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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.

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).

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.

A digital twin is a digital representation of a planned or real physical system, product, or process that functions as its practically identical digital counterpart for tasks such as testing, integration, monitoring, and maintenance. Creating digital twins allows the ‘digital system’ or ‘digital product’ to be tested faster-than-real-time improving overall efficiency and reducing time of a programme. The HORIBA Intelligent Lab virtual engineering toolset was used produce an empirically based digital twin of a contemporary off-highway diesel Internal Combustion Engine (ICE). These empirical models were then coupled with simulations developed by AgriSI and IPG CarMaker to predict performance and emissions for real-world machine handling cycles of off-highway machines such as ploughing, planting, weeding, and fertilising.

Waste cooking oil can be converted into fuel for internal combustion (IC) engine applications by transesterification or pyrolysis. Transesterification results in the production of fatty acid methyl esters called biodiesel. The variability in biodiesel composition and properties from diesel fuel leads to engine re-calibration that requires significant time and effort. Diesel-like hydrocarbons can be produced by catalytic pyrolysis of used cooking oil. Such fuel can be used as a drop-in fuel in IC engine applications. Hydrogen at high pressures and a catalyst generally promote deoxygenation during pyrolysis. Recently, novel heterogenous acid catalysts such as Ni-impregnated activated carbon (AC) and Ag-Co-impregnated AC catalysts were developed to produce deoxygenated fuel by pyrolysis at atmospheric pressure without using hydrogen. Homogenous base catalysts such as sodium hydroxide can also be used in pyrolysis to produce diesel-like fuel.

Accurate flywheel torque estimation in combustion engines can be used for monitoring engine performance, creating the potential for lowering emissions and fuel costs. Recently a method was proposed to determine the mean flywheel torque from instantaneous engine speed using the n-th order Fourier series, where n is the number of cylinders firing per crank revolution. However, instantaneous engine speed is affected by two separate torque contributions. The torque resulting from reciprocating masses in the engine, i.e., reciprocating torque, and the torque produced by combustion pressure, i.e., gas torque. Gas torque and reciprocating torque signals have the same frequency but are in opposite phases. Since the resultant torque at the flywheel is the sum of gas and reciprocating torques, there is a need to remove reciprocating torque from the total torque at the flywheel. This requires knowing whether gas or reciprocating torque has a larger amplitude.

The Reactivity Control Compression Ignition (RCCI) engine, with its dual fuel system and coordinated injection strategy, offers superior emission control and fuel efficiency compared to conventional diesel engines. However, cyclic variations leading to engine combustion instability poses a significant challenge to their development and commercialization. In this study, statistical (COV and Histogram) and nonlinear dynamic (Recurrence Plot and its Quantification) analysis techniques are applied on the time-series data obtained from a single-cylinder diesel engine modified to operate in CNG-Diesel RCCI mode. The engine, while advancing the main injection timing (SOI-2), is tested under various operating conditions, including different engine loads, direct injection mass ratios (DIMR) and port fuel injection (PFI) masses, to help identify the configurations with better temporal correlations and deterministic traits. Such configurations hold potential for control strategy implementation.

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°.

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.

Combustion in conventional and advanced diesel engines is an intricate process that encompasses interaction among fuel injection, fuel-air mixing, combustion, heat transfer, and engine geometry. Manipulation of fuel injection strategies has been recognized as a promising approach for optimizing diesel engine combustion. Although numerous studies have investigated this topic, the underlying physics behind flame interactions from multiple fuel injections, spray-flame-wall interaction and their effects on reaction zones, and NOx/soot emissions are still not well understood. To this end, a computational fluid dynamics (CFD) study is performed to investigate the effects of pilot and post injections on in-cylinder combustion process and emissions (NOx and soot) formation in a heavy-duty (HD) diesel engine.

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.

High-efficiency lean-burn compression ignition using high-reactivity fuels, known as Gasoline Compression Ignition (GCI), demonstrates potential in reducing particulate matter (PM) and nitrogen oxide (NOx) emissions by controlling the charge ignition through both local strength and auto-ignition chemistry. This study explores the combustion strategy for GCI fuel with a Research Octane Number (RON) of 61 under a wide range of operating conditions using a Single Cylinder Research Engine (SCRE) calibrated to Euro 5 emission standards. The SCRE, with a compression ratio (CR) of 16.50, is designed for high-reactivity fuels and features a centrally located multi-hole injector and a piston bowl shape tailored to injection and spray characteristics. At steady state and part load (IMEP = 7 bar), the study investigates the impact of fuel injection strategy and the required amount of exhaust gas recirculation (EGR).

Diesel engines are largely used as power units with high fuel efficiency. Conversely, they have an adverse impact on the environment and human health as they emit high NOx and particulate Matter (PM) emissions. As more stringent regulations for emissions are introduced, low temperature combustion (LTC) strategy such as Gasoline Compression Ignition (GCI) demonstrated the potential to reduce the PM, NOx emissions by operating engines under a Partially Premixed Combustion (PPC) mode. Therefore, A 0.550 mm single cylinder engine SCE, which is operated at Gasoline Direct Injection Ignition (GDCI), was tested over range of engine loads with constant speed (1500 rpm) using RON80 without oxygenate. Different operating parameters such as injection were used to control combustion phasing and mixture stratifications. At low loads, rebreathing (RB) of hot exhaust gas produced low levels of NOx and smoke emissions.

Catalyst heating operation in compression-ignition engines is critical to ensure rapid light-off of exhaust catalysts during cold-start. This is typically achieved by using late post injections for increased exhaust enthalpy, which retardability is constrained by acceptable CO and unburned hydrocarbons emissions, since they are directly emitted through the tailpipe due to the inactivity of the oxidation catalyst at these conditions. Post-injection retardability has shown to be affected by the cetane number of the fuel [SAE 2022-01-0483], but it is unclear how other fuel properties may affect the ability to retard the combustion. This study aims to understand the impact of the distillation characteristics of the fuel on the performance of catalyst heating operation and on post-injection retardability.

In the context of energy conservation and emission reduction, high power density(HPD) and low fuel consumption are the consistent pursuit of diesel engine development. Among the small-bore diesel, the limited space in the cylinder poses higher challenges and requirements for the arrangement of sprays.The high injection pressure results in a greater impulse when the spray impinges chamber, which allows the combustibles to develop along the chamber wall. Based on these characteristics of small-bore HPD diesel, a reasonable injection scheme is proposed to help flame diffusion surface increasing and thermal efficiency enhancing. This work proposes an optimization path to increase the flame diffusion surface, then improve thermal efficiency. It can be achieved with matching between the injector extension length and the spray spray angle.

With all the environmental concern of diesel fuelled vehicle, it is a formidable challenge to phase out them completely specifically from Heavy duty application. Most pragmatic solution lies in solutions which improves the fuel economy and reduce the carbon emission of existing diesel fuelled vehicle fleet and have economical & feasible for vast geographical extent of country. With implementation of BS VI emission norms across country from April 2020, supply of BS VI complied diesel fuel started and BS VI complied vehicles with upgraded engine technologies and after treatment devices have started to come which make present vehicle fleets heterogeneous with substantive number of BS IV vehicle. Beside improvement of engine technologies, existing BS IV vehicle fleet performance can be enhanced through improved fuel and lubricants solutions.

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.

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 major challenge for auto industries is reducing NOx and other exhaust gas emissions to meet stringent Euro 7 emission regulations. A urea Selective Catalyst Reduction (SCR) after-treatment system (ATS) commonly uses upstream urea water injection to reduce NOx from the engine exhaust gas. The NOx emission conversion rate in ATSs is high for high exhaust gas temperatures but substantially low for temperatures below 200℃. This study aims to improve the NOx conversion rate using urea pulse injection in a mass-production 2.2 L diesel engine equipped with an SCR ATS operated under low exhaust gas temperature. The engine experimental results show that, under 200℃ exhaust temperature and 3.73x104 h-1 gross hourly space velocity (SV), the NOx conversion rate can be improved by 5% using 5-sec ON and 12-sec OFF (denoted as 5/12 s) urea pulse supply compared to the constant supply under time-averaged 1.0 urea equivalence ratio.

Selective catalytic reduction (SCR) technology is currently one of the most effective methods to reduce NOx emissions for engine. In order to cope with the energy crisis and environmental pollution problems, hydrogen engines have been widely studied in recent years. However, high NOx emissions under some working conditions still need to be further solved. NH3-SCR technology is considered to be the most promising hydrogen engine after-treatment device. This paper used Cu-SSZ-13, which is widely commercially available, as the research object, and explored the relationship between micron and nanoscale grain sizes through experimental methods such as BET, XRD, NH3-TPD, UV-vis-DRS and activity testing, the influence mechanism of micron-scale and nano-scale grain size on the morphology and properties of Cu-SSZ-13 catalyst was explored.