The purpose of the cooling system of diesel gen-set engine2021-04-20 14:49:04

When the diesel generator working, plenty of heat from the fuel burning in the combustion chamber, makes the temperature in the cylinder as high as 100℃. Also, the large amount of heat is generated by friction among the all high speed operating engine parts. In order to dissipate this heat for keeping the heating parts working stably by cooling, there should be enough coolant flow through the heating parts. Thus, set up cooling system in the engine to ensure enough and continuously coolant flow and suitable coolant temperature.
 
1 、cooling effects
The effects of diesel gen-set cooling system as follows:
Keep the working temperature of heating components below the allowable value of the materials, and ensure the high strength of the elements under the high temperature condition.
 
②Ensure the suitable temperature difference between the exine and intine of heating parts, and reduce the heat stress of heating parts.
 
③Ensure the normal working status of lubricating oil film on acting surface of moving parts such as plunger and cylinder sleeve. These effects should be achieved through the cooling system, thus, cooling system is an important part of engine. In a conclusion, the requirements for cooling system are: neither the diesel engine loses energy caused by the excessive cooling nor the engine is overheating caused by lack of cooling.
 
2、ways of cooling
The cooling ways of engine include air cooling method and water cooling method.
Air cooling method
Air cooling is a method which applies air as cooling medium to radiate heat of diesel engine heating parts. This method contains cooling fans, wind scooper and so on.
For increasing the heat radiating areas, there are a lot of folded cooling fins on the exteriors of cylinder block, cylinder cover and all the radiators. The fan rotates the air along the wind guide to the cylinder body and the surface of the cylinder cover, the heat would be taken away from the cylinder body and the cylinder cover when the cold air flows through the heat sink,
The air cooling system is simple and lighter, but the cooling effect is not good, As a result it’s used in small diesel engines at water-deficient areas.
Water-cooling method
 
Water-cooling is a method which applies water as cooling medium to radiate heat of diesel engine heating parts. The feature of this cooling method is easy to adjust the intensity of cooling if the temperature and operating load have been changed.
The water cooling methods include open circuit and close circuit. In the open loop cooling system, circulating water is connected with atmosphere, and the steam pressure in cooling system is always the same as atmospheric pressure. In the close type, the water is circulated in a closed system, and the steam pressure in cooling system is higher than atmospheric pressure, Due to the temperature difference between cooling water temperature and outside air temperature, the ability of heat dissipation in the whole cooling system will be improved.
 
3. Water- cooling system
The specific way of water-cooling
At the present time the most of the diesel engine adopts closed water cooling system. Perkins diesel engine with closed water cooling system is divided into integral header tank, split type header tank and heat exchanger.
Integral header tank: One-piece tank is an integral structure of radiating tank which fixed on the front base of the diesel engine. Diesel engine drives the fan to rotate the wind into the gap of header tank fins for cooling by header tank. The advantage is shorter of the cooling water pipeline connected to tank and gen-set for saving the materials and fan driven by diesel engine directly for reduce investment in equipment.
Split type header tank: Split type header tank refers to place a header tank which with a fan driven by motor far away diesel gen set. Generally it is outside of plant room, and connected by long transportation pipeline between the water tank and the diesel engine.  The advantage of this method is that it could apply the favorable condition of good air circulation and the temperature of environment lower than that in the plant room.
Heat exchangers: The another type header tank is that there is a heat exchanger in the diesel engine, which plays an role in intermediating heat exchange, to separate the diesel engine cooling system from cooling liquid of high heads split type tank. The standard installation of diesel engine with a heat exchanger .The pump of diesel makes the cooling liquid circulating between diesel engine and heat exchanger, and the another auxiliary feed pump makes the cooling liquid circulating between split type tank and heat exchanger.
 
The way of water temperature adjustment
In the closed water cooling system, cooling water circulate continuously in diesel engine by the water pump, and take the heat into air though header tank and fans, to keep the working temperature of diesel engine within a certain range.
Two ways of water temperature regulation in the water cooling system: regulate the cooling water flow and air volume
( 1 ) regulation of cooling water flow
This way of regulating is controlled automatically by thermostat. The thermostat is operated with outer loop or inner loop according to the water temperature. When the water temperature is lower than preset temperature, the thermostat will be closed and cooling water is circulating in inner loop (exclude the cooling water tank) to raise the cooling water temperature quickly. The thermostat will be opened until the water temperature reaching to preset temperature, and the cooling water circulates in outer loop (flow though radiator) to change the cooling temperature. Now most diesel engines apply with the thermostat control, and all Perkins series diesel engines are of this form
 
(2) air volume adjustment
Air volume adjustment is changing air volume by the radiator. It is to open or close the louver of cooling water tank according to the working condition, or change the rotating speed of fans to adjust the water temperature.

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