Wartsila 31, Product Manual

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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, while the LT water circulates through the 2nd stage of the charge air
cooler and through the lubricating oil 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-water pump is circulating
the cooling water in the circuit and a thermostatic valve controls the outlet temperature.
HT-thermostatic valve(s) can be mounted as option outside of the engine. The LT-water pump
is circulating the cooling water in the circuit and an LT-thermostatic valve mounted in the
external cooling water system, controls the inlet temperature for correct receiver temperature.
It is mandatory that the actuated type thermostatic valve is controlled by the automation
system.
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.
Wärtsilä 31 Product Guide - a1 - 18 October 2016 9-7
9. Cooling Water System Wärtsilä 31 Product Guide