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Mass extraction and saturation of bulk solution
Posted May 14, 2013, 7:22 a.m. EDT Chemical Reaction Engineering 2 Replies
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Hi all,
I am fairly new to COMSOL. I am after solving a non steady-state packed bed extractor with fluid flow convection in the axial direction of the extractor and diffusion of soluble material from the solid particles.
The first thing I am trying is to solve the diffusion equation in 2D with different boundary conditions, as if the particles were in a stirred vessel.
My question is:
When a forced convection boundary condition is imposed, how can be the saturation of the bulk fluid be accounted for?
Manually the process would be
1) Bulk concentration of the fluid is 0 at time 0
2) After the first time step has elapsed, the solution of the diffusion equation gives a total flow (mass released) out of the particle. That mass divided by the volume of the vessel gives the bulk concentration for the next time step.
In COMSOL, how can I update the bulk concentration by imposing that it would be the volume integral over the particle divided by the volume of the vessel for each time step? Is there a way to create a for loop of should I combine this problem with Matlab?
Thanks in advance
B
I am fairly new to COMSOL. I am after solving a non steady-state packed bed extractor with fluid flow convection in the axial direction of the extractor and diffusion of soluble material from the solid particles.
The first thing I am trying is to solve the diffusion equation in 2D with different boundary conditions, as if the particles were in a stirred vessel.
My question is:
When a forced convection boundary condition is imposed, how can be the saturation of the bulk fluid be accounted for?
Manually the process would be
1) Bulk concentration of the fluid is 0 at time 0
2) After the first time step has elapsed, the solution of the diffusion equation gives a total flow (mass released) out of the particle. That mass divided by the volume of the vessel gives the bulk concentration for the next time step.
In COMSOL, how can I update the bulk concentration by imposing that it would be the volume integral over the particle divided by the volume of the vessel for each time step? Is there a way to create a for loop of should I combine this problem with Matlab?
Thanks in advance
B
2 Replies Last Post May 16, 2013, 7:58 a.m. EDT
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Posted:
1 decade ago
I attach a picture be clearer about the problem.
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Posted:
1 decade ago
In case this is useful for anyone:
-The approach I followed was to solve the increment of concentration in the tank analytically
(V*dCbulk/dt = kA(Cbulk-C(t)), and define and expression with the analytical solution over the considered boundary, and then use the boundary condition "Flux" It seems to work but still I would like to know how to implement straight away a boundary condition which is a differential equation...
-The approach I followed was to solve the increment of concentration in the tank analytically
(V*dCbulk/dt = kA(Cbulk-C(t)), and define and expression with the analytical solution over the considered boundary, and then use the boundary condition "Flux" It seems to work but still I would like to know how to implement straight away a boundary condition which is a differential equation...