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A new combustion concept has been developed and tested for improving the low to moderate load efficiency and NOx emissions of natural gas engines. This concept involves operation of a dual-fuel natural gas engine on Homogeneous Charge Compression Ignition (HCCI) in the load regime of idle up to 35 % of the peak torque. A dual-fuel approach is used to control the combustion phasing of the engine during HCCI operation, and conventional spark-ignited natural gas combustion is used for the high-load regime. This concept has resulted in an engine with power output and high-load fuel efficiency that are unchanged from the base engine, but with a 10 - 15 % improvement to the low to moderate load fuel efficiency. In addition, the engine-out NOx emissions during HCCI operation are over 90% lower than on spark-ignited natural gas operation over the equivalent load range.

AN INVESTIGATION OF THE EFFECTS of methanol fuel on spark ignition engine wear and deposits is being conducted using a Ford 2.3-liter engine and a modified ASTM sequence V-D test procedure. This testing indicates that at the low temperature conditions of this procedure, methanol reduces the buildup of engine deposits but greatly increases the engine wear rate. Various experiments to identify the wear mechanisms were conducted in a CLR single-cylinder engine and are reported here.

One of the major problems created by the use of methanol fuels in SI engines is the high cylinder bore and ring wear rates observed during operation at low engine temperatures. The objective of the work reported in this paper was to identify the processes controlling the corrosion/wear mechanism in methanol-fueled, spark-ignition engines. Basically, three different types of experiments were performed during this project. The experiments consisted of: 1. Combustion experiments designed to identify the combustion products of methanol at various locations within a confined methanol flame; 2. Exposure studies designed to define the specific role of each of the combustion products on the corrosion mechanism; 3. Lubricant screening experiments designed to identify the mode of penetration of the oil film, and the location, in the microscale, of the surface attack. Performic acid was identified as the corrosive agent.