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in Wiley Online Library (wileyonlinelibrary.com).Supercritical fluids have been extensively used for particle production of many natural and pharmaceutical substances providing useful alternatives for pharmaceutical and nutraceutical particulate system formulation. Among the different methods, the gas or supercritical antisolvent (GAS or SAS) process and its variants, have received a considerable interest due to the wide range of materials that can be micronized. Controlling particle formation in order to nucleate small particles is a key issue in GAS and SAS processes and this is directly related to mixing at all scales. In this work, we focus on numerical simulation of the process, emphasizing mixing modeling. Different mixing devices characterized by different nozzles are analyzed, to get an insight into mixing dynamics and its influence on the final particle size distribution. Results show that mixing is determinant in obtaining smallCorrespondence concerning this article should be addressed to J. Sierra-Pallares at jsierra@cfd1.eis.uva.es.

(2016) Understanding bottom-up continuous hydrothermal synthesis of nanoparticles using empirical measurement and computational simulation. Nano Research, 9 (11). pp. 3377-3387. ISSN 1998-0000 Access from the University of Nottingham repository: http://eprints.nottingham.ac.uk/41016/1/1215_proof.pdf Copyright and reuse:The Nottingham ePrints service makes this work by researchers of the University of Nottingham available open access under the following conditions. This article is made available under the University of Nottingham End User licence and may be reused according to the conditions of the licence. For more details see: http://eprints.nottingham.ac.uk/end_user_agreement.pdf A note on versions:The version presented here may differ from the published version or from the version of record. If you wish to cite this item you are advised to consult the publisher's version. Please see the repository url above for details on accessing the published version and note that access may require a subscription. ABSTRACTContinuous hydrothermal synthesis was highlighted in a recent review as an enabling technology for the production of nanoparticles. In recent years, it has been shown to be a suitable reaction medium for the synthesis of a wide range of nanomaterials. Many single and complex nanomaterials such as metals, metal oxides, doped oxides, carbonates, sulfides, hydroxides, phosphates, and metal organic frameworks can be formed using continuous hydrothermal synthesis techniques. This work presents a methodology to characterize continuous hydrothermal flow systems both experimentally and numerically, and to determine the scalability of a counter current supercritical water reactor for the large scale production (>1,000 T•year -1 ) of nanomaterials. Experiments were performed using a purpose-built continuous flow rig, featuring an injection loop on a metal salt feed line, which allowed the injection of a chromophoric tracer. At the system outlet, the tracer was detected using UV/Vis absorption, which could be used to measure the residence time distribution within the reactor volume. Computational fluid dynamics (CFD) calculations were also conducted using a modeled geometry to represent the experimental apparatus. The performance of the CFD model was tested against experimental data, verifying that the CFD model accurately predicted the nucleation and growth of the nanomaterials inside the reactor.

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