Cooling system

ENGINE COOLING

NEED FOR COOLING

ONLY ABOUT 20% OF HEAT IS USED AS POWER AT CRANK SHAFT

35% OF HEAT IS TRASMITTED TO THE CYLINDER WALLS WHICH CONSTITUTES POWER LOSS

THE HEAT SHOULD BE PREVENTED FROM BEING TRANSFERRED TO CYLINDER WALLS AS IT CAUSES PREIGNITION OF CHARGE

LUBRICANT MIGHT ALSO BE BURNED BECAUSE OF EXCESSIVE HEAT

THE BURNING OF LUBRICANT LEAD TO SEIZURE OF THE PISTON

WHILE ENGINE IS RUNNING HEAT MUST BE REMOVED CONTINOUSLY FROM THE ENGINE

TYPES OF COOLING

DIRECT COOLING OR COOLING BY AIR

INDIRECT COOLING OR LIQUID COOLING

AIR COOLINGAir cooling is a method of dissipating

heat

It works by making the object to be cooled have a larger surface area or have an increased flow of air over its surface, or both.

An example of the former is to add fins to the surface of the object, either by making them integral or by attaching them tightly to the object's surface (to ensure efficient heat transfer).

In the case of the latter it is done by using a fan blowing air into or onto the object one wants to cool.

In many cases the addition of fins adds to the total surface area making a heatsink that makes for greater efficiency in cooling.

In all cases, the air has to be cooler than the object or surface from which it is expected to remove heat.

ADVANTAGES NO NEED OF RADIATOR COOLANT AND

WATER PUMPLESS WEIGHT AND LOW COSTIN DESERTS AIR COOLING IS THE

PREFFERABLE METHODIN COLD COUNTRIES AIR COOLING IS

UTILIZED FOR THE VEHICLES AS WATER FREEZES INSIDE THE SYSTEM

DISADVANTAGESThe cooling tends to be uneven and leads to

cylinder distortion. Even though this has been remedied by placing the fins in a different manner, it is a problem nonetheless.

It is almost impossible to manage with air-cooling if the number of cylinders increases beyond two.

The fins vibrate sometimes leading to a lot of noise

LIQUID COOLINGIN WATER COOLING SYSTEMS, WATER

JACKETS ARE PROVIDED IN THE CYLINDER BLOCK AND THE CYLINDER HEAD.

WATER FILLS UP THESE JACKETS AND THE HEAT IS TRANSFERRED TO THE WATER IN THE WATER JACKETS THUS COOLING THE CYLINDER

TYPES OF LIQUID COOLING SYSTEMS

THERMOSIPHON SYSTEM

PUMP COOLING

THERMOSIPHON SYSTEMThermosiphon refers to a method of passive heat

exchange based on natural convection which circulates liquid without the necessity of a mechanical pump.

Its intended purpose is to simplify the pumping of liquid and/or heat transfer ,by avoiding the cost and complexity of a conventional liquid pump

PUMP COOLING SYSTEMA water pump is an important part of the engine

cooling system. It provides circulation of the engine coolant (antifreeze) through the cooling system.

A water pump pushes the coolant through the passages (water jackets) in the engine cylinder block and cylinder head and then out into the radiator.

This helps to keep the engine from overheating; the hot coolant passes through the radiator where it cools down and then returns back to the engine.

Water pump problems

Typical water pump problems include coolant leaks, noisy or defective bearing, damaged or corroded impeller.

Faulty water pump might cause the engine to overheat, which can result in serious engine damage. If defective, a water pump is replaced as a unit.

THERMOSTAT Any liquid-cooled car engine has a small

device called the thermostat that sits between the engine and the radiator

Its job is to block the flow of coolant to the radiator until the engine has warmed up.

When the engine is cold, no coolant flows through the engine. Once the engine reaches its operating temperature (generally about 95 degrees C), the thermostat opens.

By letting the engine warm up as quickly as possible, the thermostat reduces engine wear, deposits and emissions.

RADIATOR A radiator is a type of heat exchanger. It is designed to transfer heat from the hot

coolant that flows through it to the air blown through it by the fan.

These radiators are made by brazing thin aluminum fins to flattened aluminum tubes.

The coolant flows from the inlet to the outlet through many tubes mounted in a parallel arrangement. The fins conduct the heat from the tubes and transfer it to the air flowing through the radiator.

RADIATOR CAPIt keeps the cooling system sealed from

outside contaminants.

By keeping pressure on the cooling system, it raises the boiling point.

It contains pressure valve and the vaccum valve.

ANTI FREEZE SOLUTIONA fluid, such as methanol or ethylene glycol,

which is added to vehicle engine coolant or used in solar heating system heat transfer fluids, to protect the system from freezing.

The expansion of water exerts high pressure inside the cooling system and causes serious damage to the pipe in the cooling system

SCALES AND CORROSION Scale formation and corrosion or rust are the

most common problems encountered in the cooling systems of engines

The composition of the water used for cooling leads to scale formation

The impurities present in water combine with air sucked into the cooling systemthrough the water pump to produce rust.

CORROSION AND SCALE PREVENTION

A special rust inhibitor is addedwith water in the cooling system to prevent the formation of rust.

Alkalies and acids are added to prevent scale formation.

Kerosene and alkalies like washing soda reduce oil or grease in the cooling system.

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