A6 Use of the Zymotis Packed Bed Bioreactor Model

This section gives advice about the use of the model for the Zymotis packed-bed bioreactor that was presented in Chap. 24.3. 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 of this file are shown in Fig. A.4. Change the values as appropriate, save the file (as a text file), and exit the file editor.

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

• Name of file for output at top of bioreactor (Z=H)?

• Name of file for 2-D output of temperatures?

• Name of file for 2-D output of water activities?

• Name of file for 2-D output effect of T on growth?

• Name of file for 2-D output effect of Aw on growth?

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 six output files "out-

put.txt", "temp.txt", "water.txt", "tempgro.txt", "watergro.txt", and "echo.txt", respectively.

• output.txt will have nine columns, with the headings shown in Table A.6. These values represent the conditions at the top of the bioreactor; at a position midway between two heat transfer plates.

• temp.txt, water.txt, tempgro.txt, and watergro.txt contain output data tabulated as a function of both horizontal and vertical position. Fig. A.5 shows how these files are organized.

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

.10 xL = half of the distance between plates (m)

.03 Vz = superficial velocity of the air (m/s)

38. Tair = temperature of the air fed into the bioreactor (deg C)

2.0 Gain factor for the temperature control scheme for the cooling water(-)

700. RhoS0 = density of moist subsrate particles at t=0 (kg/m3)

.35 Epsilon = void fraction of the bed (dimensionless)

.002 Bo = initial biomass concentration (kgX/kg DRY S)

.25 Bm = maximum biomass concentration (kgX/kg DRY S)

95. hwall (W/m2/K) (heat transfer coefficient at the wall)

0.5 Ybiom/sub = kg biomass produced per kg of substrate consumed

0.3 Yh20/biom = kg H2O produced per kg of biomass produced

0.5 FMo Fraction of moisture at t=0 (kg H2O/kg total moist substrate)

0.236 Specific growth rate constant at Topt (1/h)

38. Topt = optimum temperature for growth (deg C)

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

50. Final time for the simulation (h)

50 Number of outputs (MUST BE AN INTEGER)

Fig A. 4. Appearance of the input file (input.txt) for the Zymotis packed-bed bioreactor model

Table A.6. Significance of the column headings in the "OUTPUT" file generated by the Zymotis packed-bed bioreactor model




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