A7 Use of the Model of an Intermittently Mixed Forcefully Aerated Bioreactor

This section gives advice about the use of the model for the intermittently-mixed, forcefully-aerated bioreactor that was presented in Chap. 25. 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.6. 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.

• Filename for output of average biomass? (BI)

• Filename for gas temperature? (TG)

• Filename for solid temperature? (TS)

• Filename for gas water activity? (WG)

• Filename for solid water activity? (WS)

• Filename for actual specific growth rate? (MU)

• Filename for specific growth rate as f(T)? (MT)

• Filename for specific growth rate as f(W)? (MR)

• Filename for water ratio in the solid? (FS)

• Filename for eqm water ratio in the solid? (FE)

• Filename for mixing event output? (EV)

• Filename for 3-dimensional temperature output (TD)

The letters in parentheses after the question represent suggestions as to the final letters that you might use within the filename in order to help organize your files. After you answer the last question, the program will run automatically. When the instruction "Press any key to continue" appears, press a key (e.g., the space bar).

Inspect the output files. Assuming that you have used the suggested endings for the file names and called the fourteen output files "outbi.txt", "outbd.txt", "outtg.txt", "outts.txt", "outwg.txt", "outws.txt", "outmu.txt", "outmt.txt, "outmr.txt", "outfg.txt", "outfs.txt", "outfe.txt", "outev.txt", and "echo.txt", respectively:

• outbi.txt will have three columns with the time (h), the biomass concentration (kg-dry-biomass kg-dry-solids-1), and the solids per unit volume (kg-dry-solids m-3). The biomass and solids values are weighted averages calculated over the whole bed.

• outbd.txt, outts.txt, outwg.txt, outws.txt, outmu.txt, outmt.txt, outmr.txt, outfg.txt, outfs.txt, and outfe.txt will each have 6 columns. In all cases, the first column represents the time (h). The other five columns are various variables at different heights within the bed. "Z~0+" represents one-fortieth of the overall bed height, "Z=H/4" represents one quarter of the overall bed height, "Z=H/2" represents a half of the overall bed height, "Z=3H/4" represents three quarters of the overall bed height, and "Z=H" represents the top of the bed. The specific information that will appear within each file is shown in Table A.7.

• "outev.txt" gives information about the mixing events. For each mixing event are listed the time (h) at which it began, the time (h) at which it ended, the average biomass (kg-dry-biomass kg-dry-solids-1) at the end of the mixing event, the average solids per unit volume (kg-dry-solids m-3), the amount of energy that needed to be removed from the solids to bring them back to the initial bed temperature (J kg-dry-solids-1), and the amount of water that needed to be added to the solids in order to bring their water activity back to the initial water activity (kg-water kg-dry-solids-1);

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

Was this article helpful?

0 0

Post a comment