Port Injection Research Articles

Combustion analysis of methane-hydrogen port injection combined with [formula omitted] spray injection in an RCCI engine

Compressed Natural Gas (CNG) is recognized as an environmentally friendly alternative vehicle fuel, but it has a low flame speed. Combining hydrogen with CNG to create ‘hydrogen compressed natural gas’ (HCNG) allows for faster and leaner combustion. Additionally, OME2−4 with varying cetane numbers, from 63 for OME2 to 90 for OME4, serves as a highly reactive fuel suitable for use in a dual fuel strategy known as RCCI (reactivity-controlled compression ignition). This project investigates the impact of adding OME2−4 to HCNG, focusing on pressure, temperature, and emissions. Results indicate that lengthening the OME chain advances the peak heat release rate but delays the second combustion phase. In diesel+HCNG, the first-phase combustion is 2 °CA shorter than OME2+HCNG, resulting in a 6.5% higher peak pressure than OME2+HCNG and a 20% increase over basic diesel. Lengthening the OME chain from OME2 to OME4 raises the peak pressure by about 6.2%. The addition of gaseous fuels, especially hydrogen, increases peak temperature by 16%. OME4+HCNG has a similar peak temperature to OME3+HCNG, while OME2+HCNG is about 1.5% lower than OME4+HCNG.

Effects of hydrogen peroxide on the combustion and emissions of an ethanol/gasoline combined injection engine under different excess air ratios

Hydrogen peroxide (H2O2) can prompt hydroxyl radicals and chain reactions in the combustion process. Compared with the research on compression ignition engines, the effects of H2O2 were less studied in spark ignition (SI) engines. In this paper, 30 % laboratory-grade H2O2 (H2O2-30 %) was utilized to obtain the H2O2-ethanol blend, which was applied to a direct injection system in a combined injection SI engine. Gasoline was used for the port injection system. The effects of H2O2-30 % ratio (H2O2r) = 0 %, 5 %, 10 %, 15 % and 20 % on combustion and emission performance of an ethanol/gasoline engine were explored at three excess air ratios (λ = 0.9, 1 and 1.2). Engine operating condition was set at engine speed = 1500 rpm and intake manifold pressure = 49.5 kPa. The results showed that H2O2-30 % could reduce the Tmax and Pmax, and extend CA0-10, CA50 and CA10-90. The inhibition effects of water on combustion performance can be alleviated due to the hyperactive H2O2 at the H2O2r > 5 %. Optimal H2O2r increased engine IMEP by 0.14 bar, 0.11 bar and 0.05 bar, and reduced BSHC and BSCO by 30.5 %, 36.6 %, 31.6 % and 17.9 %, 32.1 % and 40.8 %, respectively. BSNOx were reduced by an average of 38.0 %, 28.8 % and 42.2 % at λ = 0.9, 1 and 1.2, respectively.

Effects of hydrogen blending ratio on combustion and emission characteristics of an ammonia/hydrogen compound injection engine under different excess air coefficients

Currently, hydrogen and ammonia are the best green, zero-carbon energies worldwide. Applying ammonia and hydrogen to internal combustion engines is a top priority for achieving the dual-carbon goal for the automotive industry. However, both ammonia and hydrogen have disadvantages that make them unsuitable for use as fuels on their own. Hydrogen internal combustion engines can suffer from abnormal burning, such as premature ignition, backfiring, and detonation. At the same time, the difficulty of hydrogen storage, transportation, and refilling can also lead to the problem of high cost of use. Ammonia suffers from high ignition energy, poor flame-spreading speed, and inadequate burning stabilization. When used alone, it causes incomplete combustion of large amounts of ammonia. Therefore, our group uses the spray pattern of “hydrogen direct injection (HDI) plus ammonia port injection (API). ” The influence of hydrogen blending ratio (HBR) on the combustion and emission characteristics of an ammonia/hydrogen compound injection engine with various excess air coefficients (λ) is investigated. The blending ratios of hydrogen are 6.1 %, 16.8 %, 27.3 %, 37.7 %, 47.8 %, and 57.7 %, respectively. The experimental data suggests that the indicated mean effective pressure (IMEP) shows an incremental trend as the hydrogen blending ratio grows. Not only CA0-10 but also CA10-90 have been reduced. The whole combustion process is shortened. The temperature and pressure rise. When the ratio of hydrogen blending is higher than 27.3 %, the enhancement of the burning characteristics by hydrogen is not apparent. NOX emissions rise with the ratio of hydrogen blending. NH3 emissions tend to drop as the blending ratio of hydrogen rises. Combining the emission and combustion characteristics, the general engine performance is better when the λ is 1.2 and the ratio of hydrogen blending is 27.3 %.

Effect of direct injection of small amounts of ethanol on port-injected hydrogen internal combustion engines

Hydrogen is a renewable fuel with excellent combustion characteristics. However, the direct use of hydrogen in existing engines faces obstacles such as abnormal combustion and high NOx emissions. This study proposes a strategy for controlling the combustion and emissions performance of a port-injection (PI) hydrogen internal combustion engine using ethanol direct injection (DI). The test conditions are 1000 rpm, 1500 rpm, and 2000 rpm respectively, the excess air coefficient is 1, 1.5, and 2, and 3%, 6%, and 9% ethanol is added. The results showed that the addition of ethanol can significantly reduce the pressure rise rate of the hydrogen engine and prolong CA0-10 and CA10-90. The addition of ethanol can promote the BMEP and BTE of the hydrogen engine. The addition of ethanol can reduce NOx emissions under lean burn conditions by 18%. The disadvantage is that the addition of ethanol increases the hydrocarbon emissions of hydrogen engines by about 50%, but the total amount is less. After the addition of ethanol, the flashback phenomenon of the hydrogen engine was significantly improved.

Injection strategy of methanol for high loads and low NOx emissions in a neat methanol LTC engine

Methanol is a low carbon and clean burning renewable fuel. Though low temperature combustion (LTC) of neat methanol results in almost no smoke with ultra-low NOx, the extremely low cetane number poses challenges. This experimental study demonstrates LTC of neat methanol at full load by combining direct and port injection of this fuel with controlled intake air temperature (IAT). The effects of important variables including IAT and port (premixed) and direct-injected methanol shares on combustion, performance, regulated and unregulated emissions were investigated. The timing of the direct-injected methanol had to be retarded with an increase in the premixed methanol share and IAT in order to limit the pressure rise rate without affecting the ITE. At high IATs, the premixed methanol burned first, followed by the directly injected methanol, at low IATs, these phases merged, resulting in a high rate of heat release. Employing the lowest possible IAT and the highest possible premixed methanol share led to high ITE. Increase in the MDIP to 450 bar was advantageous due to better fuel evaporation and enhanced combustion. Negligible smoke, very low NOx of 2.7 g/kWh, high ITE of 45% and unburned HC and methanol emissions lesser than 3 g/kWh could be achieved.

Ozone-assisted combustion and emission control in RCCI engines: A comprehensive study

This paper presents an investigation into the combustion and emission characteristics of reactivity-controlled compression ignition (RCCI) engines using ozone seeding, which is known as one of the most highly oxidizing chemical species. The study aims to address challenges pertaining to combustion control and emissions deterioration. Therefore, the current work investigates the RCCI mode of operation in a single-cylinder diesel engine with intake air that has been seeded with ozone by introducing conventional diesel fuel as a high-reactivity fuel using a high-pressure direct injection method and iso-octane as a low reactivity fuel using a low-pressure port injection method. In the experimental study, different ozone concentrations up to 300 ppm and three different energy-based premixed ratios of low reactivity fuel from 0% to 45% with a 15% rise rate were examined under various engine loads and constant engine speed. The methodology used in this research provided for simultaneous decreases in unburned hydrocarbon (HC) emissions and smoke opacity for RCCI engines. According to the experimental findings, simultaneous utilization of RCCI mode and ozone seeding led to a decrease of up to 36% in HC emissions and a reduction of up to 98.7% in smoke opacity. Moreover, nitrogen oxides (NOx) emissions were reduced by up to 39.5% at 20% engine load, whereas carbon monoxide (CO) emissions exhibited a decrease of up to 46% at 60% load. The RCCI mode also yields significant reductions in pollutant emissions and notable increases in brake thermal efficiency (BTE) when compared to the conventional diesel mode (CDM). In conclusion, this experimental study presents a promising solution for addressing emissions deterioration in RCCI engines while simultaneously achieving reductions in pollutant emissions.

Flame Characteristics and Abnormal Combustion of Methane Port Injection and Isooctane Direct Injection with Injection Timings Considered

Natural gas (NG) is a low-carbon fuel that can achieve low carbon emissions and high efficiencies. However, the low mean molecular mass and low energy density of methane result in low engine performance, and blending methane with gasoline is an effective way of improving the performance of NG engines. In this study, flame characteristics (including abnormal combustion) and engine performance are optically studied under methane port injection and isooctane direct injection conditions. The results indicate that the addition of isooctane can significantly increase the power output of NG engines. Under partial-load conditions, the minimum ignition advance for best IMEP is delayed with the addition of isooctane because of the higher flame speed of isooctane, and isooctane addition primarily improves the turbulent flame propagation rather than the initial flame formation. As for the isooctane injection timing, the indicated mean effective pressure (IMEP) first increases and then decreases with the delay in isooctane injection. The hot spots in the flame images confirm that late injection results in isooctane inhomogeneity, which reduces the engine’s thermal efficiency. At high loads, the low energy density of methane can lower the knocking intensity, even in the presence of auto-ignition at a speed of 120.7 m/s. The knocking pressure can lead to the ejection of oil droplets, which can increase the flame speed in the subsequent cycle.

Effect of direct methanol injection based on low-flow injector on knock of gasoline engine under heavy load condition

Under appropriate strategies, direct methanol injection can suppress the knock effectively. In this paper, methanol was injected as an anti-knock agent by modified low-flow direct injectors into the cylinder of a high-load port injection gasoline engine. The effects of methanol injection timing and methanol ratio on knock suppression were investigated. The knock intensity (KI), knock probability, and auto-ignition timing were used as the primary basis for quantifying the knock. The results show that methanol injection timing has a significant impact on combustion. Maximum knock suppression can be achieved when methanol is injected near the bottom dead center. The too-early and too-late injections will affect the knock suppression. There was an apparent knock phenomenon when methanol was injected near the end of the compression stroke. When the ratio of methanol is meager, methanol will instead increase the intensity of the knock. As the methanol ratio rises, the knock is gradually and effectively suppressed. There is a specific methanol ratio beyond which higher methanol ratios do not significantly increase the knock suppression effect. When methanol was injected late in the compression stroke, low methanol ratios did not seriously increase the knock intensity, but high methanol ratios did not eliminate the knock either.

Experimental study of triple fuel physiognomies on LDRCCI diesel engine combustion

Environmental deterioration and the current energy crisis are the driving factors for better combustion technologies and renewable, clean energy sources. To improve engine combustion efficiency and reduce emissions, numerous low-temperature combustion techniques have been investigated. Among all low-temperature combustion engines, the reactivity-control compression ignition (RCCI) engine is the most recent and preferred one to reduce PM and NOx emissions to govern the ignition and combustion processes. However, it has not yet revealed the optimal solutions. The port injection is used for the secondary fuel system to manage emissions, in-cylinder charge reactivity, and combustion phasing during RCCI operation. A triple-fuel RCCI engine that burns a port-injected blend and direct-injected diesel fuel has been experimentally investigated in this work. The G5E15-RCCI engine was observed to run at a maximum cylinder pressure and HRR of 90.76 bar, and 63.02J/deg respectively at 3000 rpm while for the baseline fuel they are much lower at 58.69 bar and 11.8J/deg respectively with the speed being 2500 rpm. The NOx and CO2 emissions were at their lowest levels with the engine running on G5E15, whereas they were at their highest for the engine running on baseline mode. Under G5E15-RCCI engine operation, CO and UHC increase as usual while G10E10-RCCI emits a minimum that can be taken as a novel finding in which CO and HC emission reduction was demonstrated with RCCI in this study. The brake power in all experiment cases was observed as approximately the same with slight increases for G10E10 at speeds greater than 2400 rpm. The maximum engine brake torque occurred in the speed range of 2000-2600 rpm for G10E10 and in the narrower range of 2200- 2400 rpm for the G5E15 port-injected blend. Better brake thermal efficiency was noted for the engine running on baseline fuel in the speed range of 2200-2600 rpm while being higher for the engine running on G5E15 RCCI mode at 2800 and 3000 rpm as such.

Multi-objective optimization of a compression ignition engine using on-board methanol reforming

The dual-fuel combustion technology utilizing hydrogen and diesel fuel shows potential in enhancing the performance of compression ignition engines and reducing carbon emissions. However, this approach is accompanied by several significant challenges, such as hydrogen transportation and storage, as well as low combustion efficiency at low loads. To address these challenges, this study integrates low-temperature combustion technology with online hydrogen production through methanol steam reforming to achieve efficient and clean combustion. The results of methanol steam reforming, mainly consisting of hydrogen, carbon dioxide, and unreacted methanol, is premixed via port injection as a low-reactivity fuel. Simultaneously, diesel fuel is directly injected into the cylinder as a high-reactivity fuel to achieve reactivity-controlled compression ignition mode. The primary fuels employed in compression ignition engines comprise reformate gas (mainly hydrogen), unreacted methanol, and diesel. This combination is collectively termed as tri-fuel combustion. This study utilizes a combination of genetic algorithms and 3D engine simulation to determine the optimal strategy for the methanol/reformed gas/diesel tri-fuel engine under different loads. The results of the optimization reveal that the tri-fuel combustion mode has the highest indicated thermal efficiency, surpassing the methanol/diesel dual-fuel mode and the reformed gas/diesel dual-fuel mode. Meanwhile, the optimized engine demonstrates significantly lower NOx and soot emissions than those required by the Euro VI emission regulations. Additionally, the study summarizes engine operating parameters impact on performance. Moreover, the tri-fuel combustion mode has a distinct advantage in increasing the methanol energy substitution rate at all three different loads. The dual-fuel mode leads to increased unburned hydrogen and methanol concentration near cylinder liner due to lower combustion temperature. In contrast, tri-fuel mode substantially reduces unburned hydrogen and methanol due to high combustion temperature and methanol reactivity.

Enhancing the mixing characteristics of multi-hydrogen jets in scramjet engines through the implementation of fuel injection strategies and vortex generator positioning

Fuel injection strategies and vortex generators (VGs) play vital roles in effectively managing temperature distribution within the combustion chamber of scramjet engines. By optimizing the fuel injection mechanism and strategically positioning VGs, the efficiency of fuel/air mixing can be significantly improved. In this study, k-epsilon turbulence model used to accurately capture shock waves. The operating Mach number was maintained at 2.0 through the use of a pressure far-field inlet. The investigation focused on three different fuel injection mechanisms: backward-facing, transverse, and forward-facing, while also examining the mixing capabilities of VGs located at varying distances from the inlet. Detailed analysis was conducted to understand the impact of these factors. Backward flow injection was found to promote efficient mixing and reduce the risk of flame blowout. Furthermore, optimizing the injection location proved instrumental in enhancing fuel and air mixing efficiency, leading to higher Mach numbers and improved combustion efficiency. However, it is important to avoid excessively high Mach numbers as they can induce flame instability and blowout. Among the different injection methods, multiple port injection demonstrated the highest Mach numbers, while backward-facing injection yielded the lowest. Multiple port injection also achieved high static pressure. Introducing VGs into the system significantly increased static pressure, and optimal fuel injection and VGs location resulted in stable combustion, improved combustion efficiency, and minimized unburned fuel. The injection method and the presence of VGs greatly influenced turbulence kinetic energy. Notably, VGs located at distances of 81 mm and 31 mm from the inlet produced the highest turbulence intensity for forward-facing injection and transverse fuel injection, respectively.

Numerical investigation of ammonia-rich combustion produces hydrogen to accelerate ammonia combustion in a direct injection SI engine

Ammonia is a carbon-free fuel with significant potential to minimize carbon emissions. However, ammonia has weak combustion properties, necessitating more study to improve its combustion performance in engines. A numerical simulation was conducted to evaluate the impact of fuel composition and injection-ignition synergy strategy on the performance of an ammonia-hydrogen spark ignition engine with liquid ammonia direct injection and hydrogen port injection. Specifically, two distinct injection modes were investigated: injection after intake valve close (IAIVC) and injection before top dead center (IBTDC). The outcomes reveal that the IBTDC mode generates a strong stratification of ammonia near the top dead center, resulting in ammonia-rich combustion, then leading to enriched hydrogen production and finally enhancing ammonia combustion and shorting the combustion duration. Liquid ammonia in-cylinder direct injection reduces the combustion temperature and decreases NO emissions. Optimizing the injection timing and spark timing based on a split injection strategy results in lower fuel consumption and emissions. Specifically, NO emissions decrease from 30.5 g/kWh to 21.7 g/kWh at a similar ITE (≈43.5%), and ITE increased from 43.3% to 44.3% for similar NO emission (≈30.0 g/kWh), respectively, with the reduction in both NH3 and N2O emissions.

Energy and Exergy Assessments of a Diesel-, Biodiesel-, and Ammonia-Fueled Compression Ignition Engine

The research is aimed at investigating ammonia in a compression ignition internal combustion engine as a promising alternative fuel towards decarbonization. This study presents energy and exergy assessments of a low-power engine for three cases of fuel supply, diesel oil, biodiesel oil, and ammonia with pilot biodiesel oil, across the entire engine’s range. While diesel or biodiesel was administered directly into the engine cylinder, the ammonia was delivered through port injection. The results show that the maximum thermal efficiency of 33.56% and exergy efficiency of 31.88% were found at 1800 rpm and 71% load for the diesel fuel system. For the biodiesel fuel system, the efficiencies were 32.72% and 30.93%, respectively, at 1800 rpm and 100% load, and for the ammonia with pilot biodiesel system, they were at 31.98% and 30.04%, respectively, for the same rpm and load. The exergy assessment indicates that exergy destruction, which accounts for the irreversibility of processes such as combustion and friction, is responsible for the greatest loss of useful energy. Optimizing these processes could significantly improve the engine’s performance for all three fuel cases. This research found that ammonia could successfully substitute diesel or biodiesel fuel, as the engine’s efficiency was comparable in all three tested scenarios; however, further research and optimization in terms of the ammonia-fueled engine emissions are required.

Effect of dual port-direct injection of syngas in a rotary engine

Using syngas as a primary fuel for internal combustion engines with spark ignition is a bridge technology for transitioning from carbon-based to hydrogen-based energy sources. There are two different ways of syngas delivery into combustion chamber: port injection or direct injection. In this study, the combination of these methods is considered for integration benefits of each injection technology and promotion of syngas utilization in rotary engines. In the novel concept of syngas dual injection, part of the fuel is delivered by a port injector during the induction stroke, while another part is directly injected during the compression stroke. The ratio of fuel mass delivered by port and direct injection is changed within the range of 0.0 (direct injection only) to 1.0 (port injection only) and chosen as a key parameter of concentration stratification. This study aims to investigate the optimal fuel injection strategy with numerical simulation of mixture formation, ignition, and combustion processes. It was shown that dual injection strongly influences turbulence intensity and mixture heterogeneity. The turbulence lengthscales generally increase with dual injection ratio growth. The direct injection case demonstrates maximum performance characteristics. However, the case with a small portion of directly injected fuel (10%–25%) increases fuel conversion efficiency by 5%–7% and decrease fuel consumption by 4%–6% with lower level of CO emission. The results show that the dual injection strategy provides flexibility in controlling the combustion process and emission reduction.

Knock control in hydrogen-fueled argon power cycle engine with higher compression ratio by water port injection

Hydrogen-fueled Argon Power Cycle engine is a novel concept for high efficiency and zero emissions, which chooses high specific heat ratio argon‑oxygen mixture as working fluid. However, the low specific heat of argon also increases the in-cylinder temperature, causing severe knock, which limits the efficiency of the engine. A typical knock-limited compression ratio for a hydrogen port-injected Argon Power Cycle engine is about 5.5:1 if no specific method is used. This article presents experimental research on the effect of water port injection under 1000 r/min at a compression ratio of 9.6:1 with IMEP ranging from 0.1 to 0.6 MPa and argon ratios of 79%, 85%, and 90%. The net indicated thermal efficiency peaks at 53.50% without a water injection but the knock intensity reaches 3.4 MPa. With the water injection, 16 mg/cycle water is sufficient to eliminate knock and the maximum net indicated thermal efficiency slightly reduces to 52.41%. With the water increased to 51 mg/cycle, a maximum IMEP of 0.64 MPa is achieved with an argon ratio of 85%. Argon ratio shows a marginal effect on the peak net indicated thermal efficiency, but the diagram factor is lower with higher argon ratios. At peak net indicated thermal efficiency conditions of different argon ratios, the diagram factor of Argon Power Cycle engine ranges from 76% to 80%, while a typical diagram factor of an air-breathing hydrogen engine can reach 90%. Both argon‑oxygen and air-breaching hydrogen engines can currently achieve the indicated thermal efficiency of over 52%, but the Argon Power Cycle engine shows a greater potential for further efficiency improvement. This paper suggests that the water injection is a feasible method for the knock suppression of the Argon Power Cycle engine with a marginal negative effect on efficiencies.

Optimization of port injection of n‐decanol in a PCCI engine using response surface methodology

AbstractThis work aims to define the optimum n‐decanol fraction in the inlet port and the corresponding engine load for the better emissions and performance characteristics of a partially premixed charged compression ignition (PCCI) engine by response surface methodology (RSM). The numerical model based on multi‐linear regression was established using experimental data. For this, the influence of various proportions of n‐decanol through intake port including 10%, 20%, 30%, and 40% were experimentally investigated besides the primary injection of neem oil biodiesel in the volumetric ratio of 80% diesel and 20% neem biodiesel, namely NB20. The optimization using RSM is exploited to capitalize the brake thermal efficiency (BTE) and diminish the emissions including oxides of nitrogen (NOx), carbon monoxide (CO) emission, smoke opacity, and hydrocarbon (HC) emission. The n‐decanol fraction in the port injection of 31.43% and the engine load in terms of brake power of 2.950 kW were found to be optimum parameters with the maximum desirability of 0.752. The optimal responses for brake‐specific fuel consumption (BSFC), BTE, CO, HC, smoke, and NOx under these operating conditions were found to be 0.305 kg/kWh, 28.8%, 0.145%, 19.61%, 54.85 ppm, and 837.7 ppm, respectively. Likewise, the correlation coefficient R2 values for BSFC, BTE, CO, HC, smoke and NOx have been found to be 99.85%, 99.95%, 93.58%, 90.32%, 99.97%, and 99.93%, respectively. According to the study's findings, the RSM is a realistic method for calculating and enhancing a diesel engine's emission and performance values operating in PCCI mode and using n‐decanol and NB20 as fuels.

Experimental study of a dual-fuel spark-assisted compression ignition engine with polyoxymethylene dimethyl ether and methanol as fuels

Polyoxymethylene dimethyl ethers (PODE) and methanol are promising alternative fuels for internal combustion engines, offering emission reduction and compatibility with existing engine combustion technologies. They can be chemically synthesized, providing a renewable and clean energy source for sustainable transportation. Additionally, dual-fuel spark-assisted compression ignition (SACI) is an advanced combustion mode that offers precise control of the combustion. However, there is limited research on dual-fuel SACI based on PODE and methanol, and the understanding of its multi-stage combustion, the cross-effects of multiple parameters, and the transition between ignition and compression ignition are still unclear. In this study, a modified gasoline engine was used to investigate the combustion characteristics of a dual-fuel SACI engine. The engine was fueled with direct injection PODE and port injection methanol. The combustion process was examined with a focus on the cooperative control of multiple parameters. The effects of the mass ratio of PODE, spark ignition timing, and start of injection timing were analyzed. The results demonstrated the presence of multiple heat-release stages during dual-fuel SACI combustion, involving both compression ignition and flame propagation ignition. An optimal interval between the start of injection timing and spark ignition timing was observed, leading to high brake thermal efficiency. This interval facilitated the formation of a highly reactive mixture during ignition, enabling efficient ignition of methanol by PODE. At a brake mean effective pressure of 0.8 MPa, a brake thermal efficiency of 44% was achieved with a 75% methanol ratio. Additionally, by appropriately increasing the mass ratio of PODE and advancing the start of injection timing, a significant reduction in hydrocarbon emissions was observed, albeit with a slight increase in nitrogen oxide emissions. These findings provide support for low-carbon operation of engines.

Simulations of ammonia spray evaporation, cooling, mixture formation and combustion in a direct injection compression ignition engine

This study investigates the novel approach of direct liquid ammonia injection into the combustion chamber of a compression ignition engine. Unlike traditional gaseous ammonia port injection, this method shows promise in reducing ammonia slip and emissions. To simulate and analyze the behavior of the liquid ammonia spray, we employed numerical models based on existing literature on flashing and non-flashing spray simulations, as well as recent experimental studies on ammonia spray characteristics using a gasoline direct injection (GDI) injector. Our approach utilized a Lagrangian discrete phase modelling technique to perform a series of three-dimensional computational fluid dynamics (CFD) simulations. The primary objectives of this research were to evaluate the evaporation process of ammonia and its cooling effect, as well as to gain insights into mixture formation within the engine cylinder under different operating conditions. The simulations encompassed the entire engine cycle, considering a multi-hole GDI ammonia spray in conjunction with pilot n-heptane, a diesel surrogate, in equal proportions on an energy basis. Three distinct injection timings for ammonia were examined, leading to varying thermodynamic conditions within the combustion chamber during each spray formation. Consequently, different modelling parameters and initial conditions were necessary to accurately replicate the spray behavior. To address this, we proposed a systematic procedure for assigning pre-defined spray angles. The non-reacting, evaporating spray simulations yielded valuable insights into the mixture formation process, which guided our analysis. Finally, reacting conditions were considered to evaluate engine performance and resulting exhaust gas emissions. This study provides a comprehensive overview of critical aspects related to direct ammonia injection in internal combustion engine (ICE) systems. Moreover, it uncovers performance trends that can serve as a foundation for future investigations in this field.

Exploration of the dual fuel combustion mode on a direct injection diesel engine powered with hydrogen as gaseous fuel in port injection and diesel-diethyl ether blend as liquid fuel

The present study explores the possibilities of the use of diesel-diethyl ether (DDEE) blends as pilot fuel, and hydrogen (H2) as inducted gaseous fuel in a diesel engine operated on dual fuel mode (DFM). DEE was added to diesel in ratios of 5–25% in increasing steps of 5%, to prepare the DDEE5, DDEE10, DDEE15, DDEE20, and DDEE25 blends that were used as pilot fuel. In this current study, for hydrogen gas generation, a hydrogen production kit was fabricated which was powered by solar energy. The hydrogen gas was produced from the electrolysis of water-KOH solution. During the experiment, hydrogen was inducted through the engine intake port employing an electronic gas injector. The quantity of hydrogen injection was set constant of 0.2 lpm for all the test cases. DDEE-hydrogen (DDEE+H2) blends accomplished overall good results compared to diesel. DDEE20+H2 furnished optimal results compared to diesel and other DDEE+H2 blends. Peak cylinder pressure for DDEE20+H2 was 66.91 bar at 5.2oCA aTDC, and the maximum HRR was 32.75 J/deg.CA. Compared to diesel, the BTE of engine for DDEE20+H2 was augmented by about 0.6% and the BSFC was diminished by about 3.7%, at maximum load conditions. A decline in CO and HC emissions of 29.6%, and 35% were observed for DDEE20+H2 at maximum load condition, but the NO and CO2 emanation was observed to be higher by around 29.4%, and 17.4% in comparison to diesel respectively.

Investigations on reactivity controlled compression ignition combustion with different injection strategies using alternative fuels produced from waste resources

Reactivity-controlled compression ignition (RCCI) is a promising low-temperature combustion (LTC) strategy that results in low oxides of nitrogen (NOx) and soot emissions while maintaining high thermal efficiency. At the same time, RCCI leads to increased unburned hydrocarbon (HC) and carbon monoxide (CO) emissions in the exhaust, particularly under low loads. The current work experimented novel port-injected RCCI (PI-RCCI) strategy to overcome the high unburned emission limitations at low load conditions in RCCI. PI-RCCI is a port injection strategy in which low-reactivity fuel (LRF) is injected using a low-pressure injector, and the high-reactivity fuel (HRF) is injected through a high-pressure common rail direct injection (CRDI) injector. The low volatile HRF is injected into a heated fuel vaporizer maintained at 180°C in the intake manifold during the suction stroke. Modifying a single-cylinder, light-duty diesel engine with the necessary intake and fuel injection systems allows engine operation in both RCCI and PI-RCCI modes. Alternative fuels from waste resources such as waste cooking oil biodiesel (WCO) and plastic waste oil (WPO) are used as the HRF and LRF fuel in RCCI and PI-RCCI. To achieve maximum thermal efficiency in RCCI, the premixed energy ratio and the start of injection of the direct-injected fuel are optimized at all load conditions. The engine performance and exhaust emissions characteristics in PI-RCCI are compared with RCCI as a baseline reference. The results show a 70% and 48% reduction in CO and HC emissions, respectively, in PI-RCCI than in RCCI. Further, the brake thermal efficiency (BTE) was enhanced by around 20%, and the brake-specific fuel consumption (BSFC) was reduced by 13% in PI-RCCI. The NOx emissions decreased without any considerable changes in soot emission in PI-RCCI. The current study shows that fuels derived from waste resources can be used in RCCI and PI-RCCI modes with better engine performance and lower emissions.