Air Cooled System:
Air cooled system is generally used in small engines say up to 15-20 Kw and in aero plane engines. In this system fins or extended surfaces are provided on the cylinder walls, cylinder head, etc. Heat generated due to combustion in the engine cylinder will be conducted to the fins and when the air flows over the fins, heat will be dissipated to air. The amount of heat dissipated to air depends upon : (a) Amount of air flowing through the fins. (b) Fin surface area. I Thermal conductivity of metal used for fins.
Advantages of Air Cooled System Following are the advantages of air cooled system:
(a) Radiator/pump is absent hence the system is light. (b) In case of water cooling system there are leakages, but in this case there are no leakages. I Coolant and antifreeze solutions are not required. (d) This system can be used in cold climates, where if water is used it may freeze. Disadvantages of Air Cooled System (a) Comparatively it is less efficient. (b) It is used only in aero planes and motorcycle engines where the engines are exposed to air directly.
Water Cooling System:
In this method, cooling water jackets are provided around the cylinder, cylinder head, valve seats etc. The water when circulated through the jackets, it absorbs heat of combustion. This hot water will then be cooling in the radiator partially by a fan and partially by the flow developed by the forward motion of the vehicle. The cooled water is again recirculated through the water jackets
Thermo Syphon System:
In this system the circulation of water is due to difference in temperature (i.e.
difference in densities) of water. So in this system pump is not required but water is circulated because of density difference only.
Pump Circulation System: In this system circulation of water is obtained by a pump. This pump is driven by means of engine output shaft through V-belts.