No abstract

In the early 1980s, General Electric—Transportation Systems (GE-TS), a manufacturer of locomotive diesel engines, announced plans to develop a coal-fueled locomotive due to the availability and low cost of coal. In 1985 and 1988, the General Electric Company (GE) was awarded major contracts from the Department of Energy, Morgantown Energy Technology Center, to continue the research and development of a coal-fueled diesel engine. This paper is a review of the technical accomplishments and discoveries of the GE coal-fueled diesel engine research and development program during the years 1982–1993. The results of an economic assessment completed by GE-TS indicated the merits for the development of a coal fueled diesel engine for locomotive applications and therefore, GE-TS embarked on an ambitious program to develop and commercialize a coal-fueled diesel engine. Among the major accomplishments of this program were the development of specialized fuel injection equipment for coal–water slurries, diamond compact inserts for the nozzle tips for wear resistance, and an integrated emissions control system. Over 500 hours of engine operation was accumulated using coal fuel during the duration of this program. A major milestone was attained when, during November and December 1991, a coal-fueled diesel engine powered a locomotive on the General Electric test track.

In the GE 7FDL single-cylinder research diesel engine, coal-water slurry (CWS) fuel combustion optimization studies were conducted using electronically controlled CWS and pilot accumulator injectors. The most important performance parameters of peak firing pressure, combustion efficiency (coal burnout), and specific fuel comsumption were evaluated in relationship to CWS and pilot injection timing, CWS injector hole size, shape, and number, CWS fuel injection spray angles and injection pressure. Heat release diagrams, as well as exhaust samples (gaseous and particulate), were analyzed for each case. Interesting effects of fuel spray impingement and CWS fuel “Delayed Ignition” were observed. With the engine operating at 2.0 MPa IMEP and 1050 rpm, it was able to obtain over 99.5 percent combustion efficiency while holding the cylinder firing pressure below 17 MPa and thermal efficiency equivalent to diesel fuel operation.

Coal-water-slurry (CWS) engine tests designed to evaluate a new accumulator-based injection system are described in this paper. The new injection system was found to improve CWS burnout considerably at both full and part engine loads. The peak cylinder firing pressure when operating with CWS was no higher than when operating with diesel oil. These data demonstrate the improved engine performance that can be achieved with the accumulator-based injection system.

A micronized de-ashed coal-water slurry (CWS) fuel of approximately 50 percent coal loading has been successfully ignited and burned in one GE 7FDL engine cylinder at 1050 rpm. For this study, only about 1/3 of the full load fuel engery was supplied due to limitations of the fuel injection equipment used. Three types of ignition methods have been investigated: compression ignition with no ignition aid; separate diesel pilot fuel injection to ignite the CWS fuel; combined CWS and pilot diesel fuel injection (stratified pilot ignition). Conditions of ignition and the burning characteristics that immediately followed using the above three ignition methods are described.