How “Maxxrecovery” additives restore the spray geometry of the nozzles
Modern engine building is developing along the path of forcing diesel engines in such parameters as average effective pressure, engine crankshaft speed and reduction of harmful substances during exhaust gas emissions. This direction is associated with the increased requirements for diesel fuel equipment, in particular, the main element of the nozzle – the atomizer.
The main parameter by which the correct operation of the atomizer is assessed is the atomization geometry of the fuel. The figure below shows examples of sprayer operation.
Violation of the spray geometry of the injectors occurs due to the physicochemical properties of diesel fuel, as well as high mechanical, hydrodynamic and thermal loads during engine operation. As a result of the oxidation and decomposition of diesel fuel, solid deposits accumulate inside the injectors. The reactivity of the unsaturated hydrocarbon chains (olefins, aromatic hydrocarbons) in diesel fuel contributes to the deposition of carbon in the nozzle openings and the formation of protrusions at the end of the injector nozzle. And the presence of small traces of Na, Zn, Cu and Ca in the fuel (metal contamination) significantly increases the contamination of the nozzle and, more generally, cokes the injectors.
In the injectors of high-pressure fuel systems, fuel must pass through small gaps from high-pressure zones to low-pressure zones. But the formation of deposits on the surfaces of the injector parts lead to a change in their initial geometric parameters, as a result of which the cyclic fuel supply decreases, the pressure at the beginning of injection and the fuel injection advance angle decrease. The figure below shows an example of deposits accumulating on injector parts.
The spray holes are characterized by an effective flow area “μf”. The dependence of the change in “μf” of nozzles on their operating time is shown in the graph below.
In the precision pair “spray needle – spray body” the size of the gap between the mating cylindrical surfaces is 2.5-6.0 microns. Such a design provides the mobility of the nozzle needle in the housing and the water tightness of the nozzle.
The mobility of the needle is assessed by the quality of the fuel atomization. Hanging of the nozzle needle occurs as a result of the accumulation of solid deposits and the ingress of small mechanical particles in the fuel (as shown in the figure below).
Such a hanging of the nozzle needle leads to the absence of fuel injection into the engine cylinders, as a result, the crankshaft speed decreases sharply, and ultra-high pressure is formed in the fuel system, which can cause destruction in the parts of the fuel pump.
In order to ensure the identity of the injection rates in the designs of the nozzles, the stroke of the nozzle needle is strictly regulated. The maximum stroke of the needle of diesel nozzles ranges from 0.2-0.45 mm. An important parameter of the nozzle atomizer is its hydraulic characteristic, i.e. dependence of the effective flow area of the atomizer on the stroke of the needle and the atomizer.
During the operation of the nozzles, the stroke of the sprayer needle increases, which is due to the wear of the nozzle body at the point of contact with the shut-off cone.
Thus, the main element of the nozzle, the technical condition of which significantly reduces the technical and economic indicators of the diesel engine, is the sprayer. With an increase in the operating time of the atomizers and the accumulation of solid deposits, the operating power of the engine decreases and in order to stabilize the technical and economic indicators of the engine, it is necessary to carry out expensive repairs or replace the injectors.
In order to avoid costly repairs of the fuel system due to premature failure of the fuel system, and to maintain its normal operating parameters, it is recommended to regularly use Maxxrecovery fuel additives “Diesel Additive Clean & Protect”, “Diesel Additive Clean & Protect Advance”. This additive package effectively helps to remove solid deposits on the parts of the fuel system, thereby restoring the operating parameters of engines (power, fuel consumption), and also extends the service life of the fuel system and engine by increasing the lubricity of the fuel and its completeness of combustion.
As shown by the above data, in accordance with CEC Procedure F-23-01, the use of the recommended dosage of the Maxxrecovery multipurpose additive package provides excellent removal of deposits formed on the injectors.