Fuels properties

This section contains data on common fuel properties. The following tables of information are provided in this section  

The following definitions are for terms used in the tables provided  

Net (or lower) Heating Value - The net or lower heating value is obtained by subtracting the latent heat of vaporization of the water vap or formed by the combustion horn the gross or higher heating value. 

The following are common units used for heating value  

Other useful units also include the following  

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Anon. (1983), Handbook of aviation fuel properties. Coordinating Research Council, report No. 530, Atlanta, GA. Distributed by SAE, Inc., Warrendale, PA,... 

Cetane number is difficult to measure experimentally. Therefore, various correlation equations have been developed to predict cetane number from fuel properties. One such equation may be found in ASTM D4737 to calculate a cetane index (Cl). ASTM D975 allows use of Cl as an approximation if cetane numbers are not available. 

The fuel properties of wood can be summarized by ultimate and proximate analyses and deterrnination of heating value. The analytical procedures are the same as those for coal, but with some modifications. Analytical results generally vary about as much within a species as they do between species, except that softwood species generally have a higher carbon content and higher heating values than hardwood species because of the presence of more lignin and resinous materials in softwood species (see Fuels from waste). 

Liquid fuel is injected through a pressure-atomizing or an air-blast nozzle. This spray is sheared by air streams into laminae and droplets that vaporize and bum. Because the atomization process is so important for subsequent mixing and burning, fuel-injector design is as critical as fuel properties. Figure 5 is a schematic of the processes occurring in a typical combustor. 

Exhaust emissions of CO, unbumed hydrocarbons, and nitrogen oxides reflect combustion conditions rather than fuel properties. The only fuel component that degrades exhaust is sulfur the SO2 concentrations ia emissions are directly proportional to the content of bound sulfur ia the fuel. Sulfur concentrations ia fuel are determined by cmde type and desulfurization processes. Specifications for aircraft fuels impose limits of 3000 —4000 ppm total sulfur but the average is half of these values. Sulfur content ia heavier fuels is determined by legal limits on stack emissions. 

Water plays a primary role in corrosion of the metal walls of tanks and pipes (17), and increases the tendency for high speed pumps to produce wear particles and to exhibit shortened life. Formation of corrosion products can be controlled by addition of corrosion inhibitors, a mandatory additive in military fuels. However, corrosion inhibitors may also degrade other fuel properties and adversely affect ground filtration equipment. Thus they are not generally acceptable in commercial fuels where rigorous attention is given to clean and dry fuels upon aircraft fueling. 

Use of kerosene fuel rather than air as a coolant focuses attention on another fuel property, specific heat, which is a measure of its efficiency to... 

H. F. Butze and R. C. Ehlers, Effect of Fuel Properties on Peformance of a Single Aircraft Turbojet Combustor, NASA TM X-71789, National Aeronautics and Space Administration, Lewis Research Center, Cleveland, Ohio, Oct. 1975. 

G. M. Varga and A. J. AveW, Jet Fuel Property Changes and Their Effect on Producibility and Cost in U.S., Canada, and Europe,F ASA Contract Report 174840, Lewis Research Center, Qeveland, Ohio, Feb. 1985. 

Fuel requirements are defined by various fuel properties. By eoineidenee, the heating-value requirement is also a property and needs no further mention. 

Important liquid fuel properties for a gas turbine are shown in Table 12-5. The flash point is the temperature at which vapors begin combustion. The flash point is the maximum temperature at which a fuel can be handled safely. 

Beeause gas turbine fuel properties are not the ones that determine eost, in some instanees the better gas turbine fuel will sell for less than the poorer one. The seleetion of the most eeonomieal fuel depends on many eonsiderations. 

Because the jet engine was free of the demanding need for high-octane fuel, in the early days of the jet-engine development it was thought that it could use practically any liquid fuel. However, subsequent experience proved this to be untrue, as a number of potential problem areas indicated that control of fuel properties, reflecting both bulk and trace components, were important for satisfactory use. Over the years these important property requirements were translated into specification requirements that put restrictions on what is acceptable as jet fuel. 

Coordinating Research Council. (1983). Handbook of Aviation Fuel Properties. Atlanta, GA Author. 

Methanol, the second major product from synthesis gas, is a unique compound of high chemical reactivity as well as good fuel properties. It... 

It has been reported by Lewis et al. [1] that the equivalence ratio where the minimum ignition energy has a minimum is dependent on the fuel property for hydrocarbon fuel and air mixtures, and that it moves to the rich side as the molecular weight of the fuel increases. This equivalence ratio dependency has been explained by the preferential diffusion effect. 

An important reaction in the manufacture of gasoline is isomerization of straight-chain paraffins to more highly branched compounds, which have better fuel properties (higher octane rating). 

The choice of immobilization strategy obviously depends on the enzyme, electrode surface, and fuel properties, and on whether a mediator is required, and a wide range of strategies have been employed. Some general examples are represented in Fig. 17.4. Key goals are to stabilize the enzyme under fuel cell operating conditions and to optimize both electron transfer and the efficiency of fuel/oxidant mass transport. Here, we highlight a few approaches that have been particularly useful in electrocatalysis directed towards fuel cell applications. 

Selected Diesel Fuel Properties from Different German Co-LTFT-Derived Straight-Run Distillate Fractions and the German Sonder Diesel Kraftstoff (SDK) Specifications of the 1940s... 

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