Ahmad Azari - MSc student of chemical Engineering, Faculty of Engineering, Un. Tehran
Shohreh Fatemi - Chemical Engineering Department, Faculty of Engineering, University of Tehran

Two different modeling techniques are introduced and compared for solid-state fermentation process in packed-bed bioreactors, in order to simulate and upscale these reactors; one based on a dynamic heat transfer model and the other based on a modified Damkohler number. The limiting parameter of upscaling bioreactors is the temperature of substrate at the top of reactor which ends or limits the growth of microorganisms in the fermentation process, therefore a critical bed height is required to be proposed by the model. The maximum bed height which can be used without undesirable temperatures being reached in the substrate bed is the critical bed height in the fermentation bioreactor process. Critical bed height depends on the microbial specific growth rate as well as superficial velocity and inlet temperature of the air. In this work, the mentioned two models were compared and the outlet temperature resulted by both techniques were obtained close together. It is concluded that, both models are in agreement and can be used as for upscaling these processes. Although the modified Damkohler number is a simple technique, it can be used Instead of heat transfer model. In addition, the effect of two different growth kinetics; logistic and exponential equation, are studied in the models comparatively and the effect of model variables, such as specific growth rate, and superficial velocity are investigated on the critical bed height and outlet temperature.

Bioreactor, Heat transfer, Packed-bed bioreactors, Solid-state fermentation, Iimplicit finite method