Man B&W L35MC6-TII - Exhaust Gas Amount and Temperature; Influencing Factors; Summarising Equations for Exhaust Gas Amounts and Temperatures

MAN B&W 6.04
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MAN Diesel
MAN B&W MC/MC-C engines 198 61 76-4.0
Exhaust Gas Amount and Temperature
Inuencing factors
The exhaust gas data to be expected in practice
depends, primarily, on the following three factors:
a) The specied MCR point of the engine (point M):
P
M
: power in kW at SMCR point
n
M
: speed in r/min at SMCR point
and to a certain degree on the optimising point
O with the percentage power P
O%
= % of SMCR
power:
P
O%
= (P
O
/P
M
) x 100%
b) The ambient conditions, and exhaust gas
backpressure:
T
air
: actual ambient air temperature, in °C
p
bar
: actual barometric pressure, in mbar
T
CW
: actual scavenge air coolant temperature,
in °C
∆p
M
: exhaust gas backpressure in mm WC at
specied MCR
c) The continuous service rating of the engine
(point S), valid for xed pitch propeller or control-
lable pitch propeller (constant engine speed):
P
S
: continuous service rating of engine, in kW
Calculation Method
To enable the project engineer to estimate the ac-
tual exhaust gas data at an arbitrary service rating,
the following method of calculation may be used.
The partial calculations based on the above inu-
encing factors have been summarised in equations
[4] and [5].
Fig. 6.04.06: Summarising equations for exhaust gas amounts and temperatures
The partial calculations based on the inuencing
factors are described in the following:
a) CorrectionforchoiceofspeciedMCRpoint
When choosing a specied MCR point ‘M’ other
than the nominal MCR point ‘L
1
’, the resulting
changes in specic exhaust gas amount and
temperature are found by using as input in dia-
grams the corresponding percentage values (of
L
1
) for specied MCR power P
M%
and speed n
M%
:
P
M%
= P
M
/P
L1
x 100%
n
M%
= n
M
/n
L1
x 100%
M
exh
= M
L1
x
P
M
___
P
L1
x 1 +
∆m
M%
______
100
x 1 +
∆M
amb%
_______
100
x 1 +
∆m
s%
_____
100
x
P
S%
____
100
kg/h +/5% [4]
T
exh
= T
L1
+ ∆T
M
+ ∆T
O
+ ∆T
amb
+ ∆T
S
°C /+15 °C [5]
where, according to ‘List of capacities’, i.e. referring to ISO ambient conditions and 300 mm WC
backpressure and specied/optimised in L
1
:
M
L1
: exhaust gas amount in kg/h at nominal MCR (L
1
)
T
L1
: exhaust gas temperature after turbocharger in °C at nominal MCR (L
1
)
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M
exh
: exhaust gas amount in kg/h, to be found
T
exh
: exhaust gas temperature in °C, to be found