Fuel performance

Nelson, O.L., R.W. Krumm, R.S. Fein, D.D. Fuller, G.K. Rightmire and G.E, Ducker (1989), "A broad spectrum, non metallic additive for gasoline and diesel fuels performance in gasoline engines". SAE paper No. 89-0214, fnt. Congress, Detroit, MI. 

These two test methods and the octane numbers of the fuels measured are ultimately used to evaluate the performance of vehicles. The two methods provide usehil information about how fuels perform in cars. The RON corresponds to light load, low speed conditions, whereas the MON corresponds to heavier loads, and high speed severe driving conditions. 

Aromatics, olefins and in general, unsaturated compounds undergo hydrogenation reactions, usually unwanted due to their detrimental effect on the operating costs, derived from an excessive consumption of hydrogen. Aromatic saturation, however, is used in jet fuel to improve the smoke point and in diesel for cetane enhancement. In the case of gasoline, extreme hydrogenation leads to a deterioration of the fuel performance parameters. 

Table 3. Standard molecules for scale of fuel performance parameters...

Dan Resasco (with colleagues Phuong Do, Steven Crossley, Malee Santikuna-porn University of Oklahoma) examine strategies for improving important fuel properties catalytically—e.g., cetane number and threshold soot index. They show that proper choice of catalysts and reaction conditions can significantly improve these widely used measures of fuel performance. 

Additives are introduced into aviation fuel for a variety of reasons. Primarily, additives are added to improve fuel performance or to prevent undesirable behavior. They may be introduced into fuel under the following limitations ... 

Desired burner fuel performance characteristics and fuel properties which affect performance are provided in TABLE 3-17. 

Elements of the environment continually impact fuel performance. The effect of water, cold temperatures, heat, air, light, and external contamination can initiate a variety of problems. The first place to begin looking for the cause of a fuel handling or performance problem would be these environmental sources. 

It is unique because of its powerful hydrogen bonding character and its distinct polarity. However, in fuel systems, these characteristics of water make it a source of a variety of problems. Corrosion of metal fuel system components, emulsification with fuel performance additives, and ice formation in fuel lines are some of the problems directly related to the presence of water in fuel. 

Evaporation and loss of fuel components upon storage resultant loss of fuel performance... 

Fuel performance problems initiated by light are not common. However, fuel quality can be affected. The primary concern of light exposure is fuel color darkening and the possible formation of high-molecular-weight deposits due to free-radical-initiated polymerization of fuel components. 

A variety of fuel performance problems can be directly linked to the presence of olefinic compounds in a fuel. Problems such as darkening of fuel color, gum and sludge formation, and combustion system deposits can be directly linked to the presence of olefins. 

One effect of valve sleeve, piston ring, and cylinder wall wear is leakage of lubricating oil into the combustion chamber. When lubricating oil accumulates in the combustion chamber and bums with fuel, the exhaust smoke appears blue in color. Wear due to abrasion or corrosion has the same effect. At times, unbumed fuel can also appear as blue smoke if fuel droplets are finely dispersed in the exhaust. Blue smoke is a symptom of a mechanical problem rather than a fuel performance problem. 

Problems associated with difficulty in filtering, mixing, and pumping fuel can usually be linked to an increase in fuel viscosity. Some examples of fuel performance problems associated with high fuel viscosity are described below. 

Linear, branched, and cyclic paraffins all exist in refined fuel. Fuel performance problems can often be directly related to the type and concentration of paraffin present. TABLE 5-3 provides information on the typical carbon number range and boiling-point temperatures of paraffins found in several representative fuels and other petroleum products. 

One of the easiest ways to determine the character and sometimes the quality of a fuel is to examine the distillation profile. Certain characteristics of fuel performance and potential fuel problems can be determined from the distillation profile of the fuel. Some important and known examples are provided as follows ... 

A wide range of fuel performance problems can often be solved by the use of chemical additives. Although in some circumstances the additives used may be no substitute for refining processes such as hydrotreating, caustic washing, or distillation, they can provide an alternative to further processing. 

Some chemical additives such as corrosion inhibitors, wax crystal modifiers, detergents, and demulsifiers provide performance which is difficult to duplicate through refining without adversely affecting some other fuel property. Other additives such as metal chelators, fuel sweeteners, biocides, lubricity improvers, foam control agents and combustion enhancers can also be used to solve fuel performance problems. 

Typically has no negative impact on fuel performance properties Short-term effectiveness due to biodegradation of biocide Will contact Treat cost is plaques which typically higher may reside on sidewalls of tank which are above the water interface ... 

Rapid kill at the interface Frequent treatment may be necessary No advantages High treat rates may have negative impact on certain fuel performance properties... 

Fuel performance problems which typically cannot be solved by a wax crystal... 

Jet fuel, burner kerosene, heating oil, and heavy marine fuel oils do not typically contain detergents. The widespread need for detergents to improve fuel performance in these applications has not yet developed. Although in some small markets, combustion catalysts and burner nozzle antifoulants are utilized. 

Additives identified as lubricity improvers are sometimes used to improve the wear-inhibiting properties of low-viscosity 1 diesel fuel and higher viscosity hydrotreated low-sulfur 2 diesel fuel. Lubricity improvers are available as single products or may be contained within a diesel fuel performance additive package. In addition to distillate fuel lubricity, gasoline lubricity is being investigated. 

The additive may react with another chemical component in the fuel or with other fuel performance additives. 

There are a few additional analytical tests which are frequently used to help identify the cause of a fuel performance problem. Some of these tests are listed below ... 

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