Ever since the invention of the internal combustion engine, scientists and engineers have worked to increase its efficiency. As it stands now, the average internal combustion automobile engine only converts roughly 20% of its energy into useful motivational power. Most of the rest is expended through heat loss in various locations.
The cooling system in an automobile is used to remove heat from all the moving parts so that they can still
function properly without melting, seizing, or overheating. If an engine was ideal, it would release no heat because all of its energy would be converted into the power transferred to the wheels, but no such engine exists in reality. With all the many moving parts that must remain in contact with one another (in order to maintain compression and prevent various other leaks), friction is inevitable and thus, so is heat. Therefore, the cooling system in the car is exceedingly important.
The way it works is basically a simple matter of heat transfer. Water cooled vehicles use a combination of air
and liquid cooling mechanisms, routing coolant hoses past the hotter parts of the engine so that heat can transfer from the engine parts into the coolant, which then goes back into the radiator to be cooled off by the incoming air. Air cooled vehicles typically have large fans installed strategically on the engine and heat dissipating fins on the heads.
What may come as a surprise to some is that the heater in the cab of your car is actually a part of the car's
cooling system. Heat that is removed from the engine is simply piped into the cab so that the driver doesn't freeze to death in the middle of winter. The removal of this heat draws colder air into the engine compartment from outside which provides cooling circulation to the automobile's vital moving parts.
One of the major reasons for the loss of efficiency in an engine is the sheer number of parts moving at high
speeds. The movement creates great amounts o f friction between parts, which uses much of their moving energy to create heat. Lubricants and cooling systems can only do so much about this problem, and the typical internal combustion engine remains only about 20-25% efficient.
One can calculate the engine efficiency of a Carnot cycle engine using the thermal efficiency equation:
ec = 1- (Tc/Th)
This equation does not portray the level of inefficiency in a normal combustion engine because everyday engines experience more frictional effects.
The process shown below is an illustration of the movement of a piston in a four-stroke engine. The strokes are,
from left to right, intake, compression, ignition, power, and exhaust. This process is important to illustrate because inside the cylinders is where engines lose a great deal of potential power to heat expenditure. Friction between the cylinder wall and the sides of the piston creates resistance and heat, some of the ignition heat conducts through the...