Ignition quality assessment of alternative marine fuels using a small compression ignition engine

This study investigates the ignition delay for various alternative fuels using a modified small compression ignition (CI) engine. As potential alternative fuels for conventional marine CI engines, ethanol with a commercial ignition-improving additive (ED95), methanol with the commercial ignition-improving additives (MD95 and MD97), and cold-processed Lignin Ethanol Oils (CLEO) were applied to the small CI engine, and ignition delays were measured across a wide range of chamber pressures and temperatures. Additionally, pure alcohols (1-pentanol and 1-heptanol) and a diesel reference fuel (U-34) were also tested as reference fuels for comparison. The obtained ignition delays were used for correlating Arrhenius equation coefficients using the least squares method. All the experimental data showed excellent alignment with the Arrhenius equation, except for the negative temperature coefficient (NTC) behavior of CLEO. The correlation to the Arrhenius equation reveals differences in the sensitivity of ignition delays to chamber temperature and pressure among the fuels. This highlights the importance of evaluating ignition quality under the specific conditions in which the fuel will be applied when the fuel is not a conventional hydrocarbon fuel. Relying solely on a cetane number could lead to unexpected ignition behavior when these unconventional fuels are used in real engines.