Please cite this article in press as: Adamczyk, W. P., et al. Comparison of the standard Euler–Euler and hybrid Euler–Lagrange approaches for modeling particle transport in a pilot-scale circulating fluidized bed. Particuology (2013), http://dx.doi.org/10.1016/j.partic.2013.06.008 ARTICLE IN PRESS G Model PARTIC-594; No. of Pages 9 Particuology xxx (2013) xxx–xxx Contents lists available at ScienceDirect Particuology jo ur nal home page: www.elsevier.com/locate/partic Comparison of the standard Euler–Euler and hybrid Euler–Lagrange approaches for modeling particle transport in a pilot-scale circulating fluidized bed Wojciech P. Adamczyk a,∗ , Adam Klimanek a , Ryszard A. Bialecki a , Gabriel W˛ ecel a , Pawel Kozolub a , Tomasz Czakiert b a Institute of Thermal Technology, Silesian University of Technology, 44-100 Gliwice, Konarskiego 22, Poland b Institute of Advanced Energy Technologies, Czestochowa University of Technology, Czestochowa, Poland a r t i c l e i n f o Article history: Received 10 March 2013 Received in revised form 13 May 2013 Accepted 1 June 2013 Keywords: Particle Multiphase flow CFD Particulate processes CFB Fluidized bed a b s t r a c t Particle transport phenomena in small-scale circulating fluidized beds (CFB) can be simulated using the Euler–Euler, discrete element method, and Euler–Lagrange approaches. In this work, a hybrid Euler–Lagrange model known as the dense discrete phase model (DDPM), which has common roots with the multiphase particle-in-cell model, was applied in simulating particle transport within a mid-sized experimental CFB facility. Implementation of the DDPM into the commercial ANSYS Fluent CFD package is relatively young in comparison with the granular Eulerian model. For that reason, validation of the DDPM approach against experimental data is still required and is addressed in this paper. Additional difficulties encountered in modeling fluidization processes are connected with long calculation times. To reduce times, the complete boiler models are simplified to include just the combustion chamber. Such simplifications introduce errors in the predicted solid distribution in the boiler. To investigate the conse- quences of model reduction, simulations were made using the simplified and complete pilot geometries and compared with experimental data. All simulations were performed using the ANSYSFLUENT 14.0 package. A set of user defined functions were used in the hybrid DDPM and Euler–Euler approaches to recirculate solid particles. © 2013 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved. 1. Introduction Circulating fluidized bed (CFB) and bubbling fluidized bed boil- ers are popular alternatives to the traditional pulverized coal boilers because of their maturity and insensibility to the qual- ity of fuel. Numerical simulations of the flow conditions inside such devices require solving complex multiphase transport equa- tions in mixtures of gases and particles with high solid mass loadings. Methods used for the granular flow simulations differ by the temporal and spatial scales covered in flow phenomena (Myohanen & Hyppanen, 2011). Because scales range from the small-scale molecular up to large-scale system levels, differing by many orders of magnitude, the computational effort is much differ- ent in these approaches. It is attractive to tend toward small-scale models which describe the flow system on fundamental grounds ∗ Corresponding author. E-mail address: wojciech.adamczyk@polsl.pl (W.P. Adamczyk). that inherently cover the large-scale phenomena. However, these models are not affordable for large industrial facility simulations. The large-scale systems need to be modeled using less general and experimentally supported approaches. As computer power increases, more detailed and computationally expensive methods are being applied more frequently. The approaches discussed in this paper can be termed meso-scale models (Myohanen & Hyppanen, 2011) and cover time and length scales greater than the particle level. The methods under consideration can be divided by the way the dispersed phase is treated (Wischnewski, Ratschow, Hartge, & Werther, 2010). High concentration of the particulate matter in the fluidization units results in a significant increase in the influence of mutual par- ticle interactions on the flow conditions. The available numerical models used for solving the particle transport and their interac- tions can be divided into two main groups, namely Euler–Euler and Euler–Lagrange approaches. The Eulerian models have been derived based on the assumption that a solid phase can be treated as a continuous medium with representative properties similarly as for a fluid. 1674-2001/$ – see front matter © 2013 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.partic.2013.06.008