MAN B&W 6.04
Page 11 of 12
MAN Diesel
MAN B&W S50MC-C8-TII 198 72 13-0.0
Calculation of Exhaust Data for Derated Engine
Example 3:
Expected exhaust gas data for a derated 6S50MC-C8-TII with high efficiency MAN Diesel turbocharger
type TCA and fixed pitch propeller.
Based on the engine ratings below, and by means of an example, this chapter will show how to calculate
the expected exhaust gas amount and temperature at service rating, and for a given ambient reference
condition different from ISO.
The calculation is made for the service rating (S) being 80% of the specified MCR power of the diesel engine.
Nominal MCR, (L
1
) P
L1
: 9,960 kW (100.0%) and 127.0 r/min (100.0%)
Specified MCR, (M) P
M
: 8,466 kW (85.0%) and 114.3 r/min (90.0%)
Optmising point, (O) P
O
: 8,466 kW (85.0%) and 114.3 r/min (90.0%), P
O
= 100.0% of P
M
Service rating, (S) P
S
: 6,773 kW and 106.1 r/min, P
S
= 80.0% of P
M
Reference conditions
Air temperature T
air
........................................ 20 °C
Scavenge air coolant temperature T
CW
......... 18 °C
Barometric pressure p
bar
....................... 1,013 mbar
Exhaust gas backpressure
at specified MCR ∆ p
M
......................... 300 mm WC
a) Correction for choice of specified MCR point M
and optmising point O:
P
M%
=
8,466
____
9,960
x 100 = 85.0%
n
M%
=
114.3
____
127.0
x 100 = 90.0%
By means of Figs. 6.04.07 and 6.04.08:
∆m
M%
= + 0.25%
∆T
M
= 7.2 °C
As the engine is optmised in O lower than 100% M,
and P
O%
= 100.0% of P
M
we get by means of equation [6]
∆T
O
= 0.3 x (100 100.0) = 0.0 °C
b) Correction for ambient conditions and
backpressure:
By means of equations [7] and [8]:
∆M
amb%
= 0.41 x (20 25) + 0.03 x (1,013 1,000)
+ 0.19 x (18 25) 0.011 x (300 300)%
∆M
amb%
= + 1.11%
∆T
amb
= 1.6 x (20 25) 0.01 x (1,013 1,000)
+ 0.1 x (18 25) + 0.05 x (300 300) °C
∆T
amb
= 8.8 °C
c) Correction for the engine load:
Service rating = 80% of specified MCR power
By means of Figs. 6.04.11 and 6.04.12:
∆m
S%
= + 7.1%
∆T
S
= 18.8 °C
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