Automotive Systems/Cooling System
Cooling systems remove heat from the engine using the properties of heat transfer. Modern cars use liquid cooling systems. These use a fluid circulated within the engine, that is then pumped out of the engine into a radiator, where the heat is released. Less common is the air cooled engine. These engines are common in non automotive applications, and have been used successfully in cars. Air cooled engines use airflow over the surface of the engine to remove excess heat. Automotive applications generally include a fan to force air over the engine.
In a liquid cooled engine, the liquid coolant is a mixture of distilled water and antifreeze, of which the base ingredient is methyl alcohol. The fluid is pumped through channels that are manufactured into the engine block. The fluid draws heat out of the engine and flows into the radiator to be cooled. The radiator is a set of pipes with thousands of thin metal fins mounted them. The fins conduct the heat out of the liquid which is cooled enough to be cycled back into the engine to repeat the process. The radiator has a fan that blows outside air against the fins. This increases the amount of air that flows over the cooling fins of the radiator and allow for more heat to be removed from the liquid coolant.
Since combustion engines operate better at a higher temperature, a device called a 'thermostat' is designed into the cooling system of modern engines to help them warm up more quickly. A thermostat is a small valve in the cooling system which is closed when the engine is cold. This blocks the coolant from flowing into the radiator and allows it to heat up at a quicker pace. As the coolant reaches the desired temperature, wax in the thermostat melts and pressurizes which forces the valve open. The coolant is now able to flow into the radiator ensuring that the engine temperature stays constant and does not overheat.