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Engine Tribology

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One important market that will use alternative fuels increasingly, namely ethanol is lawn mower engine application with millions of units built in US annually and using fossil fuels.

During start-up and cold run, the bio-fuels condense on the cold cylinder walls and they are scrapped by the rings diluting the mineral oil in the oil pan. The authors’ engine-based research is investigating the tribology of the contact surfaces in a lawn mower internal combustion engine while lubricated with mineral oil contaminated with different percentages of ethanol at various temperatures.

The experimental engine is instrumented to measure resistive forces and torques and in order to achieve that, the camshaft is being instrumented with a full bridge of strain gages and the rocker arm will be instrumented with an accelerometer.

An in-cylinder pressure pick-up through the spark plug is being used to record cylinder pressure and obtain the indicated diagrams while the time line will be given by a crankshaft rotary encoder. Appropriate design of experiments and response surface methodologies will be used in the range of interest of controlled variables (e.g., biofuel concentration, temperature, load, speed and number of cycles). The fired engine experiments will be correlated with pin-on-disk tribometer measurements of friction and estimate wear and contact temperatures for mixtures of mineral oil and ethanol.

Renewable Energy and Engines Laboratory • (912) 478-2293 • vsoloiu@georgiasouthern.edu