Search Results (27)

Methanol is a potential carbon-neutral fuel. It has a high latent heat of vaporization, making it difficult to achieve evaporation and mixing, and it is prone to forming a liquid film, which in turn affects engine performance. To reduce the liquid film and improve engine performance, this work investigates the influence mechanism of injection strategies on the generation of liquid films in the intake port and cylinder of an inline 6-cylinder port fuel injection (PFI) spark-ignition (SI) methanol engine and further explores the optimization scheme for improving engine performance. The results show that the end of injection (EOI) influences the methanol evaporation rate and the methanol–air mixing process, thereby determining the liquid film deposition, mixture distribution, and temperature distribution in the cylinder. As the EOI advances, the higher methanol evaporation rate during the intake process reduces the amount of methanol droplets and the deposition of a liquid film in the cylinder. The in-cylinder temperature is relatively high, while the mixture inhomogeneity slightly increases. As the EOI increases from 170 °CA to 360 °CA, the higher in-cylinder temperature and properly stratified mixture accelerate the early and middle stages of combustion, shorten the ignition delay, advance the center of combustion, and improve the brake thermal efficiency (BTE). However, further advancing the EOI results in the BTE remaining basically unchanged. Optimized injection timing can enhance the BTE by 1.4% to 2.4% under various load conditions. The increase in the EOI contributes to the reduction of HC emissions due to the weakening of the crevice effect with lower masses of methanol droplets and liquid film in the cylinder, while the increase in mixture inhomogeneity leads to an increase in CO emissions. In general, controlling the EOI at around 360 °CA can maintain relatively low CO emissions under various load conditions, while significantly reducing HC emissions by 71.2–76.4% and improving the BTE. Full article

The increasing demand for vehicles is leading to a rise in pollutant emissions across the world. This decline in air quality is significantly impacting public health, with internal combustion engines being a major contributor to this concerning trend. Ever-stringent regulations demand high engine efficiency and reduced pollutant emissions. Therefore, every automobile company requires rigorous methods for accurately estimating engine emissions. The implementation of advanced technologies, including machine learning methods, has proven to be a promising solution. The present work aims to develop an artificial intelligence-based model to estimate the pollutant emissions produced by an internal combustion engine under varying operating conditions. Experimental activities have been conducted on a single-cylinder spark ignition research engine with gasoline port fuel injection under both stationary and dynamic operating conditions. This work explores different artificial intelligence architectures and compares their performance in order to determine the best approach for the presented task. These structures have been trained and tested based on data obtained from the engine control unit and fast emission analyzer. The main target is to evaluate the possibility of applying the presented artificial intelligence predictive model as an on-board virtual tool in the estimation of emissions in real driving conditions. Full article

In the current global scenario, it is essential to find more effective and practical solutions to mitigate the problem of particulate emissions from vehicles. In this research, particulate emission characteristics with changing GDI pressure or applying a split GDI strategy with different second injection timings were initially explored in a Dual-Fuel Spark Ignition (DFSI) engine, which employs Ethanol Port Injection (EPI) plus Gasoline Direct Injection (GDI). The experimental results show that by increasing GDI pressure ($P_{GDI}$) from 5.5 MPa to 18 MPa, ignition delay (${\theta }_F$) shows a small decrease of 0.68 degrees. The parameters, such as maximum in-cylinder temperature ($T_{MI}$) and exhaust gas temperature ($T_{EG}$), each increase by 53.75 K and 13.84 K. An apparent reduction of 59.5% and 36.26% was achieved for the concentrations of particulate number ($N_P$) and particulate mass ($M_P$), respectively. Particulate emissions are effectively reduced by a split GDI strategy with an appropriate range of second injection timing ($t_{GDI2}$). Under $t_{GDI2}$ = −260 °CA, $N_P$ and $M_P$ concentrations exhibit a relatively lower level. However, by delaying $t_{GDI2}$ from −260 °CA to −140 °CA, there is an increase of more than 60% in $N_P$ concentration. The research findings help offer new and valuable insights into optimising particulate number and mass emissions from DFSI engines. Moreover, the findings could contribute novel and valuable insights into the optimisation of particulate emission characteristics in DFSI engines. Full article

IC Engines have played a vital role in past years and will in future years too. The only way that engines are made popular is the power they produce, which is useful in the transportation sector, with which humans’ daily lives become easier concerning time and effort. The only issues with these engines are the depletion of fossil fuels and harmful emissions. To regulate these threats, in the current study an SI engine is modified to duel fuel mode in such a way that the engine runs with hydrogen gas at different flow rates along with air. Engine speed is varied from 1800 to 3400 rpm under constant load by letting an ethanol, methanol, and gasoline mixture enter into the cylinder. Performance parameters like brake thermal efficiency, HC emissions, and vibrations produced from the engine are in agreement with the blended fuels used in this study. Full article

The gasification of residues into syngas offers a versatile gaseous fuel that can be used to produce heat and power in various applications. However, the application of syngas in engines presents several challenges due to the changes in its composition. Such variations can significantly alter the optimal operational conditions of the engines that are fueled with syngas, resulting in combustion instability, high engine variability, and misfires. In this context, this work presents an experimental investigation conducted on a port-fuel injection spark-ignition optical research engine using three different syngas mixtures, with a particular focus on the effects of CO/H₂ and diluent ratios. A comparative analysis is made against methane, considered as the baseline fuel. The in-cylinder pressure and related parameters are examined as indicators of combustion behavior. Additionally, 2D cycle-resolved digital visualization is employed to trace flame front propagation. Custom image processing techniques are applied to estimate flame speed, displacement, and morphological parameters. The engine runs at a constant speed (900 rpm) and with full throttle like stationary engine applications. The excess air–fuel ratios vary from 1.0 to 1.4 by adjusting the injection time and the spark timing according to the maximum brake torque of the baseline fuel. A thermodynamic analysis revealed notable trends in in-cylinder pressure traces, indicative of differences in combustion evolution and peak pressures among the syngas mixtures and methane. Moreover, the study quantified parameters such as the mass fraction burned, combustion stability (COVIMEP), and fuel conversion efficiency. The analysis provided insights into flame morphology, propagation speed, and distortion under varying conditions, shedding light on the influence of fuel composition and air dilution. Overall, the results contribute to advancing the understanding of syngas combustion behavior in SI engines and hold implications for optimizing engine performance and developing numerical models. Full article

This study explores the potentiality of low/zero carbon fuels such as methanol, methane and hydrogen for motor applications to pursue the goal of energy security and environmental sustainability. An experimental investigation was performed on a spark ignition engine equipped with both a port fuel and a direct injection system. Liquid fuels were injected into the intake manifold to benefit from a homogeneous charge formation. Gaseous fuels were injected in direct mode to enhance the efficiency and prevent abnormal combustion. Tests were realized at a fixed indicated mean effective pressure and at three different engine speeds. The experimental results highlighted the reduction of CO and CO₂ emissions for the alternative fuels to an extent depending on their properties. Methanol exhibited high THC and low NO_x emissions compared to gasoline. Methane and, even more so, hydrogen, allowed for a reduction in THC emissions. With regard to the impact of gaseous fuels on the NO_x emissions, this was strongly related to the operating conditions. A surprising result concerns the particle emissions that were affected not only by the fuel characteristics and the engine test point but also by the lubricating oil. The oil contribution was particularly evident for hydrogen fuel, which showed high particle emissions, although they did not contain carbon atoms. Full article

To utilize the high efficiency of gasoline direct injection (GDI) and solve the high particulate number (PN) issue, hydrogen-rich syngas has been adopted as a favorable sustainable fuel. This paper compares and analyzes the effects of the injection configurations (GDI, gasoline port injection combined with GDI (PGDI), and gasoline port injection combined with hydrogen-rich syngas direct injection (PSDI)) and fuel properties on combustion and emissions in a spark-ignition engine. The operational points were fixed at 1800 rpm with a 15% throttle position, and the excess air ratio was 1.1. The conclusions show that PSDI gained the highest maximum brake thermal efficiency (BTE) at the MBT point, and the maximum BTE for GDI was only 94% of that for PSDI. PSDI’s CoV_IMEP decreased by 22% compared with GDI’s CoV_IMEP. CO and HC emissions were reduced by approximately 78% and 60% from GDI to PSDI among all the spark timings, respectively, while PSDI emitted the highest NO_X emissions. As for particulate emissions, PSDI emitted the highest nucleation-mode PN, while GDI emitted the lowest. However, the accumulation-mode PN emitted from PSDI was approximately 52% of that from PGDI and 5% of that from GDI. This study demonstrates the benefits of PSDI for sustainability in vehicle engineering. Full article

Water injection strategy is considered a promising technique to improve the performance of boosted engine and reduce the NOx emission via the latent heat of water vaporization. Numerous research on water injection has been conducted on in-cylinder and intake port water injection. However, the water injection focusing on the spark ignition (SI) engine exhaust system is still lacking. This study proposed a pre-turbocharger turbine water injection (PTWI) concept to reduce the turbine inlet temperature. This was done so that the stoichiometric engine operation could be achieved at a medium–high load and engine speed without resorting to a fuel enrichment strategy to reduce the exhaust gas temperature. This study aims to investigate the effect of injecting water into the exhaust gas at the pre-turbine of a turbocharged spark ignition engine. This study experimented on a 1.3-L 4-cylinder turbocharged engine to collect engine data for computational fluid dynamics (CFD) baseline model validation. A one-dimensional engine model was then developed based on the 1.6-L 4-cylinder turbocharged engine experiment using AVL BOOST software. The CFD model was used to investigate the effects of water injection pressure, pipe diameter, and water injector location. The CFD results showed that a 50 mm connecting pipe with 4 bar of injection pressure gives the largest reduction in exhaust temperature. The CFD results were then applied to the one-dimensional engine model. The engine model simulation results showed that the fuel consumption could be reduced up to 13% at 4000 rpm during wide-open throttle and 75% engine load. The PTWI is a new approach, but this study has proved the potential of using water injection at the pre-turbine turbocharger to reduce the fuel consumption of a turbocharged SI engine. Full article

The intake manifold and its components play a key role in the proper formation of air–fuel mixtures suitable for correct engine operation. In this article, starting from the original intake manifold design fitted to an optically accessible spark-ignited engine, a new solution was developed so as to allow the application of high-speed imaging of the fuel jet located between the runner and intake valves (Port Fuel Injection). To compare the two designs in terms of overall engine performance parameters such as volumetric efficiency, 0D/1D simulations were performed in motored conditions. Measurements at different crankshaft speed values were used for calibrating the intake line parameters and providing boundary conditions. Finite Element Analysis (FEM) was performed in SolidWorks to verify the structural strength of the new design when operating in the most critical conditions, i.e., boosted operation. As an overall conclusion, the results show that the new design guarantees a wider range of intake pressure values during the intake stroke, thus expanding the possible operative points. This can be obtained without compromising structural integrity, given that predicted safety factors were well above acceptable limits even for relatively high boost levels. Full article

Hydrogen, as a suitable and clean energy carrier, has been long considered a primary fuel or in combination with other conventional fuels such as gasoline and diesel. Since the density of hydrogen is very low, in port fuel-injection configuration, the engine’s volumetric efficiency reduces due to the replacement of hydrogen by intake air. Therefore, hydrogen direct in-cylinder injection (injection after the intake valve closes) can be a suitable solution for hydrogen utilization in spark ignition (SI) engines. In this study, the effects of hydrogen direct injection with different hydrogen energy shares (HES) on the performance and emissions characteristics of a gasoline port-injection SI engine are investigated based on reactive computational fluid dynamics. Three different injection timings of hydrogen together with five different HES are applied at low and full load on a hydrogen–gasoline dual-fuel SI engine. The results show that retarded hydrogen injection timing increases the concentration of hydrogen near the spark plug, resulting in areas with higher average temperatures, which led to NO_X emission deterioration at −120 Crank angle degree After Top Dead Center (CAD aTDC) start of injection (SOI) compared to the other modes. At −120 CAD aTDC SOI for 50% HES, the amount of NO_X was 26% higher than −140 CAD aTDC SOI. In the meanwhile, an advanced hydrogen injection timing formed a homogeneous mixture of hydrogen, which decreased the HC and soot concentration, so that −140 CAD aTDC SOI implied the lowest amount of HC and soot. Moreover, with the increase in the amount of HES, the concentrations of CO, CO₂ and soot were reduced. Having the HES by 50% at −140 CAD aTDC SOI, the concentrations of particulate matter (PM), CO and CO₂ were reduced by 96.3%, 90% and 46%, respectively. However, due to more complete combustion and an elevated combustion average temperature, the amount of NO_X emission increased drastically. Full article

Hydrogen is a carbon-free fuel that can be produced in many ways starting from different sources. Its use as a fuel in internal combustion engines could be a method of significantly reducing their environmental impact. In spark-ignition (SI) engines, lean hydrogen–air mixtures can be burnt. When a gaseous fuel like hydrogen is port-injected in an SI engine, working with lean mixtures, supercharging becomes very useful in order not to excessively penalize the engine performance. In this work, the performance of a turbocharged PFI spark-ignition engine fueled by hydrogen has been investigated by means of 1-D numerical simulations. The analysis focused on the engine behavior both at full and partial load considering low and medium engine speeds (1500 and 3000 rpm). Equivalence ratios higher than 0.35 have been considered in order to ensure acceptable cycle-to-cycle variations. The constraints that ensure the safety of engine components have also been respected. The results of the analysis provide a guideline able to set up the load control strategy of a SI hydrogen engine based on the variation of the air to fuel ratio, boost pressure, and throttle opening. Furthermore, performance and efficiency of the hydrogen engine have been compared to those of the base gasoline engine. At 1500 and 3000 rpm, except for very low loads, the hydrogen engine load can be regulated by properly combining the equivalence ratio and the boost pressure. At 3000 rpm, the gasoline engine maximum power is not reached but, for each engine load, lean burning allows the hydrogen engine achieving much higher efficiencies than those of the gasoline engine. At full load, the maximum power output decreases from 120 kW to about 97 kW, but the engine efficiency of the hydrogen engine is higher than that of the gasoline one for each full load operating point. Full article

Hydrogen as carbon-free fuel is a very promising candidate for climate-neutral internal combustion engine operation. In comparison to other renewable fuels, hydrogen does obviously not produce CO₂ emissions. In this work, two concepts of hydrogen internal combustion engines (H₂-ICEs) are investigated experimentally. One approach is the modification of a state-of-the-art gasoline passenger car engine using hydrogen direct injection. It targets gasoline-like specific power output by mixture enrichment down to stoichiometric operation. Another approach is to use a heavy-duty diesel engine equipped with spark ignition and hydrogen port fuel injection. Here, a diesel-like indicated efficiency is targeted through constant lean-burn operation. The measurement results show that both approaches are applicable. For the gasoline engine-based concept, stoichiometric operation requires a three-way catalyst or a three-way NO_X storage catalyst as the primary exhaust gas aftertreatment system. For the diesel engine-based concept, state-of-the-art selective catalytic reduction (SCR) catalysts can be used to reduce the NOx emissions, provided the engine calibration ensures sufficient exhaust gas temperature levels. In conclusion, while H₂-ICEs present new challenges for the development of the exhaust gas aftertreatment systems, they are capable to realize zero-impact tailpipe emission operation. Full article

This paper provides a comprehensive review and critical analysis of the latest research results in addition to an overview of the future challenges and opportunities regarding the use of hydrogen to power internal combustion engines (ICEs). The experiences and opinions of various international research centers on the technical possibilities of using hydrogen as a fuel in ICE are summarized. The advantages and disadvantages of the use of hydrogen as a solution are described. Attention is drawn to the specific physical, chemical, and operational properties of hydrogen for ICEs. A critical review of hydrogen combustion concepts is provided, drawing on previous research results and experiences described in a number of research papers. Much space is devoted to discussing the challenges and opportunities associated with port and direct hydrogen injection technology. A comparison of different fuel injection and ignition strategies and the benefits of using the synergies of selected solutions are presented. Pointing to the previous experiences of various research centers, the hazards related to incorrect hydrogen combustion, such as early pre-ignition, late pre-ignition, knocking combustion, and backfire, are described. Attention is focused on the fundamental importance of air ratio optimization from the point of view of combustion quality, NOx emissions, engine efficiency, and performance. Exhaust gas scrubbing to meet future emission regulations for hydrogen powered internal combustion engines is another issue that is considered. The article also discusses the modifications required to adapt existing engines to run on hydrogen. Referring to still-unsolved problems, the reliability challenges faced by fuel injection systems, in particular, are presented. An analysis of more than 150 articles shows that hydrogen is a suitable alternative fuel for spark-ignition engines. It will significantly improve their performance and greatly reduce emissions to a fraction of their current level. However, its use also has some drawbacks, the most significant of which are its high NOx emissions and low power output, and problems in terms of the durability and reliability of hydrogen-fueled engines. Full article

Combustion stability, engine efficiency and emissions in a multi-cylinder spark-ignition internal combustion engines can be improved through the advanced control and optimization of individual cylinder operation. In this work, experimental and numerical analyses were carried out on a twin-cylinder turbocharged port fuel injection (PFI) spark-ignition engine to evaluate the influence of cylinder-by-cylinder variation on performance and pollutant emissions. In a first stage, experimental tests are performed on the engine at different speed/load points and exhaust gas recirculation (EGR) rates, covering operating conditions typical of Worldwide harmonized Light-duty vehicles Test Cycle (WLTC). Measurements highlighted relevant differences in combustion evolution between cylinders, mainly due to non-uniform effective in-cylinder air/fuel ratio. Experimental data are utilized to validate a one-dimensional (1D) engine model, enhanced with user-defined sub-models of turbulence, combustion, heat transfer and noxious emissions. The model shows a satisfactory accuracy in reproducing the combustion evolution in each cylinder and the temperature of exhaust gases at turbine inlet. The pollutant species (HC, CO and NOx) predicted by the model show a good agreement with the ones measured at engine exhaust. Furthermore, the impact of cylinder-by-cylinder variation on gaseous emissions is also satisfactorily reproduced. The novel contribution of present work mainly consists in the extended numerical/experimental analysis on the effects of cylinder-by-cylinder variation on performance and emissions of spark-ignition engines. The proposed numerical methodology represents a valuable tool to support the engine design and calibration, with the aim to improve both performance and emissions. Full article

This study aims to investigate the effect of the port injection of ammonia on performance, knock and NOx emission across a range of engine speeds in a gasoline/ethanol dual-fuel engine. An experimentally validated numerical model of a naturally aspirated spark-ignition (SI) engine was developed in AVL BOOST for the purpose of this investigation. The vibe two zone combustion model, which is widely used for the mathematical modeling of spark-ignition engines is employed for the numerical analysis of the combustion process. A significant reduction of ~50% in NOx emissions was observed across the engine speed range. However, the port injection of ammonia imposed some negative impacts on engine equivalent BSFC, CO and HC emissions, increasing these parameters by 3%, 30% and 21%, respectively, at the 10% ammonia injection ratio. Additionally, the minimum octane number of primary fuel required to prevent knock was reduced by up to 3.6% by adding ammonia between 5 and 10%. All in all, the injection of ammonia inside a bio-fueled engine could make it robust and produce less NOx, while having some undesirable effects on BSFC, CO and HC emissions. Full article