Lubricating properties of diesel
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Discuss the relationship between diesel lubricity and its components, as well as methods to improve its properties
As far as I know, lubrication properties are not taken into account for diesel; for diesel engines that use diesel, what is considered are the fuel’s atomization properties, evaporation properties, combustion properties, fuel supply properties, stability, and thermal stability. Also, to my knowledge, there are no mature mechanical devices that use diesel as a lubricant yet.
The National Standards 3 and 4 will include diesel lubrication performance criteria, which will be expressed in terms of viscosity.
The question raised by the poster is very good. Currently, there is relatively little research on this topic in China, while it is more common abroad; it is recommended to consult more foreign literature. The mechanism behind the lubricity of diesel is not yet fully understood, and no quantitative relationship has been established with certain indicators, but it is mainly related to polycyclic aromatic hydrocarbons, heteroatoms, boiling range, and viscosity.
Currently, there are clear requirements regarding the lubricity of diesel, as indicated by the wear mark diameter at 60°C as specified in national standards; this value should be less than 460. However, due to the properties of the raw materials, factors such as the composition of the diesel components, the amount of aromatics, sulfur content, and the 95% distillation temperature can all affect the lubricity of diesel. High lubricity can lead to carbon buildup in engines, while low lubricity has a negative impact on compression engines and is harmful to the cylinders. Japan has conducted specialized research on diesel lubricity; you can look up relevant literature on this topic. The reduction of sulfur content in hydrogenated diesel also leads to a decrease in its lubricity.
It is most related to the sulfur content! The lower the sulfur content, the worse the lubricity! The most economical option is to add an anti-wear agent!
The cost of adding lubricity improvers is not very high either; many companies currently produce such improvers.