Fuel carbon coefficients

Hydrogen distribution costs for nine H2Sim scenarios low production (100000 kg/ day), short distance (100 miles) Hydrogen distribution costs for nine H2Sim scenarios high production (1000 000 kg/day), long distance (500 miles) Default vehicle assumptions Fuel carbon coefficients... 

H2Sim calculates the carbon emissions associated with each fuel choice. Table 8.2 summarizes the carbon coefficients, in million metric tons carbon per quad (MtCOj/quad), used in H2Sim. These coefficients do not include carbon emissions associated with car manufacture or fuel delivery, and hence understate total carbon emissions. Actual emissions are determined by the efficiency of the conversion process as well as the use. For example, the total emissions from a vehicle using hydrogen produced by electrolysis are determined by the efficiency of the electricity production, electrolysis process, and FCV. 

Carbon dioxide supply, for the molten carbonate fuel cell, 72 220 Carbon dioxide ternary systems, phase behavior of, 24 4—5 Carbon diselenide, 22 75t Carbon disulfide, 4 822-842 23 567, 568, 621. See also CS2 in cellulose xanthation, 77 254 chemical reactions, 4 824—828 diffusion coefficient in air at 0° C, 7 70t economic aspects, 4 834-835 electrostatic properties of, 7 621t handling, shipment, and storage, 4 833-834... 

Figure 19 shows the stoichiometric coefficient y versus time. The y-coefficient is the molar ratio between the amount of hydrogen in the conversion gas and the amount of carbon in the conversion gas. In this particular selection of y-graphs the dynamic ranges for the different wood fuels during a batch are fuel wood 3 0, wood pellets 2.6 0, and wood chips 2.4 0. These dynamic ranges are quite representative of the whole range of volume fluxes tested. 

Numerous studies by other workers (I, 10) have shown that the releases of iodine and the noble-gas fission products from pyrolytic carbon-coated fuel particles are controlled by diffusion of these nuclides through grain boundaries, cracks, and defects in the isotropic pyrolytic carbon coating. When coatings are intact, however, the release of these fission product nuclides is low. However, the pyrolytic carbon coating constitutes only a delaying barrier to the metallic nuclides barium and strontium through which they diffuse with diffusion coefficients of the order of 10 9 cm.2/sec. (at — 1400°C.). The steady-state release of these metallic nuclides is controlled instead by diffusion out of the fuel kernel,... 

A conventional typical convection section often has tube bundles for fuel gas or air preheat, feed preheat, boiler feed water preheat, steam generation, and steam superheating. In the convection section, the heat transfer is mainly gas-to-gas heat transfer and the overall heat-transfer coefficients are relatively low. Finned tubes are generally used to improve heat-transfer rates. Material for the convection section tubes varies from carbon steel to a high temperature alloy. Sometimes, high-alloy tubes are positioned in the lower section... 

Here 50, denotes the observed deviation of the atmospheric O, concentration from a standard. The atmospheric tracer APO is dominated primarily by oceanic gas exchanges in addition to a relatively small contribution from fossil fuel not accounted for by the terrestrial stoichiometric factor (i.e., the fossil fuel component scaled by the factor Observations of the seasonal variation of APO in conjuction with surface-water oxy gen measurements have been used to constrain the large-scale magnitude of the air-sea gas exchange coefficient (Keeling et al, 1998) and of marine productivity (Six and Maier-Reimer, 1996 Balkan.ski et al, 1999). Mean annual gradients of APO have also been shown to provide powerful constraints on biogeochemical air-sea fluxes computed by ocean-circulation models with an embedded ocean carbon cycle (Stephens et al, 1998). 

The full compartmental model and numerical values of the coefficients are given in Table 22.1. It is assumed that all reforested land increases the terrestrial biota, so ar = 1.0. The value of ad = 0.23 is that suggested by Schmitz (2002) [Lenton (2000) proposed 0.27]. Initial values for all M, are the preindustrial values given in Figure 22.6. The preindustrial fossil fuel reservoir is assumed to have contained 5300 Pg carbon the actual value is not important, only the emission rate Ff(t). The model requires as input Ff(t), Fd(t), and Fr(t) from preindustrial times to the present. Ff(t) is obtained from the historical record of carbon emissions from fossil fuels Fd(t) is that for deforestation, expressed also in units of Pg C yr-1. Until very recently, reforestation, Fr, can be assumed to have been negligibly small. 

It is worth noting that the remarkable effect described for the carbon support porosity on the metal utilization factor and hence on the specific electrocat-alytic activity in methanol electrooxidation was only observed when the catalysts were incorporated in ME As and measured in a single cell. The measurements performed for thin catalytic layers in a conventional electrochemical cell with liquid electrolyte provided similar specific catalytic activities for Pt-Ru/C samples with similar metal dispersions but different BET surface areas of carbon supports [223]. The conclusions drawn from measurements performed in liquid electrolytes are thus not always directly transferable to PEM fuel cells, where catalytic particles are in contact with a solid electrolyte. Discrepancies between the measurements performed with liquid and solid electrolytes may arise from (1) different utilization factors (higher utilization factors are usually expected in the former case), (2) different solubilities and diffusion coefficients, and (3) different electrode structures. Thus, to access the influence of carbon support porosity... 

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