Page 52 - Piston Engine-Based Power Plants
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44 Piston Engine-Based Power Plants
Diesel injector
Intake system
Natural gas–Air
mixture
Air
Natural gas
Diesel
Piston
Crankshaft
Figure 4.4 Schematic of a dual-fuel engine.
TWO-STROKE CYCLE CONSIDERATIONS
The moving components of all reciprocating engines must be kept
lubricated to reduce friction between components and in the extreme
to stop them binding together and failing. Four-stroke engines usually
have a sophisticated oil circulation system that ensures all the major
components including the pistons and cylinders are kept lubricated.
Some of the oil that is used to lubricate the engine will inevitably be
burnt and end up in the exhaust but in modern four-stroke engines the
amount is normally limited.
Two-stroke engines are much simpler and the lubrication system is
often simple too. In fact in many small two-stroke engines, the oil that
is needed to keep the pistons and cylinders well lubricated is actually
mixed with the fuel so that it is left behind when the combustion mix-
ture burns. This system generally leads to much higher levels of burnt,
