Measurement techniques for local and global fluid dynamic quantities in two and three phase systems

Abstract

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Hydrodynamics and gas holdup in a cocurrent air-water-fiber bubble column

“…For a cocurrent bubble column, gas holdup is generally determined from (Hills, 1976;Merchuk and Stein, 1981;Kumar et al, 1997)…”

“…Gas holdup values can also be estimated with the bed expansion method (i.e., from liquid level changes between the ungassed and gassed condition) (Kumar et al, 1997). Figure 3.4 compares the average gas holdup values in sections 1-3 estimated with the bed expansion method and those obtained using the pressure difference method represented by Eq.…”

“…When a solid phase is present, the differential pressure gradient method can be used to measure gas holdup if the liquid-solid slurry behaves as a pseudohomogeneous mixture or if the solids concentration as a function of height is known (Kumar et al, 1997).…”

Phase distribution in an upflow monolith reactor using computed tomography

“…The CT used in this study is based on a third generation fan‐beam configuration developed at the Chemical Reaction Engineering Laboratory (CREL). Details of the hardware and software have been described in previous work (Kumar, 1994; Kumar et al, 1995, 1997a, b). The key system elements are illustrated in Figure 2.…”

Using X-ray computed tomography to measure local gas holdup in a stirred tank reactor

“…A phototransistor gives an analog signal output proportional to the received light intensity. Kumar et al (1997) report that optical probes should mainly be used in transparent systems, with low void fractions, and at moderate temperatures. The probe would have a hard time detecting changes in voids if the bubble size was too small.…”