Ignition Delay Period of Mixture for 200kw Deutz Diesel Generatorby Generator D. Diesel Generator
The period from the injection of diesel oil into the cylinder to the beginning of the ignition is called the ignition delay period.
Today 200kw Deutz diesel generators manufacturer shares ignition delay period of mixture with you.
During the ignition delay period, the mixture in the combustion chamber undergoes physical and chemical preparation.
Physical preparation process: crushing, dispersing, evaporating, vaporizing and mixing of fuel;
Chemical preparation process: the initial chemical reaction of the mixture until spontaneous combustion begins
Characteristics: pressure does not deviate from the compression line.
The length of ignition delay period of diesel engine will affect the amount of fuel injection and prefabricated mixture in this stage, thus affecting the combustion characteristics, power, economy, emission characteristics and noise and vibration of diesel engine. We should control it.
Main factors affecting ignition delay:
The higher the temperature and pressure in the cylinder, the shorter the ignition delay.
Diesel oil has better spontaneous combustion (higher cetane number) and shorter ignition delay.
The shape and wall temperature of combustion chamber.
Injection advance angle: from the beginning of injection to the piston reaching the top dead center, the corresponding crankshaft rotation angle is the injection advance angle.
Cetane number: it is the index of spontaneous combustion of diesel oil when it is burned in a diesel engine. The spontaneous combustion of pure hexadecane is good, and the cetane number is set at 100.
Pure alpha-methylnaphthalene is not easy to burn, and its cetane number is set to zero. When mixed in different proportions, standard fuels with different explosion resistance grades of cetane number 0 to 100 can be obtained, and compared with diesel oil to be tested on a single cylinder test machine with certain structure.
The ignition retardation period is from pressure point to temperature point. At the beginning of the retardation period, although combustion products have been formed in the cylinder, a large amount of mixture is still burning.
Flame retardation characteristics:
The fuel injection process ended basically, and the combustion rate decreased (the concentration of oxygen and diesel oil decreased, and the exhaust gas increased).
Pressure start to reduce( Cylinder Volume Increasing). The temperature reaches a high point. Generally, the temperature can reach about 2000K, which usually appears at the 200 crankshaft corner after the top dead-end point.
From the high point of temperature until the fuel is almost burnt out, it called reimbursement period. It is difficult to accurately determine the end point of the reimbursement period. Generally, the end of the reimbursement period can be considered when the heat release reaches 95% to 99% of the total heat release in the cycle.
The combustion of internal combustion oil during the supplementary combustion period can be called afterburning. Due to the burning time is short, mixture is not very uniform, there is always a small amount of fuel delayed to continue burning during expansion. Especially in high-speed and high-load conditions, because of the small excess air coefficient, the time of mixture formation and combustion is shorter, and this phenomenon of afterburning is more serious.
During the reimbursement period, because the piston goes down a considerable distance, the volume of the cylinder increases a lot, and the pressure and temperature in the cylinder decrease rapidly, the combustion speed is very slow, the heat emitted is difficult to use effectively, and the exhaust temperature rises, resulting in an increase in heat loss, which is not conducive to the economy of the diesel engine.
In addition, the afterburning also increases the heat load of the parts concerned. Therefore, the supplementary combustion period should be shortened as far as possible to reduce the amount of fuel burned in the supplementary combustion period.
Above is the ignition Delay Period of Mixture for 200kw Deutz Diesel Generator
Created on Aug 30th 2019 21:10. Viewed 147 times.