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Impacts of oxidant characteristics on the ignition of n-propanol-air hydrothermal flames in supercritical water

Published on May 1, 2019in Combustion and Flame 4.12
· DOI :10.1016/j.combustflame.2019.02.004
Sivamohan N. Reddy11
Estimated H-index: 11
(IITR: Indian Institute of Technology Roorkee),
Sonil Nanda3
Estimated H-index: 3
(UWO: University of Western Ontario)
+ 3 AuthorsJanusz A. Kozinski1
Estimated H-index: 1
(UW: University of Waterloo)
Cite
Abstract
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.
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References47
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Published on Apr 1, 2019in Journal of Energy Chemistry 5.16
Rachita Rana3
Estimated H-index: 3
(U of S: University of Saskatchewan),
Sonil Nanda3
Estimated H-index: 3
(UWO: University of Western Ontario)
+ 3 AuthorsAjay K. Dalai54
Estimated H-index: 54
(U of S: University of Saskatchewan)
Abstract Subcritical and supercritical water gasification of petroleum coke and asphaltene was performed at variable temperatures (350–650 °C), feed concentrations (15–30 wt%) and reaction times (15–60 min). Nickel-impregnated activated carbon (Ni/AC) was synthesized as a catalyst for enhancing syngas yields at optimal gasification conditions (650 °C, 15 wt% and 60 min). Structural chemistry of precursors and chars developed at different gasification temperatures was studied using physicochemica...
Published on Feb 1, 2019in Chemical Engineering Science 3.37
Sonil Nanda3
Estimated H-index: 3
(UWO: University of Western Ontario),
Sonil Nanda8
Estimated H-index: 8
(UWO: University of Western Ontario)
+ 3 AuthorsJanusz A. Kozinski1
Estimated H-index: 1
(UW: University of Waterloo)
Abstract Substantial amounts of waste cooking oil are obtained worldwide from household and catering enterprises because of deep-frying and other cooking activities. Supercritical water gasification is considered as an aqueous phase reforming process to produce hydrogen enriched syngas from biomass and other organic wastes. In this study, waste cooking oil was gasified at variable temperatures (375–675 °C), feed concentration (25–40 wt%) and reaction time (15–60 min) to investigate their effects...
Published on Oct 1, 2018in Energy Science & Engineering 2.89
Sonil Nanda3
Estimated H-index: 3
(UWO: University of Western Ontario),
Sonil Nanda8
Estimated H-index: 8
(UWO: University of Western Ontario)
+ 2 AuthorsJanusz A. Kozinski3
Estimated H-index: 3
(American Hereford Association)
To supplement the increasing energy demands and cope with the greenhouse gas emissions, biofuels generated from lignocellulosic biomass are gaining widespread attention. In this study, wheat straw was used as a candidate lignocellulosic biomass to produce hydrogen fuel through hydrothermal gasification. The fluid phases of water investigated for gasification included subcritical (300 and 370°C) and supercritical (450 and 550°C) phases. Along with the effects of temperature (300‐550°C), the influ...
Published on May 10, 2017in Industrial & Engineering Chemistry Research 3.38
Mengmeng Ren1
Estimated H-index: 1
,
Shuzhong Wang22
Estimated H-index: 22
+ 3 AuthorsYulong Wang1
Estimated H-index: 1
Hydrothermal flame is a promising solution for problems in the preheating process of supercritical water oxidation (SCWO) technology. A detailed chemical kinetics coupled with a simple flow model is developed and validated to reflect the characteristic of hydrothermal flame. Analysis of free radicals accumulation show that the high quantity of free radicals induced by high methanol concentration leads to ignition. A method to approach the ignition temperature through ignition delay time calculat...
Published on May 1, 2017in Chemical Engineering Science 3.37
Daniel Bassing1
Estimated H-index: 1
(FAU: University of Erlangen-Nuremberg),
Andreas Braeuer17
Estimated H-index: 17
(FAU: University of Erlangen-Nuremberg)
Abstract We report the application of a novel optical Raman-based measurement technique for the simultaneous determination of the progress of mixing on the micro- and on the macro-scale. The introduced measurement technique is applicable to mixing systems containing one compound, which potentially can form hydrogen bonds, such as water, alcohols or amines, and does not rely on the addition of traces of indicator compounds. Here we demonstrate its applicability by analyzing the lag of micro-mixin...
Published on Feb 1, 2017in Renewable & Sustainable Energy Reviews 10.56
Athanasios Dimitriadis10
Estimated H-index: 10
,
Stella Bezergianni14
Estimated H-index: 14
The continuing use of fossil fuels accelerated the energy crisis, environmental pollution, and global warming in recent years. These problems are the driving force of the worldwide search for new alternative energy, among which biomass is considered to be one of the most promising candidates due to its renewable, carbon neutral and high productivity characteristics. Hydrothermal liquefaction (HTL) is an alternative technology of exploiting different types of biomass for fuels production, involvi...
Published on Jan 1, 2017in Sustainable Energy and Fuels
Sonil Nanda8
Estimated H-index: 8
(York University),
Rachita Rana3
Estimated H-index: 3
(U of S: University of Saskatchewan)
+ 2 AuthorsAjay K. Dalai54
Estimated H-index: 54
(U of S: University of Saskatchewan)
Growing apprehensions on greenhouse gas emissions, global warming, and pollution problems are directly related to fossil fuels consumption. To counteract these environmental issues, global efforts are being made to diversify energy supplies towards cleaner fuels, especially for the transportation sector. Hydrogen surpasses all other biofuels such as biodiesel, bio-oil, ethanol, and butanol because of its high energy content, no greenhouse gas emissions, rapid combustion properties, non-corrosive...
Published on Jan 1, 2017
Sivamohan N. Reddy11
Estimated H-index: 11
(IITR: Indian Institute of Technology Roorkee),
Sonil Nanda8
Estimated H-index: 8
(York University)
+ 2 AuthorsJanusz A. Kozinski31
Estimated H-index: 31
(York University)
Abstract A novel concept was applied for the in situ study of the ignition of n -propanol–air hydrothermal flames during supercritical water oxidation. An innovative experimental arrangement including NASA's supercritical water oxidation facility was used to study the effect of reactor and oxidant (air) temperature on the spontaneous ignition of hydrothermal flames. New data were obtained concerning time- and temperature-resolved profiles of n -propanol in hydrothermal flames. Transient temperat...
Published on Feb 1, 2016in Water Research 7.91
Lili Qian5
Estimated H-index: 5
(Xi'an Jiaotong University),
Shuzhong Wang22
Estimated H-index: 22
(Xi'an Jiaotong University)
+ 3 AuthorsLaisheng Wang1
Estimated H-index: 1
(Xi'an Jiaotong University)
With increasing construction of wastewater treatment plants and stricter policies, municipal sewage sludge (MSS) disposal has become a serious problem. Treatment of MSS in supercritical water (SCW) can avoid the pre-drying procedure and secondary pollution of conventional methods. SCW treatment methods can be divided into supercritical water gasification (SCWG), supercritical water partial oxidation (SCWPO) and supercritical water oxidation (SCWO) technologies with increasing amounts of oxidants...
Published on Nov 1, 2015in Chemical Engineering & Technology 2.42
Fengming Zhang5
Estimated H-index: 5
(CAS: Chinese Academy of Sciences),
Yong Zhang2
Estimated H-index: 2
(SDU: Shandong University)
+ 3 AuthorsChunyuan Ma10
Estimated H-index: 10
(SDU: Shandong University)
An inner-preheating transpiring-wall reactor with a hydrothermal flame was designed and tested to avoid plugging in the preheating section. Hot water was used as auxiliary heating fluid to preheat the fuel to the ignition temperature. This work focused on the flame characteristics (i.e., the ignition and extinction processes, the ignition and extinction temperatures) inside the inner-preheating transpiring-wall reactor. The result shows that higher fuel concentrations and fuel flows permit lower...
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