Study of Liquid–Solid Mass Transfer and Hydrodynamics in Micropacked Bed with Gas–Liquid Flow

Abstract

The volumetric liquid–solid (L-S) mass transfer coefficient under gas–liquid (G-L) two-phase flow in a silicon-chip-based micropacked bed reactor (MPBR) was studied using the copper dissolution method and was related to the reactor hydrodynamic behavior. Using a high-speed camera and a robust computational image analysis method that selectively analyzed the bed voidage around the copper particles, the observed hydrodynamics were directly related to the L-S mass transfer rates in the MPBR. This hydrodynamic study revealed different pulsing structures inside the packed copper bed depending on the flow patterns established preceding the packed bed upon increasing gas velocity. A “liquid-dominated slug” flow regime was associated with an upstream slug flow feed. A “sparse slug” flow regime developed with an upstream slug-annular flow feed. At higher gas velocity, a “gas continuous with pulsing” regime developed with an annular flow feed, which had similar features to the pulsing flow in macroscale packed beds, but it was sensitive and easily destabilized by disturbances from upstream or downstream pressure fluctuations. The volumetric L-S mass transfer coefficient decreased with increasing gas velocity under the liquid-dominated slug flow regime and became rather less affected under the sparse slug flow regime. By resolving the transition from the liquid-dominated slug flow to the sparse slug flow and capturing the onset of the gas-continuous with pulsing regime, we gained new insights into the hydrodynamic effects of G-L flows on the L-S mass transfer rates in a MPBR.

Nature and characteristics of gas–liquid flow regimes in a micro‐packed bed reactor

“…Krishnamurthy et al 31 proposed the bubbly slug, gas slug, bridged, and annular flow regimes in the μPBR by their studies. Cao et al 39 displayed the liquid‐dominated slug, sparse slug, and gas continuous with pulsing flow regimes in the μPBR. The gas and liquid superficial velocities in Krishnamurthy et al 31 and Cao et al 39 studies were at least two or three orders of magnitude higher than that of other studies, which represented the flow behaviors of the μPBR in the extreme situations.…”

Study on the Solid–Liquid Mass-Transfer Performance of Suspension in a Rotating Packed Bed

“…Of course, new methods for measuring solid–liquid mass transfer have also been reported, , such as limiting current electrochemical technique and so forth. However, the obtained Sh in the traditional STR is usually less than 100 where the obtained k S is in a low level. ,− …”

Local and global gas–liquid mass transfer in a micro‐packed bed reactor utilizing a noninvasive colorimetric technique

“…Mass transfer studies, as one of the crucial parts in fundamental researches, were the hotspots in the realm of reactor design, which was beneficial for the cognitive enhancement and better understanding of the scaling‐up processes 14–16 . Several mass transfer studies have been carried out in the μPBRs, including gas–liquid, liquid–solid, and gas–liquid–solid systems.…”

“…13 Mass transfer studies, as one of the crucial parts in fundamental researches, were the hotspots in the realm of reactor design, which was beneficial for the cognitive enhancement and better understanding of the scaling-up processes. [14][15][16] Several mass transfer studies have been carried out in the μPBRs, including gas-liquid, liquid-solid, and gas-liquid-solid systems. Losey et al 17 evaluated mass transfer in the μPBR within Pt/Al 2 O 3 catalyst by cyclohexene hydrogenation reaction and showed that overall mass-transfer coefficients were two orders of magnitude larger than that of the conventional packed bed.…”