Exhaust Gas Amount And Temperature; Influencing Factors; Summarising Equations For Exhaust Gas Amounts And Temperatures; Correction For Choice Of Specified Mcr Point - Man B&W S80ME-C7 Project Manual

MAN B&W

Exhaust Gas Amount and Temperature

Influencing factors

The exhaust gas data to be expected in practice
depends, primarily, on the following three factors:
a) The specified MCR point of the engine (point M):
P : power in kW at SMCR point
M
n : speed in r/min at SMCR point
M
and to a certain degree on the matching point O
with the percentage power P
power:
P = (P /P ) x 100%
O% O M
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.
M : exhaust gas amount in kg/h, to be found
exh
T : exhaust gas temperature in °C, to be found
exh
P
___
M
M = M x x 1 +
exh L1 P
L1
T = T + ∆T + ∆T
exh L1 M
where, according to 'List of capacities', i.e. referring to ISO ambient conditions and 300 mm WC
backpressure and specified/matched in L
M : exhaust gas amount in kg/h at nominal MCR (L
L1
T : exhaust gas temperature after turbocharger in °C at nominal MCR (L
L1
Fig. 6.04.06: Summarising equations for exhaust gas amounts and temperatures
The partial calculations based on the influencing
factors are described in the following:
a) Correction for choice of specified MCR point
When choosing a specified MCR point 'M' other
than the nominal MCR point 'L
MAN B&W ME-B, ME/MEC, MEGI engines
= % of SMCR
O%
 

∆m ∆M
______ _______
M%
x 1 +
 

100
 

+ ∆T + ∆T °C /+15 °C
O amb S
', the resulting
1
b) The ambient conditions, and exhaust gas
backpressure:
T
air
p
bar
T
CW
∆p
M
c) The continuous service rating of the engine
(point S), valid for fixed pitch propeller or control-
lable pitch propeller (constant engine speed):
P
S
The partial calculations based on the above influ-
encing factors have been summarised in equations
[4] and [5].

 
∆m
_____
amb% s%
x 1 +

 
100 100

 
:
1
)
1
changes in specific exhaust gas amount and
temperature are found by using as input in dia-
grams the corresponding percentage values (of
L ) for specified MCR power P
1
P
M%
n = n
M%
MAN Diesel
: actual ambient air temperature, in °C
: actual barometric pressure, in mbar
: actual scavenge air coolant temperature,
in °C
: exhaust gas backpressure in mm WC at
specified MCR
: continuous service rating of engine, in kW
P
____
S%
x kg/h
100
)
1
= P /P x 100%
M L1
/n x 100%
M L1
6.04
Page  of 12
+/5% [4]
[5]
and speed n :
M% M%
198 43 181.2