Fuel Component and Heteroatom Effects on Deposits and Wear

Abstract

Abstract : The objective of this project was to investigate the effects of fuel heteroatom compounds on diesel engine performance, particularly engine deposition and wear. This work involved operating a single-cylinder diesel research engine using a highly controlled base fuel (JP-7) which was extremely low in sulfur and nitrogen. The engine lubricant was a synthetic polyalphaolefin material, also free of sulfur and nitrogen. Thus, wear and deposit effects observed during the 60-hour single-cylinder laboratory engine test were directly related to the heteroatom compound added to the base fuel. Through these controlled laboratory engine tests, wear and deposit effects were studied using four different types of known fuel sulfur complexes, and two different fuels containing naturally occurring sulfur compounds. Fuel sulfur type did not appear to directly influence wear rate, whereas the disulfide-type sulfur was found to produce high piston deposit tendencies. No increase in engine wear was observed for three fuels each of which contain a different known nitrogen compound. Fuel injector deposits and fouling occurred with some of the nitrogen-containing fuels. A fuel containing a combination of both known sulfur and nitrogen hetero- atoms was tested and no synergistic effects on wear or deposits were observed. Keywords: Diesel fuels.