Friday, 16 September 2016

Air-Cooled Engines vs. Liquid-Cooled Engines

An internal combustion engine generates heat in order to produce power. However, only a small percentage of the heat can be utilized for the conversion of power into mechanical force. The rest is discarded either through the exhaust, cylinder walls, cylinder heads, crankcase walls or engine oil.
To remove the waste heat in the most efficient and reliable manner possible, engines are either air-cooled or liquid-cooled.

Air-Cooled Engines:-

Air-cooled engines have an increased surface area for quicker heat exchange and usually have fins on them. Air-cooled engines have a high heat tolerance, which means the parts of the engines are rated to perform over a higher temperature range. This is very important in extreme conditions such as during extremely hot summers. The parts of the engine are made in a way to accommodate the expansion of the metal in the hottest of climates.

Liquid-Cooled Engines:

Liquid-cooled engines have their heads without fins and are surrounded by a water cooling system. Although the term ‘Water-cooled’ is more popular term for these engines, of late, the water in the radiator is replaced by Ethylene Glycol based coolant which has got better thermal conductivity than water. The coolant is used to keep the temperature of the engine at an optimum level. The coolant flows through the channels and absorbs the engine heat and transfers it out of the engine through radiator fan. The flow pattern, rate, temperature and pressure can all be adjusted in order to provide maximum cooling effectiveness without increasing the surface area of the cylinder head or walls.

Which is Better?

Generally, both of them have an equal number of advantages and disadvantages.
Below are the features of both types of engines:

a.Air cooled engines have lesser moving parts and hence less maintenance is required.

b.Setting up a cooling package of a Liquid cooled engine is complex affair as many hoses, pipes and accurate sizing of radiator is required.

c.With the same size of engine, a liquid cooled engine produces more power compared to an air cooled engine.

d.Due to higher thermal conductivity of Ethylene Glycol based coolant, liquid cooled engines are more efficient in removing heat and thus can operate at full load at longer time duration's.

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