HI,
i am working gas separation using flat sheet membranes and I am new to this topic. I tried to find the permeability of nitrogen in the membrane by varying the inlet pressure and measuring the corresponding permeate volumetric flow rate. i tried to plot a graph of pressure drop/thickness of membrane versus the flux and tried to find the slope of the graph to find the permeability. however, the permeability is very small and once converted to barrer it becomes even smaller. can anyone suggest me what I am doing wrong. Thanks in advance
You will find all the explanations through this link.
https://en.wikipedia.org/wiki/Barrer
Regards
Poiseuille’s equation for viscous flow in a cylindrical tube is a well-known equation
V=d2∆P/32 μL
v = fluid velocity, cm/sec.
d = tube diameter, cm.
∆P = pressure loss over length L,
μ = fluid viscosity, centipoise.
L = length over which pressure loss is measured, cm.
Permeability Coefficient
The permeability coefficient, P (or simply the permeability) is defined as the transport flux of material through the membrane per unit driving force per unit membrane thickness. It's value must be experimentally determined. The barrer is the commonly used unit for gas separation and it is defined as:
The term cm3 @STP / cm2.s refers to the volumetric trans-membrane flux of the diffusing species in terms of standard conditions of 0oC and 1 atm, the term cm refers to the membrane thickness, and cm-Hg refers to the trans-membrane partial pressure driving force for the diffusing species.
1 Barrer = 3.35 X 10-16.Mol X m/m2.m.Pa
Permeability P=Q(STP)x t/(Ax ∆ P)
where Q(STP) is flow rate (cm3/s) at standard temperature and pressure
t=thickness of the membrane (cm)
A= Area of the membrane (cm2)
∆ P= Pressure difference of both sides of membrane (cm.Hg)
So 1 barrer=10^(-10) cm3(STP).cm/(cm2.s. cmHg)
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