Computational Approach to Characterize the Mass Transfer between the Counter‐Current Gas‐Liquid Flow

Post-combustion carbon capture in structured packing columns is considered as a promising technology to reduce greenhouse gas (GHG) emissions because of its maturity and the possibility of being retrofitted to existing power plants. CFD plays an important role in the optimization of this technology. However, due to the current computational capacity limitations, the simulations need to be divided into three scales (i.e. micro-, meso- and macro-scale) depending on the flow characteristics to be analyzed. This study presents a 3D micro-scale approach to describe the hydrodynamics and reactive mass transfer of the CO2-MEA chemical system within structured packing materials. Higbie's penetration theory is used to describe the mass transfer characteristics whereas enhancement factors are implemented to represent the gain in the absorption rate attributable to the chemical reaction. The results show a detrimental effect of the liquid load on the absorption rate via a decrease in the enhancement factor. The evolution of the wetted area for MEA solutions is compared to the case of pure water highlighting the differences in the transient behavior. The CO2 concentration profiles are examined showing the capability of the model to reproduce the depletion of the solute within the bulk liquid ascribed to the high value of the Hatta number. Also, several approaches on the reaction mechanism such as reversibility and instantaneous behavior are assessed. The results from micro-scale are to be used in meso-scale analysis in future studies to optimize the reactive absorption characteristics of structured packing materials

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“…The interfacial area per unit volume is computed as the gradient of the volume fraction (Xu et al, 2009).…”

Section: Physical Mass Transfermentioning

confidence: 99%

Micro-scale CFD modeling of reactive mass transfer in falling liquid films within structured packing materials

Sebastia‐Saez

Ranganathan

et al. 2015

International Journal of Greenhouse Gas Control

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“…From the viewpoint of control and operation, the interfacial area for heat and mass transfer as well as the residence time should be increased in order to improve the separation efficiencies for the structured packed columns. It has been known that film flow provides a relatively large interfacial area in distillation and absorption processes comparing to the other flow behaviors (Xu et al, 2009). Therefore, investigations of the influencing factors for film flow and its flow characteristics have attracted many researchers.…”

Section: Introductionmentioning

confidence: 99%

CFD Study on Liquid Flow Behavior on Inclined Flat Plate Focusing on Effect of Flow Rate

Yuan

Repke

et al. 2012

Engineering Applications of Computational Fluid Mechanics

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ABSTRACT:The factors affecting the separation efficiencies of structured packed columns are multi-scale, including the macroscopic variables (eg feed rate, pressure and temperature) and the microscopic liquid flow behavior and distribution. Especially in the situation in which the second liquid phase is inevitable within distillation columns, the microscopic liquid flow behavior could lead to the uncertainty of the separation efficiencies. This work mainly focuses on the investigation of the local flow behavior of a liquid phase flowing on an inclined steel plate at different situations. On one hand, a three-dimensional CFD model based on the VOF model is developed with the commercial CFD package, FLUENT 6.3. On the other hand, the results of the experimental study are adopted to validate partially the model. Within the developed model, the influences of the liquid and gas flow rates are studied with respect to the specific wetted area, the thickness profile of film and rivulet flows as well as the average velocity of the liquid phase.

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“…(2) One-dimensional transient heat and mass transfer are considered [36]. (3) Air flow is uniform [37]. (4) Constant specific heat capacities are for dry air and liquid desiccant.…”

Section: Governing Equationmentioning

confidence: 99%

“…(2) One-dimensional transient heat and mass transfer are considered [36]. (3) Air flow is uniform [37]. The governing equations can be mathematically derived from appropriate balances applied to an infinitesimal control volume of the air and solution desiccant flowing through the dehumidification tower, leading to the following lumped-capacitance model with the definitions of number of dimensionless mass transfer unit (NTU m ) and Lewis number (Le) [21,36,[38][39][40]:…”

Section: Governing Equationmentioning

confidence: 99%

Simplified Heat and Mass Transfer Model for Cross-Flow and Countercurrent Flow Packed Bed Tower Dehumidifiers with a Liquid Desiccant System

Shiue

Chiu³

et al. 2016

Sustainability

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A mathematical model is developed using the Matlab/Simulink platform to investigate heat and mass transfer performance of cross-flow and counterflow dehumidifiers with Lithium Chloride (LiCl) solution. In the liquid desiccant dehumidifier, the orthogonal polynomial basis is used to simulate the combined processes of heat and mass transfer. The temperature profiles on cross-flow and countercurrent flow dehumidifiers are demonstrated. The resultant counter flow air changes the temperature profile of the LiCl solution in the longitudinal direction because of the drag forces. In addition, when inlet airflow rate reaches 15 kg·s −1 , the temperature effect becomes less obvious and may be reasonably negligible. Under these conditions, the air changes the design factor and determines the interfacial temperature. It is demonstrated that the mathematical model can be of great value in the design and improvement of cross-flow and countercurrent flow dehumidifiers.

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Computational Approach to Characterize the Mass Transfer between the Counter‐Current Gas‐Liquid Flow

Cited by 40 publications

References 39 publications

Micro-scale CFD modeling of reactive mass transfer in falling liquid films within structured packing materials

Micro-scale CFD modeling of reactive mass transfer in falling liquid films within structured packing materials

CFD Study on Liquid Flow Behavior on Inclined Flat Plate Focusing on Effect of Flow Rate

Simplified Heat and Mass Transfer Model for Cross-Flow and Countercurrent Flow Packed Bed Tower Dehumidifiers with a Liquid Desiccant System

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