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MAN B&W Diesel A/S 6.04
Calculation of L<strong>is</strong>t of Capacities for Derated Engine
Example 1:
Pump and cooler capacities for a derated 6S65ME-C with high efficiency MAN B&W turbocharger,
type TCA with fixed pitch propeller and central cooling water system.
Nominal MCR, (L 1 ) P L1 : 17,220 kW (100%) and 95.0 r/min (100.0%)
Specified MCR, (M) P M : 14,637 kW (85.0%) and 92.2 r/min (97.0%)
Matching point, (O) P O : 13,173 kW (76.5%) and 89.0 r/min (93.7%), P O = 90.0% of P M
The method of calculating the reduced capacities
for point M (n M% = 97.0 and P M% = 85.0) <strong>is</strong> shown
below.
The values valid for the nominal rated engine are
found in the ‘L<strong>is</strong>t of Capacities’, Figs. 6.03.01 and
6.03.02, and are l<strong>is</strong>ted together with the result in
the figure on the next page.
Heat d<strong>is</strong>sipation of scavenge air cooler
Fig. 6.04.01 which approximate indicates a Q = air%
78.1% heat d<strong>is</strong>sipation, and corrected for matching
point O lower than M, by applying correcting
factor k , equal 78.1 x (1 + 0.27 x (1 – 0.900)) = 80.2%
O
i.e.:
Q =Q air,M air,L1 x Q / 100
air%
Q air,M = 6,980 x 0.802 = 5,598 kW
Heat d<strong>is</strong>sipation of jacket water cooler
Fig. 6.04.02 indicates a Q = 87.9% heat d<strong>is</strong>sipa-
jw%
tion; i.e.:
Q = Q jw,M jw,L1 x Q / 100
jw%
Q jw,M = 2,490 x 0.879 = 2,189 kW
Heat d<strong>is</strong>sipation of lube oil cooler
Fig. 6.04.03 indicates a Q lub% = 96.7% heat d<strong>is</strong>sipation;
i.e.:
Q lub,M = Q lub, L1 x Q lub% / 100
Q lub,M = 1,360 x 0.967 = 1,315 kW
Heat d<strong>is</strong>sipation of central water cooler
Q cent,M = Q air,M + Q jw,M + Q lub, M
Page 3 of 12
Q cent,M = 5,598 + 2,189 + 1,315 = 9,102 kW
Scavenge air coolers:
V = V cw,air,M cw,air,L1 x Q / 100
air%
V cw,air,M = 246 x 0.802 = 197 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 = 184 x 0.967 = 178 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 = 197 + 178 = 375 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 = 178 m 3 /h
Seawater pump for central cooler
As the seawater pump capacity and the central
cooler heat d<strong>is</strong>sipation for the nominal rated engine
found in the ‘L<strong>is</strong>t of Capacities’ are 530 m 3 /h and
10,830 kW the derated seawater pump flow equals:
Seawater pump:
V sw,cent,M = V sw,cent,L1 x Q cent,M / Q cent,L1
530 x 9,102 / 10,830 = 445 m 3 /h
S65ME-C 198 48 26-1.1