Rotating packed beds have received considerable attention as a means of process intensification for gas−liquid mass transfer over the past 2 decades. In this work, we take a critical view of the developments in understanding the transport processes in rotating packed beds. The intensification achieved so far falls short of the goal of 2−3 orders of magnitude volume reduction compared to that obtained conventional columns. The directions toward achieving this goal are outlined.

The high centrifugal force field in a rotating packed bed (HIGEE) permits the use of packing with a large surface area and enhances the liquid-side mass-transfer coefficient. However, the gas-side mass-transfer coefficient is in the same range as that of the conventional packed columns.Recent studies indicate that the tangential slip velocity between the gas and the packing is negligible. We have split the packing into annular rings to rotate adjacent rings in the counterdirection to promote the tangential slip velocity in the range of 5-30 m/s and to enhance the gas-side mass-transfer coefficient. In this work, we present the frictional and centrifugal pressure drops and the tangential slip velocity of the gas in a HIGEE with split packing. Counter to intuition, the total pressure drop with counterrotation of the rings is found to be less than that with corotation of the rings.

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A new fiber bundle approach to the gauge theory of a group G that involves space-time symmetries as well as internal symmetries is presented. The ungauged group G is regarded as the group of left translations on a fiber bundle G(G/H,H), where H is a closed subgroup and G/H is space-time. The Yang–Mills potential is the pullback of the Maurer–Cartan form and the Yang–Mills fields are zero. More general diffeomorphisms on the bundle space are then identified as the appropriate gauged generalizations of the left translations, and the Yang–Mills potential is identified as the pullback of the dual of a certain kind of vielbein on the group manifold. The Yang–Mills fields include a torsion on space-time.

A combinatorial approach to diffeomorphism invariant quantum gauge theories Any (N + M)-parameter Lie group G with an N-parameter subgroup H can be realized as a global group of diffeomorphisms on an M-dimensional base space B, with representations in terms of transformation laws of fields on B belonging to linear representations of H. The gauged generalization of the global diffeomorphisms consists of general ditreomorphisms (or coordinate transformations) on a base space together with a local action of H on the fields. The particular applications of the scheme to space-time symmetries is discussed in terms of Lagrangians, field equations, currents, and source identities.2415