Gas-powered operation of the 7L51/60DF dual-fuel engine with
TCA55-41V turbocharger
For stable, knock-free combustion, gas-powered engines require a limited
gas/air ratio, which is achieved by regulating the charge pressure. If the load
drops below 50%, a significant reduction of the charge pressure is required.
Furthermore, a control reserve must be provided for load applications and
high intake temperatures in the load range of 50-100% MCR. For a rigid
geometry, this can be achieved by means of blow-off during operation at
normal conditions or partial load with significant charging efficiency losses, or
efficiently by opening the VTA position. Moreover, an open VTA position at
partial load allows a more efficiency-optimized setting than a rigid turbine
nozzle ring.
The resulting increase in charging efficiency with VTA compared with the
bypass concept is illustrated in the diagram
Improvement of the charging effi-
ciency with TCA55-41V on 7L51/60DF engine
.
2 0
3 0
4 0
5 0
6 0
7 0
8 0
9 0
1 0 0
11 0
C
h
a
rg
in
g
e
ff
ic
ie
n
c
y
in
%
V TA
B yp as s
MCR Maximum Continuous Rating
Figure 4: Improvement of the charging efficiency with a TCA55-41V on an 7L51/60DF engine
For a gas-powered engine operated predominantly in the load range of 50 –
100%, this results in a potential improvement of approx. 0.5 percentage
points in the thermal efficiency of the engine.
See Figure
Improvement of the thermal efficiency with TCA55-41V on
.
Fuel saving for 4-stroke gas-
powered engine
Increased
charging efficiency
Thermal efficiency
1 Adjustable turbine nozzle ring (VTA)
1.2 Application Examples
2013-12-04 - de
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MAN Diesel & Turbo
10 (38)
EN-US