Engine Cooling System
by ER. Afzal Ahamed Malik
- COOLING SYSTEM An automobile's cooling system is the collection of parts and substances (coolants) that work together to maintain the engine's temperature at optimal levels. Comprising many different components such as water pump, coolant, a thermostat etc. The system enables smooth and efficient functioning of the engine at the same time protecting it from damage The temperature produced on the power stroke of an engine can be as high as 1600 degree and this is greater than melting point of engine parts.
- TRANSFORMATION OF FUEL ENERGY 35% Exhaust & Cooling 35 % Heat Dissipation 25-30 % Mechanica l Work 4
- Effects of high temperature in the engine Due to high temperature, the piston would seized in cylinder and stop the engine. Lubricating quality of the oil inside the cylinder would be destroyed. Preignition of fuel mixture which cause engine knocking as well as loss of power.7. TYPES OF COOLING In order to cool the engine a cooling medium is required. On the basis of medium ,in general use for cooling I.C. engine ,types of cooling system are:- Air cooling system Liquid or water cooling system
- AIR COOLING SYSTEM
- AIR COOLING SYSTEM Air cooled engines are those engines, in which heat is conducted from the working components of the engine to the atmosphere directly. The cylinder of an air cooled engine has fins to increase the area of contact of air for speedy cooling. The amount of heat dissipated to air depends upon : Amount of air flowing through the fins. Fin surface area. Thermal conductivity of metal used for fins.
- COOLING FINS
- MERITS & DEMERITS OF AIR COOLING SYSTEM MERITS: It is more simple in design and construction Water jackets, radiators, water pumps, thermostat, pipes, hoses etc. are not needed It is more compact It is comparatively lighter in weight DEMERITS: There is uneven cooling of engine parts Engine temperature is generally high during working period
- LIQUID COOLING SYSTEM
- LIQUID COOLING SYSTEM A liquid is circulated around the cylinders and absorb heat from the cylinder walls and cylinder head. Coolant absorbs heat as it passes through the engine and also lubricates the water pump. Hot coolant enters the radiator in which the heat is passed on to air that is flowing through the radiator.. Working principle of water- cooled system. MERITS AND DEMERITS OF LIQUID COOLING SYSTEM MERITS: Uniform cooling of cylinder, cylinder head and valves Specific fuel consumption of engine improves by using water cooling system If we employ water cooling system, then engine need may not be provided at the front end of moving vehicle. Engine is less noisy as compared with air cooled engines, as it has water for damping noise DEMERITS: It depends upon the supply of water If the water cooling system fails then it will result in severe damage of engine The water cooling system is costlier as it has more number of parts
- TYPES OF WATER COOLED SYSTEM Open Jacket System Thermo syphon Cooling System Forced Circulation Cooling System
- OPEN JACKET SYSTEM This system is used where plenty of water is available. The water is supplied from large tank or river through the inlet valve of cooling water jacket. The main specification of this system is that Hot water is not cooled but simply discharged.
- THERMOSYPHON COOLING SYSTEM The basic principle of this system is based upon the relative density of the water. The main advantage of this system is it’s simplicity and automatic circulation of cooling water.. FORCED CIRCULATION SYSTEM This system is used in large number of automobiles like Cars, tractor and even Heavy Trucks. Here flow of water from radiator to the water jackets is assisted by pump.
- To supply the water forcely into the systemWATER PUMP • To dissipates the heat from coolantRADIATOR • To provide strong draft of air through the radiatorFAN • Designed to keep engine block and cylinder head cool.WATER JACKETS • To control the flow of coolant, it opens at 70 degree and fully open at 82 degreeTHERMOSTAT VALVE • To store the coolantSTORAGE TANK COMPONENTS OF LIQUID COOLING SYSTEM
- RADIATOR Radiators are heat exchangers used to transfer thermal energy from one medium to another for the purpose of cooling and heating. 21
- THERMOSTAT VALVE Its job is to block the flow of coolant to the radiator until the engine has warmed up.
- Thermostat Closed Thermostat Open When engine is cold When engine reaches the specified temperature
- WATER JACKETS Cooling water jackets are provided around the cylinder, cylinder head, valve seats, and any hot part which are to be cooled. Heat generated in the cylinder is conducted to the Jacket.
- ANTIFREEZE MIXTURE To prevent the freezing of cooling water in western countries antifreeze mixture are added to the cooling water There are the following type of antifreeze mixtures :- Ethylene glycol Propylene glycol Organic acid technology (OAT) Hybrid organic acid technology (HOAT)
- Coolant/Anti-freeze Engine coolant is a mixture of water and antifreeze/coolant. Water alone has a boiling point of 100°C and a freezing point of 0°C at sea level. Engine coolant has a higher boiling temperature and a lower freezing point than water. The exact boiling or freezing temperatures depend on the mixture. The typical recommended mixture is a 50/50 solution of water and antifreeze/coolant.
