Research Paper Simplified numerical modelling of oxy-fuel combustion of pulverized coal in a swirl burner Pranit Gaikwad, Hrishikesh Kulkarni, S. Sreedhara ⇑ I. C. Engine and Combustion Lab, Department of Mechanical Engineering, Indian Institute of Technology Bombay, Mumbai 400076, India highlights  2D simulation has been carried out to analyze pulverized coal combustion in oxy-fuel environment.  Radiation and turbulence models have been evaluated.  The proposed simplified model has been validated against experimental data.  Validated model has been used to evaluate the effects of combustion environments. article info Article history: Received 7 October 2016 Revised 9 May 2017 Accepted 11 June 2017 Available online 13 June 2017 Keywords: Pulverized coal Swirl burner CFD Devolatilization Oxy-fuel WSGGM abstract In this work, a computational fluid dynamics (CFD) modelling has been performed to analyze pulverized coal combustion in a vertical pilot-scale furnace. The furnace with swirl burner is located at the Institute of Heat and Mass Transfer at RWTH Aachen University, where O 2 /CO 2 combustion environment was adopted to study pulverized coal combustion experimentally (Toporov et al., 2008). A two-dimensional axisymmetric domain has been used in this work with a Lagrangian method to track coal particles. Performances of different Reynolds-Averaged-Navier-Stokes (RANS) turbulence models have been inves- tigated. The radiative heat transfer using discrete ordinate (DO) model coupled with variants of weighted-sum-of-grey-gases (WSGGM) methods has been examined. The results obtained by these mod- els have been compared with the experimental data. The DO radiation model with domain based WSGGM and SST k-omega turbulence model showed a very good match with the experimental data among other tested models. The accuracy of predicted results was comparable to LES results available in the literature. It is observed that to get preliminary results the current simplified model is good enough with accuracy comparable to LES modelling. By using this validated model, the influence of combustion environments such as air, oxy-steam (O 2 /H 2 O) and oxy-RFG (O 2 /CO 2 ) on temperature and NO concentration distribution has been investigated. NO x produced was least in the oxy-steam environment. Ó 2017 Elsevier Ltd. All rights reserved. 1. Introduction Carbon dioxide (CO 2 ) is one of the most important greenhouse gas which contributes significantly to global warming [1]. Nowa- days, capturing and sequestering of CO 2 produced from coal com- bustion is considered to be a good alternative to diminish greenhouse emissions [2]. Oxy-coal combustion with capturing and sequestering of CO 2 is considered as a promising technology to reduce emissions in coal-fired power generation [3]. In this tech- nology, the recycled flue gas (RFG) (CO 2 ) is mixed with pure O 2 in the furnace and combustion occurs in an O 2 /CO 2 environment [4]. Abraham et al. [5] have given a description of the process which was used to burn coal in pure oxygen and recirculated flue gas (not air) for enhancing oil recovery. Silva et al. [6] have carried out experiments on a test facility with a capacity of 40 MWth fired by a staged feed-gas burner to study combustion parameters, espe- cially the flame temperature. In the experiments, the burner was operated at different swirl numbers and different levels of O 2 frac- tion were tested under oxy-fired conditions and the findings revealed that swirl strength and O 2 concentration in the feed gas affect the heat transfer process in the furnace. Liu et al. [7] inves- tigated ignition in O 2 /CO 2 and O 2 /N 2 atmospheres and it was revealed that ignition is delayed in O 2 /CO 2 atmosphere. The inves- tigation on the pulverized coal in the O 2 /CO 2 atmosphere and in the swirl burner by Toporov et al. [8] has provided data set of tem- perature, velocity and species concentration which may be used for http://dx.doi.org/10.1016/j.applthermaleng.2017.06.069 1359-4311/Ó 2017 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. E-mail address: sreedhara.s@iitb.ac.in (S. Sreedhara). Applied Thermal Engineering 124 (2017) 734–745 Contents lists available at ScienceDirect Applied Thermal Engineering journal homepage: www.elsevier.com/locate/apthermeng