Emission factors vaporization

Wadden RA, Scheff PA, Franke JE. 1989. Emission factors for trichloroethylene vapor degreasers. Am Ind Hyg Assoc J 50 496-500. 

Schuetzle, D., and J. A. Frazier, Factors Influencing the Emission of Vapor and Particulate Phase Components from Diesel Engines, in Carcinogenic and Mutagenic Effects of Diesel Engine Exhaust (N. Ishinishi, A. Koizumi, R. O. McClellan, and W. Stober, Eds.), pp. 41-63, Elsevier, Amsterdam/New York, 1986. 

Consider that the outer film heat transfer coefficient, /a-i, is a function of the Grashof and Prandtl numbers and that the emissivity factor F is equivalent to the emissivity of snow. If it is further assumed that the enthalpies of water vapor, and hi, are functions of temperature alone, then measurements of the unit area heat transfer rate q /A, the ambient temperature, and the time rate of frost formation w, can now be made in order to yield the remaining unknown in (la), the temperature of the frost surface Ti. Additional measurements of the container skin temperature, T2, the frost thickness, and... 

Radiation differs from conduction and convection not only in mathematical structure but in its much higher sensitivity to temperature. It is of dominating importance in furnaces because of their temperature, and in ciyogenic insulation because of the vacuum existing between particles. The temperature at which it accounts for roughly half of the total heat loss from a surface in air depends on such factors as surface emissivity and the convection coefficient. For pipes in free convection, this is room temperature for fine wires of low emissivity it is above red heat. Gases at combustion-chamber temperatures lose more than 90 percent of their energy by radiation from the carbon dioxide, water vapor, and particulate matter. 

Water Vapor The contribution to the emissivity of a gas containing H9O depends on Tc andp L and on total pressure P and partial pressure p . Table 5-8 gives constants for use in evaluating . Allowance for departure from the special pressure conditions is made by multiplying by a correction factor C read from Fig. 5-21 as a function of (p + P) and p ,L. The absorptivity 0t of water vapor for blackbody radiation is evaluated from Table 5-8 but at T instead of Tc and at p LT /Tc instead of p, h. Multiply by (Tc/Ti)° . ... 

The correction factor C still applies. Spectral data for water vapor, tabulated for 371 wavelength intervals from 1 to 40 Im, are also available [Ferriso, Ludwig, and Thompson, J. Quant. Spectm.s. Radiat. Tran.sfer, 6, 241-273 (1966)]. The principal emission is in bands at about 2.55 to 2.84, 5.6 to 7.6, and 12 to 25 jlm. 

FIG. 5-21 Cor rection factor for converting emissivity of water vapor to values of P, and Fj other than 0 to 1 atm respectively. To convert atmosphere-feet to Idlopascal-meters, multiply by 30.89 to convert atmospheres to Idlo-pascals, multiply hy (1.0133)(10 ). 

Environmental Factors These inchrde (I) eqrripment location, (2) available space, (3) ambient conditions, (4) availabuity of adeqrrate rrtilities (i.e., power, water, etc.) and ancillary-system facilities (i.e., waste treatment and disposal, etc.), (5) maximrrm aUowable emission (air polhrtion codes), (6) aesthetic considerations (i.e., visible steam or water-vapor phrme, etc.), (7) contribrrtions of the air-poUrrtion-control system to wastewater and land poUrrtion, and (8) contribrrtion of the air-poUrrtion-control system to plant noise levels. 

The generation of au pollutants, ineluding VOC s, from automotive vehieles was identified to eome from two prineipal sourees vehiele exhaust emissions, and fuel system evaporative emissions [4], Evaporative emissions are defmed as the automotive fuel vapors generated and released from the vehiele s fuel system due to the interactions of the speeific fuel in use, the fuel system characteristics, and environmental factors. The sources of the evaporative emissions are discussed below and, as presented m the remainder of this chapter, control of these evaporative emissions are the focus of the application of activated carbon technology in automotive systems. 

As initially discussed in Section 3, carbon canisters are used in the automotive emission control system to temporarily store hydrocarbon vapors. The vapors are later purged into the air charge stream of the air induction system, thus regenerating the carbon canister. Carbon canister design is dependent on the characteristics of the vapors sent to the canister and the amount of purge air available. In the following section, factors that affect the performance of the evaporative emission control system will be discussed. 

Hydrophilic liquids can also cause stabilization and amplification of fluorescence Thus, Dunphy et al employed water or ethanol vapor to intensify the emissions of their chromatograms after treatment with 2, 7 dichlorofluorescein [260] Some groups of workers have pointed out that the layer matenal itself can affect the yield of fluorescent energy [261 —263] Thus, polyamide and cellulose layers were employed m addition to silica gel ones [245] The fluorescence yield was generally increased by a factor of 5 to 10 [264], but the increase can reach 100-fold [234, 265]... 

In order to compute the thermal radiation effects produced by a burning vapor cloud, it is necessary to know the flame s temperature, size, and dynamics during its propagation through the cloud. Thermal radiation intercepted by an object in the vicinity is determined by the emissive power of the flame (determined by the flame temperature), the flame s emissivity, the view factor, and an atmospheric-attenuation factor. The fundamentals of heat-radiation modeling are described in Section 3.5. 

Exhaust system The engine operating mode controls the tailpipe emissions of hydrocarbons (HC) and carbon monoxide (CO). Over 80% of HC and CO emissions are generated during cold-start and warm-up due to incomplete combustion. Fuel vaporization and fuel/ air mixing are important factors in achieving thorough combustion of the hydrocarbons. 

The type of vapor treatment that is used will depend on factors such as the contaminant concentrations in the extracted vapors and the air emission discharge limitations for the site. Highly contaminated vapors at a site with stringent air emission limitations may require a multistep vapor treatment train, such as thermal oxidation, followed by carbon adsorption. Less contaminated vapors at a site with less stringent air emission limitation may require minimal or no vapor treatment. Fields et al.38 described the following rules of thumb for selecting vapor treatment ... 

The field emission properties of carbon nanotube forests and single nanotubes are described. Controlled emission is possible for aligned CNT arrays where the spacing is twice the CNT height, as grown by plasma enhanced chemical vapor deposition. This leads to the maximum field enhancement factor. For random forests, the field enhancement obeys an exponential distribution, leading to a lower emission site density and imperfect current sharing. Ballast resistors can help alleviate this problem. Random nanocarbons perform less well than CNTs. Some applications are covered. Elec-... 

Based on data from the U.S. Environmental Protection Agency (EPA) Superfund Innovative Technology Evaluation (SITE) demonstration, the total cost for PF extraction was estimated to be 307/kg of trichloroethene (TCE) removed. This demonstration was conducted over a 4-week period in August and September of 1992 at an industrial site in Somerville, New Jersey. The cost estimate includes expenses associated with both PF and soil vapor extraction. Major cost factors were labor (29%), capital equipment (22%), VOC emission control (19%), site preparation (11%), and residuals management (10%) (D10589F, p. v). 

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