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Article ; Online: Solution and Parameter Identification of a Fixed-Bed Reactor Model for Catalytic CO 2 Methanation Using Physics-Informed Neural Networks

Son Ich Ngo / Young-Il Lim

Catalysts, Vol 11, Iss 1304, p

2021 Volume 1304

Abstract: In this study, we develop physics-informed neural networks (PINNs) to solve an isothermal fixed-bed (IFB) model for catalytic CO 2 methanation. The PINN includes a feed-forward artificial neural network (FF-ANN) and physics-informed constraints, such as ... ...

Abstract	In this study, we develop physics-informed neural networks (PINNs) to solve an isothermal fixed-bed (IFB) model for catalytic CO 2 methanation. The PINN includes a feed-forward artificial neural network (FF-ANN) and physics-informed constraints, such as governing equations, boundary conditions, and reaction kinetics. The most effective PINN structure consists of 5–7 hidden layers, 256 neurons per layer, and a hyperbolic tangent ( tanh ) activation function. The forward PINN model solves the plug-flow reactor model of the IFB, whereas the inverse PINN model reveals an unknown effectiveness factor involved in the reaction kinetics. The forward PINN shows excellent extrapolation performance with an accuracy of 88.1% when concentrations outside the training domain are predicted using only one-sixth of the entire domain. The inverse PINN model identifies an unknown effectiveness factor with an error of 0.3%, even for a small number of observation datasets (e.g., 20 sets). These results suggest that forward and inverse PINNs can be used in the solution and system identification of fixed-bed models with chemical reaction kinetics.
Keywords	catalytic CO 2 methanation ; fixed-bed reactor ; reaction kinetics ; system identification ; machine learning ; physics-informed neural network ; Chemical technology ; TP1-1185 ; Chemistry ; QD1-999
Subject code	660
Language	English
Publishing date	2021-10-01T00:00:00Z
Publisher	MDPI AG
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: Multiscale Eulerian CFD of Chemical Processes

Son Ich Ngo / Young-Il Lim

ChemEngineering, Vol 4, Iss 23, p

A Review

2020 Volume 23

Abstract: This review covers the scope of multiscale computational fluid dynamics (CFD), laying the framework for studying hydrodynamics with and without chemical reactions in single and multiple phases regarded as continuum fluids. The molecular, coarse-grained ... ...

Abstract	This review covers the scope of multiscale computational fluid dynamics (CFD), laying the framework for studying hydrodynamics with and without chemical reactions in single and multiple phases regarded as continuum fluids. The molecular, coarse-grained particle, and meso-scale dynamics at the individual scale are excluded in this review. Scoping single-scale Eulerian CFD approaches, the necessity of multiscale CFD is highlighted. First, the Eulerian CFD theory, including the governing and turbulence equations, is described for single and multiple phases. The Reynolds-averaged Navier–Stokes (RANS)-based turbulence model such as the standard k- equation is briefly presented, which is commonly used for industrial flow conditions. Following the general CFD theories based on the first-principle laws, a multiscale CFD strategy interacting between micro- and macroscale domains is introduced. Next, the applications of single-scale CFD are presented for chemical and biological processes such as gas distributors, combustors, gas storage tanks, bioreactors, fuel cells, random- and structured-packing columns, gas-liquid bubble columns, and gas-solid and gas-liquid-solid fluidized beds. Several multiscale simulations coupled with Eulerian CFD are reported, focusing on the coupling strategy between two scales. Finally, challenges to multiscale CFD simulations are discussed. The need for experimental validation of CFD results is also presented to lay the groundwork for digital twins supported by CFD. This review culminates in conclusions and perspectives of multiscale CFD.
Keywords	computational fluid dynamics (CFD) ; Eulerian continuum fluid ; volume of fluid (VOF) ; multiscale simulation ; multiphase flow ; multiphysics ; Chemistry ; QD1-999
Subject code	532 ; 621
Language	English
Publishing date	2020-03-01T00:00:00Z
Publisher	MDPI AG
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: Wave Characteristics of Coagulation Bath in Dry-Jet Wet-Spinning Process for Polyacrylonitrile Fiber Production Using Computational Fluid Dynamics

Son Ich Ngo / Young-Il Lim / Soo-Chan Kim

Processes, Vol 7, Iss 5, p

2019 Volume 314

Abstract: In this work, a three-dimensional volume-of-fluid computational fluid dynamics (VOF-CFD) model was developed for a coagulation bath of the dry-jet wet spinning (DJWS) process for the production of polyacrylonitrile (PAN)-based carbon fiber under long- ... ...

Abstract	In this work, a three-dimensional volume-of-fluid computational fluid dynamics (VOF-CFD) model was developed for a coagulation bath of the dry-jet wet spinning (DJWS) process for the production of polyacrylonitrile (PAN)-based carbon fiber under long-term operating conditions. The PAN-fiber was assumed to be a deformable porous zone with variations in moving speed, porosity, and permeability. The Froude number, interpreted as the wave-making resistance on the liquid surface, was analyzed according to the PAN-fiber wind-up speed ( <math display="inline"> <semantics> <mrow> <msub> <mi>v</mi> <mrow> <mi>P</mi> <mi>A</mi> <mi>N</mi> </mrow> </msub> </mrow> </semantics> </math> ). The effect of the PAN speed on the reflection and wake flow formed by drag between a moving object and fluid is presented. A method for tracking the wave amplitude with time is proposed based on the iso-surface of the liquid volume fraction of 0.95. The wave signal for 30 min was divided into the initial and resonance states that were distinguished at 8 min. The maximum wave amplitude was less than 0.5 mm around the PAN-fiber inlet nozzle for <math display="inline"> <semantics> <mrow> <msub> <mi>v</mi> <mrow> <mi>P</mi> <mi>A</mi> <mi>N</mi> </mrow> </msub> </mrow> </semantics> </math> = 0.1−0.5 m/s in the resonance state. The VOF-CFD model is useful in determining the maximum <math display="inline"> <semantics> <mrow> <msub> <mi>v</mi> <mrow> <mi>P</mi> <mi>A</mi> <mi>N</mi> </mrow> </msub> </mrow> </semantics> </math> under an allowable air gap of the DJWS process.
Keywords	polyacrylonitrile-based carbon fiber ; coagulation bath ; dry-jet wet spinning process ; computational fluid dynamics ; wave resonance ; maximum wave amplitude ; Chemical technology ; TP1-1185 ; Chemistry ; QD1-999
Language	English
Publishing date	2019-05-01T00:00:00Z
Publisher	MDPI AG
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: Reaction Characteristics of Ni-Based Catalyst Supported by Al 2 O 3 in a Fluidized Bed for CO 2 Methanation

Byungwook Hwang / Son Ich Ngo / Young-Il Lim / Myung Won Seo / Sung Jin Park / Ho-Jung Ryu / Hyungseok Nam / Doyeon Lee

Catalysts, Vol 12, Iss 1346, p

2022 Volume 1346

Abstract: CO 2 methanation is a promising technology to store renewable energy by converting carbon dioxide with green hydrogen into methane, which is known as power to gas (PtG). In this study, CO 2 methanation performance of a Ni/Al 2 O 3 catalyst was ... ...

Abstract	CO 2 methanation is a promising technology to store renewable energy by converting carbon dioxide with green hydrogen into methane, which is known as power to gas (PtG). In this study, CO 2 methanation performance of a Ni/Al 2 O 3 catalyst was investigated in a bubbling fluidized bed (BFB) and the axial gas concentration, temperature, and CO 2 conversion were densely analyzed. Moreover, a modified reaction kinetic model was proposed, and the results were compared with experimental data. The bed temperature increased by 11 °C from 340 °C to 351 °C within the first 30 mm of the fluidized bed. The CO 2 conversion was approximately 90% within 50 mm from the bottom of the reactor and was maintained above this height. The Ni/Al 2 O 3 catalyst exhibited the highest CO 2 conversion (95%) at 320 °C. Using a simple plug-flow reactor model, three optimized kinetic modification factors (1.5094, 0.0238, and 0.2466) were used to fit the experimental data. The hydrodynamic effects significantly influenced the chemical reaction kinetics of the BFB.
Keywords	CO 2 utilization ; methanation ; power-to-gas ; nickel oxide ; bubbling fluidized bed ; reaction kinetics ; Chemical technology ; TP1-1185 ; Chemistry ; QD1-999
Subject code	660 ; 290
Language	English
Publishing date	2022-11-01T00:00:00Z
Publisher	MDPI AG
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article: Computational fluid dynamics and experimental validation of a compact steam methane reformer for hydrogen production from natural gas

Ngo, Son Ich / Young-Il Lim / Woohyun Kim / Dong Joo Seo / Wang Lai Yoon

Applied energy. 2019 Feb. 15, v. 236

2019

Abstract: A three-dimensional (3D) computational fluid dynamics (CFD) model of an annulus steam methane reforming (SMR) reactor was developed for producing 2.5 Nm3/h of H2 from natural gas. The feed and combustion gases played a role in a counter-current heat ... ...

Abstract	A three-dimensional (3D) computational fluid dynamics (CFD) model of an annulus steam methane reforming (SMR) reactor was developed for producing 2.5 Nm3/h of H2 from natural gas. The feed and combustion gases played a role in a counter-current heat exchange owing to a narrow sleeve equipped between the combustor and catalytic reactor. The momentum, energy, and mass conservation equations were integrated with a realizable k–ε turbulence model, discrete ordinates radiation model, and reversible SMR reaction kinetics. The CFD results such as axial temperature profiles and producer gas compositions were validated against the experimental data measured in this study. The thermal efficiency of the compact SMR reactor was 60%, and the heat flux through the reactor wall was 39 kW/m2. The overall heat transfer coefficient from the sleeve to the catalytic reactor was 158 W/m2/K. The sleeve-type SMR reactor flattened the temperature profile along the reactor length.
Keywords	combustion ; energy ; equations ; heat transfer ; heat transfer coefficient ; hydrogen ; hydrogen production ; methane ; models ; momentum ; natural gas ; producer gas ; reaction kinetics ; steam ; temperature profiles ; turbulent flow
Language	English
Dates of publication	2019-0215
Size	p. 340-353.
Publishing place	Elsevier Ltd
Document type	Article
ZDB-ID	2000772-3
ISSN	0306-2619
ISSN	0306-2619
DOI	10.1016/j.apenergy.2018.11.075
Database	NAL-Catalogue (AGRICOLA)

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Article: Techno-economic comparison of three energy conversion pathways from empty fruit bunches

Do, Truong Xuan / Young-il Lim

Renewable energy. 2016 May, v. 90

2016

Abstract: Empty fruit bunches (EFB) of oil-palm are one of the most recent renewable energy resources. The objective of this study is to find the most economically-feasible pathway among three energy conversions from 400 t/d wet EFB, which are bioethanol and jet ... ...

Abstract	Empty fruit bunches (EFB) of oil-palm are one of the most recent renewable energy resources. The objective of this study is to find the most economically-feasible pathway among three energy conversions from 400 t/d wet EFB, which are bioethanol and jet fuel by bioconversion, combined heat and power via gasification, and hydrocarbons through fast pyrolysis and biooil upgrading. A hierarchical four-level economic potential approach (4-level EP) was employed to perform the preliminary techno-economic analysis (TEA) for the three pathways. The 4-level EP includes the input/output structure, the flowsheet structure, the heat integration (HI), and the economic feasibility. The economic potential of the three plants was compared at each level, and the most promising process among them was identified at Level 4, where economic criteria including return on investment (ROI), payback period (PBP), and internal rate of return (IRR) were evaluated. It was found that the biooil hydrocarbon plant is most economical due to the highest economic potential, ROI, and IRR. The heat consumption was reduced considerably by HI in the bioethanol and jet fuel plant. The sensitivity analysis informed that the plant size, the product yield, and the total capital investment highly influenced ROI and PBP in all three processes.
Keywords	bioethanol ; biotransformation ; economic feasibility ; economic investment ; energy conversion ; gasification ; heat ; hydrocarbons ; pyrolysis
Language	English
Dates of publication	2016-05
Size	p. 307-318.
Publishing place	Elsevier Ltd
Document type	Article
ZDB-ID	2001449-1
ISSN	0960-1481
ISSN	0960-1481
DOI	10.1016/j.renene.2016.01.030
Database	NAL-Catalogue (AGRICOLA)

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Article: Techno-economic analysis of biooil production process from palm empty fruit bunches

Do, Truong Xuan / Heejung Yeo / Young-il Lim

Energy conversion and management. 2014 Apr., v. 80

2014

Abstract: Empty fruit bunches (EFB), a main residue of the palm oil industry, are one of the most recent renewable energy resources and they promise a high yield of liquid with low gas and char. The objective of this study is to evaluate the economic feasibility ... ...

Abstract	Empty fruit bunches (EFB), a main residue of the palm oil industry, are one of the most recent renewable energy resources and they promise a high yield of liquid with low gas and char. The objective of this study is to evaluate the economic feasibility of the biooil production process from EFB via fast pyrolysis using the fluidized-bed. A comprehensive model of a biooil production plant was developed utilizing a commercial process simulator. The total capital investment (TCI) was estimated for five different plant sizes. The EFB biooil plant was analyzed in terms of the specific capital cost (SCC), payback period (PBP), return on investment (ROI), and the product value (PV). The minimum profitable plant size was found to be 20kton-dryEFB/yr at a PV of 0.47$/kg of biooil including 39% of water. Sensitivity analysis was performed on the basis of the minimum plant size to identify key variables that have a strong impact on the PV. The plant size and the biooil yield showed a major influence on the PV. In the most optimistic scenario investigated in this study, biooil can be produced at a PV of 0.27$/kg.
Keywords	biofuels ; capital ; economic feasibility ; economic investment ; fats and oils industry ; fluidized beds ; fruits ; liquids ; models ; pyrolysis
Language	English
Dates of publication	2014-04
Size	p. 525-534.
Publishing place	Elsevier Ltd
Document type	Article
ZDB-ID	2000891-0
ISSN	0196-8904
ISSN	0196-8904
DOI	10.1016/j.enconman.2014.01.024
Database	NAL-Catalogue (AGRICOLA)

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Article: Techno-economic analysis of fry-drying and torrefaction plant for bio-solid fuel production

Do, Truong Xuan / Byeong-Yun Park / Chanwoo Park / Hyodeuk Cho / Jaehui Shim / Jeongkeun Yoo / Kyutai Rho / Seong-Geun Choi / Young-il Lim

Renewable energy. 2018 Apr., v. 119

2018

Abstract: A total of 10 t/d of bio-solid (BS) fuel was produced from 45 t/d of organic solid waste (OSW) containing 80 wt% water using a fry-drying and torrefaction (FDT) plant. This study aimed at evaluating economic feasibility of the FDT plant in terms of the ... ...

Abstract	A total of 10 t/d of bio-solid (BS) fuel was produced from 45 t/d of organic solid waste (OSW) containing 80 wt% water using a fry-drying and torrefaction (FDT) plant. This study aimed at evaluating economic feasibility of the FDT plant in terms of the total capital investment (TCI), total production cost (TPC), return on investment (ROI) and payback period (PBP). Two different heating sources for steam generation were used: Case 1 using BS produced in this plant, and Case 2 using LNG provided externally. A four-level economic potential approach was applied to evaluate economic feasibility. A sensitivity analysis was conducted to determine the major factors influencing ROI. Case 1 using BS showed a higher ROI than Case 2 using LNG because the LNG cost overwhelmed the TCI increment of Case 1. For Case 1 with 45 t/d of OSW, the TCI, TPC, ROI and PBP were $3.6 million, $1.3 million/yr, 6.0%/yr and 9.8 yr, respectively. To achieve a desired ROI of 10%/yr, the plant sizes of Cases 1 and 2 were 60 and 90 t/d, respectively. When the OSW treatment credit increased from 100 $/t to 120 $/t, ROI exceeded 10% in Case 1 with 45 t/d.
Keywords	credit ; economic feasibility ; economic investment ; fuel production ; fuels ; renewable energy sources ; solid wastes ; steam ; torrefaction
Language	English
Dates of publication	2018-04
Size	p. 45-53.
Publishing place	Elsevier Ltd
Document type	Article
ZDB-ID	2001449-1
ISSN	0960-1481
ISSN	0960-1481
DOI	10.1016/j.renene.2017.11.085
Database	NAL-Catalogue (AGRICOLA)

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Article: Effects of fluidization velocity on solid stack volume in a bubbling fluidized-bed with nozzle-type distributor

Ngo, Son Ich / Byung-Ho Song / Jae-Hun Song / Jeung-Woo Lee / Uen-Do Lee / Young-Il Lim

Powder technology. 2015 May, v. 275

2015

Abstract: Hydrodynamic characteristics in a wind-box and bubbling fluidized-bed (BFB) gasifier zone of a dual fluidized-bed (DFB) were investigated by a two-phase three-dimensional computational fluid dynamics (CFD) model. The gas and solid phases were treated by ... ...

Abstract	Hydrodynamic characteristics in a wind-box and bubbling fluidized-bed (BFB) gasifier zone of a dual fluidized-bed (DFB) were investigated by a two-phase three-dimensional computational fluid dynamics (CFD) model. The gas and solid phases were treated by an Eulerian–Eulerian two-fluid model, coupled with the realizable k–epsilon turbulence model and the kinetic theory of granular flow (KTGF) describing the random motion of solid particles. Pressure drops obtained from the cold-rig CFD simulation were validated with experimental data which were measured in a pilot-scale BFB using air as a fluidization agent and sand as heat carrier particles at an operating temperature of 800°C. Hydrodynamics of the fluidized-bed with a uniform gas distributor (Ideal case) and a nozzle-type gas distributor (Real case) were evaluated in terms of the pressure drop, solid volume fraction (SVF), uniformity index (UI), and solid stack volume (SSV) for three inlet air flow rates (low, medium and high). Similar behaviors were shown for both the two cases in pressure drop along the gasifier height. However, significant differences were observed in SVF, UI, and SSV. A threshold changing the slope of SSV to the air flow rate was found at a fluidization index (u/umf) of 2.9.
Keywords	air ; air flow ; fluidized beds ; heat ; hydrodynamics ; models ; powders ; sand ; temperature ; turbulent flow
Language	English
Dates of publication	2015-05
Size	p. 188-198.
Publishing place	Elsevier B.V.
Document type	Article
ISSN	0032-5910
DOI	10.1016/j.powtec.2015.02.017
Database	NAL-Catalogue (AGRICOLA)

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Article: Process modeling and energy consumption of fry-drying and torrefaction of organic solid waste

Do, Truong Xuan / Young-il Lim / Hyodeuk Cho / Jaehui Shim / Jeongkeun Yoo / Kyutai Rho / Seong-Geun Choi / Byung-Yoon Park

Drying technology. 2017 Apr. 26, v. 35, no. 6

2017

Abstract: A commercial fry-drying and torrefaction (FDT) plant for producing bio-solid fuel from 45âton/d organic sludge with 80% water was proposed. The FDT plant was modeled by a process simulator with the aid of plant data. Two double-effect evaporators were ... ...

Abstract	A commercial fry-drying and torrefaction (FDT) plant for producing bio-solid fuel from 45âton/d organic sludge with 80% water was proposed. The FDT plant was modeled by a process simulator with the aid of plant data. Two double-effect evaporators were used in series to vaporize water, using heat-carrying oil. Torrefied and pelletized bio-solid was produced at 413âkg/h, comprising 4.4 and 4.8% of water and oil, respectively, and 67% of its mass was used as heat source. The total energy consumption was 1,369âkW, including 93âkW electrical and 1,276âkW thermal energies. The total heat duty was 788âkcal/kg-water.
Keywords	energy ; evaporators ; fuels ; heat ; models ; oils ; sludge ; solid wastes ; torrefaction
Language	English
Dates of publication	2017-0426
Size	p. 754-765.
Publishing place	Taylor & Francis
Document type	Article
ZDB-ID	2049461-0
ISSN	1532-2300 ; 0737-3937
ISSN (online)	1532-2300
ISSN	0737-3937
DOI	10.1080/07373937.2016.1211674
Database	NAL-Catalogue (AGRICOLA)

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