Air-cooled diesel generator VS Water-cooled generator

You may find this item in the technical specification of a diesel generator set: cooling method. Some are air-cooled and some are water-cooled, so what’s the difference? The first thing we have to understand is how does the cooling system work? The generator set will generate a lot of heat in operation. Too much heat will cause the temperature of the unit to be too high, which will affect work efficiency. Therefore, the cooling system should be equipped in the unit to reduce the temperature of the unit. The cooling system keeps the generator in the proper temperature range under all conditions. It dissipates the heat transferred to the generator when the fuel is burned. Common cooling systems are water cooling and air cooling, the difference between them mainly lies in the cooling medium. Air cooling uses wind as the cooling medium, that is, it directly uses wind to cool the diesel generator set. The cooling medium for water cooling is water, which is then dissipated by cooling tanks and fans.

Air cooled diesel generator set

A diesel engine is a single – and two-cylinder generator with one or more fans that vent air and dissipate heat against the generator block. Generally gasoline generator and small diesel generator mainly. The air-cooled generator set has the advantages of a simple structure, low failure rate, good starting performance, less air required, low fan power consumption, low fuel consumption, no danger of freezing cracks or overheating boiling, which is conducive to maintenance; The air-cooled generator set is suitable for the plateau or the water shortage or cold place, without considering the problems of adding water, boiling point, freezing and so on. Because of the limitation of thermal load and mechanical load, the power is generally small. But need to be installed in the open cabin, noise is larger.

Water cooled diesel generator set

Mainly four cylinders, six cylinders, twelve cylinders and other large units, the internal and external water circulation of the machine, through the cooling water tank and the fan away the heat generated inside the body. The water-cooled generator set has a complex structure and more requirements for the environment. When it is used on the plateau, it is necessary to consider reducing the power and the boiling point of the coolant water. A certain proportion of additives can be added to improve the boiling point and freezing point. The water-cooled generator set has ideal cooling effect. Compared with the motor with the same technical parameters, the water-cooled generator has small volume, light weight, large energy density and better heat transfer performance. High power generator set is usually water cooled generator set.

Which is better? Air-cooled or water-cooled generator set

Under the condition of a certain gas temperature, the higher the cylinder wall temperature of an air-cooled diesel engine, the less heat will be emitted, so the higher the thermal value. Generally, the cylinder wall temperature of an air-cooled diesel generator is dozens of times higher than that of a water-cooled diesel engine, so its thermal efficiency is higher than that of a water-cooled diesel generator. The same as the air-cooled diesel engine to the air less heat, so its cooling air is only about 2/3 of the water-cooled diesel engine, coupled with low fan power consumption, so the fuel consumption of air-cooled diesel generator is also low.

The normal service life of diesel engines mainly depends on the wear and tear of piston group and cylinder liner. And important wear such as cylinder liner mainly depends on the length of engine operating time. Because of the high temperature and fast heating of the cylinder wall of air-cooled diesel engines, acid corrosion and wear are avoided to the greatest extent.

The practice has proved that more than 25-30% of the faults of water-cooled diesel generators are caused by the cooling system. As the air-cooled diesel generator does not involve the water cooling system, it will not produce any corrosion, cavitation, corrosion and scale in the cylinder block, cylinder head and radiator, so its failure rate is about 27% lower than that of the water-cooled diesel generator, which is more suitable for harsh environment.

The temperature difference between the radiator and the surrounding air in a water-cooled diesel generator is small because the radiator temperature is limited by the boiling point of water. The average cooling surface temperature of the cylinder head of the air-cooled diesel generator is 170 degrees, which has a greater temperature difference with the surrounding air. Even in the hot environment, there is no danger of overheating and boiling like the water diesel generator. Air-cooled diesel generators start well and work reliably at -35 ° without the risk of freezing and cracking, and without the need for antifreeze or water heaters. Air-cooled diesel generator used in arid desert areas is not afraid of water shortage, used in plateau and low pressure areas, even if used in coastal saline areas, its cylinder block, and cylinder liner will not be damaged by the erosion of cooling water.

Their individual personalities make them suitable for different applications. Air-cooled diesel generators are generally used in geological exploration, oil exploitation, military and other special industries and plateau or water shortage or cold places, without considering the problems of adding water, boiling point, freezing and so on. However, due to the limitation of thermal load and mechanical load, the capacity of air-cooled diesel generator is generally relatively small and the fuel consumption is too low. Its material and manufacturing process is higher than that of a water-cooled diesel generator, and its heat resistance, wear resistance and expansion coefficient of metal materials are higher because air cooling is not uniform like water cooling, and its cost is higher than that of the water-cooled generator. Large-capacity diesel generators are generally water cooled, such as Cummins generator sets. The water cooling effect is ideal, the same technical indicators of the motor, water cooling volume are small, light gross weight, high energy density, heat transfer performance is better. However, water cooling has more requirements on the environment. The boiling point of water is reduced when used on the plateau, and it is easy to freeze when shut down. At this time, a certain proportion of additives should be added to improve the boiling point and freezing point.