Man B&W S80ME-C7 User Manual

S80ME-C 198 44 11-4.1
MAN B&W Diesel A/S 6.04
Page 7 of 12
Calculation of Freshwater Production for Derated Engine
Example 2:
Freshwater production from a derated 6S80ME-C with high efficiency MAN B&W turbocharger of TCA type
and with fixed pitch propeller.
Based on the engine ratings below, this example will show how to calculate the expected available jacket
cooling water heat removed from the diesel engine, together with the corresponding freshwater production
from a freshwater generator.
The calculation is made for the service rating (S) of the diesel engine being 80% of the specified MCR.
Nominal MCR, (L
1
)P
L
1
: 23,280 kW (100.0%) and 76.0 r/min (100.0%)
Specified MCR, (M) P
M
: 18,624 kW (80.0%) and 68.4 r/min (90.0%)
Matching point, (O) P
O
: 16,762 kW (72.0%) and 66.0 r/min (86.9%) P
O
= 90.0% of P
M
Service rating, (S) P
S
: 14,899 kW and 63.5 r/min P
S
= 80.0% of P
M
and P
S
= 88.9% of P
O
Ambient reference conditions: 20° C air and 18° C cooling water.
The expected available jacket cooling water heat at
service rating is found as follows:
Q
jw,L
1
= 3,430 kW from List of Capacities
Q
jw%
= 77.6% using 72.0% power and 86.9%
speed for O in Fig. 6.04.02
By means of equation [1], and using factor 0.88 for
actual ambient condition the heat dissipation in the
matching point (O) is found:
Q
jw,O
=Q
jw,L
1
x x 0.88
= 3,480 x x 0.88 = 2,342 kW
By means of equation [2], the heat dissipation in the
service point (S) i.e. for 88.9% of matching power,
is found:
k
p
= 0.918 using 88.9% in Fig. 6.05.04
Q
jw
=Q
jw,O
x k
p
= 2,342 x 0.918 = 2,150 kW
-15%/0%
77.6
100
Q
jw%
100
For the service point the corresponding expected
obtainable freshwater production from a freshwa-
ter generator of the single´effect vacuum evapora-
tor type is then found from equation [3]:
M
fw
= 0.03 x Q
jw
= 0.03 x 2,150 = 64.5 t/24h
-15%/0%

Man B&W S80ME-C7 Specifications

General

Brand	Man
Model	B&W S80ME-C7
Category	Engine
Language	English