A3 Use of the Well Mixed Bioreactor Model

This section gives advice about the use of the model for the well-mixed bioreactor that was presented in Chap. 22. The following steps should be followed.

First use a text editor to edit the input data file. An input data file (text file) has been supplied with the name "input.txt". The contents and format of this file are shown in Fig. A.1. Change the values as appropriate, save the file (as a text file), and exit the file editor.

Then click twice on "WellMixed.exe". A "DOS window" will appear on the screen. Several questions will appear, one after the other.

• What is the name of the OUTPUT file?

• What is the name of the COOLING CONTRIBUTIONS file?

After you answer the last question, the program will run automatically. When the instruction "Press any key to continue" appears, press the space bar.

Inspect the output files. Assuming that you have called the three output files "output.txt", "cooling.txt", and "echo.txt", respectively:

• Output.txt will have 15 columns with the headings that are explained in Table A.2. The number of rows will depend on the "number of outputs to be reported" that was selected in the input file.

• Cooling.txt will have 6 columns with the headings that are explained in Table A.3. The number of rows will depend on the "number of outputs to be reported" that was specified in the input file.

• Echo.txt contains an echo of various input values and other values calculated in the program. The content is self-explanatory.

2.0 diameter = bioreactor diameter (m)

5.0 wallthickness (mm)

1.0 vvm = volumes of air per total bed volume per minute

0.87 outlet gas water activity setpoint for triggering water addition

1.0 fold increase in transfer due to mixing

35.0 initial system temperature (deg C) Wall solids gas

35.0 Tin = temperature of air at the air inlet (deg C)

35.0 Tsetpoint = setpoint temperature used in water jacket temperature control scheme (C)

0.0 gain = gain factor used in the water jacket temperature control scheme

0.99 awgo = initial water activity of the gas phase

0.50 awgin = water activity of the inlet air

0.99 awso initial water activity of the solid phase

0.002 Y(1) = initial biomass concentration (kg biomass/kg solid)

0.5 Yxs

1 Organism type 1=Aspergillus 2=Rhizopus (MUST BE AN INTEGER)

0.5 Effective bed porosity during mixing (volvoids/voltotal)

450.0 Density of dry solid particles (the particles in themselves, not a bed of particles)

60.0 Total time to be simulated (h)

60 Number of outputs to be reported (MUST BE AN INTEGER)

200. heat transfer coefficient (wall to cooling water)(W/(m2.K))

200. heat transfer coefficient (solid phase in bed to wall)(W/(m2.K))

200. heat transfer coefficient (gas phase in bed to wall)(W/(m2.K))

Fig A.1 Appearance of the input file (input.txt) for the well-mixed bioreactor model

Table A.2. Significance of the column headings in the "OUTPUT" file generated by the well-mixed bioreactor model

No.

Heading

Significance

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