Search Results

Fuel injection into the negative valve overlap (NVO) period is a common method for controlling combustion phasing in homogeneous charge compression ignition (HCCI) and other forms of advanced combustion. When fuel is injected into O2-deficient NVO conditions, a portion of the fuel can be converted to products containing significant levels of H2 and CO. Additionally, other short chain hydrocarbons are produced by means of thermal cracking, water-gas shift, and partial oxidation reactions. The present study experimentally investigates the fuel reforming chemistry that occurs during NVO. To this end, two very different experimental facilities are utilized and their results are compared. One facility is located at Oak Ridge National Laboratory, which uses a custom research engine cycle developed to isolate the NVO event from main combustion, allowing a steady stream of NVO reformate to be exhausted from the engine and chemically analyzed.

In-cylinder blending of gasoline and diesel to achieve reactivity controlled compression ignition (RCCI) has been shown to reduce NOX and PM emissions while maintaining or improving brake thermal efficiency as compared to conventional diesel combustion (CDC). The RCCI concept has an advantage over many advanced combustion strategies in that the fuel reactivity can be tailored to the engine speed and load allowing stable low-temperature combustion to be extended over more of the light-duty drive cycle load range. However, the current range of the experimental RCCI engine map investigated here does not allow for RCCI operation over the entirety of some drive cycles and may require a multi-mode strategy where the engine switches from RCCI to CDC when speed and load fall outside of the RCCI range.

The U.S. Department of Energy's Office of Energy Efficiency & Renewable Energy initiated a study that conducted coastdown testing and chassis dynamometer testing of three vehicles, each at multiple test weights, in an effort to determine the impact of a vehicle's mass on road load force and energy consumption. The testing and analysis also investigated the sensitivity of the vehicle's powertrain architecture (i.e., conventional internal combustion powertrain, hybrid electric, or all-electric) on the magnitude of the impact of vehicle mass. The three vehicles used in testing are a 2012 Ford Fusion V6, a 2012 Ford Fusion Hybrid, and a 2011 Nissan Leaf. Testing included coastdown testing on a test track to determine the drag forces and road load at each test weight for each vehicle. Many quality measures were used to ensure only mass variations impact the road load measurements.

In recent years a number of studies have demonstrated that boosted operation combined with external EGR is a path forward for expanding the high load limit of homogeneous charge compression ignition (HCCI) operation with the negative valve overlap (NVO) valve strategy. However, the effects of fuel composition with this strategy have not been fully explored. In this study boosted HCCI combustion is investigated in a single-cylinder research engine equipped with direct injection (DI) fueling, cooled external exhaust gas recirculation (EGR), laboratory pressurized intake air, and a fully-variable hydraulic valve actuation (HVA) valve train. Three fuels with significant compositional differences are investigated: regular grade gasoline (RON = 90.2), 30% ethanol-gasoline blend (E30, RON = 100.3), and 24% iso-butanol-gasoline blend (IB24, RON = 96.6). Results include engine loads from 350 to 800 kPa IMEPg for all fuels at three engine speeds 1600, 2000, and 2500 rpm.

The present study experimentally investigates spark-ignited combustion with 87 AKI E0 gasoline in its neat form and in mid-level alcohol-gasoline blends with 24% vol./vol. iso-butanol-gasoline (IB24) and 30% vol./vol. ethanol-gasoline (E30). A single-cylinder research engine is used with a low and high compression ratio of 9.2:1 and 11.85:1 respectively. The engine is equipped with hydraulically actuated valves, laboratory intake air, and is capable of external exhaust gas recirculation (EGR). All fuels are operated to full-load conditions with λ=1, using both 0% and 15% external cooled EGR. The results demonstrate that higher octane number bio-fuels better utilize higher compression ratios with high stoichiometric torque capability. Specifically, the unique properties of ethanol enabled a doubling of the stoichiometric torque capability with the 11.85:1 compression ratio using E30 as compared to 87 AKI, up to 20 bar IMEPg at λ=1 (with 15% EGR, 18.5 bar with 0% EGR).

A methodology for developing modal vehicle emissions and fuel consumption models is described. These models, in the form of look-up tables for fuel consumption and emissions as functions of vehicle speed and acceleration, are designed for simulations such as the Federal Highway Administration's TRAF-series of models. These traffic models are used to evaluate the impacts of roadway design on emissions and fuel consumption. Vehicles are tested on-road and on a chassis dynamometer to characterize the entire operating range of each vehicle. As a verification exercise the models were used to predict cycle emissions and fuel consumption, and the results were compared to certification-type tests on a different population of vehicles. Results of the verification exercise show that the developed models can generally predict cycle emissions and fuel consumption with error comparable to the variability of repeat dynamometer tests.

Producing and using renewable fuels for transportation is one approach for a sustainable energy future for the United States, as well as the rest of the world. Renewable fuels may also substantially reduce contributions to global climate change. In the transportation sector, ethanol produced from biomass shows promise as a future fuel for spark-ignited engines because of its high octane quality. Ethanol, however, is not a high-quality compression-ignition fuel. Ethanol can be easily converted through a dehydration process to produce diethyl ether (DEE), which is an excellent compression-ignition fuel with higher energy density than ethanol. DEE has long been known as a cold-start aid for engines, but little is known about using DEE as a significant component in a blend or as a complete replacement for diesel fuel.

Hydrogen fuel cell vehicles (FCVs) appear to be a promising solution for the future of clean and efficient personal transportation. Issues of how to generate the hydrogen and then store it on-board to provide satisfactory driving range must still be resolved before they can compete with conventional vehicles. Alternatively, FCVs could obtain hydrogen from on-board reforming of gasoline or other fuels such as methanol or ethanol. On-board reformers convert fuel into a hydrogen-rich fuel stream through catalytic reactions in several stages. The high temperatures associated with fuel processing present an engineering challenge to warm up the reformer quickly and efficiently in a vehicle environment. Without a special warmup phase or vehicle hybridization, the reformer and fuel cell system must provide all power to move the vehicle, including ¼ power in 30 s, and ½ power in 3 min to satisfy the Federal Test Procedure (FTP) cycle demands.

This paper summarizes the Next Generation Natural Gas Vehicle (NG-NGV) Program that is led by the U.S. Department Of Energy's (DOE's) Office of Heavy Vehicle Technologies (OHVT) through the National Renewable Energy Laboratory (NREL). The goal of this program is to develop and implement one Class 3-6 compressed natural gas (CNG) prototype vehicle and one Class 7-8 liquefied natural gas (LNG) prototype vehicle in the 2004 to 2007 timeframe. OHVT intends for these vehicles to have 0.5 g/bhp-hr or lower emissions of oxides of nitrogen (NOx) by 2004 and 0.2 g/bhp-hr or lower NOx by 2007. These vehicles will also have particulate matter (PM) emissions of 0.01 g/bhp-hr or lower by 2004. In addition to ambitious emissions goals, these vehicles will target life-cycle economics that are compatible with their conventionally fueled counterparts.

This paper summarizes the several of the studies in the Environmental Science Program being sponsored by DOE's Office of Heavy Vehicle Technologies (OHVT) through the National Renewable Energy Laboratory (NREL). The goal of the Environmental Science Program is to understand atmospheric impacts and potential health effects that may be caused by the use of petroleum-based fuels and alternative transportation fuels from mobile sources. The Program is regulatory-driven, and focuses on ozone, airborne particles, visibility and regional haze, air toxics, and health effects of air pollutants. Each project in the Program is designed to address policy-relevant objectives. Current projects in the Environmental Science Program have four areas of focus: improving technology for emissions measurements; vehicle emissions measurements; emission inventory development/improvement; ambient impacts, including health effects.

The Heavy Vehicle Propulsion Materials Program provides enabling materials technology for the U.S. DOE Office of Heavy Vehicle Technologies (OHVT). The technical agenda for the program is based on an industry assessment and the technology roadmap for the OHVT. A five-year program plan was published in 2000. Major efforts in the program are materials for diesel engine fuel systems, exhaust aftertreatment, and air handling. Additional efforts include diesel engine valve-train materials, structural components, and thermal management. Advanced materials, including high-temperature metal alloys, intermetallics, cermets, ceramics, amorphous materials, metal- and ceramic-matrix composites, and coatings, are investigated for critical engine applications. Selected technical issues and planned and ongoing projects as well as brief summaries of several technical highlights are given.

The Office of Heavy Vehicle Technologies supports research to enable high-efficiency diesel engines to meet future emissions regulations, thus clearing the way for their use in light trucks as well as continuing as the most efficient powerplant for freight-haulers. Compliance with Tier 2 emission regulations for light-duty vehicles will require effective exhaust emission controls (aftertreatment) for diesels in these applications. Diesel-powered heavy trucks face a similar situation for the 2007 regulations announced by EPA in December 2000. DOE laboratories are working with industry to improve emission control technologies in projects ranging from application of new diagnostics for elucidating key mechanisms, to development and evaluation of prototype devices. This paper provides an overview of these R&D efforts, with examples of key findings and developments.

Today's advanced-technology vehicles (ATVs) feature hybrid-electric engines, regenerative braking, advanced electric drive motors and batteries, and eventually fuel cell engines. There is considerable environmental and regulatory pressure on fleets to adopt these vehicles, resulting in high-risk purchase decisions on vehicles that do not have documented performance histories. The Department of Energy's Field Operations Program tests ATVs and disseminates the results to provide accurate and unbiased information on vehicle performance (http://ev.inel.gov/fop). Enhancing the fleet manager's knowledge base increases the likelihood that ATVs will be successfully and optimally placed into fleet missions. The ATVs are tested using one or more methods - Baseline Performance, Accelerated Reliability, and Fleet Testing. The Program and its 10 testing partners have tested over three-dozen electric and hybrid electric vehicle models, accumulating over 4 million miles of testing experience.

One of the biggest barriers to commercialization of fuel cell vehicles is the high cost of materials and manufacturing of fuel cell components. Precious metal materials in the membrane electrode assemblies (MEAs) account for more than 17 percent of the total cost of polymer electrolyte membrane (PEM) fuel cell systems. Precious metals such as platinum may also be required for fuel processing catalysts. The Department of Energy (DOE) is addressing the important issue of the cost of fuel cell components by supporting R&D projects aimed at improving the performance of fuel cells which would lead to reduced platinum loading, as well as developing low-cost automated industrial processes for the manufacture of electrodes and MEAs. Other projects include development of a supply-demand elasticity model. The long term reserves and availability of platinum is a serious issue facing the commercial viability of fuel cell vehicles.

The potential peaking of world conventional oil production and the possible imperative to reduce carbon emissions will put great pressure on vehicle manufacturers to produce more efficient vehicles, on vehicle buyers to seek them out in the marketplace, and on energy suppliers to develop new fuels and delivery systems. Four cases for stabilizing or reducing light vehicle fuel use, oil use, and/or carbon emissions over the next 50 years are presented. Case 1 - Improve mpg so that the fuel use in 2020 is stabilized for the next 30 years. Case 2 - Improve mpg so that by 2030 the fuel use is reduced to the 2000 level and is reduced further in subsequent years. Case 3 - Case 1 plus 50% ethanol use and 50% low-carbon fuel cell vehicles by 2050. Case 4 - Case 2 plus 50% ethanol use and 50% low-carbon fuel cell vehicles by 2050. The mpg targets for new cars and light trucks require that significant advances be made in developing cost-effective and very efficient vehicle technologies.

A methanol and a gasoline vehicle were each subjected to testing under severe short-trip driving conditions. Results show that the cool oil sump temperatures caused more fuel and water to collect in the oil of the methanol vehicle. Protective properties of both vehicles' oils degraded during short trips but rebounded somewhat during a subsequent long trip. Slightly warmer sump temperatures in longer short-trip driving resulted in no methanol dilution in the methanol vehicle's oil, and higher total volatiles contamination in the gasoline vehicle's oil. Freeway driving following the longer short trips promoted less rebound in the degraded oils' protective properties.

Previous work has shown that wallboard can be successfully manufactured to contain up to 30% phase change material (PCM), or wax, thus enabling this common building material to serve as a thermal energy storage device. This material was analyzed for passive solar applications and found to save energy with a reasonable pay-back time period. Further evaluations of the wallboard are reported in this paper. This analysis looks at potential applications of PCM wallboard as a load management device and as a comfort enhancer. Results show that the wallboard is ineffective in modifying the comfort level but can provide significant load management relief with no energy penalty. Modifications to typical heating and air-conditioner control strategies were necessary for successful load management.

For most air conditioning systems, usually only 85% of the evaporator is effectively used. The other 15% is used to superheat the refrigerant so that the compressor will be protected from liquid slugging, but this practice results in excessive evaporator volume. In mobile air conditioning (MAC) systems where the space available for the evaporator is very limited, the evaporator should be fully used, yet MAC designs have not reflected this need. This study reports on the designing and testing of a novel liquid over-feeding (LOF) MAC system that can use 100% of the evaporator effectively. A LOF system is designed so that not all liquid refrigerant is evaporated in the evaporator. The low-pressure liquid and vapor flow into an accumulator-heat exchanger where the liquid is boiled off by the warm, high-pressure liquid leaving the condenser. This concept not only allows 100% evaporator utilization, but will also reduce system power consumption and improve compressor reliability.

The Partnership for a New Generation of Vehicles (PNGV) is linking the research efforts of a broad spectrum of U.S. Federal agencies and laboratories with those of the domestic auto manufacturers in pursuit of three specific, interrelated goals: 1) reduce manufacturing production costs and product development times for all car and truck production; 2) pursue advanced technologies for near-term vehicle improvements that increase fuel efficiency and reduce emissions of standard vehicles; and 3) within the next decade, develop a new class of vehicle that will achieve up to three times the fuel efficiency of today's comparable vehicle, and, at the same time, cost no more to own and drive than today's automobile, maintain performance, size, and utility of comparable vehicles, and meet or exceed safety and emission requirements.

Temperature measurement of internal components and surfaces can enhance understanding of thermal processes that occur during engine operation. Such measurements have typically been made with thermocouples, temperature sensitive paints or plugs, or infrared emission methods. Phosphor thermometry, a non-contact measurement technique, is an alternative that can be applied when more traditional methods are not feasible or are too costly. Recent efforts described in this paper have used phosphor thermometry to measure steady state piston crown temperature in a single cylinder engine. Additional testing with this technique included monitoring intake valve temperature in a multicylinder engine under cold start conditions. Packaging of the optical hardware necessary for this technique was substantially refined during these tests for use in modern engine geometries.