Question

# When filling the combustion tank, one often thinks of adding the oxidizer (air or oxygen)

first and the fuel

(say methane) second. In fact, the characteristic diffusion time is

surprisingly long. Show this assuming the combustion tube is 10 m long, 1m in diameter.

For simplicity assume the tube is full of methane for 5 m and the balance is air for 5m.

- Assume that the pressure is 60 bar and the diffusivity of CH4 -air is D = 10
^{-5 }m^{2}/s at

p = 1 bar. What is the characteristic time for diffusive mixing?

My answer is coming **(t= 0.000000613 s)**

**I dont know if its correct**

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