[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: modelling a stirred tank reactor

> Now are there more elegant ways to do it ?

I've included an input file that performs a mixing calculation. I think it
is close to what you want to do if you add the kinetic reaction. In the
setup, solution 3 mixes with solution 1 in a two-cell transport
calculation. It uses two cells because the minimum number of cells in a
column for TRANSPORT is two, but calculations for cell 2 are ignored.

For the transport calculation, there is no flow (flow_direction
diffusion_only) and boundary conditions closed. A single stagnant cell is
defined for each cell of the column; this allows explicit mixing factors to
be defined for each cell. The mixing characteristics of cell 1 are defined
explicitly by MIX 1, in this case .9 of solution 1 remains and .1 of
solution 3 is added at each shift (mix). The composition of solution 3 does
not change. The number of mixes is determined by the number of "shifts" in
the transport calculation. You can run a transport calculation for a number
of shifts, then redefine solution 3, and define another transport
calculation to simulate a change in the feed to the reactor. Adding a
definition for KINETICS 1 (and RATES and appropriate time_step in
TRANSPORT) will include a kinetic reaction for cell 1. Similarly, you can
include those processes in the reactor.

The example runs two mixes and the amount of bromide initially present in
cell 1 decreases from 1 to .9 to .81 in the successive shifts in accordance
with the mixing fraction of .9 of the solution remains and no additional Br
is added.

> How can I define a new solution from previously stored parameters OUTSIDE
rate function ?

Hopefully you do not have to do this. It is probably possible to use clever
definitions of another stagnant cell to save a solution. It is probably
also possible to define a series of kinetic reactions, each of which adds
back a saved quantity for a single element.

> Can one make a DO LOOP to group a MIX and RATE function

No, I've thought about it, but never got around to coding it.


solution 0-4
      Na    1
      Cl    1
solution 1-2
      K     1
      Br    1
      3     .1
      1     .9
    -cells                 2
    -shifts                2
    -time_step             1 # seconds
    -flow_direction        diffusion_only
    -boundary_conditions   closed closed
    -stagnant              1  0  0  0
    -print_cells           1
    -punch_cells           1
    -warnings              true

David Parkhurst (dlpark@xxxxxxxx)
U.S. Geological Survey
Box 25046, MS 413
Denver Federal Center
Denver, CO 80225

Project web page: https://wwwbrr.cr.usgs.gov/projects/GWC_coupled

Project Home Page
Complete Water Resources Division Software
USGS Home Page
Water Resources Division Home Page
NRP Home Page
Help Page
USGS Privacy Statement       

Please note that some U.S. Geological Survey (USGS) information accessed through this page may be preliminary in nature and presented prior to final review and approval by the Director of the USGS. This information is provided with the understanding that it is not guaranteed to be correct or complete and conclusions drawn from such information are the sole responsibility of the user.

Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply endorsement by the U.S. Government. 

The URL of this page is: https://wwwbrr.cr.usgs.gov/projects/GWC_coupled/phreeqc/mail/msg00112.html
Last modified: $Date: 2005-09-13 21:04:21 -0600 (Tue, 13 Sep 2005) $
Visitor number 1753 since Jan 22, 1998.