What are the main indicators for evaluating diesel generator fuel?

Diesel oil is the main fuel for diesel generator sets and an important working medium for diesel generator sets to do mechanical work. The main requirements of diesel generator sets for diesel oil are good ignition, good atomization, good low temperature fluidity, and less carbon deposits in combustion products. The six items of corrosive small shaking mechanical acrobatics and less moisture, then do you know what are the main indicators for evaluating the fuel of diesel generator sets? Let's learn about it with Dingbo Power.

 

       Diesel oil is the main fuel for diesel generator sets and an important working medium for diesel generator sets to do mechanical work. The main requirements of diesel generator sets for diesel oil are good ignition, good atomization, good low temperature fluidity, and less carbon deposits in combustion products. The six items of corrosive small shaking mechanical acrobatics and less moisture, then do you know what are the main indicators for evaluating the fuel of diesel generator sets? Let's learn about it with Dingbo Power.

 

       1. Cetane number

       The cetane number is an index for evaluating the ignition performance and fuel performance of diesel fuel. Good ignition performance of diesel refers to the low self-ignition temperature of diesel. ) is shorter, the less combustible gas mixture is formed during the flame retardation period, the lower the pressure rise rate after ignition, and the softer the work.

 

       The cetane number determination method for diesel is similar to the octane number for gasoline. The best self-ignitable hexadecane C16H34 (specified its cetane number is 100) and the worst self-ignitable alpha-methyl tea (specified its cetane number 0) are mixed in a fixed proportion. When the self-ignition of the tested diesel is the same as that of the mixed liquid, the volume percentage of cetane contained in the mixed liquid is the cetane number of the tested diesel.

 

       The higher the cetane number of diesel, the better the self-ignition, the diesel engine is easy to start, and the work is soft. However, the higher the cetane number, the heavier the diesel fraction, the higher the viscosity, the poorer spray quality, the short ignition delay period, and the ignition before a good flammable mixture can be formed, so the combustion is incomplete and black smoke is emitted. Therefore, the cetane number of diesel should be adapted. The diesel for high-speed diesel engines is between 40 and 60, and the diesel for low-speed diesel engines is between 30 and 50.

 

       The freezing point and cloud point

       The low temperature fluidity of diesel oil is determined by the freezing point and cloud point.

       When the temperature is low, the paraffin and water contained in the diesel begin to crystallize, and the diesel becomes cloudy. This temperature is called the cloud point. When the temperature is lowered again, a paraffin crystal network is formed, and the fuel loses its fluidity and solidifies. This temperature is called the freezing point. Generally, the cloud point is 5~10°C higher than the freezing point. Domestic light diesel oil is labeled according to its freezing point, for example, -10th light diesel oil has a freezing point of -10°C. When the freezing point of diesel oil is too high, it is easy to block the oil circuit and filter in winter, resulting in insufficient fuel supply or even interruption. When diesel is selected, the freezing point is required to be 4~6°C lower than the minimum ambient temperature.

 

       3. Viscosity

       The atomization performance of diesel is mainly determined by the viscosity. Viscosity is an important physical property parameter of fuel. It affects the spray quality of diesel fuel, the filterability and fluidity of combustion. The higher the viscosity, the larger the oil particles sprayed, making the combustion worse. If the viscosity is too low, the oil leakage and wear of the fuel injection pump and nozzle coupler will increase, so the viscosity of diesel oil should be adapted. Generally, the kinematic viscosity of light diesel oil is 2.5~8mm2/s at 20°C.

 

       4. Distillation range

       Distillation range indicates the evaporability of diesel fuel. The lighter the diesel fraction (the lower the temperature at which it is distilled), the faster it evaporates, which favors gas mixture formation. The heavy fraction evaporates slowly, and it catches fire before it evaporates in a high-speed diesel engine, and it is easy to emit black smoke. However, it is not good if the fraction is too light, because the evaporation is too good, too much mixed gas is formed during the ignition delay period, the pressure rises sharply after ignition, and the work is rough.

 

       The above four items are the main indicators for evaluating diesel performance. At present, light diesel is used for high-speed diesel engines, heavy diesel is used for medium and low-speed diesel engines, and heavy oil is used for large low-speed diesel engines.