The fresh water cooling system is divided into a high temperature (HT) and a low temperature (LT) circuit.
The HT water circulates through cylinder jackets, cylinder heads and the 1st stage of the charge air cooler,
if the engine is equipped with a two-stage charge air cooler. V-engines are equipped with a two-stage
charge air cooler, while in-line engines have a single-stage charge air cooler.
A two-stage charge air cooler enables more efficient heat recovery and heating of cold combustion air.
The LT water circulates through the charge air cooler and the lubricating oil cooler, which is built on the
engine.
Temperature control valves regulate the temperature of the water out from the engine, by circulating some
water back to the cooling water pump inlet. The HT temperature control valve is always mounted on the
engine, while the LT temperature control valve can be either on the engine or separate. In installations where
the engines operate on MDF only it is possible to install the LT temperature control valve in the external
system and thus control the LT water temperature before the engine.
9.2.1 Engine driven circulating pumps
The LT and HT cooling water pumps are engine driven. The engine driven pumps are located at the free
end of the engine.
Pump curves for engine driven pumps are shown in the diagrams. The nominal pressure and capacity can
be found in the chapter Technical data.
Figure 9.3
Pump curves for engine driven HT- and LT- water pumps
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Product Guide Wärtsilä 34DF - 3/2012
Product Guide
9. Cooling Water System
