Internal Combustion Engine Cooling Methods | HSD

There are two methods of cooling the I.C. Engines. 

1. Air cooling 

2. Water cooling. 

Air Cooling: It is a direct method of cooling. In air cooled engine fins are cast on the cylinder head and cylinder barrel to increase its exposed surface of contact with air. Air passes over fins and carried away heat, with it. Air for cooling the fins may be lined from a blower or fan driven by the engine. Air moment relative to engine may be used to cool the engine as in case of motor cycle’s engine. About 13 to 15% of heat is lost by this method. It own air cooling system. Simplicity and lightness are the ad shows not as effective as water cooling. The rate of cooling depends upon the velocity, quantity and temperature of cooling air and size of surface being cooled. 

The position of valves, Fins and head in air cooling system. This system is used in motor cycles, scooters and aero plans. 

 

Water Cooling: It is the indirect method of cooling the engine The various cooling systems used are shown in below figure. Water after circulating in water jackets (passages around the cylinder, combustion chamber valves etc.) goes as waste or in recirculation method of cooling water is continuously circulated through water jackets. Water takes up the heat and leaves for radiator where it is cooled for recirculation.  

 

 

 

In stationary diesel engine plants the water cooling systems are as follows: 

1. Open or Single Circuit System:  In this system pump draws the water from cooling pond and forces it into the main engine jackets. Water after circulating through the engine return to the cooling pond. 

 

2. Closed or Double Circuit System: In this system raw water is made to flow through the heat exchanger when it takes up the heat of jacket water and returns back to the cooling pond. 

 

Heat lost by water cooling is about 25 to 35%. The amount of heat lost is called jacket loss. The rate of flow of water should be so adjusted that the outlet temperature of cooling water does not exceed 60’c and rise in temperature of cooling water is limited to 11’c the water used for cooling purposes should be free from impurities. Water cooling methods permit uniform cooling. Water cooling creates troubles in very cold weather. Cooling efficiency is reduced due to scaling in the pipes, jackets and radiator. Engine efficiency affected by power needed to drive the water pump and radiator fan. 

 

Closed system of cooling is mostly used in power stations. A closed cooling system comprises the following equipment. 

1. A surge tank. 

2. Soft water circulating pump. 

3. Soft water circulation pipe. 

3. Soft water heat exchanger or cooler. 

4. Raw water softening plant. 

5. Raw water circulation pump. 

6. Raw water circulation pipe. 

7. Raw water cooling arrangement such as cooling tower. 

8. Thermometer for measuring inlet and outlet temperatures. 

9. Temperature regulator to control the Excessive jacket temperature. 

10. Safety device to control the excessive jacket temperature. 

 

This system shown is in use soft water for jack cooling. The hot jacket water from the engine is passed through cooler (heat exchanger) where it is cooled with the help of raw water. 

The raw water in turn is cooled by cooling towers.