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Uncertainty Quantification Analysis of Both Experimental and CFD Simulation Data of a Bench-scale Fluidized Bed Gasifier
Creators: Shahnam, Mehrdad [National Energy Technology Lab. (NETL), Morgantown, WV (United States). Research and Innovation Center, Energy Conversion Engineering Directorate]; Gel, Aytekin [ALPEMI Consulting, LLC, Phoeniz, AZ (United States)]; Subramaniyan, Arun K. [GE Global Research Center, Niskayuna, NY (United States)]; Musser, Jordan [National Energy Technology Lab. (NETL), Morgantown, WV (United States). Research and Innovation Center, Energy Conversion Engineering Directorate]; Dietiker, Jean-Francois [West Virginia Univ. Research Corporation, Morgantown, WV (United States)]
Date: 10/02/2017
Description: Adequate assessment of the uncertainties in modeling and simulation is becoming an integral part of the simulation based engineering design. The goal of this study is to demonstrate the application of non-intrusive Bayesian uncertainty quantification (UQ) methodology in multiphase (gas-solid) flows with experimental and simulation data, as part of our research efforts to determine the most suited approach for UQ of a bench scale fluidized bed gasifier. UQ analysis was first performed on the available experimental data. Global sensitivity analysis performed as part of the UQ analysis shows that among the three operating factors, steam to oxygen ratio has the most influence on syngas composition in the bench-scale gasifier experiments. An analysis for forward propagation of uncertainties was performed and results show that an increase in steam to oxygen ratio leads to an increase in H2 mole fraction and a decrease in CO mole fraction. These findings are in agreement with the ANOVA analysis performed in the reference experimental study. Another contribution in addition to the UQ analysis is the optimization-based approach to guide to identify next best set of additional experimental samples, should the possibility arise for additional experiments. Hence, the surrogate models constructed as part of the UQ analysis is employed to improve the information gain and make incremental recommendation, should the possibility to add more experiments arise. In the second step, series of simulations were carried out with the open-source computational fluid dynamics software MFiX to reproduce the experimental conditions, where three operating factors, i.e., coal flow rate, coal particle diameter, and steam-to-oxygen ratio, were systematically varied to understand their effect on the syngas composition. Bayesian UQ analysis was performed on the numerical results. As part of Bayesian UQ analysis, a global sensitivity analysis was performed based on the simulation results, which shows that the predicted syngas composition is strongly affected not only by the steam-to-oxygen ratio (which was observed in experiments as well) but also by variation in the coal flow rate and particle diameter (which was not observed in experiments). The carbon monoxide mole fraction is underpredicted at lower steam-to-oxygen ratios and overpredicted at higher steam-to-oxygen ratios. The opposite trend is observed for the carbon dioxide mole fraction. These discrepancies are attributed to either excessive segregation of the phases that leads to the fuel-rich or -lean regions or alternatively the selection of reaction models, where different reaction models and kinetics can lead to different syngas compositions throughout the gasifier. To improve quality of numerical models used, the effect that uncertainties in reaction models for gasification, char oxidation, carbon monoxide oxidation, and water gas shift will have on the syngas composition at different grid resolution, along with bed temperature were investigated. The global sensitivity analysis showed that among various reaction models employed for water gas shift, gasification, char oxidation, the choice of reaction model for water gas shift has the greatest influence on syngas composition, with gasification reaction model being second. Syngas composition also shows a small sensitivity to temperature of the bed. The hydrodynamic behavior of the bed did not change beyond grid spacing of 18 times the particle diameter. However, the syngas concentration continued to be affected by the grid resolution as low as 9 times the particle diameter. This is due to a better resolution of the phasic interface between the gases and solid that leads to stronger heterogeneous reactions. This report is a compilation of three manuscripts published in peer-reviewed journals for the series of studies mentioned above.


Linking Initial Microstructure to ORR Related Property Degradation in SOFC Cathode: A Phase Field Simulation
Creators: Lei, Y. [National Energy Technology Laboratory (NETL), Pittsburgh, PA, and Morgantown, WV (United States). Albany Research Center (ARC)] (ORCID:0000000202001491); Cheng, T. -L. [National Energy Technology Laboratory (NETL), Pittsburgh, PA, and Morgantown, WV (United States). Albany Research Center (ARC); AECOM, Albany, OR (United States)]; Wen, Y. H. [National Energy Technology Laboratory (NETL), Pittsburgh, PA, and Morgantown, WV (United States). Albany Research Center (ARC)]
Date: 07/05/2017
Description: Microstructure evolution driven by thermal coarsening is an important factor for the loss of oxygen reduction reaction rates in SOFC cathode. In this work, the effect of an initial microstructure on the microstructure evolution in SOFC cathode is investigated using a recently developed phase field model. Specifically, we tune the phase fraction, the average grain size, the standard deviation of the grain size and the grain shape in the initial microstructure, and explore their effect on the evolution of the grain size, the density of triple phase boundary, the specific surface area and the effective conductivity in LSM-YSZ cathodes. It is found that the degradation rate of TPB density and SSA of LSM is lower with less LSM phase fraction (with constant porosity assumed) and greater average grain size, while the degradation rate of effective conductivity can also be tuned by adjusting the standard deviation of grain size distribution and grain aspect ratio. The implication of this study on the designing of an optimal initial microstructure of SOFC cathodes is discussed.


Pre-treating water with non-thermal plasma
Creators: Cho, Young I.; Fridman, Alexander; Rabinovich, Alexander; Cho, Daniel J.
Date: 07/04/2017
Description: The present invention consists of a method of pre-treatment of adulterated water for distillation, including adulterated water produced during hydraulic fracturing ("fracking") of shale rock during natural gas drilling. In particular, the invention is directed to a method of treating adulterated water, said adulterated water having an initial level of bicarbonate ion in a range of about 250 ppm to about 5000 ppm and an initial level of calcium ion in a range of about 500 ppm to about 50,000 ppm, said method comprising contacting the adulterated water with a non-thermal arc discharge plasma to produce plasma treated water having a level of bicarbonate ion of less than about 100 ppm. Optionally, the plasma treated water may be further distilled.


Spatio-temporal distribution of Oklahoma earthquakes: Exploring relationships using a nearest-neighbor approach: Nearest-neighbor analysis of Oklahoma
Creators: Vasylkivska, Veronika S. [National Energy Technology Laboratory, Albany OR USA; Oak Ridge Institute for Science and Education, Oak Ridge TN USA] (ORCID:0000000211481271); Huerta, Nicolas J. [National Energy Technology Laboratory, Albany OR USA]
Date: 06/24/2017
Description:


Two modes of grain boundary pinning by coherent precipitates
Creators: Wang, Nan; Ji, Yanzhou; Wang, Yongbiao; Wen, Youhai; Chen, Long-Qing
Date: 06/18/2017
Description:


Plasmonic nanopatch array with integrated metal–organic framework for enhanced infrared absorption gas sensing
Creators: Chong, Xinyuan [Oregon State University, Corvallis, OR (United States). School of Electrical Engineering and Computer Science]; Kim, Ki-joong [Oregon State University, Corvallis, OR (United States). School of Chemical, Biological and Environmental Engineering; National Energy Technology Lab. (NETL), Pittsburgh, PA (United States); AECOM, Pittsburgh, PA (United States)]; Zhang, Yujing [Oregon State University, Corvallis, OR (United States). School of Chemical, Biological and Environmental Engineering]; Li, Erwen [Oregon State University, Corvallis, OR (United States). School of Electrical Engineering and Computer Science]; Ohodnicki, Paul R. [National Energy Technology Lab. (NETL), Pittsburgh, PA (United States); Carnegie Mellon University, Pittsburgh, PA (United States). Materials Science and Engineering, Department]; Chang, Chih-Hung [Oregon State University, Corvallis, OR (United States). School of Chemical, Biological and Environmental Engineering]; Wang, Alan X. [Oregon State University, Corvallis, OR (United States). School of Electrical Engineering and Computer Science]
Date: 06/06/2017
Description: In this letter, we present a nanophotonic device consisting of plasmonic nanopatch array (NPA) with integrated metal–organic framework (MOF) for enhanced infrared absorption gas sensing. By designing a gold NPA on a sapphire substrate, we are able to achieve enhanced optical field that spatially overlaps with the MOF layer, which can adsorb carbon dioxide (CO2) with high capacity. Additionally, experimental results show that this hybrid plasmonic–MOF device can effectively increase the infrared absorption path of on-chip gas sensors by more than 1100-fold. Lastly, the demonstration of infrared absorption spectroscopy of CO2 using the hybrid plasmonic–MOF device proves a promising strategy for future on-chip gas sensing with ultra-compact size.


Mechanistic insights into the oxidation behavior of Ni alloys in high-temperature CO2
Creators: Oleksak, Richard P.; Baltrus, John P.; Nakano, Jinichiro; Nakano, Anna; Holcomb, Gordon R.; Dogan, Omer N.
Date: 06/01/2017
Description: We present results of a Ni superalloy oxidized for short times in high purity CO2 and similarly in Ar containing ≤ 1 ppb O2. A detailed analysis of the oxidized surfaces reveals striking similarities for the two exposure environments, suggesting O2 impurities control the oxidation process in high-temperature CO2. Selective oxidation results in Cr-rich oxide layers grown by 2 outward diffusion, while Cr vacancies left in the metal contribute to significant void formation at the oxide/metal interface. Unlike for most of the alloy surface, the oxidation behavior of secondary phase metal carbides is considerably different in the two environments.


Modeling and Optimization of Solid Oxide Fuel Cells
Creators: Panagakos, Grigorios [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States)]; Hackett, Greg [National Energy Technology Lab. (NETL), Morgantown, WV (United States)]; Romanov, Vyacheslav [National Energy Technology Lab. (NETL), Morgantown, WV (United States)]
Date: 06/01/2017
Description:


Normal stress effects in the gravity driven flow of granular materials
Creators: Wu, Wei-Tao; Aubry, Nadine; Antaki, James F.; Massoudi, Mehrdad
Date: 06/01/2017
Description:


NETL Crosscutting Research Video Series – LIBSense™ Sensor
Creators: Bhatt, Chet
Date: 05/22/2017
Description: NETL’s LIBSense™ Sensor is a small optical sensing device that can be used to detect elements in downhole applications. Since the sensor is an all-optical device and uses no electronics, it can be deployed into extreme environments.


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