Man B&W S50ME-B9.3-TII, Project Manual

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MAN B&W 2.08
Page 1 of 2
MAN Diesel
198 83 41-6.1 MAN B&W TII .4 and .3 engines
MAN B&W TII .2 engines: 90-50ME-C/-GI,
70-35MC-C, 60-35ME-B/-GI
MAN B&W TII .1 engines: K98ME/ME-C7
With
p
max
adjusted
Without
p
max
adjusted
Parameter
Condition
change
SFOC
change
SFOC
change
Scav. air coolant
temperature
per 10 °C rise + 0.60% + 0.41%
Blower inlet tem-
perature
per 10 °C rise + 0.20% + 0.71%
Blower inlet
pressure per 10 mbar
rise
 0.02%  0.05%
Fuel oil lower
calorific value rise 1%
(42,700 kJ/kg)
1.00%  1.00%
All engine design criteria, e.g. heat load, bearing
load and mechanical stresses on the construc-
tion are defined at 100% load independent of the
guarantee point selected. This means that turbo-
charger matching, engine adjustment and engine
load calibration must also be performed at 100%
independent of guarantee point. At 100% load,
the SFOC tolerance is 5%.
When choosing an SFOC guarantee below 100%,
the tolerances, which were previously compensat-
ed for by the matching, adjustment and calibration
at 100%, will affect engine running at the lower
SFOC guarantee load point. This includes toler-
ances on measurement equipment, engine proc-
ess control and turbocharger performance.
Consequently, SFOC guarantee tolerances are:
• 100% – 85%: 5% tolerance
• 84% – 65%: 6% tolerance
• 64% – 50%: 7% tolerance
Please note that the SFOC guarantee can only be
given in one (1) load point.
Recommended cooling water temperature
during normal operation
In general, it is recommended to operate the main
engine with the lowest possible cooling water
temperature to the air coolers, as this will reduce
the fuel consumption of the engine, i.e. the engine
performance will be improved.
However, shipyards often specify a constant
(maximum) central cooling water temperature of
36 °C, not only for tropical ambient temperature
conditions, but also for lower ambient temperature
conditions. The purpose is probably to reduce the
electric power consumption of the cooling water
pumps and/or to reduce water condensation in
the air coolers.
Thus, when operating with 36 °C cooling water
instead of for example 10 °C (to the air coolers),
the specific fuel oil consumption will increase by
approx. 2 g/kWh.
SFOC at reference conditions
The SFOC is given in g/kWh based on
the reference ambient conditions stated in
ISO 3046-1:2002(E) and ISO 15550:2002(E):
• 1,000 mbar ambient air pressure
• 25 °C ambient air temperature
• 25 °C scavenge air coolant temperature
and is related to a fuel oil with a lower calorific
value of 42,700 kJ/kg (~10,200 kcal/kg).
Any discrepancies between g/kWh and g/BHPh
are due to the rounding of numbers for the latter.
For lower calorific values and for ambient condi-
tions that are different from the ISO reference
conditions, the SFOC will be adjusted according
to the conversion factors in the table below.
With for instance 1 °C increase of the scavenge
air coolant temperature, a corresponding 1 °C in-
crease of the scavenge air temperature will occur
and involves an SFOC increase of 0.06% if p
max
is
adjusted to the same value.
SFOC guarantee
The Energy Efficiency Design Index (EEDI) has
increased the focus on part- load SFOC. We
therefore offer the option of selecting the SFOC
guarantee at a load point in the range between
50% and 100%, EoD: 4 02 002.
SFOC reference conditions and guarantee