Discharge of Carbon Dioxide

If not discharged, the CO2 gas produced in the anode reaction would fill and block the fiow field [50]. Therefore, the gas flow has to be separated from the liquid flow of the methanol-water solution in the anode. One approach is to use microstructured flow flelds with a T-shaped channel design. The methanol is distributed in a wide channel on the bottom. If CO2 bubbles evolve, they will grow until they reach the ceiling of the channel. If the channel ceiling is tapered and leads to a small channel, set on top of the wide channel, the bubbles will be driven into the small channel by capillary forces [51]. The same principle is used for separating water droplets from a gas stream, as described above. 

As in micro fuel cells, the use of a valve is not desirable owing to size, reliability, costs, and parasitic energy losses. The integration of a C02-permeable membrane can be used to separate the gas bubbles from the methanol solution. Additionally, the buoyancy of the bubbles in the aqueous solution can be used to force the methanol convection [52, 53]. 

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Direct ethanol fuel cells (DEFCs) produce power directly from ethanol without prior reforming. Compared with methanol used as the fuel for DMFCs, ethanol is nontoxic, environmentally friendly, and universally available, and making the handling easy. Since ethanol is also a liquid alcohol like methanol, the technological issues of crossover, discharge of carbon dioxide, and passive operation are comparable. 

A few years later carbon dioxide was injected into an underground tank containing Jet fuel as a tryout of a fire-fighting system. The tank blew up, killing 18 people who were standing on top of the tank. In this case the discharge may have occurred from the cloud of carbon dioxide particles. 

Procedure Weigh accurately about 1.5 g of sodium hydroxide and dissolve in about 40 ml of carbon-dioxide free distilled water (i.e., boiled and cooled DW). Cool and titrate with 1 N sulphuric acid using phenolphthalein solution as indicator. When the pink colour of the solution is discharged record the volume of acid solution required. 

Barhng J, Arnold GL, Anbar AD (2001) Natural mass-dependent variations in the isotopic composition of molybdenum. Earth Planet Sci Lett 193 447 57 Barnes I, Irwin WP, White DE (1978) Global distribution of carbon dioxide discharges and major zones of seismicity. US Geological Survey, Water-Resources Investigation 78-39, Open File Report... 

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