We know that diesel oil is required for the operation of diesel generator set. The fuel supply system can atomize diesel oil into fine particles, so that they can be properly distributed in the combustion chamber to form a good combustible mixture. The quality of fuel atomization will directly affect the power and economy of the diesel generator set, as well as the smoke color of the unit. When the unit is in normal operation, the exhaust gas is almost colorless and transparent. When the fuel atomization of the unit is poor, the exhaust gas is black, white, blue and other abnormal colors. The fuel atomization effect is related to the structure and size of the fuel injector, injection pressure, the back pressure of the compressed air in the cylinder, the shape and speed of the injection pump cam, and the viscosity of the fuel in varying degrees. Dingbo Powerwill analyze it in detail.
(1) Fuel injector construction and dimensions. Different structures of fuel injectors cause different internal disturbances in the formation of fuel spray, resulting in different forms of fuel spray. The fuel spray should closely cooperate with the combustion system. Different combustion methods require different forms of fuel spray, so different structures of fuel injectors are used.
When the injection pressure and the back pressure of the compressed air of the cylinder remain unchanged and the total cross-sectional area of the nozzle remains unchanged, increasing the number of orifices will reduce the diameter of each orifice, fuel will be more throttled when it flows out of the orifice, and disturbances in the orifice will also increase, so the atomization quality will be improved; If the orifice diameter is increased, the core of the oil cluster is dense and the range is increased.
(2) Injection pressure. The greater the injection pressure of fuel, the greater the initial velocity of fuel outflow, and the greater the fuel disturbance in the nozzle and the resistance of compressed air after flowing out of the nozzle, so as to improve the atomization fineness and uniformity, that is, the better the atomization quality. When the injection pressure increases, the range of the fuel spray also increases.
(3) Counter pressure of compressed air in the cylinder. When the back pressure of the compressed air in the cylinder increases, the density of the compressed air increases, resulting in an increase in the air resistance acting on the fuel beam. Therefore, the fuel atomization is improved, the spray cone angle is increased, and the range is reduced. In the non supercharged diesel generator set, the back pressure of the compressed air in the cylinder changes little, so the influence on the fuel spray characteristics is not significant.
(4) Profile and speed of injection pump cam. When the cam profile is steeper or the camshaft speed is higher, the fuel delivery speed of the plunger of the fuel injection pump is accelerated. Due to the throttling of the injector orifice, the fuel cannot flow out quickly, resulting in an increase in the fuel pressure in the fuel pipe and an increase in the speed of the fuel flowing out from the orifice. Therefore, the atomization becomes better, and the range of the fuel beam and the spray cone angle increase.
(5) Fuel viscosity. When the fuel viscosity increases, the oil particles are not easy to disperse into fine droplets, resulting in poor atomization. Therefore, high speed diesel generator sets generally use light diesel oil with low viscosity as fuel.
When you find that the diesel generator set has abnormal smoke color during operation, it is mostly caused by poor fuel atomization due to the failure of the fuel system. Users can carefully investigate the causes according to the above reasons and deal with them in a timely manner.
Guangxi Dingbo Power Equipment Manufacturing Co., Ltd. is one of leading manufacturer for diesel generator and alternator in China, was set up in 1974. The genset includes Cummins, Perkins, Yuchai, Shangchai, Weichai, MTU, Ricardo etc. If you have purchase plan, welcome to contact us by email firstname.lastname@example.org or call us +8613481024441.