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In the present work, five surrogate components (n-Hexadecane, n-Tetradecane, Heptamethylnonane, Decalin, 1-Methylnaphthalene) are proposed to represent liquid phase of diesel fuel, and another different five surrogate components (n-Decane, n-Heptane, iso-Octane, MCH (methylcyclohexane), Toluene) are proposed to represent vapor phase of diesel fuel. For the vapor phase, a 5-component surrogate chemical kinetic mechanism has been developed and validated. In the mechanism, a recently updated H2/O2/CO/C1 detailed sub-mechanism is adopted for accurately predicting the laminar flame speeds over a wide range of operating conditions, also a recently updated C2-C3 detailed sub-mechanism is used due to its potential benefit on accurate flame propagation simulation. For each of the five diesel vapor surrogate components, a skeletal sub-mechanism, which determines the simulation of ignition delay times, is constructed for species C4-Cn.

This study investigated the potential of generating reactive chemical species (including radicals) through pilot fuel injection in negative valve overlap for improving the combustion and emissions performances of spark ignition gasoline engines under low load and low speed operating conditions. Several Ford sub-models were used for simulating the physics and chemistry processes of injecting a small amount of fuel in NVO (negative valve overlap). Effects of different NVO degrees and different pilot injection timings, factors for fuel conversion were simulated and investigated. CO and H2 conversions during NVO, CO and H2 amounts before spark timing were used for comparing different schemes.

A series of cold start experiments using a 2.0 liter gasoline turbocharged direct injection (GTDI) engine with custom controls and calibration were carried out using gasoline and iso-pentane fuels, to obtain the cold start emissions profiles for the first 5 firing cycles at an ambient temperature of 22°C. The exhaust gases, both emitted during the cold start firing and emitted during the cranking process right after the firing, were captured, and unburned hydrocarbon emissions (HC), CO, and CO2 on a cycle-by-cycle basis during an engine cold start were analyzed and quantified. The HCs emitted during gasoline-fueled cold starts was found to reduce significantly as the engine cycle increased, while CO and CO2 emissions were found to stay consistent for each cycle. Crankcase ventilation into the intake manifold through the positive-crankcase ventilation (PCV) valve system was found to have little effect on the emissions results.

There is keen interest in understanding the origins of engine-out unburned hydrocarbons emitted during SI engine cold start. This is especially true for the first few firing cycles, which can contribute disproportionately to the total emissions measured over standard drive cycles such as the US Federal Test Procedure (FTP). This study reports on the development of a novel methodology for capturing and quantifying unburned hydrocarbon emissions (HC), CO, and CO2 on a cycle-by-cycle basis during an engine cold start. The method was demonstrated by applying it to a 4 cylinder 2 liter GTDI (Gasoline Turbocharged Direct Injection) engine for cold start conditions at an ambient temperature of 22°C. For this technique, the entirety of the engine exhaust gas was captured for a predetermined number of firing cycles.

In this work we studied the effects of piston bowl design on combustion in a small-bore direct-injection diesel engine. Two bowl designs were compared: a conventional, omega-shaped bowl and a stepped-lip piston bowl. Experiments were carried out in the Sandia single-cylinder optical engine facility, with a medium-load, mild-boosted operating condition featuring a pilot+main injection strategy. CFD simulations were carried out with the FRESCO platform featuring full-geometric body-fitted mesh modeling of the engine and were validated against measured in-cylinder performance as well as soot natural luminosity images. Differences in combustion development were studied using the simulation results, and sensitivities to in-cylinder flow field (swirl ratio) and injection rate parameters were also analyzed.

The Single Sequential Turbocharger (SST) used in Ford’s 6.7L Scorpion Diesel is analyzed using Computational Fluid Dynamics (CFD) to draw conclusions about the compressor stability at low mass flows. The SST compressor concept consists of a double-sided wheel which flows in parallel fed by two separate inlets (front and rear), followed by a single vane-less diffuser, and a volute. CFD simulations for the full stage are performed at low mass flow rates Both, front and rear, sides have ported shroud casing-treatment (CT) in the inlet region. An objective of the analysis is to determine which side of the SST unit compressor (front or rear on the double-sided wheel) suffers flow break down first as the mass flow is reduced, and its impact on the overall stability of the SST compressor. Another objective is to better understand the interactions between the compressor inlet flow and the flow through the casing-treatment.

Electrically assisted turbochargers are a promising technology for improving boost response of turbocharged engines. These systems include a turbocharger shaft mounted electric motor/generator. In the assist mode, electrical energy is applied to the turbocharger shaft via the motor function, while in the regenerative mode energy can be extracted from the shaft via the generator function, hence these systems are also referred to as regenerative electrically assisted turbochargers (REAT). REAT allows simultaneous improvement of boost response and fuel economy of boosted engines. This is achieved by optimally scheduling the electrical assist and regeneration actions. REAT also allows the exhaust turbine to operate within a narrow range of optimal vane positions relative to the unassisted variable geometry turbocharger (VGT). The ability to operate within a narrow range of VGT vane positions allows an opportunity for a more optimal turbine design for a REAT system.

In light-duty direct-injection (DI) diesel engines, combustion chamber geometry influences the complex interactions between swirl and squish flows, spray-wall interactions, as well as late-cycle mixing. Because of these interactions, piston bowl geometry significantly affects fuel efficiency and emissions behavior. However, due to lack of reliable in-cylinder measurements, the mechanisms responsible for piston-induced changes in engine behavior are not well understood. Non-intrusive, in situ optical measurement techniques are necessary to provide a deeper understanding of the piston geometry effect on in-cylinder processes and to assist in the development of predictive engine simulation models. This study compares two substantially different piston bowls with geometries representative of existing technology: a conventional re-entrant bowl and a stepped-lip bowl. Both pistons are tested in a single-cylinder optical diesel engine under identical boundary conditions.

Future LEV-III tailpipe (TP) emission regulations pose an enormous challenge forcing the fleet average of light-duty vehicles produced in the 2025 model year to perform at the super ultralow emission vehicle (SULEV-30) certification levels (versus less than 20% produced today). To achieve SULEV-30, regulated TP emissions of non-methane organic gas (NMOG) hydrocarbons (HCs) and oxygenates plus oxides of nitrogen (NOx) must be below a combined 30 mg/mi (18.6 mg/km) standard as measured on the federal emissions certification cycle (FTP-75). However, when flex-fuel vehicles use E85 fuel instead of gasoline, NMOG emissions at cold start are nearly doubled, before the catalytic converter is active. Passive HC traps (HCTs) are a potential solution to reduce TP NMOG emissions. The conventional HCT design was modified by changing the zeolite chemistry so as to improve HC retention coupled with more efficient combustion during the desorption phase.

In the development of HC traps (HCT) for reducing vehicle cold start hydrocarbon (HC)/nitrogen oxide (NOx) emissions, zeolite-based adsorbent materials were studied as key components for the capture and release of the main gasoline-type HC/NOx species in the vehicle exhaust gas. Typical zeolite materials capture and release certain HC and NOx species at low temperatures (<200°C), which is lower than the light-off temperature of a typical three-way catalyst (TWC) (≥250°C). Therefore, a zeolite alone is not effective in enhancing cold start HC/NOx emission control. We have found that a small amount of Pd (<0.5 wt%) dispersed in the zeolite (i.e., BEA) can significantly increase the conversion efficiency of certain HC/NOx species by increasing their release temperature. Pd was also found to modify the adsorption process from pure physisorption to chemisorption and may have played a role in the transformation of the adsorbed HCs to higher molecular weight species.

Passive in-line catalyzed hydrocarbon (HC) traps have been used by some manufacturers in the automotive industry to reduce regulated tailpipe (TP) emissions of non-methane organic gas (NMOG) during engine cold-start conditions. However, most NMOG molecules produced during gasoline combustion are only weakly adsorbed via physisorption onto the zeolites typically used in a HC trap. As a consequence, NMOG desorption occurs at low temperatures resulting in the use of very high platinum group metal (PGM) loadings in an effort to combust NMOG before it escapes from a HC trap. In the current study, a 2.0 L direct-injection (DI) Ford Focus running on gasoline fuel was evaluated with full useful life aftertreatment where the underbody converter was either a three-way catalyst (TWC) or a HC trap. A new HC trap technology developed by Ford and Umicore demonstrated reduced TP NMOG emissions of 50% over the TWC-only system without any increase in oxides of oxygen (NOx) emissions.

Due to the increasing concerns on energy and environmental issues, the automotive industry has seen increased growth and development of electric and electrified vehicles [1]. The power-split design is one of the most common drivetrain configurations of a hybrid or electrified vehicle. The propulsion system of a power-split hybrid vehicle typically comprises of an engine drive system in which the engine, drivetrain and generator are mechanically coupled on a planetary gear set driveline while the electric drive system consists of a high voltage battery and a traction motor [2]. In recent years, Hardware-in-the-Loop (HIL) simulation has become an increasingly common approach for controls rapid prototyping and validation as part of the automotive product development cycle [2, 3].

In light- and medium-duty diesel engines, piston bowl shape influences thermal efficiency, either due to changes in wall heat loss or to changes in the heat release rate. The relative contributions of these two factors are not clearly described in the literature. In this work, two production piston bowls are adapted for use in a single cylinder research engine: a conventional, re-entrant piston, and a stepped-lip piston. An injection timing sweep is performed at constant load with each piston, and heat release analyses provide information about thermal efficiency, wall heat loss, and the degree of constant volume combustion. Zero-dimensional thermodynamic simulations provide further insight and support for the experimental results. The effect of bowl geometry on wall heat loss depends on injection timing, but changes in wall heat loss cannot explain changes in efficiency.

Boost converter is widely applied to hybrid electric vehicles (HEV). Typical control methods employ two proportional-integral (PI) regulators to fulfill DC bus voltage closed-loop control and inductor current closed-loop control, respectively. They have intrinsic performance limitations: 1) slow dynamic response of DC bus voltage regulation; 2) high overshoot voltage during transient state; 3) it is difficult to design four gains best fit all operational conditions. This paper proposes a model prediction based boost converter control method for HEV applications. The proposed control method employs model based instantaneous power prediction and dynamic optimization in real time by minimizing a defined cost function to overcome above issues. First of all, the issues of typical control methods are analyzed. Then, the proposed control method is presented in detail, followed by simulation verification and comparison with PI based control method.

It is anticipated that future gasoline engines will have improved mechanical efficiency and consequently lower exhaust temperatures at low load conditions, although the exhaust temperatures at high load conditions are expected to remain the same or even increase due to the increasing use of downsized turbocharged engines. In 2014, a collaborative project was initiated at Ford Motor Company, Oak Ridge National Lab, and the University of Michigan to develop three-way catalysts with improved performance at low temperatures while maintaining the durability of current TWCs. This project is funded by the U.S. Department of Energy and is intended to show progress toward the USDRIVE target of 90% conversion of hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NOx) at 150 °C after high mileage aging. The testing protocols specified by the USDRIVE ACEC team for stoichiometric S-GDI engines were utilized during the evaluation of experimental catalysts at all three facilities.

The design of modern diesel-powered vehicles involves optimization and balancing of trade-offs for fuel efficiency, emissions, and noise. To meet increasingly stringent emission regulations, diesel powertrains employ aftertreatment devices to control nitrogen oxides, hydrocarbons, carbon monoxide, and particulate matter emissions and use active exhaust warm-up strategies to ensure those devices are active as quickly as possible. A typical strategy for exhaust warm-up is to operate with retarded combustion phasing, limited by combustion stability and HC emissions. The amount of exhaust enthalpy available for catalyst light-off is limited by the extent to which combustion phasing can be retarded. Diesel cetane number (CN), a measure of fuel ignition quality, has an influence on combustion stability at retarded combustion phasing. Diesel fuel in the United States tends to have a lower CN (both minimum required and average in market) than other countries.

Thermal effectiveness of Exhaust Gas Recirculation (EGR) coolers used in diesel engines can progressively decrease and stabilize over time due to inner fouling layer of the cooler tubes. Thermophoretic force has been identified as the major cause of diesel exhaust soot fouling, and models are proposed in the literature but improvements in simulation are needed especially for the long-term trend of soot deposition. To describe the fouling stabilization behavior, a removal mechanism is required to account for stabilization of the soot layer. Observations from previous experiments on surrogate circular tubes suggest there are three primary factors to determine removal mechanisms: surface temperature, thickness, and shear velocity. Based on this hypothesis, we developed a 1D CFD fouling model for predicting the thermal effectiveness reduction of real EGR coolers. The model includes the two competing mechanisms mentioned that results in fouling balance.

Emissions and fuel economy optimization of internal combustion engines is becoming more challenging as the stringency of worldwide emission regulations are constantly increasing. Aggressive transient characteristics of new emission test cycles result in transient operation where the majority of soot is produced for turbocharged diesel engines. Therefore soot optimization has become a central component of the engine calibration development process. Steady state approach for air-fuel ratio limitation calibration development is insufficient to capture the dynamic behavior of soot formation and torque build-up during transient engine operation. This paper presents a novel methodology which uses transient maneuvers to optimize the air-fuel ratio limitation calibration, focusing on the trade-off between vehicle performance and engine-out soot emissions. The proposed methodology features a procedure for determining candidate limitation curves with smoothness criteria considerations.

Hybrid Electric Vehicles (HEV) utilize a High Voltage (HV) battery pack to improve fuel economy by maximizing the capture of vehicle kinetic energy for reuse. Consequently, these HV battery packs experience frequent and rapid charge-discharge cycles. The heat generated during these cycles must be managed effectively to maintain battery cell performance and cell life. The HV battery pack cooling system must keep the HV battery pack temperature below a design target value and maintain a uniform temperature across all of the cells in the HV battery pack. Herein, the authors discuss some of the design points of the air cooled HV battery packs in Ford Motor Company’s current model C-Max and Fusion HEVs. In these vehicles, the flow of battery cooling air was required to not only provide effective cooling of the battery cells, but to simultaneously cool a direct current high voltage to low voltage (DC-DC) converter module.

To meet future particle mass and particle number standards, gasoline vehicles may require particle control, either by way of an exhaust gas filter and/or engine modifications. Soot levels for gasoline engines are much lower than diesel engines; however, non-combustible material (ash) will be collected that can potentially cause increased backpressure, reduced power, and lower fuel economy. The purpose of this work was to examine the ash loading of gasoline particle filters (GPFs) during rapid aging cycles and at real time low mileages, and compare the filter performances to both fresh and very high mileage filters. Current rapid aging cycles for gasoline exhaust systems are designed to degrade the three-way catalyst washcoat both hydrothermally and chemically to represent full useful life catalysts. The ash generated during rapid aging was low in quantity although similar in quality to real time ash. Filters were also examined after a low mileage break-in of approximately 3000 km.