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Title: Impacts of oxidant characteristics on the ignition of n-propanol-air hydrothermal flames in supercritical water
Authors: Reddy, Sivamohan N.
Nanda S.
Kumar P.
Hicks M.C.
Hegde U.G.
Kozinski J.A.
Published in: Combustion and Flame
Abstract: Hydrothermal flame is produced in an aqueous environment beyond the thermodynamic critical properties of water. It is an interface developed at the contact of oxidant and fuel in supercritical water and depends on the operating parameters. In-situ diffusion-limited hydrothermal flames were generated in a novel supercritical flame reactor designed by the National Aeronautics and Space Administration (NASA) at Glenn Research Center to investigate the impacts of oxidant flow rate and temperature on flame ignition and stabilization. The reactor system comprises of n-propanol as fuel and air as the oxidant. Two-dimensional simulation studies were performed to interpret different thermal events occurring during the process. Temperatures inside the reactor were recorded at different times to determine the onset and propagation of hydrothermal flames. Temperature profiles obtained via simulations were compared with the experimental data at near-critical temperatures (380 °C and 20.5 MPa). The study of oxidant flow rate on ignition and temperature profile at near-critical and supercritical conditions (400 °C and 22.5 MPa) was conducted by varying the air flow rate ranging from 0.5 to 3 mL/s. A flow rate of 1.5 mL/s was found to be optimal with the spontaneous ignition of hydrothermal flames. The effect of inertial and buoyant forces on hydrothermal flames was qualitatively explained using the non-dimensional Reynolds and Froude numbers. The ignition delay times of hydrothermal flames for near-critical and supercritical reactor conditions for different flow rates are reported. Ignition mechanism and impact of the oxidant characteristics during supercritical water oxidation were inferred using a two-dimensional simulation model for n-propanol-air. © 2019 The Combustion Institute
Citation: Combustion and Flame (2019), 203(): 46-55
Issue Date: 2019
Publisher: Elsevier Inc.
Keywords: Buoyant forces
Froude number
Hydrothermal flames
Ignition delay
Supercritical water
ISSN: 102180
Author Scopus IDs: 56923787200
Author Affiliations: Reddy, S.N., Department of Chemical Engineering, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand, India
Nanda, S., Department of Chemical and Biochemical Engineering, University of Western Ontario, London, Ontario, Canada
Kumar, P., Department of Chemical Engineering, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand, India
Hicks, M.C., Glenn Research Center, National Aeronautics and Space Administration, Cleveland, OH, United States
Hegde, U.G., Department of Mechanical and Aerospace Engineering, Case Western Reserve University, Cleveland, OH, United States
Kozinski, J.A., Department of Chemical Engineering, University of Waterloo, Waterloo, Ontario, Canada
Funding Details: The authors would like to thank the Natural Sciences and Engineering Research Council of Canada (NSERC) for funding this research.
Corresponding Author: Kozinski, J.A.; Department of Chemical Engineering, University of WaterlooCanada; email:
Appears in Collections:Journal Publications [CH]

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