Man B&W S50MC-C8-TII, Руководство по проекту, Страница: 182 / 403

MAN B&W 6.04
Page 3 of 12
MAN Diesel
198 72 11-7.0 MAN B&W S50MC-C8-TII
Calculation of List of Capacities for Derated Engine
Example 1:
Pump and cooler capacities for a derated 6S50MC-C8-TII with high efficiency MAN Diesel turbocharger
type TCA, fixed pitch propeller and central cooling water system.
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
Total cooling water flow through scavenge air
coolers
V
cw,air,M
= V
cw,air,L1
x Q
air%
/ 100
V
cw,air,M
= 143 x 0.831 = 119 m
3
/h
Cooling water flow through lubricating oil cooler
V
cw,lub,M
= V
cw,lub,L1
x Q
lub%
/ 100
V
cw,lub,M
= 107 x 0.917 = 98 m
3
/h
Cooling water flow through central cooler
(Central cooling water pump)
V
cw,cent,M
= V
cw,air,M
+ V
cw,lub,M
V
cw,cent,M
= 119 + 98 = 217 m
3
/h
Cooling water flow through jacket water cooler
(as for lube oil cooler)
V
cw,jw,M
= V
cw,lub,M
V
cw,jw,M
= 98 m
3
/h
Seawater pump for central cooler
As the seawater pump capacity and the central
cooler heat dissipation for the nominal rated en-
gine found in the ‘List of Capacities’ are 315 m
3
/h
and 6,380 kW the derated seawater pump flow
equals:
Seawater pump:
V
sw,cent,M
= V
sw,cent,L1
x Q
cent,M
/ Q
cent,L1
= 315 x 5,447 / 6,380 = 269 m
3
/h
The method of calculating the reduced capaci-
ties for point M (n
M%
= 90.0% and P
M%
= 85.0%) is
shown below.
The values valid for the nominal rated engine are
found in the ‘List of Capacities’, Figs. 6.03.01 and
6.03.02, and are listed together with the result in
the figure on the next page.
Heat dissipation of scavenge air cooler
Fig. 6.04.01 which approximately indicates a Q
air%
= 83.1% heat dissipation, i.e.:
Q
air,M
=Q
air,L1
x Q
air%
/ 100
Q
air,M
= 4,140 x 0.831 = 3,440 kW
Heat dissipation of jacket water cooler
Fig. 6.04.02 indicates a Q
jw%
= 88.5% heat dissi-
pation; i.e.:
Q
jw,M
= Q
jw,L1
x Q
jw%
/ 100
Q
jw,M
= 1,450 x 0.885 = 1,283 kW
Heat dissipation of lube oil cooler
Fig. 6.04.03 indicates a Q
lub%
= 91.7% heat dissi-
pation; i.e.:
Q
lub,M
= Q
lub, L1
x Q
lub%
/ 100
Q
lub,M
= 790 x 0.917 = 724 kW
Heat dissipation of central water cooler
Q
cent,M
= Q
air,M
+ Q
jw,M
+ Q
lub, M
Q
cent,M
= 3,440 + 1,283 + 724 = 5,447 kW