Diesel fuel - this is the substance that makes the engines of machines work. This is all the fuel we get every day.
HISTORY AND MODERNITY
Rudolph Diesel (1858-1913) was a talented inventor and engineer. In 1893, he developed and manufactured an internal combustion engine with efficiency of 26%. This was more than double the efficiency of steam engines of that time. In 1898, he demonstrated an engine that ran on peanut butter and had efficiency of 75%. In 1913, it may have been suicide, but this is only one version. He was heading to England to organize the work and operation of his engines there. Soon after the death of the inventor, the First World War began, and German submarines with diesel engines caused death and destruction in the ranks of the Entente fleet.
The work of the Diesel was continued by other pioneers, in particular Clessy L. Cummins. Until the 1920s diesel engines were mostly stationary and powered by biofuels. In the 1920s, engines running on more liquid natural fuels began to be used. The time began for oil tycoons and the rapid development of diesel technology.
Modern diesel engines have higher power and are more economical than their distant predecessors. This has led to the widespread use of electronics.
Using fuel is a tricky issue. Diversity in all its subtleties saves time and money on cars. Diesel fuel corresponds to its efficiency. This is not to say which of them is more important than the others. All of them contribute to the performance of the functions of fuel in the combustion process.
What are these features? First of all, fuel is a source of energy. Diesel fuel provides a combustion chamber, and also lubricates the friction surfaces of parts and cleans the nozzle. Consider some of the characteristics of diesel fuel.
DIESEL FUEL CHARACTERISTICS
This indicator characterizes the ability of diesel fuel to ignite after injection into the combustion chamber of the engine, i.e., determine the period of delay in ignition of the mixture from injection into the cylinder to the start of combustion. The higher cetane number, the easier the fuel ignites, the more quickly and smoothly the air-fuel mixture burns.
Most engine manufacturers recommend using diesel with cetane rating of at least 40. Decrease in cetane number engine flow rate and uniformity of its operation. In Europe the production of diesel fuel with a cetane number of about 51, in Japan - about 50. According to the Russian standard, diesel fuel for summer and winter production should be at least 45, since diesel fuel can count on “European” or Japanese diesel fuel.
Sometimes, in order to improve the low-temperature qualities, diesel fuel is diluted with kerosene, i.e., lighter fractions of oil having a lower boiling point. The use of diluted with kerosene fuel leads to increased consumption and reduced power, the engines work harder, reduces their resource. Direct-injection turbodiesels are particularly sensitive to such fuel.
This is another important parameter, diesel. Particles of viscous fuel fly apart less, i.e., the shape of the sprayed nozzle of the torch depends on this characteristic, the course of the combustion process depends on the shape of the torch. The combustion process should go as evenly as possible. This means that the temperature in the entire chamber must be the same, without "cold" and "hot" zones. This in turn means a reduction in the level of toxicity of exhaust gases (exhaust) while maintaining other engine performance. The level of toxic nitrogen oxides N0x rises when combustion occurs at high temperatures, therefore lowering the temperature allows lowering their content in the exhaust gas and prolonging the engine's life, since "hot spots" generate stress concentration zones. As a result of such overheating, the pistons and sleeves can be destroyed. Unfortunately, switching to less viscous fuel, along with a positive effect, has negative consequences. To ensure lubrication of fuel equipment parts, the viscosity of diesel fuel should be at least 1.3 cSt. Excessively liquid fuel does not have sufficient viscosity to lubricate the fuel pump parts, and this can cause problems: the fuel pump may fail or the wear products of the fuel pump parts - solid particles - will get into the fuel and damage parts of the power system located after the pump. Both that, and another is undesirable.
Lubricity and sulfur content.
Fuel reduces the friction force of parts in fuel pumps and injectors, as well as the piston against the cylinder mirror. Contaminants also reduce the lubricity of the fuel. Water has a particularly strong influence in this regard. Particulate matter can cause accelerated wear of parts and failure of power system components. Methods for determining the lubricating properties of fuels are not as deeply developed as they should be. There are two standard methods for checking this property: the HFRR methods (bench tests for high-frequency reciprocating motion) and SBLOCLE (ball friction in a cylinder), however, none of the methods gives unambiguously accurate results.
Studies have shown that a side effect of the hydrotreating processes used to remove sulfur compounds from the fuel is a decrease in the content of compounds on which the lubricating properties of the fuel depend. In Europe and the USA, the problem of lubricating properties has become especially acute in recent years due to stricter standards for sulfur content in fuel: immediately the number of malfunctions of high pressure fuel pumps increased.
Sulfur content - the main “environmental” indicator of diesel fuel. Sulfur combustion products react with water to form acids. Sulfur causes damage not only to nature, but also to the engine - its combustion products provoke metal corrosion, and when they come into contact with engine oil, solid deposits form (the engine is coked).
An exceptionally important parameter characterizing the presence of mechanical impurities in diesel fuel, water, tarry substances and paraffins, which affect the efficiency and reliability of fuel equipment operation. It is determined by degree of clogging of a tared paper filter after passing 20 ml of fuel through it at atmospheric pressure. For diesel fuel of the highest grade, the filterability coefficient does not exceed 2.0. As you know, foreign-made diesel engines are especially sensitive to fuel cleanliness. The service life of paper fuel filters is highly dependent on the degree of contamination of the fuel. According to some reports, with a change in the filterability coefficient from 3.0 to 2.0, the filter service life is more than doubled.
Foreign matter in the fuel.
Some foreign substances are present in the fuel initially (for example, sulfur), others appear after oil refining. Microalgae and bacteria can multiply in diesel! If microorganisms multiply greatly, they can clog the fuel system and damage nozzles and pumps. This happens if tankers do not undergo regular processing. The list of works performed during maintenance of fuel tanks must necessarily include measures to prevent the multiplication of microorganisms. Nevertheless, it is necessary to make sure before using the means of destroying microorganisms that they will not adversely affect the beneficial properties of diesel fuel.
Another substance that negatively affects the quality of diesel fuel is paraffin. It impairs combustion and clogs the power system. Alcohol is sometimes added to dissolve paraffin to dissolve diesel fuel, but this is strictly not recommended! A mixture of alcohol and diesel fuel is explosive! In addition, the addition of a small amount of alcohol will impair lubricity. It should also be noted that when alcohol is added, the cetane carrier increases the number of fuel.
The most common form of impurities is solid particles, such as dust. Dust can get into the fuel if you do not follow the rules of operation of the tanker, for example, use a dirty stick as a fuel measuring probe.
WHAT TO DO?
What measures are needed to prevent malfunctions of cars associated with the use of fuel? How to build a relationship with a fuel company? The easiest way to insure yourself against these problems is to clearly indicate in the contract that the supplier is responsible for the quality of the fuel delivered (and not received at the refinery!). Many managers of equipment parks apply this measure quite successfully. Currently, fuel suppliers value customers, especially large ones, and are ready to take responsibility for quality, especially since good fuel costs more. In farms where due attention is paid to fuel quality, it is regularly checked in the laboratory and, if substandard conditions are found, the supplier is changed.
If fuel arrives of poor quality and it is impossible to apply the measures described above, it will be difficult to “find the guilty party” and everything may end in an unpleasant trial, after which, most likely, both parties will remain unsatisfied. It also happens that the fuel company does not have its own transport and uses the services of a third-party trucker that introduces an unknown term into this equation.
The conditions for fuel storage at the delivery point may also be unsatisfactory, and if the tanks into which the fuel is drained are poorly cleaned, the fuel will get into the tanks of the vehicles already dirty. In an effort to withstand market competition, small fuel suppliers are supplying low-quality fuel. Even if the fuel is not contaminated, it may not meet the requirements of the standard for other characteristics.
So, there are a lot of possibilities in which the quality of the fuel can deteriorate, and the way out is to improve the quality of the fuel as close as possible to the moment of filling it in the tanks of cars. Organize and control this process should be the one who is most interested - the end user.
There are two ways to solve the problem, and each has supporters and opponents. One way is filtration and separation, the second is the use of additives. These methods will be discussed in the next article.
Magazine "Fixed Assets", No. 9/2007
article "What is diesel fuel and how to deal with it ..."
author S. Podgursky