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This paper quantifies the potential of electric propulsion systems to reduce petroleum use and greenhouse gas (GHG) emissions in the 2030 U.S. light-duty vehicle fleet. The propulsion systems under consideration include gasoline hybrid-electric vehicles (HEVs), plug-in hybrid vehicles (PHEVs), fuel-cell hybrid vehicles (FCVs), and battery-electric vehicles (BEVs). The performance and cost of key enabling technologies were extrapolated over a 25-30 year time horizon. These results were integrated with software simulations to model vehicle performance and tank-to-wheel energy consumption. Well-to-wheel energy and GHG emissions of future vehicle technologies were estimated by integrating the vehicle technology evaluation with assessments of different fuel pathways. The results show that, if vehicle size and performance remain constant at present-day levels, these electric propulsion systems can reduce or eliminate the transport sector's reliance on petroleum.

Transport policy research seeks to predict and substantially reduce the future transport-related greenhouse gas emissions and fuel consumption to prevent negative climate change impacts and protect the environment. However, making such predictions is made difficult due to the uncertainties associated with the anticipated developments of the technology and fuel situation in road transportation, which determine the total fuel use and emissions of the future light-duty vehicle fleet. These include uncertainties in the performance of future vehicles, fuels' emissions, availability of alternative fuels, demand, as well as market deployment of new technologies and fuels. This paper develops a methodology that quantifies the impact of uncertainty on the U.S. transport-related fuel use and emissions by introducing a stochastic technology and fleet assessment model that takes detailed technological and demand inputs.

This paper describes the use of a modified quasi-dimensional spark-ignition engine simulation code to predict the extent of cycle-to-cycle variations in combustion. The modifications primarily relate to the combustion model and include the following: 1. A flame kernel model was developed and implemented to avoid choosing the initial flame size and temperature arbitrarily. 2. Instead of the usual assumption of the flame being spherical, ellipsoidal flame shapes are permitted in the model when the gas velocity in the vicinity of the spark plug during kernel development is high. Changes in flame shape influence the flame front area and the interaction of the enflamed volume with the combustion chamber walls. 3. The flame center shifts due to convection by the gas flow in the cylinder. This influences the flame front area through the interaction between the enflamed volume and the combustion chamber walls. 4. Turbulence intensity is not uniform in cylinder, and varies cycle-to-cycle.

A methodology is presented with which aggregate emissions from the in-use automobile population can be calculated for any given calendar year. The data base needed for such a calculation is discussed, and areas in which further research is needed are pointed out. Results of a series of calculations are then presented showing the effect on aggregate emissions of various control strategies. The effects of an inspection/maintenance and retrofit program, different vehicle population growth rates, catalyst deterioration in use, and various schedules of new car emission standards for post-1975 vehicles are presented. It is shown that the rate at which old, higher-polluting vehicles are retired from the in-use vehicle population is the major factor in determining the rate at which aggregate emissions will decrease in the 1970s, with the precise level of post-1975 standards only becoming important in the 1980s.

A spark-ignition engine friction model developed by Patton et al. in the late 1980s was evaluated against current engine friction data, and improved. The model, which was based on a combination of fundamental scaling laws and empirical results, includes predictions of rubbing losses from the crankshaft, reciprocating, and valvetrain components, auxiliary losses from engine accessories, and pumping losses from the intake and exhaust systems. These predictions were based on engine friction data collected between 1980 and 1988. Some of the terms are derived from lubrication theory. Other terms were derived empirically from measurements of individual friction components from engine teardown experiments. Recent engine developments (e.g., improved oils, surface finish on piston liners, valve train mechanisms) suggested that the model needed updating.

Engine oil consumption is recognized to be a significant source of pollutant emissions. Unburned or partially burned oil in the exhaust gases contributes directly to hydrocarbon and particulate emissions. In addition, chemical compounds present in oil additives poison catalytic converters and reduce their conversion efficiency. Oil consumption can increase significantly during critical non-steady operating conditions. This study analyzes the oil consumption behavior during ramp transients in load by combining oil consumption measurements, in-cylinder measurements, and computer-based modeling. A sulfur based oil consumption method was used to measure real-time oil consumption during ramp transients in load at constant speed in a production spark ignition engine. Additionally in-cylinder liquid oil behavior along the piston was studied using a one-point Laser-Induced-Fluorescence (LIF) technique.

Today's diesel PM reduction systems are mainly based on catalyzed particulate filter(CPF) systems. However, most of their reaction kinetics remain unresolved. Among others, the soot oxidation rate over catalyst is particularly important in the evaluation of the performance of the catalysts and the efficient control of CPF regeneration. This study, therefore, investigated the oxidation rate of carbon black (Printex-U) over various Pt supported catalysts using a flow reactor setup simulating diesel exhaust conditions. Compared to non-catalyzed soot oxidation, the oxidation rate of carbon black over Pt catalysts was to an extent shifted towards low temperatures. This activity enhancement of soot oxidation over a catalyst can be attributed principally to NO to NO2 conversion because NO2 oxidizes soot with much lower activation energy (Ea=60kJ/mol) than O2 (Ea=177kJ/mol).

Passenger cars in the United States continue to incorporate increasing levels of technology and features. However, deployment of technology requires substantial development and time in the automotive sector. Prior analyses indicate that deployment of technology in the automotive sector can be described by a logistic function. These analyses refer to maximum annual growth rates as high as 17% and with developmental times of 10-15 years. However, these technologies vary widely in complexity and function, and span decades in their implementation. This work applies regression with a logistic form to a wide variety of automotive features and technologies and, using secondary regression, identifies broader trends across categories and over time.

This paper assesses the potential improvement of automotive powertrain technologies 25 years into the future. The powertrain types assessed include naturally-aspirated gasoline engines, turbocharged gasoline engines, diesel engines, gasoline-electric hybrids, and various advanced transmissions. Advancements in aerodynamics, vehicle weight reduction and tire rolling friction are also taken into account. The objective of the comparison is the potential of anticipated improvements in these powertrain technologies for reducing petroleum consumption and greenhouse gas emissions at the same level of performance as current vehicles in the U.S.A. The fuel consumption and performance of future vehicles was estimated using a combination of scaling laws and detailed vehicle simulations. The results indicate that there is significant potential for reduction of fuel consumption for all the powertrains examined.

NO2 is an effective soot oxidizer operating at lower temperatures than O2. The effect of pure NO2 on soot oxidation was evaluated and compared with the gas treated by plasma, which initially consisted of NO, O2, and hydrocarbons. The cutout of a commercial DPF was used and the pressure difference across the DPF was monitored for an hour. The concentration of NO/NO2, CO, CO2 at the outlet of the DPF was measured as a function of time. CO and CO2 concentration was measured periodically by gas chromatography. The experiment was performed at 230, 250, 300, 350°C. When NO2 only was used as an oxidizing agent, there was a close relationship between the decrease of the pressure difference across the DPF, the CO and CO2 concentration at the outlet of the DPF, and the back conversion of NO2 to NO.

LDA measurements of the flow in a motored engine near TDC of compression have been obtained, along with burnrate data in a firing engine having a near-central spark plug location. Results are reported for two different intake ports and four intake valve lifts varying from 25% to 100% of full lift. Opposite trends of swirl vs valve lift were found for the two ports, and the rms velocity fluctuation was found to be relatively insensitive to changes in valve lift. Regression analysis of the burn duration data was conducted, with swirl ratio and rms as independent variables. The analysis indicated that burn duration decreases with an increase in swirl ratio and/or rms velocity fluctuation. In light of the experimental findings, a new conceptual model is proposed regarding the effect of valve lift on the dissipation of turbulent velocity via changes in the length scale.

Experiments to study the effects of oxygenated fuels on emissions and combustion were performed in a single-cylinder direct-injection (DI) diesel engine. A matrix of oxygen containing fuels assessed the impact of weight percent oxygen content, oxygenate chemical structure, and oxygenate volatility on emissions. Several oxygenated chemicals were blended with an ultra-low sulfur diesel fuel and evaluated at an equivalent energy release and combustion phasing. Additional experiments investigated the effectiveness of oxygenated fuels at a different engine load, a matched fuel/air equivalence ratio, and blended with a diesel fuel from the Fischer-Tropsch process. Interactions between emissions and critical engine operating parameters were also quantified. A scanning mobility particle sizer (SMPS) was used to evaluate particle size distributions, in addition to particulate matter (PM) filter and oxides of nitrogen (NOx) measurements.

The wear patterns of the rings and grooves of a diesel engine were analyzed by using a ring dynamics/gas flow model and a ring-pack oil film thickness model. The analysis focused primarily on the contact pressure distribution on the ring sides and grooves as well as on the contact location on the ring running surfaces. Analysis was performed for both new and worn ring/groove profiles. Calculated results are consistent with the measured wear patterns. The effects of groove tilt and static twist on the development of wear patterns on the ring sides, grooves, and ring running surfaces were studied. Ring flutter was observed from the calculation and its effect on oil transport was discussed. Up-scraping of the top ring was studied by considering ring dynamic twist and piston tilt. This work shows that the models used have potential for providing practical guidance to optimizing the ring pack and ring grooves to control wear and reduce oil consumption.

An experimental study was performed to develop a more fundamental understanding of the effects of secondary air injection (SAI) on exhaust gas emissions and catalyst light-off characteristics during cold start of a modern SI engine. The effects of engine operating parameters and various secondary air injection strategies such as spark retardation, fuel enrichment, secondary air injection location and air flow rate were investigated to understand the mixing, heat loss, and thermal and catalytic oxidation processes associated with SAI. Time-resolved HC, CO and CO₂ concentrations were tracked from the cylinder exit to the catalytic converter outlet and converted to time-resolved mass emissions by applying an instantaneous exhaust mass flow rate model. A phenomenological model of exhaust heat transfer combined with the gas composition analysis was also developed to define the thermal and chemical energy state of the exhaust gas with SAI.

Experiments were conducted to determine the effects of substantial spark retard on combustion, hydrocarbon (HC) emissions, and exhaust temperature, under cold engine conditions. A single-cylinder research engine was operated at 20° C fluid temperatures for various spark timings and relative air/fuel ratios. Combustion stability was observed to decrease as the phasing of the 50% mass fraction burned (MFB) occurred later in the expansion stroke. A thermodynamic burn rate analysis indicated combustion was complete at exhaust valve opening with -20° before top dead center (BTDC) spark timings. Chemical and thermal energy of the exhaust gas was tracked from cylinder-exit to the exhaust runner. Time-resolved HC concentrations measured in the port and runner were mass weighted to obtain an exhaust HC mass flow rate. Results were compared to time averaged well downstream HC levels.

The high concentration of particulate matter (PM) in diesel exhaust gas causes significant soot deposition on the wall of EGR cooler, and reduces the heat transfer performance of the EGR cooler and the reduction rate of NOx. The deposition of PM tends to be occurred more severely with "heavy wet PM," which is more frequently at the LTC (low temperature combustion) engine. The objective of this work is to evaluate the effects of soluble organic fraction (SOF) on deposit characteristics of the EGR cooler. To measure reliable mean particle concentration values and surrogate SOFs, the soot generator with SOF vaporizer was used. As for two surrogate SOFs, n-dodecane and diesel lube oil, deposit mass increased when they were injected. Especially from the experiment results, it was found that the lube oil effect was more significant than the n-dodecane effect and lube oil also had a stronger effect on reduction of thermal conductivity by filling pores in deposits.

Characteristics of soot oxidation were investigated with a carbon black (Printex-U). A flow reactor system which can simulate the condition of diesel particulate filter and diesel exhaust gas (1 bar, O2 0 ∼ 10%, NO2 200 ∼ 900ppm) was designed and used with the temperature programmed oxidation (TPO) and constant temperature oxidation (CTO) techniques. The temperature increase rate was 5°C/min for TPO experiments. From the experiments, the apparent activation energy for carbon oxidation with nitrogen dioxide was determined as 60 ± 3 kJ/mol with the first order of carbon in the range of 10∼90% oxidation and the temperature range of 250∼500°C. This value was exceedingly lower than the activation energy of oxygen oxidation which was 177 ± 1 kJ/mol. When oxygen exists with nitrogen dioxide, the reaction rate increased with the concentration of oxygen. Its rate of increase was faster for low oxygen concentration and slower for high concentration.

Plasma-catalyst (Ag, Au/Al2O3) systems were applied to NOx reduction in a model lean-burn engine exhaust gas. Also, DeNOx test of real diesel exhaust gas was performed by plasma-Ag/Al2O3 system. In the case of model exhaust gas, the catalytic activity for NOx reduction was enhanced by the assistance of plasma in the wide temperature range. The NOx conversion efficiency of plasma-Ag/Al2O3 was 40∼90% under the condition of C3 H6 3200ppm (C1/NOx = 5.96) and 10% O2 over the temperature range of 250∼400°C. The plasma-Au/Al2 O3 system showed remarkable low temperature NOx reduction activity at 100∼250°C. The real engine full flow test was performed for 70% of the full load and at engine speed of 1500rpm. NOx removal of 46% from the diesel exhaust gas was achieved by the plasma-Ag/Al2O3 catalyst system at 364°C(C1/NOx = 6). In the case of higher C1/NOx = 10, the NOx conversion increased up to 73% at 381°C. Also, DeNOx engine tests were performed for full load of 1500, 2000 and 2500rpm.

The oxidation of soot (carbon black) which is assisted by Pt/CeO2 catalyst is studied using a flow reactor system simulating the condition of diesel exhaust. In this study, the temperature programmed oxidation (TPO) scheme is mainly used for different NO and O2 concentrations and soot oxidation rate is evaluated by monitoring both CO and CO2 concentrations. Pt/CeO2 catalyst lowers the temperature of the peak CO/CO2 concentrations significantly when there is either NO or O2. Oxidation starts at 200°C and the peak CO2 concentration is observed at 360°C, which depends on the amount of catalyst and NO concentration. The effect of catalyst on NO2 recycling is also investigated. For this purpose, two different types of sample have been prepared. For the mixed case, 10mg of carbon black is mixed with 50mg of Pt/CeO2 catalyst under conditions of loose contact. For the unmixed case, the catalyst layer is placed on top of soot layer without mixing.

A model for predicting the performance and emissions characteristics of Wankel engines has been developed and tested. Each chamber is treated as an open thermodynamic system and the effects of turbulent flame propagation, quench layer formation, gas motion, heat transfer and seal leakage are included. The experimental tests were carried out on a Toyo Kogyo 12B engine under both motoring and firing conditions and values for the effective seal leakage area and turbulent heat transfer coefficient were deduced. The agreement between the predicted and measured performances was reasonable. Parametric studies of the effects of reductions in seal leakage and heat transfer were carried out and the results are presented.