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High fuel stratification gasoline compression ignition (HFS-GCI) strategies allow for the use of ignition control methods similar to those used by diesel-fueled compression ignition (CI) engines while offering the emissions benefits of gasoline-like fuels. Despite this benefit, low load GCI operation requires ignition assistance viz. intake boosting, intake heating, cylinder deactivation, etc. for consistent autoignition. A novel ignition assistance methodology using an offset active prechamber (OAP) is proposed in this work to enable low load GCI operation. A 1.5cc OAP with a pressure-sensing spark plug and gaseous fuel injection system is designed and mounted in a medium-duty single-cylinder test engine based on the Cummins ISB engine. The prechamber is provided with two holes designed to ignite the fuel spray from the centrally mounted DI fuel injector. Gasoline was used as the main chamber fuel and methane was used as the prechamber fuel.

Recuperated low-pressure-ratio split-cycle engines represent a promising engine configuration for applications like transportation and stand-alone power generation by offering a potential efficiency as high as 60%. However, it can be challenging to achieve the stringent NOx emission standard, such as Euro 6 limit of 0.4 gNOx/kWh, due to the exhaust cylinder high intake temperature. This paper presents experimental investigation of hydrogen-air combustion NOx emissions for such engines for the first time. Experiments are carried out using a simplified constant-volume combustion chamber with glow-plug ignition. Two fuel injection techniques are performed: direct injection and injection via a novel convergent-divergent injector. For the direct injection scenario, NOx levels are unsatisfactory with respect to the Euro 6 standards over a range of operating temperatures from 200 °C to 550 °C.

A comprehensive experimental study of hydrogen–diesel dual-fuel and hydrogen-hydrotreated vegetable oil (HVO) dual-fuel operations was conducted in a single-cylinder diesel engine (bore 85.0 mm, stroke 96.9 mm, and compression ratio 14.3) equipped with a common rail fuel injection system and a supercharger. The hydrogen flow rate was manipulated by varying the hydrogen excess air ratio from 2.5 to 4.0 in 0.5 increments. Hydrogen was introduced into the intake pipe using a gas injector. Diesel fuel and HVO were injected as pilot fuels at a fixed injection pressure of 80 MPa. The quantity of pilot fuel was set to 3, 6, and 13 mm3/cycle. The intake and exhaust pressures were set in the range of 100–220 kPa in 20 kPa increments. The engine was operated at a constant speed of 1,800 rpm under all conditions. The pilot injection timing was varied such that the ignition timing was constant at the TDC under all conditions.

Because it can be produced in a green form, methanol is envisioned as a potential fuel to replace conventional diesel fuel and directly reduce the greenhouse gas (GHG) impact of maritime transportation. For these reasons, Original Equipment Manufacturers (OEMs) working on marine applications are focusing on making methanol easily usable in Compression Ignition (CI) engines. While it is an easy-to-use substance with manageable energy content, methanol has a few drawbacks, including a high latent heat of vaporization and a high auto-ignition temperature, all of which affect combustion quality. Therefore, solutions have been found or are still under study to give it Diesel-like behavior. One solution is to use a pilot fuel for ignition in significant quantities. A previous study conducted at the PRISME laboratory highlighted the possibility of using a Combustion Enhancer based on Nitrates (CEN) as an additive.

The Advanced Fuel Ignition Delay Analyzer (AFIDA) apparatus can measure the ignition delay times with high repeatability within very short time. The device also requires small quantities of fuel samples. During AFIDA experiments, liquid fuel is injected into a hot and constant-volume chamber at high pressure. This way the ignition of the spray combines the effects of realistic influences like liquid evaporation and combustion chemistry. The present work investigates the effects of blending ethanol and 2,5-dimethylfuran with primary reference fuels (i.e., mixtures of iso-octane and n-heptane). The primary motivation of this study is to show the differences in ignition delay times of different gasoline-ethanol and gasoline-2,5-dimethylfuran blends where both physical mixing and chemical kinetics have considerable influences. The primary reference fuel is considered as the gasoline surrogate in this work. The study has been conducted at a range of temperatures and pressures.

Modern automotive powertrains are operated using many control devices under a wide range of environmental conditions. The exhaust temperature must be controlled within a specific range to ensure low exhaust-gas emissions and engine-component protection. In this regard, physics-based exhaust-temperature prediction models are advantageous compared with the conventional exhaust-temperature map-based model developed using engine dyno testing results. This is because physics-based models can predict exhaust-temperature behavior in conditions not measured for calibration. However, increasing the computational load to illustrate all physical phenomena in the engine air path, including combustion in the cylinder, may not fully leverage the advantages of physical models for the performance of electric control units (ECUs).

Hydrogen as a chemical energy carrier is considered as one of the most promising options to achieve effective decarbonization of the transportation sector, due to its carbon-free chemical composition. This is particularly true for applications that rely on internal combustion engines (ICEs), although much research is still needed to achieve stable, reliable, and safe operations of the engine. To this purpose, direct injection (DI) of gaseous hydrogen during the compression stroke offers great potential to avoid backfire and largely reduce preignition issues, as opposed to port-fuel injection. Recently, much research has been dedicated, both experimentally and numerically, to understanding the physics and chemistry connected with hydrogen’s mixing and combustion processes in ICEs. This work presents a computational fluid dynamics (CFD) study of the hydrogen DI process in an optical engine operating at relatively low tumble conditions.

To realize a super-leanburn SI engine with a very-high compression ratio, it is required to design a new fuel which could have low ignitability at a low temperature for antiknocking, but high ignitability at a high temperature for stable combustion. Ethane shows a long ignition delay time at a low temperature close to that of methane, but a short ignition delay time at a high temperature close to that of gasoline. In the present study, the antiknocking effect of adding methane with the RON of 120, ethane with the RON of 108, or propane with the RON of 112 to a regular gasoline surrogate fuel with the RON of 90.8 has been investigated. Adding each gaseous fuel by less than 0.4 in heat fraction advances knocking limit in the descending order of SI timing advance of ethane, methane, and propane, and in the descending order of CA 50 advance of ethane, propane, and methane. Adding methane extends combustion duration slightly, but adding ethane or propane shortens it considerably.

This work numerically investigated the methanol compression ignition combustion assisted with a glow plug (GP). The GP was positioned in the middle of the two intake ports. A heating power of 50 W was applied to maintain a quasi-steady temperature of 1323 K for the heating medium. Sensitivity analyses were conducted on various parameters affecting engine combustion characteristics and performance, including radial distance (RD) between the glow plug and injector, relative angle (RA) between the GP and its nearest jet, intake temperature, split ratio of pilot injection, and intake and injection pressures. Due to the complex fuel jet-GP interaction, the optimum RA shifted from 10° at RD = 22.5 mm to 17.5° at RD = 12.5 mm. The optimal RD among the studied values (12.5, 17.5, and 22.5 mm) was found to be 12.5 mm, achieving an indicated thermal efficiency (ITE) of 42.1% at RA = 17.5°.

The use of carbon-free fuels, such as ammonia or hydrogen, or at least carbon neutral fuels, such as green methane or methanol is one of the most important paths in the development of clean internal combustion engines (ICE). Especially for large, heavy-duty engines, this seems to be the most promising route, as replacing them with battery electric or fuel cell drives poses even greater challenges, at least for the time being. But for some applications or areas of the world, even small ICEs for trucks, passenger cars or off-road vehicles, operated with alternative fuels will still remain the mean of choice. One of the biggest challenges in the development of hydrogen combustion engines is achieving high compression ratios and mean effective pressures due to combustion anomalies, caused by the low ignition delay and broad flammability limit of hydrogen. Oil droplets are considered to be one of the main triggers for pre-ignition and knocking.

The development of new fuels for internal combustion engines requires further technical support by understanding the pollutant formation mechanism in various phases of combustion so that emissions can be minimized. This research will therefore utilize a bespoke in-cylinder sampling system to analyze the precursors of PAHs and particulates during bio-derived lactone combustion in a single-cylinder diesel engine. The sampling system was composed of a poppet-type in-cylinder sampling valve that displaced one of the engine intake valves and protruded into the combustion chamber beyond the flame quenching layer, and a Gas Chromatography Flame Ionization Detector (GC-FID) that examined the samples. The sampling valve was electromagnetically actuated, and its operation was referenced to the engine crank shaft encoder, allowing the valve to open at any Crank Angle Degree (CAD) within a timing resolution of 0.2 CAD.

A reactivity-controlled compression ignition (RCCI) engine offers ultralow soot and nitrogen oxide (NOx) emission in addition to higher thermal efficiency than diesel or compression ignition (CI) engines. However, the higher emissions of unburned hydrocarbons (HC) and carbon monoxide (CO) from RCCI engines pose a significant challenge that hinders their adoption in the future automotive sector. Additionally, HC includes several hydrocarbons that harm human health and the environment. This study aims to minimize HC and CO formation and emissions by implementing different injection strategies, including adjustments to spray angle configuration, injection timing, and fuel premixing ratio. Additionally, the study examines how different injection strategies affect the spatial and temporal distribution of HC and CO inside the combustion chamber.