DETERMINATION OF OPTIMAL OPERATING MODES OF MARINE DIESEL ENGINES EXHAUST GAS BYPASS SYSTEMS

A method for determining the optimal operating modes of marine diesel exhaust gas bypass systems is considered. The aim of this research was to determine the optimal volume of exhaust gas bypass for a marine medium-speed diesel engine, specifically the 6L20 Wartsila. Electronic engine control allows flexible adjustment of exhaust gas bypass process within a range of 0 to 10 % of the total volume of gases exiting the diesel cylinder. The use of exhaust gas bypass contributes to improving the environmental performance of marine medium-speed diesel engines, particularly in the operational load range of 55–85 %, where NOx emissions in exhaust gases decrease by 3.5–15.4 %. The greatest reduction in NOx emissions occurs at loads of 75–85 %. The use of the exhaust gas bypass system is deemed effective for loads exceeding 75 %, with potential reductions in nitrogen oxide emissions ranging from 9.2 % to 15.4 %. For loads of 55–65 %, a reduction in nitrogen oxide emissions (3.3–5.6 %) is also observed, but with a simultaneous increase in specific fuel oil consumption (4.2–4.4 %). However, for certain bypass values, the diesel engine's thermal stress exceeds acceptable limits.