A PIV study of hydrodynamics in gas–liquid high throughput experimentation (HTE) reactors with eccentric impeller configurations

Quantification of power consumption and oxygen transfer characteristics of a stirred miniature bioreactor for predictive fermentation scale‐up

“…At this point however the gas hold up is not sufficient to promote gross recirculation of bubbles throughout the dispersion. The point at which gross recirculation sets in is normally taken as the left hand maximum of the curves (Hall et al, 2005).…”

Mixing studies in a model aerated bioreactor equipped with an up- or a down-pumping ‘Elephant Ear’ agitator: Power, hold-up and aerated flow field measurements

“…Khopkar et al (2003) performed measurements on a downflow pitched blade turbine, whilst Aubin et al (2004) compared the performance between up-pumping and down-pumping configurations. Hall et al (2005) performed a similar study for up-pumping impellers in a small-scale gassed high throughput experimentation (HTE) reactor using an eccentric impeller configuration. Most recently, Laakkonen et al (2005) used PIV to obtain local bubble size distributions, gas-liquid interfacial areas and gas hold-up in a stirred vessel.…”

Local gas and liquid phase velocity measurement in a miniature stirred vessel using PIV combined with a new image processing algorithm

“…Recently, Hall et al [5] used two-dimensional particle image velocimetry (PIV) to determine the local liquid phase velocities within an eccentrically agitated gas-liquid HTE vessel. This was accomplished by following the movement of neutrally buoyant seeding particles that fluoresced at a wavelength different from that of the incident laser light.…”

“…Such stirred vessels pose an additional challenge of scale, being an order of magnitude smaller than ordinary laboratory scale vessels (volume $15-250 ml). In addition to their miniature size, these vessels are of unconventional geometry; arrangements such as eccentric positioning of the agitator, low off-bottom impeller clearances, and lack of baffles because of cleaning difficulties are common, which precludes their characterisation via conventional scaling rules based upon those observed in traditional laboratory or pilot scale vessels [4][5][6]. It was shown, for example, that some of the mixing limitations imposed by the lack of baffles could be circumvented by employing eccentric or off-centre agitation; an approach which is impractical on a large scale due to the additional large stresses imposed on the impeller shaft, but which is perfectly workable on the HTE scale.…”