Car cooling system - Working principle

The car's cooling or cooling system is an important and indispensable part of every engine in a car. There are two types of engine cooling systems - a simpler one, which involves cooling the engine with air, and a somewhat more complex system for cooling the engine with coolant.

Engine cooling is extremely important and necessary, considering that during the operation of the car, the mixture inside the cylinder is ignited, and a large amount of heat is released which is transferred to the cylinder walls, but also to the entire engine. Since the metal parts of the engine would expand due to the high heat, the friction force between the piston and the cylinder would also increase.

If the friction force became greater than the power of the engine itself, the engine would automatically stop working, with great damage that it would suffer, that is, there would be a complete engine failure. To prevent the above problems, it is important that the engine is constantly cooled during its operation. This is achieved by an efficient engine cooling system.

Basic car engine cooling systems

In order to protect the engine from the harmful effects of high temperature, it is necessary to cool it during operation. For this purpose, cooling systems are used, which can be classified into two groups:

• engine air cooling systems

• engine cooling systems using coolant

Air cooling of the engine

Air cooling is mainly used for low power engines. Ribs are placed on these types of engines in order to obtain the largest possible contact surface of the cooling. In order to increase the cooling effect, it is necessary to increase the pressure and the speed of the air flow. Increasing the air flow rate is achieved by using a fan that is driven by the engine crankshaft via a V-belt.

The fan speed should be constant, so the belt should always be properly and sufficiently tightened. The ribs on the block and the cylinder head should not be greasy with oil or dirty with dust, because otherwise the air flow is prevented, and thus the cooling of the engine.

Advantages and disadvantages of this way of cooling the engine

The main advantages of this engine cooling include simplicity of design and easy maintenance of the system itself. Such a cooling system does not increase the mass of the drive unit itself, and it is also not affected by changes in the outside temperature.

Disadvantages of such a cooling system include significant intake of engine power using fans, increased noise level during operation, poorly balanced heat removal from individual engine components, inability to use the engine block system, inability to accumulate heat that is released for further use, such as heating of passenger's spaces.

Engine coolant cooling

In the case of engines that are cooled by means of the cooling liquid, there are channels in the block and the engine head through which the liquid, i.e. water, flows. These channels are located in the immediate vicinity of heated places on the engine. Coolant cooling is considered as circular forced cooling. A water pump is used, which causes the flow of coolant, but also a fan, cooler and thermostat.

A thermostat line is used to quickly reach the operating temperature of the engine. This shortened path that crosses the coolant is used only until the desired operating temperature is reached, and the coolant bypass through the radiator is used only when the car engine is warmer.

Water absorbs heat from heated places, as a result of which it also heats itself. The water heated in this way passes into the engine cooler, where it is first cooled, and then the cooled water is returned to the engine in order to receive heat again. This actually means that the coolant is constantly circulating from the engine to the radiator and back.

The advantages of this type of car engine cooling

Due to its design, a system that uses heat removal with a special fluid can efficiently remove excess heat from the mechanisms and all individual parts of the engine structure. Unlike air, the device of the engine cooling system with liquid contributes to faster adjustment, ie. reaching operating temperature at start-up. Also, antifreeze engines run much quieter and are less prone to detonation.

Coolant cooling is most often used in the engines of a large number of cars, so in the following text we will focus all our attention on this car cooling system.

Basic parts of the engine cooling system

A car cooling system that works on the principle of cooling with the help of coolant is a complex system and there are a large number of parts that are important for this system to function flawlessly and give the desired results:

• expansion vessel into which the liquid is poured,

• car refrigerator,

• car thermostat,

• water / coolant pump,

• car fan,

• piping system with channel system in the block and cylinder head,

• subsystem for heating and ventilation of the passenger compartment.

How the engine cooling system works

When starting the car, the crankshaft rotates in the engine, ie. crankshaft, and thus the fan which is placed so as to direct the air flow towards the radiator. The water pump is connected to the crankshaft via a toothed belt, and by starting the crankshaft, the water pump also starts its operation, but at idle, due to the thermostat that closed the fluid circulation circuit.

Ignition of the mixture of fuel and air in the cylinders causes an increase in engine temperature or its heating. When the engine temperature reaches the optimum operating temperature, the thermostat opens and the coolant begins to circulate through the system and performs its primary task.

The heated liquid from the engine moves towards the radiator, more precisely the lower radiator tank, where it flows through the ribbed part with channels, called the lamellar part, where it is cooled due to the circulation of outside air and thus cooled back to the engine head and engine block. And all in a circle.

Part of the heated water can also be used to heat the cabin space. The subsystem in the engine that serves for heating and ventilation of the passenger compartment is solved in different ways depending on the manufacturer.

If for any reason this system ceases with its continuous i.e. with proper operation, the engine temperature increases, and the appropriate sensors will give a signal to the driver in the form of turning on the light on the instrument panel, that the engine is too hot, i.e. to overheat the car. It is a notice to the driver to stop and turn off the car as soon as possible in order to prevent engine damage.