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    On the design of biorectors equipped with fine pore sparger
    (Maltepe Üniversitesi, 2018) Pavlidis, Theodosios
    One of the most important factors in designing a bioreactor is the dispersion of the gas phase, the suspension the microorganisms and the enhancement of heat and mass transfer in the liquid phase. Bubble columns are gas-liquid contactors that are used in a variety of applications, e.g. bioprocessing, bioremediation, fermentation, blood oxygenation etc., since they offer many advantages due to their simple construction, low operating cost, high-energy efficiency and good mass transfer capabilities. Gas holdup and bubble size are important design parameters, since they define the gas–liquid interfacial area available for mass transfer. In turn, bubble size distribution and gas holdup depend on column geometry, operating conditions, physicochemical properties of the two phases and the type of gas sparger. The work conducted in our Lab during the last decade concerns bubble columns equipped with fine pore metal spargers and has led to the development of design equations that can predict with reasonable accuracy the transition point from homogeneous to heterogeneous regime, the gas holdup and the mean Sauter diameter at the homogeneous regime. The validity of the proposed correlations was checked with data obtained using various liquids and geometrical configurations. However, in all the experiments the gas phase was atmospheric air. In the present work the effect of gas phase properties is investigated by conducting experiments using various gases (i.e., air, CO2, He) that cover a wide range of physical property values. In view of the new experimental data, the correlations were slightly modified to include the effect of gas properties. The new correlations can predict the aforementioned quantities with ±15% accuracy. Moreover, relevant CFD simulations are conducted and validated using the experimental data. Thus, they can be employed for obtaining information concerning important flow parameters, such as velocity and shear rate distribution inside the column.
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    On the design of biorectors equipped with fine pore sparger
    (Maltepe Üniversitesi, 2018) Pavlidis, Theodosios; Başoğlu, İsmail; Bayülgen, Batu; Öztopcu, Aslı; Salman, Ayşe
    One of the most important factors an designing a bioreactor is the dispersion of the gas phase, the suspension the microorganisms and the enhancement of heat and mass transfer in the liquid phase. Bubble columns are gas-liquid contactors that are used in a variely of applications, e.g. bioprocessing, bioremediation, fermentation, blood orygenation etc., since they offer many advantages due to their simple construction, low operating cost, high-energy eflicienry and good mass transfer capabiIities.