"24.22 Researchers are proposing the development of a ‘‘nano-
channel reactor’’ for steam reforming of methane (CH4) to fuel-
cell hydrogen gas to power microscale devices. Gas phase
diffusion in nanochannel A = CH4, B= H2O A+B 20 mol% CH 4
-----------------------------> Nanochannel ( NA/NB) = 0.25 300
degrees C, 0.5 atm, 200Nm diameter As each channel diameter is
so small, the gas flow is likely to be very small within a given
channel. Hence, gas diffusion pro- cesses may play a role in the
operation of this device, particularly during the mixing and
heating steps. We are specifically inter- ested in evaluating
the effective diffusion coefficient of methane gas (species A,
MA 1?4 16g/g: mol) in water vapor (species B, MB 1?4 18 g/g:
mol) at 3008C and 0.5 atm total system pressure. The diameter of
the channel is 200nm (1x 10^9 nm = 10m) A feed gas containing 20
mol % CH4 in water vapor is fed to the nanochannel with a flux
ratio NA/NB = 0:25. What is effective diffusion coefficient of
CH4 in the nanochannel a