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Modification of gasoline blendstock composition in preparing ethanol-gasoline blends has a significant impact on vehicle exhaust emissions. In “splash” blending the blendstock is fixed, ethanol-gasoline blend compositions are clearly defined, and effects on emissions are relatively straightforward to interpret. In “match” blending the blendstock composition is modified for each ethanol-gasoline blend to match one or more fuel properties. The effects on emissions depend on which fuel properties are matched and what modifications are made, making trends difficult to interpret. The purpose of this paper is to illustrate that exclusive use of a match blending approach has fundamental flaws. For typical gasolines without ethanol, the distillation profile is a smooth, roughly linear relationship of temperature vs. percent fuel distilled.

Engine dynamometer testing was performed comparing fuels having different octane ratings and ethanol content in a Ford 3.5L direct injection turbocharged (EcoBoost) engine at three compression ratios (CRs). The fuels included midlevel ethanol “splash blend” and “octane-matched blend” fuels, E10-98RON (U.S. premium), and E85-108RON. For the splash blends, denatured ethanol was added to E10-91RON, which resulted in E20-96RON and E30-101 RON. For the octane-matched blends, gasoline blendstocks were formulated to maintain constant RON and MON for E10, E20, and E30. The match blend E20-91RON and E30-91RON showed no knock benefit compared to the baseline E10-91RON fuel. However, the splash blend E20-96RON and E10-98RON enabled 11.9:1 CR with similar knock performance to E10-91RON at 10:1 CR. The splash blend E30-101RON enabled 13:1 CR with better knock performance than E10-91RON at 10:1 CR. As expected, E85-108RON exhibited dramatically better knock performance than E30-101RON.

This paper outlines the characterization of a Li-Ion Iron Phosphate battery pack with nominal voltage of 700V as well as the modeling of this pack as an equivalent electrical circuit (EEC) for the purpose of vehicle simulations. For a higher level of fidelity and accuracy, the equivalent circuit is initially modeled as an R-2RC circuit which consists of a voltage source with one resistor (R) and two resistor-capacitor (RC) branches. In this modeling effort, first, several open circuit voltage (OCV) determination methods in the literature are benchmarked and state-of-charge (SOC) dependent OCV curve which is used in the voltage source of the EEC model is derived. Then, two methods of parameter estimation of the EEC are developed for both step current and dynamic current profiles. The first estimation method is applicable to discharge or charge step currents and relies mostly on the relaxation portion of the battery response and involves some manual calibration.

Ethanol can be converted into a 1:1:1 mixture of H2, CO, and CH4 at 300°C using a copper-nickel catalyst, a process known as “low-temperature ethanol reforming.” The hydrogen content of this mixture enables an engine to operate lean or with high levels of EGR, improving fuel economy and emissions. An onboard ethanol reformer- a catalyst module providing heat exchange with exhaust-was recently reported and shown to exhibit stable high conversion of ethanol driven by exhaust heat. This paper describes the successful integration and operation of a Ford 3.5L 3 TiVCT flex-fuel engine with a compact reformer and auxiliary hardware, fueled by E85. The system constitutes an integrated power system suitable for vehicle integration. The engine was operated on a mixture of E85 and reformate using a stoichiometric air-fuel ratio with internal EGR at a 12:1 compression ratio.

The increasing numbers of hybrid electric and full electric vehicle models currently in the market or in the pipeline of automotive OEMs require creative testing mechanisms to drive down development costs and optimize the efficiency of these vehicles. In this paper, such a testing mechanism that has been successfully implemented at the US Environmental Protection Agency National Vehicle and Fuel Emissions Laboratory (EPA NVFEL) is described. In this testing scheme, the units-under-test consist of a battery pack and its associated battery management system (BMS). The remaining subsystems, components, and environment of the vehicle are virtual and modeled in high fidelity.

In this study, thermal runaway of a 3-cell Li-ion battery module is analyzed using a 3D finite-element-analysis (FEA) method. The module is stacked with three 70Ah lithium-nickel-manganese-cobalt (NMC) pouch cells and indirectly cooled with a liquid-cooled cold plate. Thermal runaway of the module is assumed to be triggered by the instantaneous increase of the middle cell temperature due to an abusive condition. The self-heating rate for the runaway cell is modeled on the basis of Accelerating Rate Calorimetry (ARC) test data. Thermal runaway of the battery module is simulated with and without cooling from the cold plate; with the latter representing a failed cooling system. Simulation results reveal that a minimum of 165°C for the middle cell is needed to trigger thermal runaway of the 3-cell module for cases with and without cold plate cooling.

For lithium-ion battery systems assembled with high-capacity, high-power pouch cells, the cells are commonly cooled with thin aluminum cooling plates in contact with the cells. The cooling plates extract the cell heat and dissipate it to a cooling medium (air or liquid). During the pack utilizations with high-pulse currents, large temperature gradients along the cell surfaces can be encountered as a result of non-uniform distributions of the ohmic heat generated in the cells. The non-uniform cell temperature distributions can be significant for large-size cells. Maximum cell temperatures typically occur near the cell terminal tabs as a result of the ohmic heat of the terminal tabs and connecting busbars and the high local current densities. In this study, a new cooling plate is proposed for improving the uniformity in temperature distributions for the cells with large capacities.

This paper provides an overview of the effects of blending ethanol with gasoline for use in spark ignition engines. The overview is written from the perspective of considering a future ethanol-gasoline blend for use in vehicles that have been designed to accommodate such a fuel. Therefore discussion of the effects of ethanol-gasoline blends on older legacy vehicles is not included. As background, highlights of future emissions regulations are discussed. The effects on fuel properties of blending ethanol and gasoline are described. The substantial increase in knock resistance and full load performance associated with the addition of ethanol to gasoline is illustrated with example data. Aspects of fuel efficiency enabled by increased ethanol content are reviewed, including downsizing and downspeeding opportunities, increased compression ratio, fundamental effects associated with ethanol combustion, and reduced enrichment requirement at high speed/high load conditions.

Thermal behavior of a Lithium-ion (Li-ion) battery module under a user-defined cycle corresponding to hybrid electrical vehicle (HEV) applications is analyzed. The module is stacked with 12 high-power 8Ah pouch Li-ion battery cells connected in series electrically. The cells are cooled indirectly with air through aluminum cooling plate sandwiched between each pair of cells. The cooling plate has extended cooling surfaces exposed in the cooling air flow channel. Thermal behavior of the battery system under a user specified electrical-load cycle for the target hybrid vehicle is characterized with the equivalent continuous load profile using a 3D finite element analysis (FEA) model for battery cooling. Analysis results are compared with measurements. Good agreement is observed between the simulated and measured cell temperatures. Improvement of the cooling system design is also studied with assistance of the battery cooling analyses.

Thermal behavior of a lithium-ion (Li-ion) battery module for hybrid electrical vehicle (HEV) applications is analyzed in this study. The module is stacked with 12 high-power pouch Li-ion battery cells. The cells are cooled indirectly with air through aluminum fins sandwiched between each two cells in the module, and each of the cooling fins has an extended cooling surface exposed in the cooling air flow channel. The cell temperatures are analyzed using a quasi-dimensional model under both the transient module load in a user-defined cycle for the battery system utilizations and an equivalent continuous load in the cycle. The cell thermal behavior is evaluated with the volume averaged cell temperature and the cell heat transfer is characterized with resistances for all thermal links in the heat transfer path from the cell to the cooling air. Simulations results are compared with measurements. Good agreement is observed between the simulated and measured cell temperatures.

Ethanol and other high heat of vaporization (HoV) fuels result in substantial cooling of the fresh charge, especially in direct injection (DI) engines. The effect of charge cooling combined with the inherent high chemical octane of ethanol make it a very knock resistant fuel. Currently, the knock resistance of a fuel is characterized by the Research Octane Number (RON) and the Motor Octane Number (MON). However, the RON and MON tests use carburetion for fuel metering and thus likely do not replicate the effect of charge cooling for DI engines. The operating conditions of the RON and MON tests also do not replicate the very retarded combustion phasing encountered with modern boosted DI engines operating at low-speed high-load. In this study, the knock resistance of a matrix of ethanol-gasoline blends was determined in a state-of-the-art single cylinder engine equipped with three separate fuel systems: upstream, pre-vaporized fuel injection (UFI); port fuel injection (PFI); and DI.

Ethanol has a high octane rating and can be added to gasoline to produce high octane fuel blends. Understanding the octane increase with ethanol blending is of great fundamental and practical importance. Potential issues with fuel flow rate and fuel vaporization have led to questions of the accuracy of octane measurements for ethanol-gasoline blends with moderate to high ethanol content (e.g., E20-E85) using the Cooperative Fuel Research (CFR™) engine. The nonlinearity of octane ratings with volumetric ethanol content makes it difficult to assess the accuracy of such measurements. In the present study, Research Octane Number (RON) and Motor Octane Number (MON) were measured for a matrix of ethanol-gasoline blends spanning a wide range of ethanol content (E0, E10, E20, E30, E50, E75) in a set of gasoline blendstocks spanning a range of RON values (82, 88, 92, and 95). Octane ratings for neat ethanol, denatured ethanol, and hydrous ethanol were also measured.

The temperature distribution is studied theoretically in a battery module stacked with 12 high-power Li-ion pouch cells. The module is cooled indirectly with ambient air through aluminum heat-sink plates or cooling plates sandwiched between each pair of cells in the module. Each of the cooling plates has an extended cooling fin exposed in the cooling air channel. The cell temperatures can be controlled by changing the air temperature and/or the heat transfer coefficient on the cooling fin surfaces by regulating the air flow rate. It is found that due to the high thermal conductivity and thermal diffusivity of the cooling plates, heat transfer of the cooling plate governs the cell temperature distribution by spreading the cell heat over the entire cell surface. Influence of thermal from the cooling fins is also simulated.

Ideal operation temperatures for Li-ion batteries fall in a narrow range from 20°C to 40°C. If the cell operation temperatures are too high, active materials in the cells may become thermally unstable. If the temperatures are too low, the resistance to lithium-ion transport in the cells may become very high, limiting the electrochemical reactions. Good battery thermal management is crucial to both the battery performance and life. Characteristics of various battery thermal management systems are reviewed. Analyses show that the advantages of direct and indirect air cooling systems are their simplicity and capability of cooling the cells in a battery pack at ambient temperatures up to 40°C. However, the disadvantages are their poor control of the cell-to-cell differential temperatures in the pack and their capability to dissipate high cell generations.

Waste heat recovery (WHR) has been recognized as a promising technology to achieve the fuel economy and green house gas reduction goals for future heavy-duty (HD) truck diesel engines. A Rankine cycle system with ethanol as the working fluid was developed at AVL Powertrain Engineering, Inc. to investigate the fuel economy benefit from recovering waste heat from a 10.8L HD truck diesel engine. Thermodynamic analysis on this WHR system demonstrated that 5% fuel saving could be achievable. The fuel economy benefit can be further improved by optimizing the design of the WHR system components and through better utilization of the available engine waste heat. Although the WHR system was designed for a stand-alone system for the laboratory testing, all the heat exchangers were sized such that their heat transfer areas are equivalent to compact heat exchangers suitable for installation on a HD truck diesel engine.

Lithium ion batteries can be developed for vehicle applications from high power specification to high energy specification. Thermal response of a battery cell is the main factor to be considered for battery selection in the design of an electrified vehicle because some materials in the cells have low thermal stability and they may become thermally unstable when their working temperature becomes higher than the upper limit of allowed operating range. In this paper the thermal characteristics of different sizes and forms of commercially available batteries is investigated through electro-thermal analysis. The relation between cell capacity and cell internal resistance is also studied. The authors find that certain criteria can be defined for battery selection for electric vehicles, hybrid electric vehicles and plug-in hybrid electric vehicles. These criteria can be served as design guidelines for battery development for vehicle applications.

It has been previously reported that ethanol can be reformed at around 300°C to a mixture of hydrogen, carbon monoxide, and methane using copper-plated nickel catalyst. This low reforming temperature enables heat to be supplied from the engine exhaust. Single-cylinder engine testing demonstrated that this gaseous mixture of "ethanol reformate" enhances engine combustion and part load dilution capability, which decreases fuel consumption while also reducing feedgas NOx emissions. In addition, excellent cold start capability with significantly reduced hydrocarbon emissions was observed. Thus, ethanol reformate has the potential to address two major barriers to wider use of ethanol as an engine fuel: ethanol's low heating value per volume and higher hydrocarbon emissions at startup relative to gasoline. In this study, the dilute capability of a multi-cylinder engine was assessed using a mixture of 50% reformate and 50% E85 on a mass basis at several key part load operating points.

Lithium-ion (Li-ion) batteries are becoming widely used high-energy sources and a replacement of the Nickel Metal Hydride batteries in electric vehicles (EV), hybrid electric vehicles (HEV) and plug-in hybrid electric vehicles (PHEV). Because of their light weight and high energy density, Li-ion cells can significantly reduce the weight and volume of the battery packs for EVs, HEVs and PHEVs. Some materials in the Li-ion cells have low thermal stabilities and they may become thermally unstable when their working temperature becomes higher than the upper limit of allowed operating temperature range. Thus, the cell working temperature has a significant impact on the life of Li-ion batteries. A proper control of the cell working temperature is crucial to the safety of the battery system and improving the battery life. This paper outlines an approach for the thermal analysis of Li-ion battery cells and modules.

Gasoline turbocharged direct injection (GTDI) engines, such as EcoBoost™ from Ford, are becoming established as a high value technology solution to improve passenger car and light truck fuel economy. Due to their high specific performance and excellent low-speed torque, improved fuel economy can be realized due to downsizing and downspeeding without sacrificing performance and driveability while meeting the most stringent future emissions standards with an inexpensive three-way catalyst. A logical and synergistic extension of the EcoBoost™ strategy is the use of E85 (approximately 85% ethanol and 15% gasoline) for knock mitigation. Direct injection of E85 is very effective in suppressing knock due to ethanol's high heat of vaporization - which increases the charge cooling benefit of direct injection - and inherently high octane rating. As a result, higher boost levels can be achieved while maintaining optimal combustion phasing giving high thermal efficiency.

The cost of fuel for commercial trucks is second only to labor in the total vehicle operating costs. Therefore, technologies that reduce fuel consumption can have a significant impact on the bottom line for both trucking fleets and owner/operators. Quantifying the fuel savings associated with different technologies, however, is complicated by many factors, and short-term testing often cannot adequately quantify small changes in fuel consumption that, over time, can add up to substantial cost savings on a vehicle. For example, fuel economy gains of less than one percent may not be reliably measurable using fuel tests, and variable environmental and use factors can cast some doubt on the appropriateness of short-term testing.