Air Cooling

Increasing Surface Area for heat exchange

While the fins on the heads of a fourstroke engiine or two stroke engine are the best example of how an engine can be air cooled by increasing the surface area, in a car or truck there are many other components that also use air cooling. Below are some examples of this:

A well designed brake roter will be engineered to work like a heat exchanger

As seen on the left, the lighterweight rotor with a wider air gap will move MORE hot air away from the thickest part of the brake rotor (where the rotor is connected to the hub and wheel).

This serves to cool the rotor, calipers, hub, axle and centre of the wheel.

The wheel rim is also working to pull excessive thermal energy out of the rotor or drum.

Changing Materials for Heat Exchange

Each material used has its own specific heat capacity. Specific heat capacity is a measurement of how much energy is needed to raise the temperature of one gram of a substance by one degree celsius.

In short, the lower the specific heat capacity the less energy needed to heat it up. The higher the specific heat capacity, the more energy needed to increase its temperature.

Below are some common materials used in building vehiicle parts and their varoius specific heat capacities:

The Best of Both Worlds

Radiators

An efficient thermal exchange unit

Engineers combined the increased surface area WITH a material that has a high specific heat capacity (aluminum) to create a radiator.

Coolant fluid is pumped through smaller lines.
the small lines have mini aluminum fins attched to them

By creating mutliple paths, more liquid is in contact with the surface of the smaller pipes

Air is pulled through the fins to absorb the thermal energy as the air hits the fins.