Out-of-phase operating conditions, a hitherto unknown phenomenon in shaking bioreactors
Out-of-phase operating conditions, a hitherto unknown phenomenon in shaking bioreactors
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DOI：
10.1016/s1369-703x(00)00113-3
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发表时间：
2001-03-01
影响因子：
3.9
通讯作者：
Milbradt, C
中科院分区：
文献类型：
--
作者：
Büchs, J;Lotter, S;Milbradt, C
表征好氧微生物发酵的重要参数之一是比功耗。介绍了一种新的方法，该方法能够准确测定振荡生物反应器的功耗。它基于驱动器中的扭矩测量和摩擦损失的适当补偿。功率消耗的测量揭示了液体第一次对于振荡生物反应器而言的“异相”现象。这发生在某些操作条件下，其特征在于液体量的增加不跟随振动台的旋转运动，从而降低了比功耗、混合和气/液传质。关于这一点，必须区分不同的流体动力学情况。然而，所有这些情况的共同之处在于，“异相”条件的可能性随着较低的摇动直径、较低的填充体积、较大的挡板数量和尺寸以及较高的粘度而增加。对于标称体积小于或等于11的无挡板烧瓶，以新定义的无量纲相数（Ph）的形式描述“异相”现象。为了避免筛选项目在不利的方向上（未识别的）发展，甚至完全失败，研究人员必须意识到“异相”现象。必须仔细选择实验方案，使得在所有实验情况下不可能发生这种不希望的流体动力学条件。(C)2001 Elsevier Science B. V.保留所有权利。
One of the important parameters in characterising fermentations of aerobic microoganisms is the specific power consumption. A new method has been introduced which enables the accurate determination of the power consumption in shaking bioreactors. It is based on torque measurements in the drive and the appropriate compensation of the friction losses. Measurements of the power consumption revealed the phenomenon of the liquid being 'out-of-phase' for the first time for shaking bioreactors. This occurs at certain operating conditions and is characterised by an increasing amount of liquid not following the rotating movement of the shaker table, thus reducing the specific power consumption, mixing and the gas/liquid mass transfer. With respect to this, different hydrodynamic cases have to be distinguished. All these cases have in common, however, that the probability of 'out-of-phase' conditions increases with lower shaking diameters, lower filling volumes, larger number and sizes of baffles and higher viscosity. For unbaffled flasks with a nominal volume less than or equal to 11 the "out-of-phase" phenomenon is described in the form of a newly defined non-dimensional Phase number (Ph). To avoid the (unidentified) development of a screening project in unfavourable directions or even its complete failure, researchers must be aware of the 'out-of-phase' phenomenon. The experimental protocols have to be carefully selected so that the occurrence of such unwanted hydrodynamic conditions is not possible under all experimental circumstances. (C) 2001 Elsevier Science B.V. All rights reserved.