Engines, Fuels, Lubricants, and Vehicle Systems

As lubricant formulations change to meet higher performance standards, the Institute continues to provide advanced testing and evaluation services to meet industry needs. Automotive test gears are subjected to elevated temperatures and pressures and other severe service conditions to evaluate a lubricant's ability to meet specified performance standards.

Engine and vehicle design, as well as fuel and lubricant research and evaluation, must keep pace with increasingly severe environmental constraints while satisfying client requirements. The Institute provides improved fuel and lubricant test services, innovative engine and engine component design, more effective emissions controls, and special vehicle designs for clients throughout the world. SwRI's dedication to evolving client needs was evidenced this year by full ISO 9002 certification in the Automotive Products and Emissions Research Division and by Ford Motor Company's selection of SwRI as a Tier 1 Product Development Engineering Services Supplier.

Engine Design and Development

An Institute-developed internal combustion engine that significantly reduces NO_x emissions in stationary engines was chosen as a 1996 R&D 100 award winner. The awards, presented by R&D Magazine, recognize the 100 most significant technical achievements of the year. The patented hybrid rich-burn/lean-burn engine requires that one cylinder of a multicylinder engine be fueled with rich natural gas-air mixtures, while the remaining cylinders operate on an extremely lean mixture of natural gas and air, supplemented with exhaust from the combustion-rich cylinder. The rich exhaust is routed through a water-gas catalyst, where carbon monoxide and water vapor react to form additional carbon dioxide and hydrogen. The catalyzed rich exhaust is then introduced to the lean air-fuel mixture in the remaining cylinders, where the hydrogen aids ignitability and flame spread. This arrangement produces exhaust gas emissions containing less than 30 parts per million oxides of nitrogen (NO_x) on a 15-percent exhaust-gas oxygen basis. The engine, sponsored by the South Coast Air Quality Management District, the Southern California Gas Company, and the Waukesha Engine Division of Dresser Industries, is undergoing field demonstration tests in California.

Institute engineers developed a unique rich-burn/lean-burn low NOx natural gas engine to meet stationary power applications in highly regulated emissions areas. The engine has the same thermal efficiency levels as current natural gas engines, but produces exhaust emissions levels that are significantly lower, without the use of complex and expensive aftertreatment systems.

A significant accomplishment in 1996 was the design of a new cylinder head with associated components for a large natural gas engine. The goals were substantial improvements in performance and durability over the previous design. Advanced computerized analyses guided the design process. Finite element analysis allowed SwRI engineers to rapidly identify and resolve potential problem areas, reducing design time from weeks to hours. Computational fluid dynamics was employed to understand the flow characteristics of the coolant passages, identify design problems, and suggest solutions that were later verified by plastic model tests. Valve train design was supported by mechanical and bearing film analyses using Institute-developed software.

The Rapid Prototyping Electronic Control System (RPECS), developed at SwRI, continues to provide engineers with an effective tool to replace original equipment manufacturer (OEM) and off-the-shelf control systems in the evaluation of components and operation of engines under development. Using a standard PC, custom hardware that includes an SwRI-designed engine controller card, and SwRI-copyrighted software, RPECS permits complete designer control over all engine parameters and provides the ability to quickly and efficiently modify control algorithms when necessary.

A second four-year cooperative industry Clean Heavy-Duty Diesel Engine (CHDDE-II) program has been launched following successful completion of the CHDDE-I program last year. CHDDE-II program objectives call for the development of emissions control technologies to meet NO_x limits of less than 1.0 gram per horsepower-hour (gm/hp-hr) and particulate limits of less than 0.035 gm/hp-hr by 1999. Other technologies to be addressed by the consortium include the effects of smaller nozzle openings, rate controls, and higher pressure on fuel injectors; the use of passive particulate traps; and the effects of exhaust gas recirculation. The consortium, which includes eight heavy-duty diesel engine manufacturers and three component suppliers, will focus on developing technical solutions to meet proposed 1999 government and industry standards while maintaining current diesel engine efficiency and durability.

The Ultra-Low Emissions Engine (ULEE) cooperative research program was brought to a successful conclusion this year. Three demonstration vehicles were produced to show the effects of different technologies developed during the program. The vehicles were based on a Ford Mondeo™, Buick LeSabre™, and Ford Escort™. Program achievements included development of a series of sophisticated engine control algorithms, several methods to rapidly heat catalysts after cold start, and an enhanced fuel injection system that reduces emissions through finer atomization of the fuel-air spray.

A newly completed 41,000-square-foot petroleum chemistry building facilitates the testing and analysis of fuels, lubricants, and other substances. In a national fuel survey program, the Institute analyzes approximately 8,000 gasoline samples each month using gas chromatography for components such as alcohols, oxygenates, and benzene. The survey includes a specially designed, reformulated gasoline program initiated for compliance with U.S. Environmental Protection Agency requirements.

The GasRail USA cooperative industry research program was established three years ago to demonstrate emissions reductions by substituting liquified natural gas (LNG) for diesel fuels in locomotive engines. The goal is a 75-percent reduction in NO_x emissions while retaining maximum efficiency. Several LNG combustion systems, including two spark-ignited systems and four that used a small quantity of diesel fuel as an ignition source, were evaluated for their ability to provide low NO_x emissions and high thermal efficiency. Factors such as performance, durability, conversion cost, and ease of integration led to selection of a Late-Cycle High Injection Pressure (LaCHIP) combustion system. The LaCHIP system involves the direct injection of natural gas at pressures exceeding 3,500 psi late in the compression cycle. A small quantity of diesel fuel is injected just before natural gas injection to provide a robust ignition source.

While improvements to the LaCHIP system continue, reductions in NO_x emissions from the diesel baseline now exceed 73 percent. Thermal efficiency closely meets levels recorded with 100-percent diesel fuel. Once the design is complete, a General Motors ElectroMotive Division F59PHI passenger locomotive will be retrofitted with the LaCHIP combustion system for a demonstration in 1997, the final year of the program. The locomotive, owned by the Southern California Regional Rail Authority, will be in commuter service in the Los Angeles area.

GasRail USA, a multiyear cooperative industry research project managed by the Institute, was formed to develop a General Motors EMD-710 locomotive engine that operates on natural gas. In 1997, the engine will be tested in commuter service in Southern California. To date, reductions in NOx emissions from the diesel baseline exceed 73 percent.

Engine components constructed of traditional materials are susceptible to accelerated corrosion and wear when exposed to alternative fuels such as natural gas. For the Gas Research Institute, Institute engineers are evaluating the use of ceramic valve seat inserts in a large natural gas engine. After more than 9,000 hours of cumulative testing, results show significant reductions in wear.

Finite element analysis of a complete cylinder head identifies potential regions of compressive stress (shown in blue) that can result from high loads and thermal expansion and lead to premature or excessive engine wear.

Work continues at the Institute on the development of an ultra-safe, ultra-low emissions, natural gas-fueled school bus for the National Renewable Energy Laboratory (NREL). The prototype bus was completed by the Blue Bird Corporation and delivered to SwRI for engine and control system modifications prior to a 10,000-mile field demonstration test. New bus chassis and body designs include safety innovations such as improved lighting, pedestrian detection, and collision avoidance features. A production 8.1-liter John Deere natural gas engine has been modified to incorporate improvements to the combustion chamber, air-handling system, and electronic control system.

The Institute is exploring ways to control lubricating oil consumption and reduce friction in production engines. An innovative instrumentation technique using electrical capacitance has been developed to measure the amount of oil trapped between piston rings, making it possible to better understand how oil is consumed in an engine. Preliminary results demonstrated the feasibility of the measurement device, which can be attached to the piston. Further development is under way to demonstrate real-time measurement of the oil in the ring pack area under both steady-state and transient operating conditions.

Radioactive tracer technology is a valuable tool for measuring engine wear in real time without disassembly. Institute engineers pioneered use of the technology to study wear as a function of engine operation, fuel and lubricant formulation, component design, and material properties. Radioactive tracer technology allows minute changes in wear to be detected and quantitatively measured, providing significant cause-and-effect information under both transient and steady-state operating conditions over short or long periods of time. Because physical inspections are not required, possible changes in material clearances and in the engine's wear state are avoided, thereby maintaining test repeatability.

Emissions Control

While gasoline and alternatively fueled vehicles have relatively low particulate emissions rates compared to diesel-fueled vehicles, proposed changes in ambient air standards, increasing numbers of gasoline-powered vehicles on the road, and potentially higher emissions from malfunctioning vehicles have generated considerable interest in particulate emissions from gasoline and alternatively fueled vehicles. The Institute was recently awarded two contracts to study particulate emissions. The first study, sponsored by NREL, characterized mass emissions and size distribution of particulate matter (PM) from a vehicle operating in a fuel-rich failure mode on reformulated gasoline, compressed natural gas, liquified petroleum gas, and methanol/gasoline and ethanol/gasoline blends. A fuel-rich failure mode simulates an engine with excess fuel injected into the cylinders, leading to increased PM production. Test results showed that alternative fuels produced fewer particulates than did gasoline under the same conditions. This program has been extended for another year to investigate the impact of winter temperatures and aggressive driving on particulate formation. In the second study, for the Coordinating Research Council, SwRI will characterize exhaust PM in a fleet of 60 gasoline-fueled vehicles.

Automotive emissions levels that meet California Ultra-Low Emissions Vehicle (ULEV) hydrocarbon standards were achieved at SwRI by injecting hydrogen gas in the exhaust, upstream of a platinum-containing catalyst, while starting the engine. By adding hydrogen, the catalytic converter was heated to an efficient operating temperature in only a few seconds, reducing cold-start emissions. Vehicle emissions tests incorporated an onboard hydrogen generator that produced hydrogen by the electrolysis of water using electrical current from the alternator. The hydrogen can be stored for release to the catalytic converter during cold engine cranking.

Hydrocarbon speciation is a powerful tool used to identify up to 160 hydrocarbon components. Using speciation data, Institute engineers and chemists can study the effects of various gasoline and alternative fuel compositions, evaporative emissions, fuel additives, and emissions control hardware. Ozone formation depends on, among other things, the reactivities of these individual components. Hydrocarbon speciation also determines the presence and level of toxic emissions from automobiles and other sources. Aldehydes, sulfates, benzene, unburned alcohols, and methane are some of the unregulated emissions routinely measured. Current projects in this area include one to characterize emissions from alternatively fueled vehicles. SwRI also conducts hydrocarbon speciation for diesel exhaust.

The Institute is participating in the second year of a two-year consortium program sponsored by heavy-duty diesel engine manufacturers and OEMs to investigate plasma and corona discharge technologies for the simultaneous reduction of PM and NO_x in diesel engine exhaust. Current aftertreatment technologies focus on PM and NO_x separately, with the reduction of one often leading to an increase in the other. Program goals are to define the advantages and disadvantages of different methods for producing plasma and corona discharges, determine the operational feasibility of each, and study the chemical processes involved.

The Institute's specially designed 1.16-mile track allows on-site vehicle performance testing and evaluation of octane requirements, shift feel, driveability, acceleration, and low-speed vehicle operation.

SwRI has been awarded a project by the California Air Resources Board (CARB) to design a closed-loop control, three-way catalyst system for off-highway vehicle engines such as those used in forklift, airport service vehicle, and utility applications. The objective is to demonstrate the feasibility and durability of applying automotive-type, low-emissions technology to a representative off-highway engine fueled by gasoline and liquified petroleum gas (LPG). A significant reduction in particulates, carbon monoxide, NO_x, and total hydrocarbons is expected. Reduced emissions will result in improved environmental and safety conditions in the enclosed areas where many of these vehicles are operated.

For the past two years, SwRI has conducted research to determine the feasibility and emissions impact of using butane and butane/propane blends as alternative fuels for on-road vehicles. Many countries already use these blends as automotive fuels, because they provide better fuel economy, lower vapor pressure, and greater ease of handling than propane alone.

Extensive emissions testing at SwRI using two vehicles converted with commercially available hardware to operate on butane/propane blend LPG indicates that the fuel can meet California ULEV standards. Operating on a 50-percent normal butane/50-percent propane blend, the vehicles produced less than half the hydrocarbon exhaust emissions emitted from a conventional gasoline engine. Using these data and CARB-published reactivity data, SwRI showed that LPG fuels with high butane concentrations could improve air quality. In response to requests from industry and government, Institute engineers are continuing to work on butane/propane fuel blends through a multiclient cooperative research program.

Fuels and Lubricants Research

Institute engineers are developing a new test procedure for the qualification of lubricating oils, to verify that oil formulations do not poison catalysts or oxygen sensors. The test is intended to replace composition limits restricting the amount of phosphorus compounds and other chemicals that can be added to oils for better wear protection, better high-temperature performance, and longer service life. New international lubricant specifications incorporating the test are proposed for the year 2000. For this project, SwRI designed and fabricated a synthetic gas reactor that determines catalyst performance using small samples of monolithic converters exposed to a precise mixture of simulated engine exhaust. Discriminating between chemical and thermal deactivation of aged catalyst pieces presents a challenge, because both types of degradation often occur simultaneously. Consequently, a previously patented acid wash technique is used after initial performance testing to remove any chemical poisons, and a subsequent test determines the effect of thermal deactivation alone, allowing calculation of the chemical poisoning effect.

Validation of car and truck exhaust components to ensure long life in consumer service, using accelerated stress testing at extreme temperature and vibration levels, is an internationally recognized Institute capability.

For more than 20 years, SwRI has conducted fuel quality survey programs for oil companies, consortia, and trade organizations. A sampling network covering the continental United States, as well as Hawaii and Alaska, is in place to acquire samples from service stations and ship the samples to SwRI for chemical analysis. The surveys include a specially designed, reformulated gasoline program initiated for compliance with U.S. Environmental Protection Agency (EPA) requirements. As a result of the success of these surveys, several automotive manufacturers, OEM suppliers, and others requested that the Institute initiate a worldwide fuel survey. The new survey is expected to begin in 1997 and will encompass countries in Asia, Europe, North America, and South America.

To create an environmentally friendly automotive coolant, the Institute has performed fleet tests to evaluate the feasibility of using substances based on a chemical other than ethylene glycol, the major component of most coolants. Ethylene glycol is harmful if ingested. This program marks one of the first fleet tests of vehicles operating with a propylene glycol coolant.

The Montana Department of Environmental Quality is sponsoring a project to evaluate the benefits of biomass-based alternative fuels and lubricants in snowmobile engines. Biomass fuels are derived from biological sources, including plant material and wastes. Emissions and fuel economy will be measured in two snowmobile engines using an SwRI-developed multimode test cycle. A potential near-term application is in Yellowstone National Park, where emissions from a large number of park-operated, conventionally fueled snowmobiles pose environmental problems. If laboratory evaluations yield promising results, a fleet demonstration program will be undertaken.

Institute engineers conduct powertrain endurance testing on a variety of off-highway vehicles used in construction and agriculture. Such vehicles develop extremely high torques at low speeds and require specialized test equipment.

U.S. Army TARDEC Fuels and Lubricants Research Facility

The Institute has staffed and operated the U.S. Army TARDEC Fuels and Lubricants Research Facility (TFLRF) since it was established in 1957 on SwRI grounds. The TFLRF functions as a dedicated in-house facility for the U.S. Army Tank Automotive and Armament Research, Development, and Engineering Center, a Department of Defense (DOD) organization responsible for the military ground fleet. The TFLRF provides the Army and DOD with unique capabilities for resolving fuel-, lubricant-, and engine-related problems and for responding rapidly to combat mobility problems in the field.

Engineers in the U.S. Army TARDEC Fuels and Lubricants Research Facility at SwRI designed and assembled fuel filtration/additive units for the Army and Marine Corps. The units contribute to combat readiness by ensuring fuel quality and save the military considerable money in fuel replacement and disposal costs.

Stringent emissions regulations are driving the development of more complex fuel injection systems that operate at high pressures with extremely close mechanical tolerances. For a cooperative industrial research program that includes filtration companies and equipment, pump, and engine manufacturers, SwRI has concluded a two-year investigation of fuel filtration problems. The studies determined the impact of critical particle size on fuel injection system wear and evaluated the effects of filter characteristics such as water removal efficiency.

In a project sponsored by the Gas Research Institute, SwRI researchers are evaluating advanced materials for use in critical engine parts, such as valve seats, that are subject to accelerated wear in natural gas-fueled engines. The project goal is to extend maintenance intervals.

Institute engineers designed and assembled a mobile fuel filtration/additive unit (FAU) for the U.S. Marine Corps. The FAU was assigned to the Marine Corps Blount Island Command in Jacksonville, Florida, after successful validation testing. Blount Island is a service facility for the Marine Corps prepositioned vehicle and equipment fleet. Fully fueled vehicles are stored onboard prepositioned ships, ready for immediate shipment and use. During this storage period, the fuel in the vehicles can deteriorate while the ships and their cargo undergo regular maintenance cycles. The FAU allows rapid removal of deteriorated fuel from the vehicles and treats the fuel with stabilization additives as it passes through a series of filters. The fuel can then be re-introduced into vehicles or used for some other purpose at the facility. Use of the FAU has already resulted in substantial savings in fuel disposal and replacement costs.

For the Defense Fuel Supply Center, the TFLRF has completed the second year of a continuing nationwide survey of fuel deliveries to U.S. military installations. The survey is being conducted to determine the quality of fuels delivered to the military and to assess the potential for fuel-related operating problems, especially those related to lubricity characteristics. A related survey is being conducted to test fuel samples collected from commercial port refueling sites throughout the world, including fuel delivered to U.S. Navy vessels.

To reduce fuel costs, the military is increasingly procuring commercial rather than military specification fuels. Biodiesel fuel is gaining attention as a renewable extender for commercial diesel fuel, much as ethanol has been for gasolines. The TFLRF is evaluating soybean-derived methyl ester compounds as diesel fuel, to help anticipate and avoid potential problems unique to military operations. The compounds have been found to provide outstanding fuel lubricity, but they can seriously degrade fuel storage stability. Stability-enhancing additives have been identified to address the problem.

The Institute's oil filter test facility features state-of-the-art instrumentation capable of characterizing lubricant oil filter performance using Society of Automotive Engineers criteria and other recognized test procedures. On this test apparatus, oil samples are collected automatically according to standardized parameters.

Vehicle Systems Design and Development

Institute engineers, in addition to helping transmission and vehicle manufacturers evaluate transmission assembly, pump, and torque converter efficiencies, have recently designed a number of novel gear boxes for use in applications supporting the Partnership for a New Generation of Vehicles (PNGV). New gear box designs are needed to handle the complex interactions between multiple power units that provide on-demand power to complement the unique driving cycle requirements of different vehicles.

Simulating an electric vehicle battery pack with a variable voltage, high-power, direct-current power supply, a dynamometer test facility was developed at SwRI to conduct fully automated, transient durability tests on electric motor powertrain assemblies. The transient test schedule includes regenerative braking and reverse gear operation. Combined with software tools created at the Institute, the facility can conduct simultaneous hardware-in-the-loop vehicle tests and simulations. A 100,000-mile durability test for a major automaker will validate a new electric drivetrain intended for production electric vehicles.

To support a number of research projects, SwRI developed a computer simulated "toolbox" that contains modular libraries of hybrid vehicle components. The toolbox is intended to assist a user in designing a hybrid vehicle. The computer models simulate dynamic operation and incorporate the latest technology for each vehicle component. One application concerns hybrid electric vehicle (HEV) system concepts for military wheeled and tracked ground vehicles. Silent maneuvers and troop delivery, zero-exhaust heat signatures in EV mode, high engine efficiency with single-point operation, and low emissions are just some of the advantages offered by HEVs in the military arena.

Fuel cells hold the promise of clean, quiet power for the 21st century. They may replace fossil fuel power in stationary and vehicle applications in environmentally sensitive areas. Through an internal research project, Institute engineers have developed three techniques for constructing cylindrical polymer electrolyte membrane (PEM) fuel cells, which have the potential to be lighter in weight and less costly than conventional fuel cells. A patent application has been filed on the techniques, which have been demonstrated with prototype devices, and experiments are under way to quantify cylindrical PEM fuel cell performance.

In support of the PNGV, the Institute is cooperating with the EPA on programs to develop hybrid hydraulic vehicle technologies to improve vehicle efficiency. These programs include the development of a lightweight, high-pressure hydraulic accumulator to store hydraulic energy generated during vehicle braking. The accumulator is made of composite materials to reduce weight and improve energy density. In another program, the Institute is developing more efficient pump motors by reducing internal leakage, friction, and compressibility losses.

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