Types of cooling system in vehicle from automobile engineering subject

Types of cooling system

1. COOLING SYSTEM

2. Cooling system We know that in case of Internal Combustion engines, combustion of air and fuel takes place inside the engine cylinder and hot gases are generated. The temperature of gases will be around 2300-2500°C. This is a very high temperature and may result into burning of oil film between the moving parts and may result into seizing or welding of the same. So, this temperature must be reduced to about 150-200°C at which the engine will work most efficiently. Too much cooling is also not desirable since it reduces the thermal efficiency. So, the object of cooling system is to keep the engine running at its most efficient operating temperature

3. Cooling system There are mainly two types of cooling systems : Air cooled system, and Water 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 and when the air flows over the fins, heat will be dissipated to air.

4. Air cooling system Have metal FINS on the outer perimeter of the engine. Heat is transferred from the engine, through these fins, into the atmosphere Advantages of Air Cooled System Radiator/pump is absent hence the system is light. In case of water cooling system there are leakages, but in this case there are no leakages. Coolant and antifreeze solutions are not required .

5. 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. Types of Water Cooling System 1. Thermo Siphon System 2. Pump Circulation System

6. Thermo Siphon System The thermosyphon cooling system is so designed that the water may circulate naturally because of the density difference between hot water and cold water.

7. Pump Cooling system This system is similar to the thermosyphon System the only difference that a pump is used for the circulation of coolant and a thermostat is employed to control the flow of coolant. The pump is driven using a belt from the engine crankshaft. The coolant is to be passed through the hose pipes and travel throughout the system. The thermostat plays a vital role in increasing the life of the radiator.

8. Pump cooling system The main components in the pump cooling system are Thermostat Fan Water pump Radiator Pressure cap

9. Thermostat The thermostat consist of a metallic part which either expands or contrasts when it comes in contact with hot or cold water. When the valve comes in contact with cold water, it closes. When the water is hot the valve rises above its seat and hot water passes through the valve to the radiator.

10. Some times the water remains at a low temperature for a long time. In this case the pump keeps circulating the cold water around the block until it is sufficiently heated. Only then is the thermostat opened.

11. Fan When the vehicle is going at high speed with light load the natural draft of air passing through the radiator may be sufficient for cooling of the engine. but when the vehicle is moving under heavy load and at a slow speed natural draft is certainly in sufficient to produce the desired cooling. this explains why fan is a necessary part of the engine cooling system. it is mounted behind the radiator on the same shaft on which the water pump is mounted. it is driven by a v belt from the crankshaft Pulley. it may have four to seven blades . it is generally made of sheet metal but these days molded plastic materials example nylon or polypropylene are also being used for making fans.

12. Water pump A pump is used in the water cooling system for increasing the velocity of the circulating water. the impeller type pump is mounted at the front end of the cylinder block. it is introduced in the water cooling system between the radiator and the engine block at the lowest side. the pump consists of a shaft the impeller and water passage. The impeller is a flat plate mounted on the pump shaft with a series of flat or curved blades when the impeller rotates, the water between the blades is thrown outwards due to the centrifugal force. the water is forced through the pump outlet to the radiator.

13. Radiator Radiator is responsible for cooling the circulating water which gets heated after removing heat from the cylinder block. the radiator has very fine pipes and is available in various designs in order to enable the water to pass through very minute parts. at the same time the outer side of these parts is also cooled by means of the incoming air.

14. Radiator

15. Radiator pressure cap Radiator pressure cap consists of a vacuum valve, pressure valve, filler cap seat and overflow pipe. when the cap is on its seat the pressure and the boiling point of the water in the radiator increase. the pressure in the radiator is kept under control by the pressure valve thereby reducing the overflow of water. On the other hand the hot radiator cool suddenly due to some changes in atmospheric conditions when this happens a vacuum is created inside the radiator which in turn may cause the collapse of the radiator at this critical juncture the vacuum valve operates does avoiding the collapse of the radiator.

16. Anti freeze solutions In order prevent the freezing of water, an anti freeze solution is added to the coolant. The anti freeze solution can be either methanol or an ethylene glycol base. Methanol is usually cheaper than ethylene glycol.