Gas and Large Engine Development

Using this large engine test facility, SwRI investigates methods of converting diesel locomotive engines to run on natural gas. The Institute has six locomotive engines available for research and development efforts.

The Institute has developed lean-burn, turbocharged, natural gas-fueled heavy-duty engines that match the power and efficiency levels of their diesel counterparts while producing lower emissions. Special electronic control systems regulate fuel metering, spark timing, boost pressure, and engine speed.

Hybrid electric vehicles utilize auxiliary power units (APU) to extend vehicle driving range. Comprised of an engine and generator, APUs provide power to maintain battery charge and augment batteries during peak power demands. This utility engine, converted to operate on natural gas for an APU application, incorporates the latest technology in controls and exhaust aftertreatment.

Institute engineers rapidly develop highly flexible, hardened PC-based control systems for use in demonstration vehicles.

With Gas Technology Institute (GTI) funding, SwRI has developed a revolutionary natural gas conversion system, known as TranslatorTM, for electronically controlled fuel-injected gasoline engines. Unlike other electronic conversion systems, this system uses the original manufacturers' electronic control modules, utilizing desirable design features built into vehicles.

Combustion Technology

Using a variety of engine models and diagnostic methods, SwRI designs and develops unique combustion systems that capitalize on the favorable combustion characteristics of natural gas. Engineers develop an appropriate combustion system -- prechamber, open chamber, direct-injection, or dual fuel -- for the engine size and application.

A focused research program investigating open-chamber, spark-ignited combustion systems has included basic research on how parameters such as engine geometry, equivalence ratio, spark timing, and fuel composition affect performance.

For combustion analysis, SwRI combines optical spark plug and ionization head gasket probes (SPION) with cylinder pressure measurement equipment to study flame development, growth, and completion. The cycle-to-cycle data help characterize cold-start cycle variability, lean misfire limits, knock, and rough idle. Using this technology, the Institute determines how spark energy, air motion, turbulence, fuel, composition, and EGR affect flame development.

Testing

To evaluate durability, reliability, and performance, SwRI conducts laboratory and field tests on prototype and demonstration gas engines. Staff members have developed a suite of advanced instruments and technology to perform tests unique to these specialized engines.

The Institute developed the compressed natural gas (CNG) engine and the CNG storage system for this Mack refuse truck. The vehicle was equipped with an SwRI data logger that allowed remote monitoring during the vehicle's one-year field test.

SwRI developed a PC-based data logger that records up to 128 channels of data, which are monitored and downloaded remotely via a built-in cellular telephone. Using this device, engineers can troubleshoot field demonstration vehicles or remote stationary engines without leaving the office. The system has been used in city transit busses, utility trucks, refuse haulers, and locomotives.

Facilities

SwRI engineers are specialists in developing natural gas-fueled engines, using advanced engine electronic control system and exhaust aftertreatment technologies.

Gas engine development projects are aided by the extensive facilities found in the Design and Development Department. Forty test cells accommodate engines from 2 to 6,000 hp, with both absorption and motoring dynamometers available. Natural gas fuel is available from an LNG storage facility capable of supplying 6,000 psi, 99 percent pure methane gas or from an eight-inch, 100 psi gas utility pipeline. A gas compressor rated at 5,000 psi and 250 scfm provides CNG for engine testing and NGV refueling. Gas composition is constantly measured using a gas chromatograph, which provides real-time correction of heating value, stoichiometric fuel-air ratio, and fuel density.

Using the latest tools and techniques, SwRI accelerates the development process. Test cell data acquisition systems acquire and process large amounts of performance and combustion data. A PC-based engine control system developed at SwRI speeds control algorithm development and engine calibration. The Institute also conducts complete gaseous and particulate emissions measurements, including EPA-recognized transient testing.

Gas Technology Institute

For more than a decade, SwRI has conducted gas engine research for the Gas Technology Institute (GTI), developing basic natural gas engine technology. Research reports on the following topics are available through GTI.

Exhaust Oxygen Sensors Open Chamber Combustion Low-Hydrocarbon Prechambers Catalytic Converters Piston Temperature Measurements Valve and Valve Seat Wear Long-Life Spark Plugs Gaseous Metering Valves Gas Composition Effects Multi-Point Fuel Injection Natural Gas Lube Oils

LNG Weathering Knock/Misfire Sensors Portable Emissions Analyzers High-Propane-Content Natural Gas Fuel Natural Gas Compressor Improvements Stratified Charge Glow Plug Ignition NOx Emissions Sensors Stoichiometric Control System Development Lean-Burn Control System Development NOx Modeling Gas Engine Durability