, Gas Operation principle, lean-burn gas engine
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1.01
0211 BC
OPERATION PRINCIPLE,
LEAN-BURN GAS ENGINE
Introduction
The Bergen engine lean burn spark ignition (s.i.) gas
engine operates according to the lean-burn Otto
cycle, i.e. a lean mixture of gas and air is compressed
and ignited by an electric system.
A lean-burn engine operates at a.e.r’s (air excess
ratios), of 1.8 and higher, and as the illustration
shows, this gives increased power, efficiency and
reduced NO
x
-emissions.
To achieve this, a special combustion system has
been developed that gives a strong increase in
ignition energy capable of firing such lean mixtures
reliably. Also, a highly efficient turbo-charging
system is used to take advantage of the possible
power increase offered by the extended knock limit
of lean mixtures
Principle of operation in brief
Air is drawn in by the turbocharger, through the
charge air cooler and into the cylinder. A timed
mechanical gas valve injects gas under over-pressure
into the inlet air stream to ensure a homogeneous
and lean mixture of air and gas.
Air flow is controlled by the variable turbine geome-
try, VTG, while gas flow is controlled by mechanical
valves before each cylinder.
The gas pressure is set electronically by the pressure
regulating valve on the fuel gas supply module
ahead of engine.
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