Iveco Marine Diesel Engines, Installation Handbook

Page: 61 / 132

MARCH 2004 AIR SUPPLY
5.61
MARINE ENGINES INSTALLATION
5.1 SUPPLY AND VENTILATION
The temperature and pressure of the air sucked by the engine influence, as seen before, the engine per-
formance and operation.
As a result, for the engine correct operation and duration, the designer of the engine room shall:
■
Ensure the correct air flow in the quantity required for the engine combustion.
■
Ensure the suitable ventilation of the environment to dissipate the heat radiated by the engines and
keep the room temperature at acceptable levels.
A temperature too high inside the engine room does not only reduce the engine performance, espe-
cially if the engines suck air directly inside it, but it would also create:
■
Difficult environmental conditions for the operators in charge of the duct and the engine main-
tenance.
■
Operating problems of the electrical systems inside the engine room which usually have tempera-
ture functional limitations.
If the engine sucks air directly from the engine room, it is necessary that the ventilation system enables
to keep temperature within acceptable limits and anyway not above 10°-15°C the exceeding of the
temperature of the engine room compared to the external environment.
The specific publications show the air capacity values for the combustion and ventilation of each engine.
The ventilation air capacity values given in the publications are those suggested to limit the tempera-
ture increase in the engine room within 15°C.
It is the shipyard responsibility to ensure the right air intake in the engine room.
5.2 ENGINE ROOM VENTILATION
The shipyard must ensure an abundant and well distributed ventilation and check, at fitting, that during
operation there is not depression in the engine room, thus benefiting the correct functional behaviour
and the duration of the engines, and therefore the hull performance.
It is not possible to define a specific standard suitable for every engine-hull combination. The solutions
to be adopted on a speedboat hull with supercharged engines are different from those needed for a
work boat with aspirated engines.
On speedboat hulls the ventilation air flow is favoured as a result of the “dynamic” effect of the travel-
ling speed; the inlets on the superstructure sides will convey the air to the low side at the front of the
engine room, while the area on the top of the rear side the suitable outlet will discharge the hot air.
If this flow is not sufficient, when, for example, the air inlets fitted with baffles and protections against
the sea water substantially reduce the air intake, it is advisable to use the suitable extractor fans to facil-
itate the flow. Similarly, they are useful to limit the temperature increase when the hull is travelling at
low speed after long operation with the engines at maximum power.
The use of fans is suggested and sometimes is necessary, also for work boats and similar boats which,
for their low travelling speed, cannot rely on a significant “dynamic” effect.
The complete development of the setting and dimensioning calculation for the ventilation system com-
ponents of the engine room, complex because influenced by different parameters, lies outside the pur-
pose of this handbook and shall be carried out at the shipyard.