Fuel atomization

In most gas turbines, liquid fuel is atomized and injeeted into the eom-bustors in the form of a fine spray. A typieal low-pressure fuel atomization nozzle is shown in Figure 10-10. The fuel spray entrains air beeause of the... 

Late cylinder injection is typically used for diesel engines. Fuel is admitted to the cylinder as the piston is nearing top center. Very high injection pressures are required for proper fuel atomization and combustion control. Pressures can exceed 20,000 psi for this type of injection. 

As above but final 02 pressure Man s fuels Atomic energy Wind, tide, hydro... 

Equation (9.41) constitutes a fundamental solution for purely convective mass burning flux in a stagnant layer. Sorting through the S-Z transformation will allow us to obtain specific stagnant layer solutions for T and Yr However, the introduction of a new variable - the mixture fraction - will allow us to express these profiles in mixture fraction space where they are universal. They only require a spatial and temporal determination of the mixture fraction/. The mixture fraction is defined as the mass fraction of original fuel atoms. It is as if the fuel atoms are all painted red in their evolved state, and as they are transported and chemically recombined, we track their mass relative to the gas phase mixture mass. Since these fuel atoms cannot be destroyed, the governing equation for their mass conservation must be... 

An alternative approach might be to address solely the mixture fraction / (mass of original fuel atoms per mass of mixture) since it has been established that there is a firm relationship between y, and/for a given fuel. Note that/moves from 1 to 0 for the start and end of the fire space and / is governed by Equation (12.45) for y, = 0. This then conserves the fuel atoms. Under this approach it is recognized that... 

TRW Systems, Inc., conducted a laboratory-scale incineration study for the U.S. Army from 1973 to 1975 (9). Eleven individual pesticide formulations and three mixed pesticide formulations containing six different active ingredients (chlordane, 2,4-D, DDT, dieldrin, lindane, and 2,4,5-T) were incinerated in a liquid injection incinerator. The experimental apparatus consisted of a fuel atomizer, combustion chamber, afterburner, quench chamber, and scrubber unit. Destruction efficiencies exceeded 99.99% for a minimum 0.4-s residence time at temperatures above 1000°C with 45 to 60% excess air. 

The observed flame features indicated that changing the atomization gas (normal or preheated air) to steam has a dramatic effect on the entire spray characteristics, including the near-nozzle exit region. Results were obtained for the droplet Sauter mean diameter (D32), number density, and velocity as a function of the radial position (from the burner centerline) with steam as the atomization fluid, under burning conditions, and are shown in Figs. 16.3 and 16.4, respectively, at axial positions of z = 10 mm, 20, 30, 40, 50, and 60 mm downstream of the nozzle exit. Results are also included for preheated and normal air at z = 10 and 50 mm to determine the effect of enthalpy associated with the preheated air on fuel atomization in near and far regions of the nozzle exit. Smaller droplet sizes were obtained with steam than with both air cases, near to the nozzle exit at all radial positions see Fig. 16.3. Droplet mean size with steam at z = 10 mm on the central axis of the spray was found to be about 58 /xm as compared to 81 pm with preheated air and 96 pm with normal unheated air. Near the spray boundary the mean droplet sizes were 42, 53, and 73 pm for steam, preheated air, and normal air, respectively. The enthalpy associated with preheated air, therefore, provides smaller droplet sizes as compared to the normal (unheated) air case near the nozzle exit. Smallest droplet mean size (with steam) is attributed to decreased viscosity of the fuel and increased viscosity of the gas. 

Liquid fuel was seldom utilized in the previous ACC studies because it was not only difficult to actuate liquid-fuel injection at high frequencies, but the combustion delays associated with liquid-fuel atomization, droplet heating, vaporization, and burning processes made such a control extremely slow for fast-response in situ type controllers. As a result, the use of liquid fuel was confined to either steady injection process ]13] or upstream addition of prevaporized fuel ]4, 7] which limited the ACC flexibility associated with temporal responsiveness. The goal of this project is to make ACC more practical for propulsion systems by studying direct liquid-fueled ACC in a closed-loop controller setting. 

Gunpowder was discovered by the Chinese many centuries ago, but they used it primarily for fireworks until it was imported to the West and used to blow up castles and then to propel projectiles. Explosives are solids that are endothermic with respect to their decomposition products. [We will consider the explosions of solids more in Chapter 10.] Typically explosives contain fuel atoms (C, H, and S) in close proximity to oxygen atoms (as nitrates and perchlorates) so that they will react to form CO2, H2O, and SO2, but only (one hopes) when intentionally ignited. Another class of exothermically decomposing solids is azides, and they are frequently used as igniters or fuses to heat up conventional explosives. 

This burner utilizes a high-pressure fuel atomizer to spray and meter heating oil into the firebox. Combustion air is supplied independently. An electronic ignition system is used to ignite the air-fuel mixture. 

This is one of the more important properties of residual fuel oil. It is an indication of both the pumpability characteristics of the fuel and the fuel atomization quality. 

The viscosity of residual fuel decreases rapidly with increasing temperature. If preheating is available, residual fuels atomize well. If preheating is not available, it may be necessary to bum lower-viscosity fuels rather than high-viscosity residual oils. 

Ignition delay between injection of fuel and autoignition can be controlled by engine design, fuel and air temperature, fuel atomization, and fuel composition. The ignition delay period is typically shorter than the fuel injection period. The effect of temperature on ignition delay is shown in FIGURE 4-10. 

Liquid atomization is an important unit operation that is employed in a variety of processes. They include fuel atomization, spray drying, metal powder production, coating of surfaces by spraying, etc. 

In a chemical explosion, energy is released by rapid combustion of a chemical fuel. Atoms of the original compounds (reactants) rearrange themselves to form different compounds (products) with consequent release of energy. 

Spraying and brushing 103-104 Spray drying, painting, fuel atomization... 

Giffen (6C) and Mock and Ganger (ISC) present the effect of various operating parameters on fuel atomization in sprays. Applications of dimensional analysis to spray-nozzle performance data are discussed by Shafer and Bovey (23C). 

Woeltjen, A., Fineness of Fuel Atomization in Oil Engines, dissertation, Technische... 

The first two equations represent the fact that the D-D reaction can follow either of two paths, producing tritium and one proton or hehum-3 and one neutron, with equal probability. The products of the first two reactions form the fuel for the third and fourth reactions and are burned with additional deuterium. The net reaction consists of the conversion of six deuterium nuclei lnlo two helium nuclei, two hydrogen nuclei, and two neutrons along with a net energy release of 43.1 MeV. The reaction products—helium, hydrogen, and neutrons—are harmless as contrasted with the myriad fission products obtained in a fission reactor. The neutrons produced may be absorbed in sodium to produce an additional 0.25 MeV per cycle. Therefore, the D-D reaction produces at least 7 MeV per deuterium atom (deuteron) and, with absorption in sodium, more than 10 MeV per fuel atom. 

Electrospray has been used for many different applications, such as the deposition of paints and coatings on metal surfaces and the deposition of metal nanoparticles and biomolecules on biosensor surfaces, and in a miniaturized version also as a propulsion mechanism in microsatellites (see also the section on electric wind). One particularly interesting application is in fuel atomization, that is, a finer fuel aerosol and atomization will give a higher combustion efficiency and less pollutant emission, which is caused by the effect that finer droplets increase the total surface area on which combustion can start (Lehr and Hiller, 1993). 

IV. A. 2. In order to alleviate the total solids problem, there are great efforts to introduce the energy-bearing fuel atom in the polymer or by substituting appropriate oxidizer groups such as nitrates in the pure polymer. 

Contents An overview of synthetic fuel combustion issues and research activities / A.A. Boni. . . [et al.] — characteristics of typical synthetic fuel components / R. B. Edelman, R. C. Farmer, and T.-S. Wang — An experimental study of synthetic fuel atomization characteristics / R. G. Oeding and W. D. Bachalo —[etc.]... 

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