Practical use of coal-fueled diesel engines depends on the improvement of component durability. The wear characteristics of standard materials in the coal-fueled engine were studied first. Candidate wear-resistant materials were sorted by bench-scale tests. The best material combinations were applied to small-scale engine tests for operation on seeded diesel fuel. Components with hard materials and coatings were scaled up for coal-water mixture testing on the locomotive engine. Results indicate practical solutions for ring and liner wear and positive progress toward defining the material requirements for the fuel injection nozzle.

This paper summarizes the technical development of the low-emission GE-7FDL series locomotive diesel engine. The development focused on reducing the engine exhaust NOx emission significantly while reducing and curbing other visible and nonvisible emissions with minimal adverse impact on the engine fuel efficiency and minimal changes to the engine system and components. Concepts were analyzed, and were investigated using a single-cylinder 7FDL research engine. A low-emission 16-cylinder 7FDL engine and a GE locomotive prototype were built and tested for performance demonstration, function evaluation, and design optimization. The GE low-emission 7FDL engines and locomotives have been in production. The newly developed low-emission locomotive engine meets the EPA Tier-0 levels without fuel efficiency penalty. This was accomplished with minimal changes to the engine system and components. The desired engine reliability performance is retained. The engines are interchangeable with the preceding 7FDL baseline models, and the upgrade of the existing baseline engines to the low-emission version is facilitated.

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EPA Tier 2 locomotive exhaust emission levels for U.S. locomotives present significant challenges in the reduction of NOx and particulate emissions compared to Tier 0 and 1 levels. Further tuning of legacy engines would have resulted in large losses in fuel economy to achieve NOx levels and provide for deterioration of PM, HC and smoke. For these reasons, GE Transportation Systems responded to the Tier 2 requirements with a new engine that will meet the emissions levels with margin against deterioration and with improvement in fuel consumption. This optimized balance of emissions and economy is achieved without the additional complexity of aftertreatment devices. The first engine of the GEVO family will be introduced in the Evolution Series locomotive in 2005. The performance development of the engine involved combustion modeling, system modeling and optimization. The fuel injection system was statistically designed to provide highly efficient and robust operation. The turbocharger design used advanced aerodynamic and structural modeling to achieve high levels of efficiency and safety. The reliability of each system and component was evaluated using a rigorous Design for Reliability (DFR) process followed by extensive locomotive field testing.

A coal-fueled diesel engine holds the promise of a rugged, modular heat engine that uses cheap, abundant fuel. Economic studies have indicated attractive returns at moderate diesel fuel prices. The compositions of coal-water fuels are being expanded to cover the major coal sources. Combustion has been developed at 1000 rpm with mechanical and electronic fuel injection. Dual fuel operation can run the engine over the load range. Erosion of fuel nozzles has been controlled with diamond compacts. Wear of piston rings and cylinder liners can be controlled with tungsten carbide coatings. Emission measurements show higher particulates and SO2 and lower NOx, CO, and HC. Particulate and SO2 control measures are being investigated.