How to choose the fuel for diesel generator sets? Most users may only know that they need to use diesel, but do you know what kind of diesel to use? The main fuel for diesel engines is diesel. Diesel is made from petroleum after refining and processing. Its main characteristics are low autoignition point, high density, strong stability, safe use, and low cost, but its volatility is poor. When the ambient temperature is low, the diesel engine is difficult to start. Light diesel is used for high-speed diesel engines, and heavy diesel is used for medium and low-speed diesel engines. The properties of diesel have a great influence on the power, economy and reliability of diesel engines.

The following are suggestions for selection

• The performance, specifications and selection of diesel The lowest temperature at which diesel spontaneously ignites without external ignition is called the autoignition temperature of diesel. The autoignition performance of diesel is expressed by the cetane number. The higher the cetane number, the lower the autoignition temperature and the easier it is to ignite. But it is not good if the cetane number is too high or too low. If the cetane number is too high, although it is easy to ignite and work softly, the stability is poor and the fuel consumption rate is large; if the cetane number is too low, the diesel engine works roughly. The cetane number of diesel used in general diesel engines is 30~60.

• The viscosity of diesel is the main indicator that affects the atomization of diesel. It indicates the thinness and flow difficulty of diesel. The higher the viscosity, the larger the oil droplets when sprayed, and the longer the spray distance, but the poorer the dispersion, the uneven mixing with the air, the easier it is for the diesel engine to smoke when working, and the higher the fuel consumption. The lower the temperature, the greater the viscosity; the opposite is true.

• The flow performance of diesel is mainly expressed by the freezing point. The so-called freezing point refers to the temperature at which diesel loses its fluidity. If the diesel temperature is lower than the freezing point, the diesel cannot flow, the fuel supply will be interrupted, and the diesel engine will not work. Therefore, the freezing point is one of the main bases for selecting diesel.

• Domestic diesel is divided into two categories: light diesel and heavy diesel. Light diesel has good volatility and is divided into three grades according to quality: superior, first-class and price-quality. Each grade is divided into six grades according to its freezing point, namely No. 10, No. 0, No. -10, No. -20, No. -35 and No. -50, indicating their respective freezing point temperatures; heavy diesel has poor volatility, high density and viscosity, and many impurities. Heavy diesel is divided into three grades according to viscosity: No. 10, No. 20, and No. 30. The larger the number, the greater its viscosity.

• Diesel engines should select diesel according to speed, use area and season. Usually, diesel engines with rated speeds above 1000r/min should use light diesel. No. 10 light diesel is suitable for high-speed diesel engines with preheating equipment; No. 0 light diesel is suitable for areas with a minimum temperature above 4°C; No. 10 light diesel is suitable for areas with a minimum temperature above 15°C; No. -20 light diesel is suitable for areas with a minimum temperature above 14°C; No. 35 light diesel is suitable for areas with a minimum temperature above -29°C; No. 50 light diesel is suitable for areas with a minimum temperature above 44°C. For heavy diesel, usually No. 10 is selected for diesel engines with rated speeds of 500~1000r/min; No. 20 is selected for diesel engines with rated speeds of 300-700r/min; No. 30 is selected for diesel engines with rated speeds below 300r/min.