Diesel fuels properties, typical

Since highly aromatic fuels have little wax, they possess better natural low-temperature handling properties than paraffinic fuels. Also, the cloud point, pour point and low-temperature filtration of aromatic diesel fuel will typically be much lower than a paraffinic diesel fuel. 

Biodiesel is diesel fuel produced from vegetable oils and other renewable resources. Many different types of oils can he used, including animal fats, used cooking oils, and soybean oil. Biodiesel is miscible with petroleum diesels and can he used in biodiesel-diesel blends. Most often blends are 20 percent biodiesel and 80 percent traditional diesel. Soy diesel can be used neat (100%), hut many other types of biodiesel are too viscous, especially in winter, and must be used in blends to remain fluid. The properties of the fuel will vaiy depending on the raw material used. Typical values for biodiesel are shown in Table 1. 

The CFPP of a typical 2 diesel fuel can be reduced by the addition of kerosene. The maximum blending volume is again limited by the effect kerosene will have on specific physical and performance properties of the 2 diesel fuel. As a general rule the diesel fuel CFPP can be reduced by 2°F to 4°F (about 1 °C to 2°C) for each 10% of kerosene added. The effect of kerosene dilution on the CFPP of a typical 2 diesel fuel is shown in FIGURE 4-7. 

Since the introduction of low-sulfur diesel fuel, much study has been completed to determine the lubricity properties of this fuel. Comparison of low-sulfur diesel with high-sulfur diesel has clearly revealed that fuel sulfur has a dramatic impact on the ability of fuel to provide a higher level of lubricity performance. A comparison of the lubricity performance of a typical high-sulfur diesel low-sulfur diesel and low-aromatic, low-sulfur diesel is shown in FIGURE 5-3. 

Liquid products contain sulfur and nitrogen and must be hydroprocessed to improve quality. Separate hydroprocessing units for upgrading the naphtha, kerosene, and gas oil fractions can be used to optimize the overall process. Refined gas oil or diesel fuel is aromatic in character and contains more cycloparaffins than conventional crude oil. The resulting fuel is low in cetane number, high in density, and typically has very good low-temperature handling properties. 

Biodiesel methyl esters blend quite easily into petroleum based conventional diesel fuel. Biodiesel esters typically have better lubricity properties and higher cetane number ratings than conventional diesel fuel, but have poorer water demulsibility and color stability properties. At sub-zero temperatures, the handling characteristics of biodiesel becomes more difficult to control than conventional diesel fuel. 

As just discussed, fuel properties affect many aspects of vehicle design, fuel storage and distribution, and safety hazards. Following are definitions of the fuel properties of most interest and an explanation of their significance. Later in this chapter, properties and specifications for the alternative fuels will be presented and compared to typical gasoline and diesel fuel. 

Unocal Hydrocarbon Sales Retardsol is a water-white kerosine that meets ASTM 2-K specifications. Kerosine consists primarily of C10-C16 aliphatic and aromatic hydrocarbons and is widely used as heating oil and diesel fuel. Because of its high solvency and high flash point Unocal Hydrocarbon Sales Retardsol finds many commercial applications in general cleaning solvents and in agricultural sprays. Specifications and typical properties are listed below. 

Emulsified fracturing fluids are typically very viscous polymer oil-inwater emulsions that may consist of60-70% hquid hydrocarbon dispersed in 30-40% aqueous solution or gel. The hydrocarbon phase may be diesel fuel, kerosene, or even crude oils and condensates. The aqueous phase may consist of gelled fresh water, a KCl solution or an acid solution. Emulsion fracturing fluids may be applied to oil or gas wells, particularly in low pressure formations susceptible to water blockage, and for bottom-hole temperatures of up to about 150 °C. They can provide excellent fluid loss control, possess good transport properties and can be less damaging to the reservoir than other fluids. However, emulsions are more difficult to prepare and can be more expensive. 

Instantaneous maps of the mixture fraction, temperature, and main combustion products (H2O, CO2, CO) are shown in Figure 7.4 for the n-heptane. N-heptane is a fuel commonly used in engines. Its cetane number is approximately 56, which is typical for diesel fuel, because its properties of ignition and combustion are similar to those of diesel fuel [7]. The n-heptane has received substantial interest because it is a major component of the primary reference fuel (PRF) in internal combustion engine studies [6] and is considered a surrogate for liquid hydrocarbon fuels used in many propulsion and power generation systems [8]. 

All the occupations listed in Table 28.2 carry with them exposures to mixtures of lipophilic and hydrophilic chemicals. Of the chemicals listed in Table 28.3, several are mixtures of compounds. These include gasoline, diesel fuel, mineral spirits, paint removers, paint thinners, and varnish makers and painters (VM P) naphtha. Though many of the studies referenced earlier consider organic solvents as only a mixture of lipophilic compounds [13-15, 17], this is inappropriate, since many of the chemicals listed in Table 28.3 are mixtures of lipophiles and hydrophiles. For example, a typical solvent-based paint remover contains the following components (/Q,w values are listed to demonstrate lipophilic or hydrophilic properties) ... 

TABLE 12.6 Typical Fuel Properties of Bio-Oil with Reference to No. 2 Diesel and Heavy Fuel Oil (Mohan et al., 2006 Zhang et al., 2007 Demirbas, 2009)... 

Table I-E-4 shows physical and chemical properties for No. 1 diesel fuel. No. 2 diesel fuel, and a typical biodiesel made from soy oil (Canakci, 2005). The fatty acid composition (%) for the soybean oil used was C16 0, 10.5 C17 0, 0.11 C18 0, 4.76 C18 l, 22.52 C18 2, 52.34 C18 3, 8.19, C20 0, 0.36 unknown components, 0.48 % saturation, 16.3. The composition of the biodiesel methyl esters prepared from the soybean oil is similar C16 0, 10.56 C17 0, 0.11, C18 0, 4.74 C18 l, 22.51 C18 2, 52.39 C18 3, 8.22 C20 0, 0.44 unknown components, 0.44 % saturation, 16.3. As seen from table I-E-4, the biodiesel has similar properties to fossil diesel. Biodiesel has a greater viscosity and tendency to gel than conventional diesel fuel, which restricts its use at low ambient temperature unless sufficient heating of the fuel and engine components is provided.

Other properties of interest are carbon residue, sediment, and acidity or neutralization number. These measure respectively the tendency of a fuel to foul combustors with soot deposits, to foul filters with dirt and rust, and to corrode metal equipment. Cetane number measures the ability of a fuel to ignite spontaneously under high temperature and pressure, and it only applies to fuel used in Diesel engines. Typical properties ol fuels in the kerosene boiling range are given in Table 1. 

Fuel Oils Refined petroleum products having specific gravities in the range of 0.85 to 0.98 and flash point temperatures above 55 °C. This includes auto diesel, industrial heating fuels, various bunker fuels, furnace fuels. Refer to Chapter 4 for specific examples and discussion of properties. Fuel Value Refers to the amount of potential energy that can be released by a fuel during combustion. Expressed in units of BTUs per pond of fuel. Examples are asphalt (17,158 BTU/lb typical value), LPG (18,000 BTU/lb), wood shavings (8,250 BTU/lb). 

Since DME characteristics are similar to those of liquefied petrol gas (LPG), it can be used in typical LPG applications, e.g. power generation, propellants, domestic cooking fuels or automotive fuels. If DME is employed as admixture, LPG properties are not significantly affected up to a DME content of around 20%. Compared to LPG, the cetane number is much higher (55-60 in contrast to 5 and 10 for propane and butane) and DME is, in principle, a suitable fuel for diesel engines. However, DME can not be blended with fossil diesel and its energy density is much lower, so that engines have to be adapted. 

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