WinGD X72DF, Installation Manual, Page: 80 / 237

Marine Installation Manual 2021-08 4-5
4 Ancillary Systems
4.2 Cooling water system
X72DF
4.2.1 Low-temperature circuit
The LT cooling water circuit for the main engine provides cooling for the SAC,
the LO cooler and the MDO/MGO cooler.
Setting of automatic
temperature control valve
for cooling water
For the main engine SAC, the automatic temperature control valve must be set to
25°C (set-point). When seawater temperatures are higher than 21°C — assuming
a maximum seawater temperature of 32°C — the cooling water temperature for
the SAC may increase to maximum 36 °C. The higher the LT cooling water tem
-
perature, the earlier DCC might be activated. Consequently, it is recommended
to keep the temperature of the LT circuit as low as possible.
Warm seawater conditions may result in higher BSFC and respectively BSEC
than in ISO standard design condition as well as in earlier DCC activation. A
scavenge air temperature increase by 1 degree Celsius results in a reduction of the
DCC activation trigger level by 1.5% of CMCR power. Therefore, high focus
must be laid on achieving a low scavenge air temperature.
Arrangements of LT
cooling water circuit
Consequently, depending on the ancillary equipment and the temperature
set-point selection, the LT circuit can be typically installed in the following ar
-
rangements:
•
Arrangement 1 — Single set-point temperature 25°C (see Figure 4 - 3,  4-6 )
•
Arrangement 2 — Dual set-point temperatures (see Figure 4 - 4,  4-6 )
•
Arrangement 3 — Separate SAC cooling circuit (see Figure 4 - 5,  4-7 )
NOTE
The automatic temperature control valve of the SAC must be set to
25°C (see Arrangement 1,

4 - 6 ).
If ancillary machinery requires a different temperature set-point, then a
separate cooling water loop must be installed as shown in Arrangement
2,

4 - 6 and Arrangement 3,

4 - 7 .