Hydrocarbon fuel spray

The substantial effect of secondary breakup of droplets on the final droplet size distributions in sprays has been reported by many researchers, particularly for overheated hydrocarbon fuel sprays. 557 A quantitative analysis of the secondary breakup process must deal with the aerodynamic effects caused by the flow around each individual, moving droplet, introducing additional difficulty in theoretical treatment. Aslanov and Shamshev 557 presented an elementary mathematical model of this highly transient phenomenon, formulated on the basis of the theory of hydrodynamic instability on the droplet-gas interface. The model and approach may be used to make estimations of the range of droplet sizes and to calculate droplet breakup in high-speed flows behind shock waves, characteristic of detonation spray processes. 

Approximately 5% of the U.S. consumption of is in agriculture. Boron is a necessary trace nutrient for plants and is added in small quantities to a number of fertilizers. Borates are also used in crop sprays for fast rehef of boron deficiency. Borates, when apphed at relatively high concentration, act as nonselective herbicides. Small quantities of borates are used in the manufacture of alloys and refractories (qv). Molten borates readily dissolve other metal oxides usage as a flux in metallurgy is an important apphcation. Other important small volume apphcations for borates are in fire retardants for both plastics and ceUulosic materials, in hydrocarbon fuels for fungus control, and in automotive antifreeze for corrosion control (see Corrosion and corrosion inhibitors). Borates are used as neutron absorbers in nuclear reactors. Several borates, which are registered with the Environmental Protection Agency (EPA) can be used for insecticidal purposes, eg, TIM-BOR. 

The investigation showed efficient supersonic combustion of a liquid hydrocarbon fuel when using effervescent sprays and elliptic nozzles for the injection of the fuel. In the future, it would be interesting to study the possibilities of supersonic combustion enhancement using the elliptic nozzles drilled at the base of NASA swept wedges. 

Hydrocarbons. Extensive pollution of air occurs from the introduction of hydrocarbons either from (a) the incomplete combustion of hydrocarbon fuels in both stationary and vehicular engines or (b) from paint spraying, solvent cleaning, printing, chemical and metallurgical, and other plants that... 

The vapor cloud of evaporated droplets bums like a diffusion flame in the turbulent state rather than as individual droplets. In the core of the spray, where droplets are evaporating, a rich mixture exists and soot formation occurs. Surrounding this core is a rich mixture zone where CO production is high and a flame front exists. Air entrainment completes the combustion, oxidizing CO to CO2 and burning the soot. Soot bumup releases radiant energy and controls flame emissivity. The relatively slow rate of soot burning compared with the rate of oxidation of CO and unbumed hydrocarbons leads to smoke formation. This model of a diffusion-controlled primary flame zone makes it possible to relate fuel chemistry to the behavior of fuels in combustors (7). 

Fuels such as diesel and kerosene readily absorb hydrocarbon vapors, the total uptake and absorption rate depending on both chemical and physical factors. If a soluble test gas is introduced above a charged test oil the concentration of flammable test gas therefore decreases with time. Liquid mist and spray produced by charged liquid increase the absorption rate relative to a quiescent liquid surface. As discussed in A-5-4, absorption could lead to an underestimation of test gas MIE near the liquid surface unless the rate of test gas introduction is sufficiently high to offset the rate of removal. Table 3-8.1.2 shows solubilities of a selection of gases in a mineral-based transformer oil at ambient temperature and pressure [200]. 

Carbon black is produced by the partial combustion or thermal decomposition of hydrocarbons. Several methods are used, including the furnace black, thermal black, lamp black and acetylene black processes. The furnace black process is the most common. In this process, natural gas (or another fuel) is burned to form a hot gas stream that is directed into a timnel. An aromatic oil is sprayed in and the black forms as the gas moves down the tunnel. The reaction is quenched with the addition of water, and the product is collected as a low density powder (fluffy black) or is further processed into millimeter sized peUets. 

Combustion of fuels produces and releases pollutants such as hydrocarbons, carbon monoxide, oxides of nitrogen, particulate matter, sulfur dioxide, and greenhouse gases such as carbon dioxide and nitrous oxide. Air pollutants are also released by some household products—for instance, paints, paint strippers, solvents, wood preservatives, aerosol sprays, cleansers and disinfectants, moth repellents, stored fuels, and automotive products. 

Most of the 300+ organic vapors that may be found in indoor pollution are derived from paints, paint strippers and other solvents, wood preservatives, aerosol sprays, cleansers and disinfectants, moth repellents, air fresheners, in addition to fuels and automotive products, and dry-cleaners. Many of these compounds are halogenated hydrocarbons, PAH, ketones and aldehydes, which exhibit different degrees of toxicity. 

Aliphatic hydrocarbon compounds are found in lighter fluid and fuel gas, as well as in paint sprays, hair sprays, and air fresheners. These compounds are highly flammable and explosive. They include compounds like acetylene, butane, hexane, isobutene, and propane. Butane is often used as the propellant in aerosol sprays. 

For liquid droplets, requirement (1) typically means that the spray must be dilute (that is, the ratio of the volume occupied by the condensed phase to the volume occupied by the gas must be small) because collisions tend to be frequent when the volume of particles per unit volume of space becomes too large. Since the mass density of the particles greatly exceeds that of the gas in many sprays and the stoichiometry of most hydrocarbon-oxidizer systems is such that the mass of the fuel is considerably less than that of the gaseous oxidizer in stoichiometric mixtures, the hypothesis of a dilute spray often is valid in hydrocarbon spray combustion. 

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