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Wednesday, April 16, 2014

Technical features of Liquid-cooled engines

Liquid-cooled engines are ones using circulation of liquids to cool the engines. A mixture of water and a fluid called the coolant are circulated through pipes into specially built sections of the engine, and then back to the radiator. In radiator, water is cooled and sent back into the engine. Even though it is called 'water cooling', the actual cooling in the radiator happens with the use of air. Liquid-cooling systems cool better because of their heat carrying capacity.

There are two kinds of Liquid cooled-engines:

Thermo-siphon: Thermo-siphon is based on the convective property of liquids. Convection is a property in liquids by which the part of liquid higher in temperature move up against gravity and the amounts that are lower in temperature settle down. This is the property that is used in a thermo- siphon. In the engine, when the coolant comes out of the engine, it is hot. Thus, it automatically flows to the radiator where there is cooler air and simultaneously, cold coolant moves into the engine.

Pump-circulation: However, as a lot of advancements were made in the engine, their efficiencies also increased. Now, it became a requirement that their cooling is faster. So, instead of using a thermo-siphon, the coolant was circulated using the method of pump-circulation, which does it by pressurizing the coolant through to the engine and back to the radiator.

Advantages
Unlike air-cooled systems, the liquid cooled system is generally more effective and faster in cooling. Liquid cooling systems less noisy too. They are also compact and economical to manufacture.

Disadvantages
At low temperatures, the liquid coolant has a tendency to freeze. Another disadvantage is that, the liquid cooling system has pipes fitted to various components. Thus, it naturally becomes necessary that they are fixed properly and there are no leakages. If there are openings in the fittings or if the sealant gives way, leakage happens, and it doesn't just affect the cooling, but also can affect other parts surrounding the cooling. While cleaning the inner parts of car machinery, extra care is needed since water could feel messy with components.

Usage
Very commonly used in maritime vessels, because of the availability of water externally. Other than that, majority of cars today use liquid cooling system. However, Porsche has used it extensively in the 911 series, BMW in its motorcycles. Another notable model to have used this kind of engine is the Volkswagen Beetle.


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