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With the introduction of EV technology into the light-duty vehicle market, the demand for gasoline in conventional spark ignition engines is projected to decline in the coming decades. Therefore, researchers have been investigating the use of gasoline and other light fuels in heavy-duty engine applications. In heavy-duty engines, the combustion mode will likely be non-premixed, mixing-controlled combustion, where the rate of combustion is determined by the fuel-air mixing process. This creates a range of mixture conditions inside the engine cylinder at every instance in time. The goal of this research is to experimentally quantify the sooting behaviors of light fuels under a range of compression ignition engine mixture conditions (i.e., a range of equivalence ratios).

Compared to conventional diesel combustion (CDC), isobaric combustion can achieve higher thermal efficiency while lowering heat transfer losses and nitrogen oxides (NOx). However, isobaric combustion suffers from higher soot emissions. While the aforementioned trends are well established, there is limited literature about the high-temperature reaction zones, the liquid-phase penetration distance, and the flame tip propagation velocity of isobaric combustion. In the present study, the line-of-sight integrated imaging of Mie-scattering, combustion luminosity, and CH* chemiluminescence were conducted in an optically accessible single-cylinder heavy-duty diesel engine. The engine was equipped with a flat-bowl-shaped optical piston to allow bottom-view imaging of the combustion chamber. The experiments were conducted using n-heptane fuel for CDC and isobaric combustion modes.

This paper presents a ultra-high pressure sensor composed the measurement membrane manufactured by MIM (Metal Powder Injection Molding). The membrane should be sufficiently deformed within the measuring pressure range and not be broken at the burst pressure. Therefore, in general, the high pressure sensor membrane made of metal using machining methods such as milling and drilling. However, it requires additional process to assembly with other parts and is difficult to make complex structure such as screw. Thus, in this paper, we propose the product and design of the measurement membrane using the MIM method. We have developed the ultra-high pressure sensor capable of measuring to 900 bar.gauge. Figure 1 shows the ultra-high pressure and measurement part. The measurement membrane thickness is 900 μm and diameter is 3.2 mm. The MEMS sensor element mounted on the measuring membrane surface outputs an electrical signal according to the pressure.

This paper presents experimental results of a 10.6L, three-cylinder opposed-piston (OP) operating on diesel fuel designed for heavy duty (Class 8) operation. The paper will describe the engine configuration and calibration of both catalyst light-off and high efficiency modes. Analysis based on measured results show the engine can comply with all 2027 California Air Resourced Board (CARB) and Environmental Protection Agency (EPA) requirements for CO2 and criteria emissions. Due to the ability of the OP Engine to combine low oxides of nitrogen (NOX) flux with high exhaust enthalpy for early catalyst light off, the engine can meet all 2027 CARB and EPA NOX standards with a current, state of the art conventional underfloor aftertreatment system. No additional emissions control technology is required.

Knock in gasoline engines at higher loads is a significant constraint on torque and efficiency. The anti-knock property of a fuel is closely related to its research octane number (RON). Ethanol has superior RON compared to gasoline and thus has been commonly used to blend with gasoline in commercial gasolines. However, as the RON of a fuel is constant, it has not been used as needed in a vehicle. To wisely use the RON, an On-Board Separation (OBS) unit that separates commercial gasoline with ethanol content into high-octane fuel with high ethanol fraction and a lower octane remainder has been developed. Then an onboard Octane-on-demand (OOD) concept uses both fuels in varying proportion to provide to the engine a fuel blend with just enough RON to meet the ever changing octane requirement that depends on driving pattern.

Despite the advantages of turbocharging in improved engine performance and reduced exhaust emissions, commercial single-cylinder engines used for automotive applications remain naturally aspirated (NA) and are not generally turbocharged. This is due to the shortcomings with pulsated and intermittent exhaust gas flow into the turbine and the phase lag between the intake and exhaust stroke. In the present study, experimental investigations are initially carried out with a suitable turbocharger closely coupled to a single-cylinder diesel engine. Results indicated that the engine power dropped significantly by 40% for the turbocharged engine compared to the NA version even though the air mass flow rate was increased by at least 1.5 times with turbocharging. A novel approach of decoupling the turbine and the compressor and coupling them separately to the engine is proposed to address these limitations.

The electrification of powertrains provides a critical opportunity to change the way that engines are designed and developed, allowing their efficiency to be increased and their cost reduced. This paper draws on ongoing Ricardo projects in the field of dedicated hybrid engines (DHEs). The Magma xEV combustion concept employs very high compression ratio, long stroke architecture, and advanced ignition and knock mitigation technologies, for DHEs requiring the highest efficiency. In the latest research project a pre-chamber combustion system (with both active and passive operation) has been applied to the Magma xEV engine, in order to enable the highest levels of charge dilution and further increase brake thermal efficiency. The research focussed on benefits of pre-chamber ignition as compared to conventional spark ignition and corona discharge ignition. The comparison of charge dilution using excess air (lean operation) and exhaust gas recirculation are presented.

Development of propulsion control systems frequently involves large-scale transient simulations, e.g. Monte Carlo simulations or drive-cycle optimizations, which require fast dynamic plant models. Models of the air-path—for internal combustion engines or fuel cells—can exhibit stiff behavior, though, causing slow numerical simulations due to either using an implicit solver or sampling much faster than the bandwidth of interest to maintain stability. This paper proposes a method to reduce air-path model stiffness by adding an impedance in series with potentially stiff components, e.g. throttles, valves, compressors, and turbines, thereby allowing the use of a fast-explicit solver. An impedance, by electrical analogy, is a frequency-dependent resistance to flow, which is shaped to suppress the high-frequency dynamics causing air-path stiffness, while maintaining model accuracy in the bandwidth of interest.

GTDI engines are becoming more efficient, whether individually or part of a HEV (Hybrid Electric Vehicle) powertrain. For the latter, this efficiency manifests itself as increase in zero emissions vehicle mileage. An ideal device for energy recovery is a turbogenerator (TG), and, when placed downstream the conventional turbine, it has minimal impact on catalyst light-off and can be used as a bolt-on aftermarket device. A Ricardo WAVE model of a representative GTDI engine was adapted to include a TG (Turbogenerator) and TBV (Turbine Bypass Valve) with the TG in a mechanical turbocompounding configuration, calibrated using steady state mapping data. This was integrated into a co-simulation environment with a SISO (Single-Input, Single-Output) dynamic controller developed in SIMULINK for the actuator control (with BMEP, manifold air pressure and TG pressure ratio as the controlled variables).

Soot particle size, particle concentration and volume fraction were measured by laser based methods in optically dense, highly turbulent combusting diesel sprays under engine-like conditions. Experiments were done in the Chalmers High Pressure, High Temperature spray rig under isobaric conditions and combusting commercial diesel fuel. Laser Induced Incandescence (LII), Elastic Scattering and Light Extinction were combined quasi-simultaneously to quantify particle characteristics spatially resolved in the middle plane of a combusting spray at two instants after the start of combustion. The influence that fuel injection pressure, gas temperature and gas pressure exert on particle size, particle concentration and volume fraction were studied. Probability density functions of particle size and two-dimensional images of particle diameter, particle concentration and volume fraction concerning instantaneous single-shot cases and average measurements are presented.

This paper describes a configuration and controller, designed using Autonomie,1 for dual-motor battery electric vehicle (BEV) heavy-duty trucks. Based on the literature and current market research, this model was designed with two electric motors, one on the front axle and the other on the rear axle. A rule-based control algorithm was designed for the new dual-motor BEV, based on the model, and the control parameters were optimized by using a genetic algorithm (GA). The model was simulated in diverse driving cycles and gradeability tests. The results show both a good following of the desired cycle and achievement of truck gradeability performance requirements. The simulation results were compared with those of a single-motor BEV and showed reduced energy consumption with the high-efficiency operation of the two motors.

Cylinder air-charge is one of the most important parts of the torque control in a gasoline engine, due to the necessity to keep a stoichiometric air-fuel ratio, for the three-way catalyst to work efficiently. Throttle and phasing of the camshafts are actuators that have a big effect on the cylinder air-charge, this results in a cross-coupling between the actuators. One approach to handle the cross-coupling that occurs with multiple actuators is to use model predictive control (MPC), that handles the cross-coupling through the use of models and optimization. Models that support computation of gradients and hessians are desirable for use in MPC. To support the model design experimental data of cylinder pressure, from an inline four-cylinder engine with dual independent cam phasing, supported by gas exchange simulation, the effects from variable valve timing on the cylinder air-charge are investigated during the valve overlap period.

Spark discharge properties were studied and characterized for varying gas compositions and spark plug geometries using a spark calorimeter and constant volume optical vessel. Two different 18 mm natural gas engine spark plugs were used in the experiments. All measurements were recorded under quiescent conditions and with a spark gap of 0.30 mm. The spark plug calorimeter was used for measuring thermal energy deposition to the gas for gas compositions of nitrogen, a stoichiometric mixture of nitrogen and methane, a stoichiometric mixture of nitrogen and methane diluted with 30% carbon dioxide by volume, and for air. Other measurements of interest included breakdown voltage, electrical energy delivered to the spark gap, electrical-to-thermal energy conversion efficiency, and spark duration, for pressures up to 28 bar at 300 K. The optical vessel was used for the combusting mixture of stoichiometric air and methane at pressures up to 28 bar.

Performance of the ignition system becomes more important than ever, because of the extensively used EGR in modern spark-ignition engines. Future lean burn SI and SACI combustion modes demand even stronger ignition capability for robust ignition control. For spark-based ignition systems, extensive research has been carried out to investigate the discharge characteristics of the ignition process, including discharge current amplitude, discharge duration, spark energy, and plasma stretching. The correlation between the spark stretch and the discharge energy, as well as the impact of discharge current level on this correlation, are important with respect to both ignition performance, and ignition system design. In this paper, a constant volume combustion chamber is applied to study the impact of plasma stretch on the spark energy release process with cross-flow speed from 0 m/s up to 70 m/s.

Octane number (ON) and octane sensitivity (S), the fuel anti-knock indices, are critical for the design of advanced jet ignition engines. In this study, ten fuels with different research octane number (RON) and varying S were formulated based on ethanol reference fuels (ERFs) to investigate the effect of S on combustion of jet ignition engine. To fully understand S effects, the combustion characteristics under EGR dilution and lean burn were further investigated. The results indicated that increasing S resulted in higher reactivity with shorter ignition delay and combustion duration. The increase of reactivity led to heavier knocking intensity. The competition between the flame speed and the reactivity of the mixture determined the auto-ignition fraction of mixture and the knocking onset crank angle as S varied. Medium S (S=3) was helpful to improve the combustion speed, reduce the auto-ignition fraction of mixture and retard the knocking onset crank angle.

Lean operation of spark ignition engines is a promising strategy for increasing thermal efficiency and minimize emissions. Variability on the other hand is one of the main shortcomings in these conditions. In this context, the present study looks at the interaction between the spark produced by a J-type plug and the surrounding fluid flow. A combined experimental and numerical approach was implemented so as to provide insight into the phenomena related to the ignition process. A sweep of cross-flow velocity of air was performed on a dedicated test rig that allowed accurate control of the volumetric flow and pressure. This last parameter was varied from ambient to 10 bar, so as to investigate conditions closer to real-world engine applications. Optical diagnostics were applied for better characterization of the arc in different operating conditions. The spatial and temporal evolution of the arc was visualized with high-speed camera to estimate the length, width and stretching.

Autoignition enhancing additives have been used for years to enhance the ignition quality of diesel fuel, with 2-ethylhexyl nitrate (EHN) being the most common additive. EHN also enhances the autoignition reactivity of gasoline, which has advantages for some low-temperature combustion techniques, such as Sandia’s Low-Temperature Gasoline Combustion (LTGC) with Additive-Mixing Fuel Injection (AMFI). LTGC-AMFI is a new high-efficiency and low-emissions engine combustion process based on supplying a small, variable amount of EHN into the fuel for better engine operation and control. However, the mechanism by which EHN interacts with the fuel remains unclear. In this work, a chemical-kinetic mechanism for EHN was developed and implemented in a detailed mechanism for gasoline fuels. The combined mechanism was validated against shock-tube experiments with EHN-doped n-heptane and HCCI engine data for EHN-doped regular E10 gasoline. Simulations showed a very good match with experiments.

Homogeneous charge compression ignition (HCCI) combustion is low-temperature combustion (LTC) mode that offers an alternative to conventional combustion modes. The advantages of HCCI combustion include high conversion efficiency and low NOx emissions. On the other hand, a direct control mechanism for combustion phasing control is not attainable as in conventional SI (spark ignition) or CI (compression ignition) engines. This limits the HCCI operational range and provides one of the biggest challenges in HCCI mode commercial implementation. High heat release rates and knock initiation limit the high load operation, whereas combustion instabilities limit the low load operation. In this context, this paper explores the use of water injection technique to control the combustion phasing and expand the load of an ethanol HCCI engine.

Progressively stringent emission regulations and increasing regulatory demands on fuel economy have led to advanced combustion development. Low temperature combustion (LTC), specifically homogenous charge compression ignition (HCCI), is a promising technology for reducing exhaust emissions and improving efficiency. However, its operating range is limited to low load without boosting and EGR, due to low volumetric efficiency and high pressure rise rates. In addition, effectively controlling the combustion phasing is another challenge in realizing the associated combustion gains. In this work, advanced valve control mechanisms known as continuously variable valve duration (CVVD) and continuously variable valve timing (CVVT) were used for both intake and exhaust valvetrains to enable negative valve overlap (NVO) for trapping hot exhaust residuals and to promote multipoint simultaneous ignition.

Internal combustion engines (ICE) will be a part of personal transportation for the foreseeable future. One recent trend for engines has been downsizing which enables the engine to be run more efficiently over regulatory drive cycles. Due to downsizing, engine power density has increased which leads to problems with engine knock. Therefore, there is an increasing need to find a means to reduce the knock propensity of downsized engines. One of the ways of reducing knock propensity is by introducing Exhaust Gas Recirculation (EGR) into the combustion chamber, however, volumetric efficiency also reduces with EGR which places challenges on the boosting system. The individual benefits of high-pressure (HP-EGR) and low-pressure (LP-EGR) loop EGR system to assist the boosting system of a 2.0 L Gasoline Direct Injection (GDI) production engine are explored in this paper.