Marine Installation Manual
2021-08
4-14
4 Ancillary Systems
4.2 Cooling water system
X72DF
Figure 4
-
7 Pre-heating power requirement per cylinder
All figures are related to requirements of the engine and should only be used for
a first concept layout of the heater capacity. However, during pre-heater selec
-
tion the shipyard or ship designer must also consider further aspects such as heat
losses in the external piping system, water volume inside the system, pipe
lengths, volume of ancillary equipment, etc.
4.2.4
Freshwater generator
A freshwater generator, using heat from the cylinder cooling system to distil sea
-
water, can be used to meet the demand for washing and potable water. The ca
-
pacity of the freshwater generator is limited by the amount of heat available,
which in turn is dependent on the service power rating of the engine.
The latest version of the
Concept Guidance
for freshwater generator installation
(DG 9721) is provided on the WinGD webpage under the following link:
Freshwater generator installation
SM-0050
Heating-up time [h]
Approx. engine heating demand [kW/cyl]
0
6
12
18
24
30
36
42
48
0
20
40
60
80
100
120
140
160
Pre-heating and heat losses of piping system to be added
0°C E/R temp.
5°C E/R temp.
10°C E/R temp.
(recommended for layout)
20°C E/R temp.
30°C E/R temp.
recommended
pre-heating time range
NOTE
It is crucial in the design stage to ensure that there are sufficient safe
-
guards to protect the main engine from thermal shock when the fresh
-
water generator is started. To reduce such a risk, it is recommended to
use valves (for instance butterfly valves), which are linked and actuated
with a large reduction ratio, at the freshwater generator inlet and in the
bypass line.
