Hang Seok Choi's research while affiliated with Yonsei University and other places

Publications (81)

Article
In this study, a spouted-bed thermogravimetric analyzer (SB-TGA) was developed to accurately investigate the reaction models and kinetic parameters of the spouted beds. In addition, the analyzer overcomes the disadvantages of conventional thermogravimetric analyzers that arise from different hydrodynamics. The spouted-bed reactor used in the SB-TGA...
Article
Owing to the rapid increase in the global automobile demand, the disposal of waste tires has become a severe problem. Most waste tires are reclaimed and incinerated; exhaust gas and ash from incineration comprise harmful substances and dust. Therefore, in this study, fast pyrolysis technology was investigated to overcome the limitations of traditio...
Article
Full-text available
In this study, computational particle fluid dynamics was applied to investigate the segregation characteristics of biochar in a bubbling fluidized bed. The aspect ratio of the bubbling fluidized bed was changed and the effects of the aspect ratio on the segregation characteristics were investigated. The segregation characteristics of a mixture of b...
Article
Biomass fast pyrolysis has been traditionally investigated through experiments or numerical simulations including hydrodynamics, transport phenomena of heat and mass, and chemical reactions. Instead of traditional methods, this study utilized data-based prediction algorithms to model a biomass fast pyrolyzer using a spouted fluidized bed, to predic...
Article
An increase in the energy consumption associated with heating, power generation, and transportation causes global warming and environmental pollution problems. In addition, global efforts such as electrification, the use of low-carbon fuels, etc., are being made to achieve the goal of net zero emissions by 2050. Because bioenergy is carbon-neutral,...
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Full-text available
The increasing global population and the rapid industrial development associated therewith have increased the demand for fossil-derived fuel oils. The sources of fossil fuels are limited, and many studies have been being conducted to find alternative fuel sources. Waste tire pyrolysis oil (WTPO) attracts considerable attention as an alternative fue...
Article
Full-text available
Over the past few decades, experimental studies have been conducted on the condensation heat transfer of vapor mixtures. However, the local heat transfer characteristics of vapor mixture affected by surface tension have not been fully investigated. The present work, for the first time, suggested the CFD simulation method for the Marangoni condensat...
Article
Full-text available
Solid recovered fuel (SRF) residue, which is leftovers from the SRF manufacturing process, usually is discarded in landfill because of its low heating value and high ash and moisture content. However, it could be used as a fuel after mechanical and biological treatment. Gasification experiments were conducted on treated SRF residue (TSRFR) to asses...
Article
Full-text available
Heavy fuel oils contain a high amount of sulfur. In this work, an extent amount of sulfur content waste tire pyrolysis oil (WTPO) was used as a fuel feedstock. A promising alternative oxidative desulfurization (ODS) method was applied in sulfur removal from WTPO using a S-ZrO2/SBA-15 solid acid catalyst, hydrogen peroxide (H2O2) as an oxidant and a...
Article
Full-text available
Proper treatment and careful management of sewage sludge are essential because its disposal can lead to adverse environmental impacts such as public health hazards, as well as air, soil, and water pollution. Several efforts are being made currently not only to safely dispose of sewage sludge but also to utilize it as an energy source. Therefore, in...
Article
In this study, computational particle fluid dynamics were applied to investigate the segregation characteristics of char particles in a bubbling fluidized bed. We examined the bubble behavior and the consequent segregation of char particles with respect to the nozzle arrangement of the distributor in a bubbling fluidized bed. The segregation charac...
Article
One of the problems commonly encountered during the gasification process for biomass is the agglomeration of residue with low efficiency, which occurs due to the use of low quality fuels containing ash and Alkali & Alkaline Earth Metallic (AAEM) compounds. In this study, the Empty Fruit bunch (EFB), which is a by-product of the palm oil industry th...
Article
The present study focused on modeling the gas-solid multi-phase flow and pyrolysis reaction of biomass in a spouted bed reactor. For the first time, the kinetics of biomass pyrolysis in a spouted bed were measured by the micro-spouted bed thermogravimetric analyzer (MSB-TGA) and applied to the fast pyrolysis reaction during computational particle f...
Article
In this study, fast pyrolysis experiments of larch sawdust were conducted in a conical spouted bed reactor to study the influences of reaction temperature, inlet gas velocity, feeding rate, and particle size on the product yield and pyrolysis oil quality. For the first time, the optimal conditions were found for various pyrolysis operating conditio...
Article
Full-text available
The production of green fuel oil is of the utmost importance for maintaining a healthy life and environment in the current world. Effective and complete removal of sulfur refractory compounds (such as 4,6-dimethyldibenzothiophene and other alkyl-substituted thiophene derivatives) from fuel oil is essential to meet the new requirements of sulfur sta...
Article
Electrical capacitance volume tomography (ECVT) was conducted to measure instantaneous gas–solid flow structures in a conical spouted bed. The sensor has 24 electrodes/channels and was used to make three-dimensional measurements of the solid volume fraction. Flow structures in the conical spouted bed were analyzed using quantitative ECVT images. Th...
Article
In recent years, an acceleration of global warming and various environmental pollution problems has been observed due to the increase in energy demand. Biomass, which has several advantages over more typical sources, is very popular as a green energy source. This study focuses on process modeling and analysis of biomass fast pyrolysis. The fast pyr...
Article
Oxy-fuel co-combustion of waste sludge and biomass with flue gas recirculation was conducted to observe the combustion characteristics and enrichment of CO2 using a 30 kWth circulating fluidized bed. The combustion reaction was accelerated and the ignition time was shortened by increasing the blending ratio of wood pellets and oxygen mixing ratio....
Article
Full-text available
The fast pyrolysis of biomass, empty fruit bunches from the palm mill industries, was conducted in a lab-scale bubbling fluidized bed reactor with a throughput of 1 kg/hr at temperatures ranging from 400 to 650 °C. For producing a higher yield of bio-crude oil with better homogeneity, washing methods were applied to the empty fruit bunch with water...
Article
Large amounts of empty fruit bunches (EFB) are generated annually during the palm oil manufacturing process; however, they are still treated as waste. In this study, gasification experiments were conducted using EFB in a fluidized bed reactor (throughput=1 kg/hr) at an experimental temperature range of 700 to 1,000 oC to assess the use of EFB as a...
Article
Computational particle-fluid dynamics (CPFD) simulation was carried out to examine the influence of air versus O2/CO2 as the fluidizing gas on the hydrodynamics of gas-solid flow in a cold-mode circulating fluidized bed. The CPFD simulation results were compared to the experimental data at constant superficial gas velocity, using air or mixed O2/CO...
Article
To investigate heat transfer of char from waste tire pyrolysis, the cooling of char was simulated by the computational fluid dynamics. To scrutinize the heat transfer characteristics, bed height, temperature of cooling wall, and mixing time were selected as calculation parameters. From the results, increasing the char bed height from 0.005 to 0.02...
Article
Full-text available
Three Ni-based catalysts were prepared for hydrodeoxygenation (HDO) of bio-oil with three different support materials (active carbon, SBA-15 and Al-SBA-15) and their catalytic effects were tested with crude bio-oil at 300 °C and under 3 MPa H2 pressure for 60 min. After the HDO reaction, gas, liquid phase (light oil and heavy oil) and char were obt...
Article
The decomposition kinetics of low grade coals was studied and compared with the kinetics of higher grade coals using thermogravimetric analysis. The effect of atmospheres (air, O2 and N2) on coal decomposition kinetics was also investigated. Experiments were carried out under non-isothermal conditions from room temperature to 950 °C at a heating ra...
Article
A fundamental understanding of the complex hydrodynamic characteristics in a reactor and its pyrolysis reaction field is required to elucidate the physical phenomena occurring in a bubbling fluidized bed (BFB) pyrolyzer. Specifically, bubble behavior is a very important factor for hydrodynamics, solid mixing, and consequent pyrolysis reaction. Acco...
Article
The aim of this study was to investigate the improvement in bio-oil stability via hydrodeoxygenation (HDO) with noble metal catalysts. The bio-oil produced by fast pyrolysis was subjected to the hydrodeoxygenative upgrading process with Pd/C, Ru/C, or Pt/C at 300 degrees C for 60 min with 3 MPa H-2 pressure. Upgraded bio-oil (heavy oil) was stored...
Article
The aim of this study was to investigate the improvement in bio-oil stability via hydrodeoxygenation (HDO) with noble metal catalysts. The bio-oil produced by fast pyrolysis was subjected to the hydrodeoxygenative upgrading process with Pd/C, Ru/C, or Pt/C at 300 °C for 60 min with 3 MPa H2 pressure. Upgraded bio-oil (heavy oil) was stored in seale...
Article
In this study, the hydrodynamics of the conical spouted bed reactor was examined to find out stable spouting regime and appropriate gas residence time. And the effects of pyrolysis reaction temperature for the production of the bio-oil in a conical spouted bed reactor were scrutinized by fast pyrolysis experiment. Stable hydrodynamic operating rang...
Article
Waste tyres have become a grave concern as their accumulation is aggregating every year. Not only the size of waste tyre has to be reduced, but also some useful energy has to be recovered out of it as the world badly requires energy from alternate sources. Pyrolysis is one such method to extract energy potential products from waste tyres. It is ext...
Article
Torrefaction is thermo-chemical process which can improve solid fuel quality as well as grindability. In previous studies, torrefaction has been studied mainly for removal of moisture and for improving grindability. In this experiment, the characteristics of torrefied waste sawdust were studied especially for its energy yield. Hence, torrefaction w...
Article
Rapid quenching of volatiles in fast pyrolysis is important for achieving high yield and quality of the bio-oil product, but few studies have examined the condensation of volatiles and their related heat exchangers. Accordingly, we have studied the condensation characteristics of volatiles by varying heat transfer conditions in a direct contact hea...
Article
Numerical simulations were conducted using computational fluid dynamics to evaluate the effect of ventilation conditions on radon (222Rn) reduction performance in a residential building. The results indicate that at the same ventilation rate, a mechanical ventilation system is more effective in reducing indoor radon than a natural ventilation syste...
Article
The physicochemical characteristics of automobile shredder residue (ASR) and its melting slag were investigated: In particular, the applicability of ASR as a reducing agent to the black copper recovery process. ASR is classified into three types after the shredding process: heavy fluff, light fluff and glass and soil. In this study, the portions of...
Article
The fast pyrolysis characteristics of Geodae-Uksae 1 were examined in a lab-scale bubbling fluidized bed reactor. First, raw material was examined thorough proximate and ultimate analyses. TGA (Thermogravimetric analysis) was carried out to determine the basic thermal degradation characteristics of the material. To study biocrude-oil yield and qual...
Article
A hydrodeoxygenation reaction (HDO) of bio-oil was conducted with Ru/C and Pt/C. Yield of heavy oil as a target product was influenced by reaction temperature irrespective of catalysts. HDO gave rise to an improvement in the following oil properties: water content, heating value, viscosity, acidity and oxygen level. Due to the de-moisturization, 61...
Article
In the present study, heat transfer through the wall of a blunt body immersed in a fluidized bed was investigated. A Eulerian approach based on the kinetic theory was used to simulate the multiphase thermal flow, and the determined heat transfer coefficients indicated the existence of different heat transfer patterns in the different walls of the b...
Article
This study focuses on process modeling and simulation of a biomass fast pyrolysis system. For the simulation of the biomass fast pyrolysis process, two types of simulation models were developed: lumped model and hybrid model. Employing the above models, the effect of reaction temperature on reaction rate and final product yields were analyzed. It w...
Article
In the present study, an experiment was performed to investigate the mixing and segregation characteristics of standard sand and rice straw particles in a cylindrical bubbling fluidized bed. The mass ratio (rice straw/standard sand = 0.5–1.25 %) of two particles and superficial gas velocity (0.13–0.18 m/s) were changed as experimental variables. Th...
Article
For designing an efficient circulating fluidized bed reactor, understanding the complex hydrodynamic characteristics in the reactor is required. Hence, in the present study, the modeling and simulation of the circulating fluidized bed gasifier using plastic waste were carried out with Eulerian-Granular approach. Several cases were investigated as c...
Article
In the palm oil industry, the palm fresh fruit bunch (FFB) is used to make crude palm oil. During the oil manufacturing process, the palm empty fruit bunch (EFB), which accounts for more than 20 wt % of the FFB, is generated as a byproduct. Although large amounts of EFB are generated every year in Malaysia, the EFB is treated as waste material beca...
Article
Growing concerns about harmful influence of radon on human body, many efforts are being made to decrease indoor radon concentration in advanced countries. To develop an indoor radon reduction technology, it is necessary to develop a technology to predict and evaluate indoor inflow and emission of radon. In line with that, the present study performe...
Article
Miscanthus bio-oil was subjected to hydrodeoxygenation (HDO) with Pd/C at different temperatures (250, 300 and 350°C) and times (30, 45 and 60min) to investigate the chemical modification of micro- and macromolecules in bio-oil. Four main products - char, gas and two immiscible oils (light and heavy oil) - were obtained from the HDO reaction. Yield...
Article
In the present study, lab-scale fast pyrolysis reactor (1 kg/hr) using lignocellulosic waste biomass was numerically modeledwith various reaction mechanism and the calculation results were compared. Three kinds of reaction mechanisms were appliedsuch as three-step mechanism, two-stage, semi global mechanism and Broido-Shafizadeh mechanism to simula...
Article
New and renewable energy sources have drawn attention because of climate change. Many studies have been carried out in waste-to-energy field. Fast pyrolysis of waste lignocelluosic biomass is one of the waste-to-energy technologies. Bubbling fluidized bed (BFB) reactor is widely used for fast pyrolysis of the biomass. In BFB pyrolyzer, bubble behav...
Conference Paper
The flexible material is often used for a caudal fin in a robot fish. In that case, the rigid body modeling of the caudal fin is not appropriate for simulating the turbulent flow field around the robot fish. In the present study, FSI (Fluid Structure Interaction) method is applied to the simulation of fish swimming considering the flexibility of ca...
Article
In the present work, fast pyrolysis of Miscanthus sinensis was performed and the product yields and properties of the resulting biocrude oil were determined for varying reactor configurations and pyrolysis temperatures. Two types of reactors (rectangular and cylindrical fluidized beds) were adopted, and pyrolysis temperature was increased from 400...
Conference Paper
The present project for developing a robot fish is aimed to make an eco-friendly robot for monitoring water pollution and quality in domestic major rivers. In line with that, the present numerical study using computational fluid dynamics (CFD) is carried out for investigating the swimming characteristics of biomimetic robot fish. Unsteady Reynolds-...
Conference Paper
In this paper, a water tank experiment was conducted to check the performance of a robotic fish. To view the function of a robotic fish swimming in flowing water, a circulating water tank should be used. 4 types of a caudal fin were made and used in the water tank experiment and the thrust of each case was measured and compared. Through this experi...
Article
In this study, an experiment was carried out to investigate the mixing and segregation of fluidizing materials and char particles in a fluidized bed reactor. Specifically, the shape of the fluidized bed column was changed and the effect of the bed column shape on the segregation characteristics of the materials was investigated by varying the super...
Article
Screening of pyrolysis reactions has been carried out with Kraft lignin and various catalysts applying the TI-mini fast pyrolyzer. Zeolite HZSM-5, FCC and Olivine in a small fixed bed were used as catalyst to investigate their influences on the pyrolysis reaction. The characteristics of catalytic pyrolysis reactions and final products were studied...
Article
The high demand of renewable energy has been growing nowadays due to shortage of fossil fuels and global warming. The studies on fast pyrolysis of biomass were mostly in progress by using woody biomass, to investigate characteristics of biocrude oil and optimum conditions of fast pyrolysis. Currently a variety of biomass have been used for sample m...
Article
Numerical study using computational fluid dynamics has been carried out to investigate the heat transfer characteristics of a laboratory fluidized bed reactor. The fluidized bed reactor of vTI (Johann Heinrich von Thünen-Institute)-Institute of Wood Technology and Wood Biology is modeled. For the simulation of multiphase flow and thermal fields, an...
Article
The vTI-mini fast pyrolyzer was applied for screening fast pyrolysis reactions of different Organosolv lignins, such as Alcell (Repap Technologies) and lignin from a German biorefinery project. To investigate the catalytic effects on the pyrolysis of the technical lignins, three catalysts such as zeolite HZSM-5, FCC, and Olivine were used. The cata...
Article
Numerical study using computational fluid dynamics (CFD) was carried out to investigate the heat transfer characteristics of an innovative inclined gravity-driven reactor (KIMM-fast pyrolysis reactor). For the simulation of multiphase flow and thermal fields, we applied an Eulerian–Eulerian approach. The flow and thermal characteristics of the reac...
Article
Full-text available
International attention has been considerably paid for the technology of CO2 capture and storage (CCS) these days because of global warming. In line with the fact that carbon dioxide capture and storage (CCS) technology has been regarded as one of the most promising option to mitigate the climate change and global warming, we have started a 10-year...
Article
A cylindrical bubbling fluidized bed reactor having 2 kg/h pyrolysis capacity was developed and using this reactor fast pyrolysis of lignocellulosic biomass was carried out to obtain biocrude oil. In the fast pyrolysis system, a commonly used spiral quenching heat exchanger with electrostatic precipitator was applied to condense volatile gases issu...
Article
The characteristics of biocrude-oil yield and quality have been investigated by changing fast pyrolysis condition for woody biomass. For the fast pyrolysis of woody biomass, a bubbling fluidized bed reactor having cylindrical shape was devised and a commonly used spiral quenching system was applied to the condensation of volatile gases from the rea...
Conference Paper
International attention has been considerably paid for the technology of CO2 capture and storage (CCS) these days because of global warming. Among the technologies of CCS, the prediction of CO2 behavior in underground is very crucial for CO2 storage design. In the present study, a pore-scale level model is developed to mimic real porous structure a...
Conference Paper
The turbulent flow fields of a parallel plate or channel with spatially periodic condition have been widely investigated by many researchers. However the rectangular or square curved duct flow has not been fundamentally scrutinized in spite of its engineering significance, especially for cooling device. Hence, in the present study large eddy simula...
Article
In the present study, computational fluid dynamics is applied to investigate fast pyrolysis characteristics of woody biomass in a gravity-driven reactor. A Eulerian-Eulerian approach is adopted, including three gas species and three solid phases, for multiphase reacting flow fields between solid and gas. Two-stage semiglobal reaction kinetics consi...
Article
Full-text available
The characteristics of heat transfer in confined multiple jet flows of a micro can combustor is investigated by means of large eddy simulation (LES). The micro combustor can be employed for a hybrid system, which consists of a micro gas turbine and a solid oxide fuel cell. In the present study, the focus is brought into heat transfer, which has a g...
Article
The mixing characteristics of a passive scalar in the turbulent flow of a selective catalytic reduction process were numerically and experimentally investigated, focusing especially on an injection nozzle with multiple holes for the reducing agent. The multihole injection nozzle studied has six holes that are perpendicular to the ambient flue gas f...
Article
Large eddy simulation (LES) has been applied to turbulent thermal fields in a channel having one wavy wall for Prandtl number = 0.7. Wall wave amplitude is changed in three steps. Increasing the wall wave amplitude, a flow separation bubble comes to appear and a separated turbulent shear layer develops above the separation bubble. Additionally, in...
Article
Turbulent flows and related heat transfer over a fully developed wavy channel is investigated by a turbulence model. The nonlinear k–ε–fμ model of Park et al. [Int. J. Heat Fluid Flow 24 (2003) 29] is slightly modified and their explicit heat flux model is employed. The Reynolds number is fixed at Reb=6760 through all wave amplitudes and the wave a...
Article
In the present study, to investigate the fast pyrolysis characteristics of woody biomass in bubbling fluidised bed reactor, numerical approach is applied by using CFD (computational fluid dynamics). For the multiphase reacting flow fields between solid and gas, Eulerian-Eulerian approach is applied including three gas species and three solid phases...

Citations

... Gasification of bio-oil produced from fast pyrolysis of biomass for gas production may be a viable route to improve the processing scales of biomass gasification [21]. Bio-oil which is economically produced at small scales (i.e. less than 20 MWth) at different places can be stored and finally transported to a central site for gasification and further conversion at any desirable time [22,23]. ...
... Therefore, we studied the formation mechanism of gaseous products from catalytic pyrolysis of tire rubber by experiments and molecular dynamics simulation. It should be noted that the rubber contained in the tire is vulcanized rubber, in which the sulfur element will generate toxic sulfide after pyrolysis [30]. The focus of this paper is the pyrolysis mechanism of rubber itself, so the research object of this paper is the tire rubber after desulfurization. ...
... The growth in global energy demand and carbon related emissions have remarkably increased and will continue to rise mainly due to the world population growth and the technological advancement in almost all aspects of life [1]. To meet the increase in energy consumption, more exploitation of conventional energy sources has occurred, and this results in critical environmental issues. ...
... Various desulfurization techniques such as hydrodesulfurization, oxidation, and alkylation have been employed to upgrade the waste tyre pyrolysis oil. 25 −28 In the past decade, several review articles on waste tyre management and/or thermochemical processing were published. The key topics covered in existing reviews are summarised in Table 1. ...
... Lee et al. [27] carried out air gasification experiments on hydrochar produced by HTC of sewage sludge. The results demonstrated that the product gas increased its LHV by 0.98 MJ/Nm 3 and cold gas efficiency by 5.8% more, compared to the product gas obtained by the gasification of the non-treated feedstock. ...
... In the meantime, the particle movement caused by fluid flow is defined by a discrete phase model which utilizes the Eulerian-Langrangian approach (ANSYS 2019; Nakhaei et al. 2020;Steven et al. 2022a). The particle velocity field is influenced by the momentum balance of each particle and is presumed no interaction within particles (inert), so it only interacts with the fluid through particle-fluid drag force which is formulated by a drag equation (Bindar 2017;Park and Choi 2019). The used empirical equation for drag coefficient ( C D ) is written in Eq. 6 (Haider and Levenspiel 1989). ...
... Hydrotreating and zeolite-based hydrocracking catalysts could be utilized to reduce the oxygen content of the bio-oil and increase the amount of aromatic compounds [212] 213. A range of intermediary reactions such as cracking, decarbonylation, decarboxylation, aromatization isomerization, cyclization, dehydrogenation, dehydration and oligomerization have all been found to occur during the upgrading process [65,[214][215][216][217]. ...
... Typically, <10% wt EFB is used as boiler fuel, 3,5,6 mainly due to ash fusibility problems and being a highly alkaline material. 7,8 Most oil extractors prefer other process residues such as fiber, palm kernel shell, or biogas to generate energy. 1 The Colombian industry requires enhanced disposal mechanisms for EFB as production capacity has increased. 9 From an energy standpoint, this is an opportunity to use thermal conversion technologies such as gasification to incorporate syngas into the value chain as an input for self-generation or through the sale of surplus electricity. ...
... This trend appears to be connected to the pace at which WMNS particles heat up. Because of the small particles, the heating rate is increased, which prevents additional dehydration processes from occurring, which would otherwise diminish the oxygen content of bio-oil [25]. The rest of the components stayed nearly consistent regardless of the particle size used in the simulation. ...