Car Cooling Systems

Cooling Systems are those components in an automobile that keep the engine at working temperature.

Why do we need Cooling Systems?

• During combustion in the engine, the temperature in the cylinder rises to 4,000 °F. A large amount of heat is absorbed by cylinder walls, cylinder heads, pistons, and valves due to the rapid rise in their temperature.
• If this absorbed heat is not dissipated, the combustion chamber surfaces will become red hot, and the valves will burn and warp. Various other parts of the engine will expand enormously, resulting in the seizure of pistons in the cylinders, bearings on the journals & pins, and scoring of cylinder walls.
• In an I.C. engine, about 20% of the latent heat produced during combustion passes through the cylinder walls into the cooling system.
• The cooling system is required to absorb and dissipate the excess heat generated from the cylinder walls, cylinder head, pistons and valves etc. and to keep the engine temperatures within safe limits.

Types of Cooling Systems

There are two types of cooling systems applicable. 

1. Air Cooling System.                
2. Liquid or Water Cooling System.

1)  Air Cooling System: -  

In the air cooling system

• Air flows over the cylinder walls & cylinder head.
• Air-cooled engines contain fins or ribs on the outer surfaces of cylinders & cylinder heads.
• These fins provide more area for air contact resulting in better radiation of heat.
• The heat produced by fuel combustion passes through the cylinder walls and heads to the fins, from where it is dissipated into the surrounding atmosphere.
• In motorcycles, the flow of air is achieved by their forward motion.

Light-weight Applications of air cooling systems: - Motor Cycles, Scooters, General aviation AirCraft, etc.

2) Liquid or Water Cooling System: - 

In the liquid/water cooling system

• Liquid or Water circulates the engine using external sources.
• In liquid or water cooling engines, heat from the cylinders is transferred to the liquid or water contained in the jackets surrounding the cylinders, combustion chambers & ports etc.
• Through the water or liquid, heat is carried into the radiator, which is conducted to its fins for radiation to the passing air.
• The vehicle's forward motion and an engine-driven fan accelerate air circulation over the radiating surface.

Heavy Weight Applications: - Cars, Trucks, Earth Moving Equipment, etc.

1. Radiator

Radiators are heat exchangers that transfer thermal energy from one medium to another for cooling and heating.

Why: - The purpose of the radiator is to cool the water received from the engine block. 

Working Mechanism: - 

It is located at the front portion (forward motion of vehicle). The Radiator consists of three parts- Upper tank, Core, and Lower tank. Upper and Lower tanks are joined by the core. The upper tank contains a neck through which water is filled into it and to the side of which an overflow pipe is connected. A connection is also provided for the inflow of hot water from the engine into it. The lower tank again contains connections for the outflow of water. A drain cock is provided at the bottom of the lower tank to remove water from the radiator. The core is in between the upper and lower tanks. Hot water flows down to the lower tank through the core, during which heat from the water is transferred to the passing air by the core.

The radiator is usually made of copper or brass to dissimulate heat rapidly.

Applications are Automobiles, Piston-engine aircraft, railway locomotives, motorcycles, and stationary generating plants.

2. Engine Jacket Cooling

A series of holes cast or bored through the main engine block and connected by inlet and outlet valves to a radiator.

Why: - The purpose of the Engine Jacket Cooling Water System (EJC) is to ‘cool water to engine jackets to prevent damage to the engine.’

Working: - It is located around the engine cylinder & engine head. 

The production temperature gradually increases when the Engine is ON and continuously running. To maintain the working temperature, Engine Jacket occurs (around the cylinder & cylinder head) a set of boreholes. Remove heat by passing cooling water from the bottom side of the borehole. At the top, the borehole's collected hot water (cylinder wall & head) passes into the radiator (upper tank). The hot water passing to the core (Air cooling by a fan) converts into cool water (collected in the Lower tank). After that, cooling water goes into the engine cylinder (bottom side).

Applications are Internal Combustion Engines used for heavy-duty vehicles (Automobiles, Marine, and Earth Moving equipment etc.).