chemical engineering research and design 1 1 7 ( 2 0 1 7 ) 250–264 Contents lists available at ScienceDirect Chemical Engineering Research and Design journal homepage: www.elsevier.com/locate/cherd CFD analysis of hydrothermal conversion of heavy oil in continuous flow reactor Yousef M. Alshammari, Klaus Hellgardt ∗ Department of Chemical Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, UK a r t i c l e i n f o Article history: Received 6 May 2016 Received in revised form 22 September 2016 Accepted 2 October 2016 Available online 13 October 2016 Keywords: CFD analysis Laminar flow Reaction rate Radial effects Hydrothermal conversion a b s t r a c t CFD analysis is an important technique for reactor modelling and optimisation. In this work, we present a new CFD model used to determine true kinetic data of hydrothermal conver- sion of a heavy oil model compound, hexadecane, in a continuous flow reactor. Based on our previously reported experimental data, this model takes into account the radial effects occurring from the laminar flow conditions which enables producing modified Arrhenius plots from which true kinetic data are be obtained. Furthermore, the determined rate con- stants were used to validate the model through prediction of conversion in comparison with experimental data under identical conditions. The developed model shows good agreement with experimental data under isothermal conditions, while discrepancies in conversion profile arise under non-isothermal conditions which were found to be dependent on tem- perature assumptions. The reaction rate profile was investigated at different residence times for the different reaction regimes. The reactor was found to be nearly isothermal with the largest temperature gradient between the inlet and wall temperatures occurring at a distance 0–0.05 m in the z direction. The effects of reactor parameters including tempera- ture and flow properties may be integrated into this model to predict the effects of various operating parameters and to optimise the design and behaviour of our reactor model. Our analysis shows that reducing the reactor diameter may be important to maximise feedstock conversion, and reaction rates, at lower temperatures. © 2016 Published by Elsevier B.V. on behalf of Institution of Chemical Engineers. 1. Introduction Computational fluid dynamics (CFD) modelling is an important tool for reactor design, optimisation, and modelling which may be partic- ularly useful for the conversion of hydrocarbons into fuels in various forms. Many CFD models for reforming and oxidation of hydrocarbons were developed, and validated, reporting parametric effects of vari- ous operating parameters (Bermejo et al., 2010; Queiroz et al., 2013; Shi et al., 2009; Xuan et al., 2009; Wang and Yan, 2008; Yoshida and Matsumura, 2009; Papadikis et al., 2009; Gidaspow and Jiradilok, 2007; Senneca, 2007; Qiang et al., 2013). For instance, a CFD model for cat- alytic autothermal reforming of n-hexadecane showed the reforming efficiency and effects of catalytic substrate on the thermal conductiv- ity on the reactor thermal profile (Shi et al., 2009). Furthermore, Qiang et al. (2013) have successfully modelled the oxidation of isopropanol in supercritical water in a hydrothermal flame. They found that the ∗ Corresponding author. E-mail addresses: yousef.alshammari08@alumni.imperial.ac.u (Y.M. Alshammari), k.hellgardt@imperial.ac.uk (K. Hellgardt). reaction rate peaks at around 0.60 kmol/m 2 s, when the reactor inlet temperature is 370 ◦ C, as the residence time ranges between 0 and 0.25 s. Recently, Jin et al. (2016) presented a new CFD model showing the minimum the reactor length needed for complete gasification of Glycerol in supercritical water. Our previous work (Alshammari and Hellgardt, 2016, 2015) examined the experimental analysis and conver- sion profile of n-hexadecane under non-oxidative sub and supercritical water conditions. Kinetic data were determined for each case using the first order plug flow reactor equation, which makes the assump- tion that the reaction takes place under plug flow conditions with no mass transport limitations (Fogler, 2006). Although such an assump- tion has been widely used (Croiset et al., 1997; Guo et al., 2012; Sasaki et al., 1998; Lee et al., 2002; Yu and Eser, 1997) as it does facilitate the estimation of kinetics from experimental data, accurate estimation of kinetic data by accounting for the radial mass transport effects, occur- ring from laminar flow conditions, is key for optimum reactor design and modelling. http://dx.doi.org/10.1016/j.cherd.2016.10.002 0263-8762/© 2016 Published by Elsevier B.V. on behalf of Institution of Chemical Engineers.