MATHEMATICAL-MODELING OF MIXING IN A HORIZONTAL ROTATING TUBULAR BIOREACTOR - SPIRAL FLOW MODEL

A horizontal rotating tubular bioreactor (HRTB) was designed as a comb ination of a ''thin-layer bioreactor'' and a ''biodisc'' reactor whose interior was divided by O-ring shaped partition walls. For the invest igation of mixing in HRTB the temperature step method was applied. Tem perature changes in the bioreactor were monitored by six Pt-100 sensor s (t(90) response time 0.08 s and resolution 0.002 degrees C) which we re connected with an interface unit and a personal computer. In this w ork a modified ''tank in series'' concept was used to establish a math ematical model. The heat balance of the model compartments was establi shed according to the physical model and the ''spiral flow'' pattern. Numerical integration was done by the Runge-Kutta-Fehlberg method. The mathematical mixing model called ''spiral flow'' model contained four adjustable parameters (N1, Ni, F-cr and F-p) and five parameters whic h characterized the plant and experimental conditions. The ''spiral fl ow'' model was capable to describe the mixing in HRTB properly, and it s applicability was much better than with the ''simple flow'' model, p resented earlier.