Report on Investigation of Alcohol Combustion Associated Wear in Spark Ignition Engines, Mechanisms and Lubricant Effects

摘要

An investigation of the effects of alcohol fuels on spark ignition engine wear and deposition was jointly sponsored by the U.S. Department of Energy and the U.S. Army Belvoir Research and Development Center. This research has investigated four alcohol-containing fuels: pure methanol, pure ethanol, methanol in unleaded gasoline, and ethanol in unleaded gasoline (gasohol). Tests were conducted using a variety of single-cylinder research engines and production multicylinder engines, mounted in dynamometer test stands. This testing indicated that pure alcohol fuels reduced the buildup of engine deposits. Also, neat methanol greatly increased engine wear rates at engine temperatures below 75 C, while anhydrous ethanol and the alcohol-gasoline blends did not increase wear rates over that of unleaded gasoline. Engine-based tests were conducted to investigate the effects of variations in lubricant base stocks and additive formulations on the wear observed with methanol. To determine interaction between fuel alcohols and engine metals, two approaches were developed. The role of nitrogen in the wear process was studied by operating a 2.3-litre engine fueled with methanol in a nitrogen-free atmosphere. Bench experiments indicated that formic-acid and peroxides are formed as methanol combustion intermediates.