An investigation of the performance of natural gas with rapeseed methyl ester pilot injection for marine diesel engine operation

摘要

While the operation of spark ignition internal combustion engines with compressed natural gas is well established, its application in marine diesel engines of vessels, other than liquefied natural gas (LNG) carriers, is only recently a growing consideration of some engine manufacturers. In this study, rapeseed methyl ester (RME) and diesel fuel were used for pilot injection in a natural gas fuelled compression ignition engine to investigate the performance and levels of exhaust emissions under steady state conditions. Higher attainable brake power was observed at a lower engine speed condition, when the gas flow was increased to the diesel knock limited range. The emissions of NO{sub}x and CO{sub}2 were found to be slightly higher when RME was used for pilot injection at all operating conditions. Hence an optimization of pollutants and power output would be necessary in the use of RME for medium-speed marine diesel engines operation. However, NO{sub}x emission was found to be below the International Maritime Organization-(IMO) MARPOL 73/78 Annex VI limits, particularly at the upper medium engine-speed range, for both diesel and RME pilot injection.