Transport Phenomena in Two-Phase Liquid-Liquid Micro-Reactors

Micro-reactors offer distinct advantages over batch reactors currently used within the pharmaceutical and fine chemical industries. Their high surface area-to-volume ratios allow for increased heat and mass transfer, which is important for controlling reaction selectivity. In addition, micro-reactors are compatible with continuous processing technology, circumventing the time delays inherent to batch systems. Rapid mixing of reactants within micro-reactors is, however, limited by the inherent difficulty of generating turbulence at reduced geometry scales. Several different passive mixing strategies have been proposed in order to produce eddy-based secondary flows and chaotic mixing. This study examines the effectiveness of these strategies by comparing the energy-density normalized heat and mass transfer coefficients for a selection of industrial micro-reactors. First single, then two-phase liquid-liquid experiments were conducted. Pressure drop measurements were obtained to calculate friction factors and to verify the presence of eddy-based secondary flows. A hot heat exchange fluid and temperature measurements were used to estimate the internal convective heat transfer coefficients within each structure. Volumetric mass transfer coefficients were also determined for the mutual extraction of partially miscible n-butanol and water. Semi-empirical correlations for the reactors’ friction factor and Nusselt number as well as a description of the overall mass transfer coefficient based on energy dissipation are presented.

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Determination of Volumetric Heat and Mass Transfer Coefficients in Filling Unit of Evaporative Cooling Tower

2020 International Multi-Conference on Industrial Engineering and Modern Technologies (FarEastCon) ◽

10.1109/fareastcon50210.2020.9271292 ◽

2020 ◽

Author(s):

I. Madyshev ◽

A. Dmitriev ◽

V. Kharkov

Keyword(s):

Mass Transfer ◽

Heat And Mass Transfer ◽

Cooling Tower ◽

Evaporative Cooling ◽

Transfer Coefficients ◽

Mass Transfer Coefficients ◽

Evaporative Cooling Tower

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Numerical Simulation of Heat and Mass Transfer Enhancement in Absorption Process With Double-Side Film-Inversion

ASME 2008 6th International Conference on Nanochannels, Microchannels, and Minichannels ◽

10.1115/icnmm2008-62259 ◽

2008 ◽

Cited By ~ 1

Author(s):

Ya-Ping Chen ◽

Chen-Jie Shi ◽

Ming-Heng Shi ◽

Chen-Min Ling

Keyword(s):

Mass Transfer ◽

Heat And Mass Transfer ◽

Vertical Plane ◽

Mathematic Model ◽

Absorption Process ◽

Transfer Coefficients ◽

Mass Transfer Coefficients ◽

Plane Plate ◽

Before And After ◽

Calculation Results

Film-inversion is an effective way recently developed to enhance heat and mass transfer in absorbers. However, only one-side of round or rectangular tube i.e. half of the total heat transfer area is used to form film-inverting configuration in the published literature. The paper presents a double-side film-inverting scheme, which consists of two plate bundles and a set of comb shaped conjunction guiders between them for leading solution film from both-sides of each couple of the upper plate bundle to the opposite sides of the bottom ones. A two-scale crosswise corrugation plate bundle, which has vertical large corrugations and horizontal small ones, is suggested instead of the plane plate bundle. The horizontal small corrugation can make the film turbulent and film distribution uniform before and after inversion with surface tension effect, thus increasing the heat and mass transfer coefficients of the absorption process. A mathematic model for heat and mass transfer in absorption process with aqueous Li-Br solution falling film-inverting on two sequential vertical plane plates was established and solved numerically. The distributions of dimensionless velocity, temperature and concentration of liquid film profile before and after film-inverting were obtained. The influence of the number of inversion on heat and mass transfer characteristics was analyzed. The calculation results show that the heat and mass transfer coefficients of the once-film-inverting scheme have about 58% and 73% increment respectively over these of the none film-inverting scheme.

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Lyon-Type Integral Forms of Wall Friction, Heat- and Mass Transfer Closure Relationships for Non-Equilibrium Two-Phase Flows: Generalization for Annular and Rod Cluster Geometries

Volume 8C: Heat Transfer and Thermal Engineering ◽

10.1115/imece2013-66044 ◽

2013 ◽

Author(s):

Yuri Kornienko

Keyword(s):

Boundary Layer ◽

Mass Transfer ◽

Heat And Mass Transfer ◽

Constitutive Relations ◽

Wall Friction ◽

Transfer Coefficients ◽

Two Phase ◽

Friction Heat ◽

Integral Forms ◽

Substance Transfer

The main goal of this paper is to describe new approach to constructing generalized closure relationships for pipe, annular and sub-channel transfer coefficients for wall friction, heat and mass transfer. The novelty of this approach is that it takes into account not only axial and transversal parameter distributions, but also an azimuthal substance transfer effects. These constitutive relations, which are primordial in the description of single- and two-phase one-dimensional (1D) flow models, can be derived from the initial 3D drift flux formulation. The approach is based on the Reynolds flow, boundary layer, and substance transfer generalized coefficient concepts. Another aim is to illustrate the validity of the “conformity principle” for the limiting cases. The method proposed in this paper is founded on the similarity theory, boundary layer model, and a phenomenological description of the regularity of the substance transfer (momentum, heat, and mass) as well as on an adequate simulation of the flow structures. With the proposed generalized approach it becomes possible to develop an integrated in form and semi-empirical in maintenance structure analytical relationships for wall friction, heat and mass transfer coefficients.

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