Liquid state fuel

In this paper, an overview of the important phenomena is given. The supercritical combustion process employed is also known to occur in liquid propellant rocket motors (e.g. in LOX/GH2-motors), liquid propellant guns (LPG), advanced aviation gas turbines and, to a lesser extent, in internal combustion engines. Supercritical combustion is characterized by (1) injection of at least one liquid state fuel component into a chamber which is thermodynamically in the supercritical state, (2) density ratios of fuel to oxidizer near one, (3) supercritical phase transitions of fluid-particles due to combustion, (4) non-ideal properties of the fluids. Additionally a short description of pertinent design criteria is given. 

The mass or volume heating value represents the quantity of energy released by a unit mass or volume of fuel during the chemical reaction for complete combustion producing CO2 and H2O. The fuel is taken to be, unless mentioned otherwise, at the liquid state and at a reference temperature, generally 25°C. The air and the combustion products are considered to be at this same temperature. 

In the expression for heating value, it is useful to define the physical state of the motor fuel for conventional motor fuels such as gasoline, diesei fuel, and jet fuels, the liquid state is chosen most often as the reference. Nevertheless, if the material is already in its vapor state before entering the combustion system because of mechanical action like atomization or thermal effects such as preheating by exhaust gases, an increase of usefui energy resufts that is not previously taken into consideration. 

If one imagine.s that the fuel is used in the liquid state in the form of droplets —as in the case of fuel injection— the specific energy of the motor fuel (SE) is expressed in kilojoules per kilogram of air utilized, under predetermined conditions of equivalence ratio (stoichiometry for example). The SE is none other than the NHY /r quotient where r represents the previously defined stoichiometric ratio. 

Safety Considerations Design and location of storage tanks, vents, piping, and connections are specified by state fire marshals, underwriters codes, and local ordinances. In NFPA 30, Flammable and Combustible Liquids Code, 1993 (published by the National Fire Protection Association, Quincy, Mass.), liquid petroleum fuels are classified as follows for safety in handhng ... 

If a fuel is in the liquid state, such as fuel oil, most of it must be vaporized to the gaseous state before combustion occurs. This vaporization can be accomplished by supplying heat from an outside source, but usually the liquid fuel is first atomized and then the finely divided fuel particles are sprayed into a hot combustion chamber to accomplish the gasification. 

This will generally be tr-ue as we proceed to look at other alkanes as the number of carbon atoms increases, so does the boiling point. All the alkanes with four car bons or less are gases at room temperature and atmospheric pressure. With the highest boiling point of the three, propane is the easiest one to liquefy. We are all faniliar- with propane tanks. These are steel containers in which a propane-rich mixture of hydrocar bons called liquefied petroleum gas (LEG) is maintained in a liquid state under high pressure as a convenient clean-burning fuel. 

The conditions that apply for the saturated liquid-vapor states can be illustrated with a typical p-v, or (1 /p), diagram for the liquid-vapor phase of a pure substance, as shown in Figure 6.5. The saturated liquid states and vapor states are given by the locus of the f and g curves respectively, with the critical point at the peak. A line of constant temperature T is sketched, and shows that the saturation temperature is a function of pressure only, Tsm (p) or psat(T). In the vapor regime, at near normal atmospheric pressures the perfect gas laws can be used as an acceptable approximation, pv = (R/M)T, where R/M is the specific gas constant for the gas of molecular weight M. Furthermore, for a mixture of perfect gases in equilibrium with the liquid fuel, the following holds for the partial pressure of the fuel vapor in the mixture ... 

The hydroformylation of alkenes was accidentally discovered by Roelen while he was studying the Fischer-Tropsch reaction (syn-gas conversion to liquid fuels) with a heterogeneous cobalt catalyst in the late thirties. In a mechanistic experiment Roelen studied whether alkenes were intermediates in the "Aufbau" process of syn-gas (from coal, Germany 1938) to fuel. He found that alkenes were converted to aldehydes or alcohols containing one more carbon atom. It took more than a decade before the reaction was taken further, but now it was the conversion of petrochemical hydrocarbons into oxygenates that was desired. It was discovered that the reaction was not catalysed by the supported cobalt but in fact by HCo(CO)4 which was formed in the liquid state. 

Electrolytes are ubiquitous and indispensable in all electrochemical devices, and their basic function is independent of the much diversified chemistries and applications of these devices. In this sense, the role of electrolytes in electrolytic cells, capacitors, fuel cells, or batteries would remain the same to serve as the medium for the transfer of charges, which are in the form of ions, between a pair of electrodes. The vast majority of the electrolytes are electrolytic solution-types that consist of salts (also called electrolyte solutes ) dissolved in solvents, either water (aqueous) or organic molecules (nonaqueous), and are in a liquid state in the service-temperature range. [Although nonaqueous has been used overwhelmingly in the literature, aprotic would be a more precise term. Either anhydrous ammonia or ethanol qualifies as a nonaqueous solvent but is unstable with lithium because of the active protons. Nevertheless, this review will conform to the convention and use nonaqueous in place of aprotic .]... 

Eluorine nitrate (FNO ) is a strong oxidizing gas or liquid. In the liquid state it explodes by shock or friction. It is used as an oxidizer for rocket propellant fuels. 

Further cooling of the fuel leads to wax crystal formation throughout the fuel matrix. The growing wax crystals develop into a larger latticelike network encompassing the bulk fuel volume. This latticelike network eventually causes the fuel to become highly viscous and to eventually gel into a semisolid mass. The lowest temperature at which fuel remains in the liquid state just prior to gellation is called the pour point. 

There exists, in the literature on high internal phase emulsions, a small number of publications on possible applications of HIPEs, involving a diverse range of topics. The production of petroleum gels as safety fuels is one such example [124,125] this was mentioned in the section on non-aqueous HIPEs. The main advantage over conventional fuels is the prevention of spillage, which reduces the risk of fire in an accident. Also, studies on the flash-point of emulsified fuels [127] showed a considerable increase, compared to the liquid state, for commercial multicomponent fuels. In addition, there may be an enhancement of the efficiency of combustion of the fuel on emulsification, as it is known that a small amount of water in fuel can improve its performance [19]. 

Gasoline and diesel fuels are used worldwide in enormous amounts and are produced by the petroleum industry by oil refining (see Chapter 2). Liquid transportation fuels are conveniently transported, distributed, and dispensed directly into our vehicles and aircraft. Increased environmental concerns did much to begin to assure cleaner burning of our fuels. In the United States, law requires significant reduction of emissions and resulted in lead-free and more recently reformulated gasoline... 

Commercial calcium carbide, containing about 80% CaC2, is formed in the liquid state. Impurities are mainly CaO and impurities present in raw materials. CO is usually collected for use as a fuel in lime production or drying of the coke used in the process. The liquid calcium carbide is tapped from the furnace into cooling molds. 

LP gas, or propane, is the alternative fuel used in highest volume in the U.S. at present. Propane is unique among alternative fuels in that it is a pressurized liquid, i.e., a modest pressure (under 43.5 kPa [300 psi]) will maintain it in the liquid state. Propane fuel tanks must thus be built to pressure vessel codes like CNG and LNG tanks, but propane is transferred using pumps because pressure differentials are low and the pressure cannot be manipulated as it can for LNG. Propane is sometimes stored in refrigerated containers which lowers the storage pressure significantly, though such containers are rarely if ever used to store propane intended for use in vehicles. 

LPG (liquefied petroleum gas)— propane or (less commonly) butane, obtained by extraction from natural gas or from refinery processes. LPG has a vapor pressure sufficiently low to permit compression and storage in a liquid state at moderate pressures and normal ambient temperatures. Pressurized in metal bottles or tanks. LPG is easily handled and readily lends itself to a variety of applications as a fuel, refrigerant, and propellant in packaged aerosols. LPG is also called LP gas and bottled gas. See natural gas liquids. 

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