When single injection is employed, high combustion pressure and temperature are generated, and the tendency to knocking combustion is greater. The use of double injection can effectively achieve fuel stratification and reduce knock tendency. With the delay of the second mixture injection timing, the peak combustion pressure is reduced, the heat release rate is slowed down, and the knock tendency is reduced correspondingly.

Experimental study of thermal efficiency and NOx emission of turbocharged direct injection hydrogen engine based on a high injection pressure

The direct injection (DI) hydrogen-fueled internal combustion engine (H2-ICE), as a promising carbon-neutral power device, has attracted more and more attention. However, the effects of the hydrogen injection strategy on the performance of H2-ICE lack in-depth analysis, even under the high injection pressure. Therefore, the present work investigated the thermal efficiency and NOx emissions with a single-hole injector over a wide range of high injection pressure and injection timing in a 3-cylinder turbocharged DI H2-ICE. The results show the strong dependence of high thermal efficiency on turbocharging and lean-burn strategies. The late-injection strategy can achieve higher thermal efficiency than the early-injection strategy, which can be applied at a wide range of loads. The effect of injection strategy on the brake thermal efficiency (BTE) mainly depends on the wall heat loss. Hydrogen late injection can reduce the wall heat loss by about 2% through strong mixture stratification. Furthermore, hydrogen late injection is always accompanied by a sharp increase in NOx emissions, even by orders of magnitude. This trade-off relationship between thermal efficiency and NOx emissions can be well optimized by a moderate late-injection strategy with an end-of-injection (EOI) of about 40 °CA. At the given load and start of injection (SOI), increasing the injection pressure from 5 MPa to 15 MPa can reduce the hydrogen injection duration by about 3 times. Under the higher injection pressure, the BTE performs a strong sensitivity to SOI. The BTE is improved by about 0.5% by optimizing SOI at PInj = 5 MPa mainly due to the reduced compression loss caused by further delay to the SOI allowed by higher injection pressure, while this improvement increases to about 2.3% at PInj = 15 MPa. However, at a given SOI, the highest BTE at PInj = 5 MPa is nearly 1.5% higher than that at PInj = 15 MPa, which implies the potential of low-pressure injection coupled with large-flow injectors. Finally, the DI H2-ICE performs well in terms of efficiency with a maximum BTE of 44.08%.

Effects of Injection Strategies on Mixture Formation and Combustion in a Spark-Ignition Engine Fueled with Syngas-Biogas-Hydrogen

The paper presents the effects of blend injection and dual injection strategies on mixture formation and combustion of syngas-biogas-hydrogen fueling engine working in the solar-biomass hybrid renewable energy system. The research was performed by simulation method on a retrofitted Honda GX200 spark-ignition engine. The results show that at the end of the compression process, in the case of blend injection of 50% syngas-50% biogas, the fuel-rich zone was positioned on the top of the combustion chamber, whereas in the case of dual injection, this zone was found on the top of the piston. In the case of 50% syngas-50% hydrogen supplied, at the end of the compression process, the fuel-rich area observed on the top of the piston with slightly deflected towards the inlet port in both cases of blend and dual injection. When shifting from blend injection mode to dual injection mode, in the case of 50% syngas-50% biogas fueling engine, the mean temperature of the exhaust gas decreased from 1208 K to 1161 K and the NOx concentration decreased from 1919 ppm to 1288 ppm. In the case of a 50% syngas-50% hydrogen fueling engine, the mean exhaust gas temperature decreases from 1283 K to 1187 K leading to a decrease in NOx concentration from 3268 ppm to 2231 ppm. The dual injection has the advantage of lower NOx emission, whereas the blend injection has the advantage of higher efficiency

Effects of Injection Strategy on the Nano-Particle Emission Characteristics of a Direct Injection Diesel Engine

Effects of Injection Strategy on the Nano-Particle Emission Characteristics of a Direct Injection Diesel Engine

A numerical study on fuel film and emissions formations during cold start in a diesel engine using an improved spray-wall impingement model

Understanding the physical process such as fuel film formation during cold start is essential to reduce engine emissions. In this study, an improved spray-wall impingement model was applied to the cold-start simulation of a diesel engine. The fuel film and emissions formations during cold start were studied in depth. The effects of injection strategies were investigated by the use of various designed injection schemes. The results showed that a certain amount of fuel film is deposited on the wall surface due to the poor spray evaporation caused by the adverse thermal atmosphere in the cylinder. The low combustion temperature, insufficient oxygen, and the deposited fuel film are the primary causes for high HC, CO and soot emissions. The NOx emissions are relatively low because of low combustion temperature and oxygen content. A double injection strategy can reduce the deposited and remaining fuel film by 13% due to improved mixing, which benefits the reduction of HC and CO emissions, while it has a negligible effect on NOx and soot emissions. The percentage of first injected fuel has little impact on the amount of the remaining fuel film and emissions in the studied range. Increasing engine speed can inhibit the formations of fuel film, HC, CO, and soot emissions, which is due to the improved fuel evaporation, better flow motion, and thermal environment in the cylinder. Double injection allows a smaller amount of injected fuel to obtain a stable ignition. Decreasing the injected fuel mass can suppress the formation of fuel film and improve mixing, thus reducing HC, CO, and soot emissions. This work expands the application scenarios of the newly developed spray-wall impingement model. The new model has been successfully applied to investigate the cold start process of diesel engines in detail. The results provide insights into the fuel film formation and its effect on emissions, which can guide the development of a cold-start emission control strategy.

Effects of injection strategies on thermal performance of a novel micro planar combustor fueled by hydrogen

As a high and uniform wall temperature is desired for thermophotovoltaic applications, a novel micro planar combustor with multi inlets and outlets is designed in this work. Effects of injection strategies on thermal performance of the novel micro planar combustor fueled by hydrogen are analyzed and discussed. It is found that there are two straight flames under Injection Strategy A (Coflow mode), while there are two curved flames under Injection Strategy B and C (Counterflow mode), which is negative to the flame stabilization. In addition, the flame interactions under Injection Strategy B and C are much stronger than that under Injection Strategy A which benefits flame stabilization. Moreover, favorable and unfavorable effects of flame interactions under Injection Strategy B and C on flame stabilization are analyzed. Furthermore, the effects of inlet velocity, hydrogen/air equivalence ratio and solid wall materials on the thermal performance of the micro planar combustor are numerically examined under different injection strategies, the application conditions of the injection strategies are determined. This work will provide us significant suggestions for micro-thermophotovoltaic applications. • A micro planar combustor with multi inlets and outlets is developed. • Effects of injection strategies on thermal performance are analyzed and discussed. • Favorable and unfavorable effects of flame interactions on flame stabilization are analyzed. • The application conditions of the optimal injection strategy are proposed.

Foam-Assisted Sagd Investigation: Effects of Injection Strategy and Reservoir Heterogeneity

Foam-Assisted Sagd Investigation: Effects of Injection Strategy and Reservoir Heterogeneity

Foam-Assisted Sagd Investigation: Effects of Injection Strategy and Reservoir Heterogeneity

Foam-Assisted Sagd Investigation: Effects of Injection Strategy and Reservoir Heterogeneity

Effects of injection strategy on the knocking behavior of a pilot ignited direct injection natural gas engine

Pilot ignited direct injection natural gas engines have become a research focus due to the high thermal efficiency and low emissions. However, when stratified combustion mode is adopted, more attention should be paid to the knocking behavior. In this paper, the effects of injection strategy on the knocking behavior of a pilot ignited direct injection natural gas engine have been studied. The results indicated that the knocking intensity will be increased at advanced natural gas injection timing, delayed diesel injection timing and raised injection pressure. The three major resonance modes that dominate the pressure oscillations are the first circumferential mode, the third circumferential mode and the first radial mode. Advancing natural gas injection has negative effects on cyclic variations of indicated mean effective pressure while have negligible effects on the cyclic variations of combustion duration. After correlation analysis of parameters, it was found that knocking behavior is highly correlated with maximum heat release rate, combustion duration and maximum combustion pressure, whereas has weak correlations with combustion phasing and cyclic variations.

Effect of injection strategy on the mixture formation and combustion process in a gasoline direct injection rotary engine

A computational fluid dynamics model was established and validated to numerically investigate the effects of different injection positions and injection angles on the mixture formation and combustion process in a gasoline direct injection rotary engine. The results show that as the injection position approaches the top dead center and the increasing injection angle, the rich zone of fuel changes from the rear to the front of the combustion chamber. The local equivalence ratio near the two spark plugs shows an increasing trend with the injection position upward and the increasing injection angle. Compared with the lower and middle injection positions, the upper injection positions can make fuel more concentrated near the leading spark plug and the trailing spark plug at ignition timing. The injection strategies corresponding to the upper injection position are conducive to complete combustion, in which the mass fraction of fuel burned all beyond 99%. Besides, with the increasing injection angle, the oil film formation position changes from the rotor recess to the middle cylinder block, which further affects the mixture formation and combustion process. Especially, the highest peak pressure is obtained at 0° injection angle corresponding to the upper injection position and is 12.39% higher than the in-cylinder peak pressure of intake port injection.

Effect of injection strategy on a diesel/methanol dual-fuel direct-injection engine

Methanol direct-injection achieves direct injection of diesel and methanol in the cylinder by using two independent fuel injection systems. This yields an extremely high methanol substitution rate and extremely low pollutant emissions. Due to these advantages, three injection strategies are proposed to investigate this injection method: D/M mode and M/D mode are where methanol injection occurs later and earlier than diesel injection respectively while M/D/M mode is where methanol is injected once before and once after the diesel injection. In this paper, these strategies are investigated, and the optimal settings of each are obtained and compared at low load and high load. The results show that in D/M mode, fuel economy is optimized and knock intensity increases with advancement of fuel injection and decreased injection dwell. This mode also effectively prevents knock but is not conducive to fuel economy. The most suitable methanol injection timings are obtained in M/D mode, namely 20°CA before the top dead center (BTDC) at low load and 30°CA BTDC at high load. Moreover, at low load the higher the first methanol injection ratio is, the better the fuel economy becomes, while at high load continued increases in the first ratio are limited by knock. Ultimately, M/D/M mode is found to be the best injection strategy at low load and high load.

On the Effects of Injection Strategy, Exhaust Gas Recirculation, and Intake Boost on TSCI With Wet Ethanol

Abstract Using a split injection of wet ethanol, where a portion of the fuel is injected during the compression stroke, has been shown to be an effective way to enable thermally stratified compression ignition (TSCI), an advanced combustion mode that aims to control the heat release process by enhancing thermal stratification, thereby extending the load range of low temperature combustion (LTC). Wet ethanol is the ideal fuel candidate to enable TSCI because it has a high latent heat of vaporization and low equivalence ratio sensitivity. Previous work has shown “early” compression stroke injections (−150 to −100 deg aTDC) have the potential to control the start of combustion (SOC) while “mid” compression stroke injections (−90 to −30 deg aTDC) have the potential to control in-cylinder thermal stratification, thereby controlling the heat release rate. In this work, a mixture of 80% ethanol and 20% water by mass is used to further study the injection strategy of TSCI combustion. Additionally, the impact of external, cooled exhaust gas recirculation (EGR), and intake boost on the effectiveness of a TSCI with wet ethanol to control the heat release process are investigated. It was found that neither external, cooled EGR, nor intake boost level has any impact on the effectiveness of the compression stroke injection(s) at controlling the burn rate of TSCI. External, cooled EGR has the potential to increase the overall tailpipe combustion efficiency, while intake boost has the potential to decrease NOx emissions at the expense of combustion efficiency by lowering the global equivalence ratio.