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Technical Paper

Ducted Fuel Injection: Confirmed re-entrainment hypothesis

2024-04-09
2024-01-2885
Testing of ducted fuel injection (DFI) in a single-cylinder engine with production-like hardware previously showed that simply adding a duct structure increased soot emissions at the full load, rated speed operating point. In the authors’ 2021 SAE paper, which reported these findings, it was hypothesized that the DFI flame, which is faster than a conventional diesel combustion (CDC) flame, and has a shorter distance to travel, was being re-entrained into the on-going injection around the lift-off length, thus reducing air entrainment into the on-going injection. The engine operating condition and the engine combustion chamber geometry were duplicated in a constant pressure vessel. The experimental setup used a 3D piston section combined with a glass fire deck allowing for a comparison between a CDC flame and a DFI flame via high-speed imaging. Testing clearly confirmed the detrimental effect of the DFI flame re-entrainment hypothesis presented in the previous on-engine work.
Technical Paper

Light Duty engine performance characteristics with Dimethyl Ether and Propane

2024-04-09
2024-01-2126
Paper documents the performance characteristics of a compression ignition HYUNDAI 2.2L engine operating with Dimethyl Ether (DME) and Propane mixtures. The engine features a high-pressure common rail fuel injection system designed to operate with DME and Propane. The main component of the fuel system is a high-pressure pump that incorporates an electronic inlet metering valve commanded on a crank angled base to control the rail pressure. The pump, which requires no pressure regulator, provides the flow needed to the injectors without flow returning to the inlet. Tests are carried out at injection pressures from 300bar to 1000bar, and the engine ECU is aided with the use of an Engine Controller High speed Oversight unit (ECHO) to provide combustion phasing control and improved cylinder-to-cylinder uniformity, providing improved optimization over the testing effort.
Technical Paper

Evaluating the effects of an Electrically Assisted Turbocharger on scavenging control for an Opposed Piston Two Stroke (OP2S) compression ignition engine

2024-04-09
2024-01-2388
Opposed piston two-stroke (OP2S) diesel engines have demonstrated a reduction in engine-out emissions and increased efficiency compared to conventional four-stroke diesel engines. Due to the higher thermal efficiency and absence of a cylinder head, the heat transfer loss to the coolant is lower near the ‘Top Dead Center’. The selection and design of the airpath are pivotal in realizing the benefits of the OP2S engine architecture. Like any two-stroke diesel engine, the scavenging process and the composition of the internal residuals are predominantly governed by the pressure differential between the intake and the exhaust ports. Moreover, a significant portion of the work involved in pumping air is carried out externally to the engine cylinder which needs to be accounted for when calculating brake efficiencies.
Technical Paper

Decarbonizing Light Vehicles with Hydrous Ethanol: Performance Analysis of a Range-Extended PHEV Using Experimental and Simulation Techniques

2024-04-09
2024-01-2161
Plug-in hybrid electric vehicles have the potential of combining the benefits of electric vehicle in terms of low emissions and internal combustion engine vehicles in terms of vehicle range. With the addition of a renewable fuel, the CO2 potential reduction increase even more. The last trends for PHEV are small combustion engine known as range extender, with battery package between full hybrid and electric powertrains. Thus, allowing an improvement in vehicle’s range, reducing battery materials while converting fuel energy through a highly efficient path. Although these vehicles have been proved to be a convenient strategy for decarbonizing the light vehicles, the use of alternative fuels is poorly studied. In this work, hydrous ethanol is chosen because is already available in some countries, such as USA and Brazil, and have an ultra-low well-to-tank CO2 emission.
Technical Paper

Post-Oxidation Phenomena as a Thermal Management Strategy for Automotive After-Treatment Systems: Assessment by means of 3D-CFD Virtual Development

2024-04-09
2024-01-2629
The target of the newly and future automotive emission regulations is to promote a fast transition to near-zero emission vehicles. As such, the range of ambient and operating conditions tested in the homologation cycles is broadening. In this context, the proposed work aims to thoroughly investigate the potential of post-oxidation phenomena in reducing the light-off time of a conventional three-way catalyst. The study is carried out on a turbocharged four-cylinder gasoline engine by means of experimental and numerical activities. Post oxidation is achieved through the oxidation of unburned fuel in the exhaust line, exploiting a rich combustion and a secondary air injection dedicated strategy. The CFD methodology consists of two different approaches: the former relying on a full-engine mesh, the latter on a detailed analysis of the chemical reactions occurring in the exhaust line.
Technical Paper

Experimental Study of Ammonia Combustion in a Heavy-Duty Diesel Engine Converted to Spark Ignition Operation

2024-04-09
2024-01-2371
Ammonia is one of the carbon-free alternatives considered for power generation and transportation sectors. But ammonia’s lower flame speed, higher ignition energy, and higher nitrogen oxides emissions are challenges in practical applications such as internal combustion engines. As a result, modifications in engine design and control and the use of a secondary fuel to initiate combustion such as natural gas are considered for ammonia-fueled engines. The higher-octane number of methane (the main component in natural gas) and ammonia allows for higher compression ratios, which in turn would increase the engine's thermal efficiency. One simple approach to initiate and control combustion for a high-octane fuel at higher compression ratios is to use a spark plug. This study experimentally investigated the operation of a heavy-duty compression ignition engine converted to spark ignition and ammonia-methane blends.
Technical Paper

Modeling and Analysis of the Hydrogen Production via Steam Reforming of Ethanol, Methanol, and Methane Fuels

2024-04-09
2024-01-2179
The global transition to alternative power sources, particularly fuel cells, hinges on the cost-effective production and distribution of hydrogen fuel. While green hydrogen produced through water electrolysis using renewable energy sources holds immense promise, it currently falls short of meeting the burgeoning demand for hydrogen. To address this challenge, alternative methods, such as steam reforming and partial oxidation of hydrocarbon fuels with integrated carbon capture, are poised to bridge the gap between supply and demand in the near to midterm. Steam reforming of methane is a well-established technology with a proven track record in the chemical industry, serving as a dependable source of hydrogen feedstock for decades. However, to meet the demand for efficient hydrogen storage, handling, and onboard reforming, researchers are increasingly exploring liquid hydrocarbon fuels at room temperature, such as methanol and ethanol.
Technical Paper

Methanol Mixing-Controlled Compression Ignition with Ignition Enhancer for Off-Road Engine Operation

2024-04-09
2024-01-2701
Methanol is one of the most promising fuels for the decarbonization of the off-road and transportation sectors. Although methanol is typically seen as an alternative fuel for spark ignition engines, mixing-controlled compression ignition (MCCI) combustion is typically preferred in most off-road and medium-and heavy-duty applications due to its high reliability, durability and high-efficiency. In this paper, the potential of using ignition enhancers to enable methanol MCCI combustion was investigated. Methanol was blended with 2-ethylhexyl nitrate (EHN) and experiments were performed in a single-cylinder production-like diesel research engine, which has a displacement volume of 0.84 L and compression ratio of 16: 1. The effect of EHN has been evaluated with three different levels (3%vol, 5%vol, and 7%vol) under low- and part-load conditions. The injection timing has been swept to find the stable injection window for each EHN level and load.
Technical Paper

Experimental study on performance and emission of BS VI complaint EFI motorbike with oxygenated fuel blends (E0, E10, E20 & M15)

2024-04-09
2024-01-2372
Net-Zero emission ambitions coupled with availability of oxygenated fuels like ethanol encouraged the Government towards commercial implementation of fuels like E20. In this background, a study was taken up to assess the impact of alcohol blended fuels on performance and emission characteristics of a BS-VI complaint motorbike. A single cylinder, 113-cc spark ignition, ECU based electronic fuel injection motorbike was used for conducting tests. Pure gasoline (E0), 10% ethanol-gasoline (E10), 20% ethanol-gasoline (E20) and 15% methanol-gasoline (M15) blends meeting respective IS standards were used as test fuels. The oxygen content of E10, E20 and M15 fuels were 3.7%, 7.4% and 8.35% by weight respectively. Experiments were conducted following worldwide motorcycle test cycle (WMTC) as per AIS 137 standard and also wide-open-throttle (WOT) test cycle, using chassis dynamometer.
Technical Paper

Piston geometries impact on Spark-Ignition light-duty hydrogen engine

2024-04-09
2024-01-2613
The European Union aims to be climate neutral by 2050 and requires the transportation sector to reduce their emissions by 90%. The deployment of H2ICE to power vehicles is one of the solutions proposed. Indeed, H2ICEs in vehicles can reduce local pollution, reduce global emissions of CO2 and increase efficiency. Although H2ICEs could be rapidly introduced, investigations on hydrogen combustion in internal combustion engines are still required. This paper aims to experimentally compare a flat piston and a bowl piston in terms of performances and emissions. For the performances, experiments were performed with the help of a single cylinder Diesel engine which has been modified. In particular, a center direct injector dedicated to H2 injection and a side-mounted spark plug were installed, and the compression ratio was reduced to 12.7:1. For the emissions, several exhaust gas measurement systems were used to monitor NO, NO2, N2O and H2.
Technical Paper

Diesel Oxidation Catalyst Performance with Biodiesel Blends and B100

2024-04-09
2024-01-2711
Biodiesel (i.e., mono-alkyl esters of long chain fatty acids derived from vegetable oils and animal fats) is a renewable diesel fuel providing life-cycle greenhouse gas emission reductions relative to petroleum-derived diesel. With the expectation that there would be widespread use of biodiesel as a substitute for ultra-low sulfur diesel (ULSD, 15 ppm sulfur), there have been many studies looking into the effects of biodiesel on engine and aftertreatment, particularly its compatibility to the current aftertreatment technologies. The objective of this study was to generate experimental data to measure the effectiveness of a current technology diesel oxidation catalysts (DOC) to oxidize soy-based biodiesel at various blend levels with ULSD. Biodiesel blends from 0 to 100% were evaluated on an engine using a conventional DOC. The DOC performance with these biodiesel blends were measured at six steady-state engine conditions encompassing most of the operating range of the engine.
Technical Paper

Conjugate Heat Transfer Analysis of an i-4 Engine including Pistons, Liners, Block, Heads, Water Cooling Jacket, and Oil Cooling Jets

2024-04-09
2024-01-2696
Internal combustion engine (IC engine) vehicles are commonly used for transportation due to their versatility. Due to this, efficiency in design process of IC engines is critical for the industry. To assess performance capabilities of an IC engine, thermal predictions are of utmost consequence. This study describes a computational method based on unsteady Reynolds-averaged Navier–Stokes equations that resolves the gas–liquid interface to examine the unsteady single phase/multiphase flow and heat transfer in a 4-cylinder Inline (i-4) engine. The study considers all important parts of the engine i.e., pistons, cylinder liners, head, block etc. The study highlights the ease of capturing complex and intricate flow paths with a robust mesh generation tool in combination with a robust high-fidelity interface capturing VOF scheme to resolve the gas-liquid interfaces.
Technical Paper

Investigation of combustion characteristics of a fuel blend consisting of methanol and ignition improver, compared to diesel fuel and pure methanol

2024-04-09
2024-01-2122
The increasing need to reduce greenhouse gas emissions and shift away from fossil fuels has raised an interest for methanol. Methanol can be produced from renewable sources and can drastically lower soot emissions from compression ignition engines (CI). As a result, research and development efforts have intensified focusing on the use of methanol as a replacement for diesel in CI engines. The issue with methanol lies in the fact that methanol is challenging to ignite through compression alone, particularly at low-load and cold starts conditions. This challenge arises from methanol's high octane number, low heating value, and high heat of vaporization, all of which collectively demand a substantial amount of heat for methanol to ignite through compression.
Technical Paper

Experimental investigation of pilot injection strategies to aid low load compression ignition of neat methanol

2024-04-09
2024-01-2119
The growing demand to lower greenhouse gas emissions and transition from fossil fuels, has put methanol in the spotlight. Methanol can be produced from renewable sources and has the property of burning almost soot-free in compression ignition (CI) engines. Consequently, there has been a notable increase in research and development activities directed towards exploring methanol as a viable substitute for diesel fuel in CI engines. The challenge with methanol lies in the fact that it is difficult to ignite through compression alone, particularly in low-load and cold start conditions. This difficulty arises from methanol's high octane number, relatively low heating value, and high heat of vaporization, collectively demanding a considerable amount of heat for methanol to ignite through compression. Previous studies have addressed the use of a pilot injection in conjunction with a larger main injection to lower the required intake air temperature for methanol to combust at low loads.
Technical Paper

Numerical Study of an EGR Dilution in a Pre-Chamber Spark Ignited Engine fuelled by Natural Gas

2024-04-09
2024-01-2081
Exhaust gas recirculation (EGR) is a proven strategy for the reduction of NOx emissions in spark ignited (SI) engine and compression ignition engines especially in lean burn conditions where increase thermal efficiency is obtained. The dilution level of the mixture with EGR is in a conventional SI engine limited by the increase of combustion instability (CoV IMEP). A possible method to extend the EGR dilution level and ensure stable combustion is the implementation of an active pre-chamber combustion system. The pre-chamber spark ignited (PCSI) engine enables fast and stable combustion of lean mixtures in the main chamber by utilizing high ignition energy of multiple flame jets penetrating from the pre-chamber to the main chamber. The main feature of an active pre-chamber is the ability to control mixture dilution at the spark plug by adding an injector to the pre-chamber.
Technical Paper

Combustion analysis of Hydrogen-DDF mode based on OH* chemiluminescence images

2024-04-09
2024-01-2367
Hydrogen-diesel dual-fuel combustion processes were studied in a rapid compression and expansion engine (RCEM). In the experiments, the combustion processes were visualized using an optically accessible RCEM that can simulate a single compression and expansion stroke of a diesel engine. A small amount of diesel was injected as a pilot ignition for the hydrogen, with injection pressures of 40, 80, and 120 MPa using a common rail injection system. The amount of diesel injected was varied as 3, 6, and 13 mm3. The hydrogen-air mixture was introduced into the combustion chamber through the intake valve. The amount of hydrogen was manipulated by varying the total excess air ratio(λtotal) at 3 and 4. The RCEM was operated at a constant speed of 900 rpm, and the in-cylinder pressure and temperature at TDC were set at 5 MPa and 700 K, respectively.
Technical Paper

Evaluation of closed-loop combustion phase optimization for varying fuel compensation and cylinder balancing in a HD SI-ICE

2024-04-09
2024-01-2837
Alternative fuels, such as natural and bio-gas, are attractive options for reducing greenhouse gas emissions from combustion engines. However, the naturally occurring variation in gas composition poses a challenge and may significantly impact engine performance. The gas composition affects fundamental fuel properties such as flame propagation speed and heat release rate. Deviations from the gas composition for which the engine was calibrated result in changes in the combustion phase, reducing engine efficiency and increasing fuel consumption and emissions. However, the efficiency loss can be limited by estimating the combustion phase and adapting the spark timing, which could be implemented favorably using a closed-loop control approach. In this paper, we evaluate the efficiency loss resulting from varying gas compositions and the benefits of using a closed-loop controller to adapt the spark timing to retain the nominal combustion phase.
Technical Paper

Study of Dimethyl Ether Fuel Spray Characteristics and Injection Profile

2024-04-09
2024-01-2702
The majority of transportation systems have continued to be powered by the internal combustion engine and fossil fuels. Heavy-duty applications especially are reliant on diesel engines for their high brake efficiency, power density, and robustness. Although engineering developments have advanced engines towards significantly fewer emissions and higher efficiency, the use of fossil-derived diesel as fuel sets a fundamental threshold in the achievable total net carbon reduction. Dimethyl ether can be produced from various renewable feedstocks and has a high chemical reactivity making it suitable for heavy-duty applications, namely compression ignition direct injection engines. Studies of dimethyl ether for engine combustion have shown positive results with an ultra-low propensity to form soot regardless of NOx levels. Further reduction in NOx and soot emission regulations presents a significant challenge to combustion performance.
Technical Paper

Utilization of recycled waste engine oil waste cooking oil and waste plastic oil as fuel for Compression Ignition Engine

2024-04-09
2024-01-2699
Using the recycled waste oils are to be focused for the protection of environment by reducing the land pollution and disposal costs.This study is to use the recycled waste engine oil, waste cooking oil and waste plastic oil along with Bio-butanol from the waste cut vegetables and fruits. Initially, a properties and solubility to choose a suitable blend for fueling into diesel engine from various proportions. These three blends from the base of three waste oils are then tested by modifying and standard engine operating parameters for performance. The properties tests results as 18% of waste engine oil with bio-butanol, 16% of waste cooking oil with bio-butanol and 24% of waste plastic oil with bio-butanol are found competent for fueling engine. These blends produces low efficiency in lower brake powers and the emissions of smoke, hydrocarbons and carbon monoxide are also higher during the operation under standard parameters.
Technical Paper

Effect of Spark Assisted Compression Ignition on the End-gas Autoignition with DME-air Mixtures in a Rapid Compression Machine

2024-04-09
2024-01-2822
Substantial effort has been devoted to utilizing homogeneous charge compression ignition (HCCI) to improve thermal efficiency and reduce emission pollutants in internal combustion engines. However, uncertainty of ignition timing and limited operational range restrict further adoption for industry. The utilization of the spark-assisted compression ignition (SACI) technique has the advantage of using a spark event to control the combustion process. This study employs a rapid compression machine to characterize the ignition and combustion process of Dimethyl ether (DME) under engine-like background temperature and pressures and combustion regimes, including HCCI, SACI, and knocking onsite. The spark ignition timing was swept to ignite the mixture under various thermodynamic conditions. This investigation demonstrates the presence of four distinct combustion regimes, including detonation, strong end-gas autoignition, mild end-gas autoignition, and HCCI.
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