Carbon specific areas, heat effects

The effects of bubble size and specific areas of heat exchangers on the transient average carbon concentration and bed temperature are presented in Figure 9. It can be seen that the critical bubble size is about 5 cm, which is much smaller than that for the type A combustor. This is because of the relatively small excess air rate used and the large carbon concentration gradient... 

The azeotropic composition of the excess isotherm determined on Chemviron (Union Carbide USA) activated carbon, an adsorbent with a large specific surface area, is x = 0.095, indicating that the adsorption layer still contains a little methanol (Fig. 9). This methanol is bound to the polar regions of the surface of the adsorbent, as shown by the exothermic heat effect detectable from Xi = 0 to Xi = 0.1. 

Catalytic tests in sc CO2 were run continuously in an oil heated flow reactor (200°C, 20 MPa) with supported precious metal fixed bed catalysts on activated carbon and polysiloxane (DELOXAN ). We also investigated immobilized metal complex fixed bed catalysts supported on DELOXAN . DELOXAN is used because of its unique chemical and physical properties (e. g. high pore volume and specific surface area in combination with a meso- and macro-pore-size distribution, which is especially attractive for catalytic reactions). The effects of reaction conditions (temperature, pressure, H2 flow, CO2 flow, LHSV) and catalyst design on reaction rates and selectivites were determined. Comparative studies were performed either continuously with precious metal fixed bed catalysts in a trickle bed reactor, or discontinuously in stirred tank reactors with powdered nickel on kieselguhr or precious metal on activated carbon catalysts. Reaction products were analyzed off-line with capillary gas chromatography. 

The RHR plots for PP-MAPP-Cloisite 20A nanocomposite and PP at 35 kW/m heat flux shown in Figure indicate a 60% - decrease of peak of RHR (Fig. 11). Comparison of the Cone calorimeter data PP and PP-MAPP- 7% Cloisite 20A reveals that the specific heat of combustion (He), specific extinction area (SEA), a measure of smoke yield, and carbon monoxide yields are practically unchanged this suggests that the source of the improved flammability properties of these materials is due to differences in condensed-phase decomposition processes and not to a gas-phase effect. The primary parameter responsible for the lower RHR of the nanocomposites is the mass loss rate (MLR) during combustion, which is significantly reduced from the value observed for the pure PP (Fig. 12). It is supposed, that this effect is caused by ability to initiate the formation of char barrier on a surface of burning polymeric nanocomposites that drastically limits the heat and mass transfer in a burning zone. 

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