In diesel engines, the combustion process takes place over a very short period of time (0.001 s). As a result, complete and timely combustion of fuel and good use of the air available in the engine cylinders can be achieved only with very high-quality mixing. The use of biofuels in modern diesel engines causes a number of problems associated with changes in the parameters of fuel supply and mixing. All types of fuel have different characteristics: density, viscosity, lubricating properties, self-ignition temperature, compressibility and. in this regard, the laws of fuel supply: spraying, combustion, will be different.
The viscosity of biofuels is higher than that of diesel fuel. For this reason, its capacity through small holes in the nozzle of the nozzle (dh= 0.25...0.40 mm) lower than diesel fuel. Due to the small diameter of the holes in the nozzle nozzles and the increased viscosity of biofuels, the nozzle holes are quickly coked. At the same time, the shape and direction of the jet initially changes, and then the hole is completely coked and the fuel supply stops. Thus, for high-quality operation of the diesel engine on biofuels, it is necessary to modernize the design of the mixing and fuel supply system. This problem can be solved by using systems with separate combustion chambers, i.e. using vortex chamber mixing.
In the vortex chamber, 60-80% of the fuel burns, the pressure increases and the burning torches of the fuel flow at high speed into the main over-piston plane of the combustion chamber, where there is a significant supply of air that is not used during the combustion of the charge in this chamber. At the same time, oxygen from the air is well used, and the operation of the diesel engine becomes more efficient at relatively low values of the excess air coefficient at the nominal mode and less toxicity of exhaust gases than for single-chamber diesels.
The economic performance of diesel engine when operating on methanol with a dual fuel supply system
