Page 33 - CARILEC CE Journal CEMAY2021

Within this engine platform the engine types named “32” operate according to the Diesel cycle, whereas the
engine named “34” operate according to the Otto cycle. The Wartsila 34 engine types with their pre-mixed
and lean-burn Otto cycle feature, offer lower NOx formation but their drawback is a need for output derating
in case of heavier gas-mixes due to risk of auto-ignition. Common for all engines running on gaseous fuels is
the need for an ignition source with higher ignitability. For the LG and DF engine types the ignition is timed
and initiated using a pilot diesel fuel injection, whereas the SG and LPG rely on a traditional spark plug. The
difference between the 32LG and a traditional dual fuel engine such as the 34DF is further illustrated in
Figures 1 and 2.

Figure 1 32LG Diesel cycle combustion process (also applies to 32GD)

Figure 2 34DF Otto cycle combustion process in gas mode

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