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A 1979 8V-71 model DDC two-stroke diesel transit bus engine was tested using ignition-improved methanol and ethanol. The testing was conducted using the Environmental Protection Agency heavy duty engine transient test procedure. The methanol and ethanol fuels were found to have very similar combustion characteristics and required the same percentage of ignition improver (7.5 volume percent) to obtain similar peak cylinder pressures and rates of pressure rise as were observed using diesel fuel. Emissions increased rapidly as the percentage of ignition improver was reduced below the optimum determined. Ignition-improved methanol and ethanol can greatly reduce fuel-produced particulate emissions with the trade-off of a small increase in total unburned fuel emissions. Carbon monoxide emissions were found to be dependent on stoichiometry only and not fuel type.

The direct utilization of minimally processed solid fuels (particularly coal) in transportation engines is assessed. Both highway and non-highway applications are considered. In general, solid fuels do not seem appropriate for highway transportation in the 1980-2000 time frame. Such fuels can be utilized for non-highway transportation with some engine types. Both technical and environmental issues are explored and a systems approach for studying the topical area is stressed. The paper features a brief historic review and current update on activities in the area of direct solid fuels utilization in transportation engines.

The concept of using alcohol fuels as alternatives to diesel fuel in diesel engines is a recent one. The scarcity of transportation petroleum fuels which developed in the early 1970's spurred many efforts to find alternatives. Alcohols were quickly recognized as prime candidates to displace or replace high octane petroleum fuels. However, alternatives to the large demand for diesel fuel in many countries were not as evident. Innovative thinking led to various techniques by which alcohol fuels can partially or completely displace diesel fuel in diesel transportation vehicles. The methods of using alcohol fuels in diesel engines (in order of increasing diesel fuel displacement) include solutions, emulsions, fumigation, dual injection, spark ignition, and ignition improvers. Power output, thermal efficiency and exhaust emissions can change significantly depending on the techniques employed. Reliability and durability still need to be demonstrated for most of these techniques.

A study was conducted to determine the feasibility, performance, and emissions of a Detroit Diesel Corporation 8V-71 transit bus engine using ignition-improved methanol as fuel. Major objectives to be achieved by the study were: 1) to determine the minimum amount of ignition improver required for acceptable engine operation; and 2) to compare the exhaust emissions with ignition-improver methanol to emissions with diesel fuel. The engine was tested for emissions using the transient and 13-mode emission procedures and for smoke using the Federal smoke test. In addition to measurement of regulated emissions and smoke, cylinder pressure traces were obtained and compared with pressure traces from operation on diesel fuel. Minimum modifications were made to the engine in adapting it for operation on the methanol/additive mixture.