A gas purification system needs to produce 2 kg/hour of purified product. If the purification membrane is 100 m2 and 0.05mm thick, and the supply gas is at 0.75 kg/m3 and the take-off side maintains a pressure of 0.05 kg/m3 find required membrane Diffusivity in sq m/sec.

Respuesta :

Answer:

The membrane diffusivity would be 3.968 x [tex]10^{-10}[/tex]  [tex]m^{2}[/tex]/s

Explanation:

According to Fick's law of diffusion, the rate of the purified product is related with to membrane diffusivity with the expression in equation 1.

[tex]V = \frac{(P_{1}-P_{2})AD }{T}[/tex] ..............................1

Where

V is the rate of purified product = 2 kg/hr = 2 kg/hr  x 1 hr / 3600 sec  =     1/1800 kg/sec

[tex]P_{1}[/tex] is the pressure at the supply gas point = 0.75 kg/[tex]m^{2}[/tex]

[tex]P_{2}[/tex] is the pressure at the take-off side = 0.05 kg/[tex]m^{2}[/tex]

A is the area of the membrane = 100 [tex]m^{2}[/tex]

T is the thickness of the membrane = 0.05 mm = 0.05/ 1000 = 5 x [tex]10^{-5}[/tex] m

Substituting the values into equation 1 we have;

[tex]\frac{1}{1800}= \frac{(0.075 - 0.05)*100*D}{5*10^{-5} }[/tex]

5 x [tex]10^{-5}[/tex]  = 126000 x D

D =  5 x [tex]10^{-5}[/tex] / 126000

D = 3.968 x [tex]10^{-10}[/tex]  [tex]m^{2}[/tex]/s

Therefore the membrane diffusivity would be 3.968 x [tex]10^{-10}[/tex]  [tex]m^{2}[/tex]/s