engleski

Comparison of dispersion model and structured model for mixing in a horizontal rotating tubular bioreactor

A horizontal rotating tubular bioreactor (HRTB) was designed as a combination of a "thin-layer bioreactor" and a "biodisc" reactor whose interior was divided by O-ring shaped partition walls (1). Mixing properties of this new type of bioreactor were investigated by using a temperature step method and different mixing models. A dispersion model for mixing with Bodenstein number as a parameter was compared with a structured "spiral flow" model (2) by using following experimental and mathematical procedures : -experimental results were obtained by measuring the response to temperature step of six Pt-100 sensors (t_90 response time 0.08 s and resolution 0.002 K) for wide range of process conditions (eight dilution rates combined with seven rotation speeds). - the two sets of differential equations for heat balances were established based on two mathematical models, the axial dispersion model and structured model with "spiral flow", respectively. - the above systems were simulated by using Runge-Kutta-Fehlberg integration and optimised by the "Monte-Carlo" method. - the comparison of mixing models was based on mathematical criteria (the sum of temperature differences between measured and simulated results for all six sensors and whole experimental time range). The results obtained with above procedure show that structured "spiral flow" model (containing four adjustable parameters) is more capable to describe mixing properties in HRTB than the one parameter axial dispersion model. 1. B. Šantek et al.; Bioprocess Eng.; 14; 195-203; 1996 2. B. Šantek et al.; Bioprocess Eng.; 14; 223-229; 1996

horizontal rotating tubular bioreactor; "spiral" flow model; dispersion model

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