WÄRTSILÄ WARTSILA 20, Product Manual

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Weight [kg] D [mm] C [mm] A [mm] rpm Engine type
290 1133 425 578 1000 W 6L20DF
310 1133 425 578 1200
310 1133 425 578 1000 W 8L20DF
330 1082 587 446 1200
340 1133 675 578 1000 W 9L20DF
470 1760 960 589 1200
As an alternative for the central coolers of the plate or of the tube type a box cooler can be
installed. The principle of box cooling is very simple. Cooling water is forced through a
U-tube-bundle, which is placed in a sea-chest having inlet- and outlet-grids. Cooling effect
is reached by natural circulation of the surrounding water. The outboard water is warmed up
and rises by its lower density, thus causing a natural upward circulation flow which removes
the heat.
Box cooling has the advantage that no raw water system is needed, and box coolers are less
sensitive for fouling and therefor well suited for shallow or muddy waters.
9.3.5 Waste heat recovery
The waste heat in the HT cooling water can be used for fresh water production, central heating,
tank heating etc. The system should in such case be provided with a temperature control
valve to avoid unnecessary cooling, as shown in the example diagrams. With this arrangement
the HT water flow through the heat recovery can be increased.
The heat available from HT cooling water is affected by ambient conditions. It should also be
taken into account that the recoverable heat is reduced by circulation to the expansion tank,
radiation from piping and leakages in temperature control valves.
9.3.6 Air venting
Air may be entrained in the system after an overhaul, or a leak may continuously add air or
gas into the system. The engine is equipped with vent pipes to evacuate air from the cooling
water circuits. The vent pipes should be drawn separately to the expansion tank from each
connection on the engine.
Venting pipes to the expansion tank are to be installed at all high points in the piping system,
where air or gas can accumulate.
The vent pipes must be continuously rising.
9.3.7 Expansion tank (4T05)
The expansion tank compensates for thermal expansion of the coolant, serves for venting of
the circuits and provides a sufficient static pressure for the circulating pumps.
Design data:
70 - 150 kPa (0.7...1.5 bar) Pressure from the expansion tank at pump inlet
min. 10% of the total system volume Volume
NOTE
The maximum pressure at the engine must not be exceeded in case an electrically
driven pump is installed significantly higher than the engine.
Wärtsilä 20 Product Guide - a13 - 6 September 2016 9-15
9. Cooling Water System Wärtsilä 20 Product Guide