: Most internal combustion engines are fluid cooled
using either air (a gaseous fluid) or a liquid coolant run through
a heat exchanger (radiator) cooled by air.
In air cooling system, heat is carried away by the air flowing
over and around the cylinder. Here fins are cast on the cylinder
head and cylinder barrel which provide additional conductive
and radiating surface. In water-cooling system of cooling
engines, the cylinder walls and heads are provided with jacket
through which the cooling liquid can circulate.
An internal combustion engine produces power byburning fuel
within the cylinders; therefore, it is oftenreferred to as a "heat
engine." However, only about25% of the heat is converted to
useful power. Whathappens to the remaining 75 percent? Thirty
to thirtyfive percent of the heat produced in the
combustionchambers by the burning fuel are dissipated by
thecooling system along with the lubrication and
fuelsystems. Forty to forty- five percent of the heatproduced
passes out with the exhaust gases. If this heatwere not removed
quickly, overheating and extensive
damage would result. Valves would burn and warp,lubricating
oil would break down, pistons and bearingwould overheat and
seize, and the engine would soonstop.The necessity for cooling
may be emphasized byconsidering the total heat developed by an
ordinary six-cylinder engine.