Characteristics of liquid flow in a rotating packed bed for CO 2 capture: A CFD analysis Peng Xie, Xuesong Lu, Xin Yang, Derek Ingham, Lin Ma ⇑ , Mohamed Pourkashanian Energy2050, Mechanical Engineering, Faculty of Engineering, University of Sheffield, Sheffield S10 2TN, UK highlights  A 2D CFD model is built using a fine grid to resolve the liquid flow in an RPB.  The model predictions are in reasonable agreement with observations.  On increasing the MEA concentration, the degree of liquid dispersion decreases.  High rotational speed decreases the holdup and increases the liquid dispersion.  At a high contact angle, more liquid droplets are formed but holdup decreases. article info Article history: Received 8 April 2017 Received in revised form 15 June 2017 Accepted 21 June 2017 Available online 23 June 2017 Keywords: Rotating packed bed CFD Flow pattern Liquid holdup VOF model abstract Rotating packed beds (RPBs) have been proposed as an emerging technology to be used for post- combustion CO 2 capture (PCC) from the flue gas. However, due to the complex structure of the packing in RPBs, characteristics of the liquid flow within RPBs are very difficult to be fully investigated by exper- imental methods. Therefore, in this paper, a two-dimensional (2D) CFD model has been built for analys- ing the characteristics of liquid flow within an RPB. The volume of fluid (VOF) multiphase flow model is implemented to calculate the flow field and capture the interface between the gas and liquid phases in the RPB. The simulation results show good agreement with the experimental data. The distinct liquid flow patterns in different regions of an RPB are clearly observed. The simulation results indicate that increasing the rotational speed dramatically decreases the liquid holdup and increases the degree of the liquid dispersion. The increasing liquid jet velocity decreases the liquid residence time but slightly increases the liquid holdup. In addition, the liquid holdup increases and the degree of the liquid disper- sion decreases with increasing MEA concentration, but the effects are weaker at a higher rotational speed. With the increasing of the contact angle, both the liquid holdup and the degree of the liquid dispersion are reduced. This proposed model leads to a much better understanding of the liquid flow characteristics within RPBs. Ó 2017 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http:// creativecommons.org/licenses/by/4.0/). 1. Introduction The rotating packed bed (RPB), as a type of process intensifica- tion (PI) technology, was invented by Ramshaw and Mallinson (1981) for enhancing the gas–liquid mass transfer in chemical pro- cesses. A schematic diagram of a typical RPB is shown in Fig. 1. In the RPB, liquid flow is injected radially from the centre of the bed and it is split continuously into discrete liquid ligaments, thin films and tiny droplets by the rotating porous packing. This can dramat- ically increase the interfacial area and promotes intensive mixing and mass transfer between the liquid phase and the gas phase that flows through the RPB (Yan et al., 2014). Applications of RPB include such as separation process intensification (Chen and Liu, 2002; Chu et al., 2014), reaction process intensification (Chen et al., 2010), nanoparticles syntheses (Chen et al., 2000), etc. In recent years, in order to control the global CO 2 emission from the power generation sector, the RPB has been proposed as an emerg- ing technology to be used for post-combustion CO 2 capture (PCC) from the flue gases (Cheng et al., 2013; Joel et al., 2014; Lin and Kuo, 2016; Wang et al., 2015; Zhao et al., 2014). It has the potential to significantly reduce the capital cost, improve the process dynamics and use high concentrated amine-based solvents, com- pared with using conventional packed columns (Wang et al., 2015). However, the fluid mechanics of the RPB is not fully under- stood, thus accurately predicting the characteristics of the liquid http://dx.doi.org/10.1016/j.ces.2017.06.040 0009-2509/Ó 2017 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). ⇑ Corresponding author. E-mail address: lin.ma@sheffield.ac.uk (L. Ma). Chemical Engineering Science 172 (2017) 216–229 Contents lists available at ScienceDirect Chemical Engineering Science journal homepage: www.elsevier.com/locate/ces