AIR COOLING SYSTEM

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

(c) Thermal conductivity of metal used for fins

>For efficient cooling the length of the fins and the spacing between them is quite important.

>Larger inter spacing between the fins offers larger area for cooling air but the heating of the 

  air is less, so more cooling air is required.

>Smaller  interspacing between the fins results in smaller  flow area of cooling  air and hence 

  input cooling air is less.

>Usually fin height varies from 15 to 25 mm.

Air cooled engines have the following advantages:

1. Its design of air-cooled engine is simple.

2.  It  is  lighter  in  weight  than  water-cooled  engines  due  to  the  absence  of  water  jackets, 

     radiator, circulating pump and the weight of the cooling water.

3. It is cheaper to manufacture.

4. It needs less care and maintenance.

5.  This  system  of  cooling  is  particularly  advantageous  where  there  are  extreme  climatic 

conditions in the arctic or where there is scarcity of water as in deserts.

6. No risk of damage from frost, such as cracking of cylinder jackets or radiator water tubes.

Disadvantages of air cooled engines

1. Cooling fins under certain conditions may vibrate and amplify the noise level.

2. Cooling is not uniform.

3.Engines are subjected to high working temperature.