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How Diesel Engine Cooling System Works?

Views: 119     Author: Site Editor     Publish Time: 2021-03-25      Origin: Site

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How Diesel Engine Cooling System Works?

How Diesel Engine Cooling System Works?

Many users are not aware of the importance of the cooling system of diesel engines and do not pay attention to the maintenance work. This paper focuses on the importance of the cooling system for KP425 6 cylinder high speed diesel engine and the structural characteristics of the cooling system.



1. Importance of Cooling System

The cooling system of powerful 6 cylinder diesel engine can ensure that the engine works at the most suitable temperature, neither under the condition of overheating nor supercooling. When the engine is working, the temperature in the cylinder can reach 1800-2000 ℃.


If the cooling system does not work, there will be some adverse consequences. For example, the metal parts will directly be in contact with high temperature gas, which will overheat and expand and deform. The mineral lubricating oil used in diesel engine will deteriorate, scorch and lose its lubrication function, which will make the diesel engine unable to work. Therefore, the cooling system of diesel engine is essential.



2. Structural Characteristics of Cooling System

The cooling system of KP425 high speed diesel engine is divided into water cooling system and air cooling system according to different cooling medium. According to different design requirements, the most favorable temperature of cooling water for diesel engine is also different. Generally, the water temperature of water-cooled diesel engine is required to be 75-95 ℃.


According to the way of cooling water circulation, the cooling system of water-cooled diesel engine can be divided into evaporation type, heat convection type and forced type.


(1) Cooling System of S195 Type Diesel Engine

The cooling system of S195 type diesel engine is (boiling) evaporative type cooling system. The cooling water is directly connected with the atmosphere and is open type. The water tank is usually cast with aluminum alloy with good thermal conductivity, which can not only be a water container but also dissipate heat.


When the KP425 high quality diesel engine is working, the water in the water jacket contacts with the high-temperature parts and is heated. When the temperature increases, the density decreases and it flows upward. The cooling water in the water tank has low temperature, high density and flows downward. Therefore, the upper and lower water form convection. The cooling principle is that after the cooling water absorbs heat, part of the water evaporates and vaporizes, and the heat is taken away and sent out to the atmosphere. Under normal operation, the temperature of cooling water can reach 100 ℃ (boiling). This kind of cooling system is simple in structure, which is often used in single cylinder diesel engines with low technical requirements. Its disadvantage is that the consumption of cooling water is large, and large volume water tank is necessary.  Cooling water should be added frequently in use and it is easy to produce incrustation scale.


(2) Closed Water Cooling System with Pressure Circulation

It is driven by the water pump (centrifugal pump), so that the cooling water in the cooling system can be in continuous circulation. The high temperature parts are cooled and the heat is dissipated into the atmosphere. This cooling method is applied by most diesel engines. It is mainly composed of water pump, radiator, fan and thermostat.


After the water pressure of the cooling water is raised by the water pump and enters the main water channel of the cylinder block, part of the cooling water directly enters the cylinder head to cool the inlet and outlet valves, air passage and combustion chambers, and the other part enters the water jacket of each cylinder. After the two parts of cooling water are heated, it flows into the water supply chamber of the water tank (radiator) through the thermostat at the front end of the cylinder head. When the water flows through the water pipe of the radiator, it is cooled by the air flow. The cooled water flows to the water chamber of the radiator, and then is sent to the cylinder block by the water pump for recycling.


The characteristics of this cooling method are that the cooling water circulation speed is fast and the heat dissipation capacity is large. The water capacity in the radiator can be reduced, which is conducive to reduce the quality of diesel engine, and the cooling is uniform and reliable. Its disadvantage is that its structure is more complex and it needs to consume a certain power of diesel engine to drive water pump.


(3) Air Cooled Cooling System

In the air-cooled cooling system, the air flow generated by the fan is directly blown to the heat sink on the cylinder block and cylinder head through the wind deflector, so that the heat is carried away with the air flow. The heat sink increases the heat dissipation area, and the air flow is fully utilized by the wind deflector.


After understanding the working principle of the KP425 6 cylinder diesel engine cooling system, it can be used correctly and maintained actively, so that the power and economy of the diesel engine can be brought into full play, and the service life of the diesel engine can be increased.

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