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    Item type:Publication,
    Optimization of a membrane-based oxidative coupling of methane reactor using surface response methodology
    (2013-01-01) ;
    Tiraset, Sirikarn
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    Saebea, Dang
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    Paengjuntuek, Woranee
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    Arpornwichanop, Amornchai
    An oxidative coupling of methane (OCM) is a promising process to convert methane into ethylene and ethane; however, it suffers from the relatively low selectivity and yield of ethylene at high methane conversion. In this study, a membrane reactor is applied to the OCM process in order to prevent the deep oxidation of a desirable ethylene product. First, simulations of the OCM reactor based on mass and energy balances coupled with detailed OCM kinetic model are performed and effects of key operating parameters, such as temperature, methane-to-oxygen feed ratio and methane flow rate, on the OCM reactor performance in terms of CH<inf>4</inf> conversion, C<inf>2</inf> selectivity and yield are analyzed. To determine its optimal operating conditions, an optimization of the OCM membrane reactor using a surface response methodology is carried out in the second part. The central composite design (CCD) is used to study the interaction of process variables (i.e., temperature, feed flowrate and CH<inf>4</inf>/O<inf>2</inf> ratio) and to find the optimum process operation to maximize the C<inf>2</inf> products yield. © 2013, AIDIC Servizi S.r.l.
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    Analysis of unbalanced pressure PEM electrolyzer for high pressure hydrogen production
    (2017-01-01)
    Saebea, Dang
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    Hacker, Viktor
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    Assabumrungrat, Sutthichai
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    Arpornwichanop, Amornchai
    Proton exchange membrane (PEM) electrolyzer is a promising technology and likely to be an important hydrogen generator. The ability to produce high purity hydrogen and deliver it at relatively high pressure is an important advantage of the PEM electrolyzer technology. In this work, the high pressure PEM electrolyzer without the need for external compression is studied. The simulation of the electrolyzer is performed based on an electrochemical model with consideration of hydrogen permeation. The effect of cathode pressure and membrane thickness on electrolyzer performance is studied. The explosion limit of a hydrogen-oxygen mixture in the anode is also taken into consideration. The electrochemical compression shows advantage in term of delivering hydrogen at high pressure with having less effect on performance and low power requirement. The increase of cathode pressure slightly affects the electrolyzer performance. The high pressure operation at the cathode and the use of thin membranes cause hydrogen crossover from the cathode to anode, especially at high current density operation.
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    Operational Analysis of a Proton-Conducting Solid Oxide Electrolysis Cell for Synthetic Fuel Production
    (2021-01-01)
    Bhichaiphab, Jinjutha
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    Saebea, Dang
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    Arpornwichanop, Amornchai
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    Methane and methanol as synthetic fuels can be produced from synthesis gas or syngas. A proton-conducting solid oxide electrolysis cell (H-SOEC) becomes a promising technology that can produce syngas from the co-electrolysis of steam and CO<inf>2</inf>. In this work, the synthetic fuel production from syngas produced by a H-SOEC was modelled and simulated through Aspen Plus simulation software. The composition of syngas and synthetic fuel were calculated by using the minimization of Gibbs free energy. Firstly, the steam to CO<inf>2</inf> (S/C) molar ratio in feed was determined to satisty the suitable stoichiometric number of each fuel. Further, the H-SOEC operating temperature was optimized. The simulation showed that at operation of H-SOEC as 650 °C and 1 atm, the optimal S/C molar ratio for methane and methanol productions is 4.69 and 3.52, respectively. Then, the effect of operation in fuel production was examined. The results indicated that methane flowrate of 0.2 kmol/h can be provided when reactor operates at 250 °C and 3 atm. For methanol production, 0.13 kmol/h of methanol can be generated at reactor operation as 250 °C and 80 atm. In addition, it was found that the methane production does not release CO and CO<inf>2</inf> to nature. Therefore, it can be concluded that the integrated system of H-SOEC and methane production is more attractive feature.
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    Methanation Process for Methane Synthesis from Waste Gas: Process Simulation
    (2022-01-01)
    Saebea, Dang
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    Chatrattanawet, Narissara
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    Soisuwan, Soipatta
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    Arpornwichanop, Amornchai
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    Waste gas from the fermentation of bioethanol production consists of high carbon dioxide concentration. The CO<inf>2</inf> emissions cause global climate change. The conversion of carbon dioxide to chemical products or fuels is an interesting solution for reducing the amount of carbon dioxide emissions. The methane synthesis via carbon dioxide methanation reaction has attracted much attention. The suitable operation of the methanation process for methane synthesis from waste gases should be studied. This work aims to investigate the methane production from the waste gas of the fermentation process. The composition of impurities in waste gases on the performance of the methanation process is investigated. The effects of hydrogen to carbon dioxide ratio and operating temperature on the carbon dioxide conversion and methane yield of the methanation are also studied. The simulation results from the thermodynamic analysis show that the methane yield of the methanation from waste gases is 3.11 - 4.61 % higher than that from pure carbon dioxide in the temperature range of 300 - 500 °C. The methane yield of the methanation process decreases with increasing temperature. The increase in the hydrogen to carbon dioxide ratio of 1 to 4 and the operating pressure of 1 to 8 bar have a significant effect on the enhancement of carbon dioxide conversion and methane yield.
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    Modeling and optimization of proton-conducting solid oxide electrolysis cell: Conversion of CO2 into value-added products
    (2016-11-01)
    Namwong, Lawit
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    Authayanun, Suthida
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    Saebea, Dang
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    Arpornwichanop, Amornchai
    Proton-conducting solid oxide electrolysis cells (SOEC-H<sup>+</sup>) are a promising technology that can utilize carbon dioxide to produce syngas. In this work, a detailed electrochemical model was developed to predict the behavior of SOEC-H<sup>+</sup> and to prove the assumption that the syngas is produced through a reversible water gas-shift (RWGS) reaction. The simulation results obtained from the model, which took into account all of the cell voltage losses (i.e., ohmic, activation, and concentration losses), were validated using experimental data to evaluate the unknown parameters. The developed model was employed to examine the structural and operational parameters. It is found that the cathode-supported SOEC-H<sup>+</sup> is the best configuration because it requires the lowest cell potential. SOEC-H<sup>+</sup> operated favorably at high temperatures and low pressures. Furthermore, the simulation results revealed that the optimal S/C molar ratio for syngas production, which can be used for methanol synthesis, is approximately 3.9 (at a constant temperature and pressure). The SOEC-H<sup>+</sup> was optimized using a response surface methodology, which was used to determine the optimal operating conditions to minimize the cell potential and maximize the carbon dioxide flow rate.
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    Effect of anode-cathode exhaust gas recirculation on energy recuperation in a solid oxide fuel cell-gas turbine hybrid power system
    (2016-01-01)
    Saebea, Dang
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    Authayanun, Suthida
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    Arpornwichanop, Amornchai
    A solid oxide fuel cell-gas turbine (SOFC-GT) hybrid system supplying liquid fuel as ethanol exhibits promise as an auxiliary power unit. In this study, the recirculation of anode and cathode exhaust gas in the SOFC-GT system is proposed to improve the efficiency of heat management in the SOFC-GT hybrid system. The key operating parameters, such as fuel utilization factor and the cell and GT temperatures, are analyzed in terms of the performance of the SOFC-GT hybrid systems. The simulation results show that the recirculation of anode and cathode exhaust gas has a direct impact on the turbine performance. To maintain the inlet temperature of the small turbine in the range of 873-1223 K, the amount of fuel and air added to the combustor to control the turbine inlet temperature on the system performance is also investigated. A SOFC-GT hybrid system with both anode and cathode exhaust gas recirculation achieves the highest system and thermal efficiency.
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    Item type:Publication,
    Exergoeconomics of hydrogen production from biomass air-steam gasification with methane co-feeding
    (2017-01-01)
    Nakyai, Teeranun
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    Authayanun, Suthida
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    Arpornwichanop, Amornchai
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    Assabumrungrat, Suttichai
    Biomass is one of the most promising energy sources for hydrogen production. However, biomass gasification has a low hydrogen content in the producer gas. To increase the hydrogen yield, the co-feeding of methane into biomass gasification is proposed in this study. The type of gasifying agent is a key factor in the determination of the content of the hydrogen product. To compare the designs and find the best performance criteria of a process, not only energy and exergy analyses but also a cost analysis of the process should be investigated. In the present study, the effects of various types of gasifying agent, i.e., air and both steam and air, for the biomass gasification with/without methane co-feeding are investigated through an exergoeconomic analysis. It is observed that the air-steam used as an agent achieves high energy and exergy efficiency. Methane co-feeding can improve the energy and exergy efficiency. In exergoeconomic analysis, the specific exergy cost (SPECO) method is applied to investigate the unit cost of hydrogen. The economic reveal that the biomass gasification using air-steam as an agent with methane co-feeding also presented the lowest unit hydrogen cost of 2.69 $/kg. The unit exergy cost of hydrogen is 0.068 $/kW h.
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    Item type:Publication,
    Energetic, economic, and environmental perspectives on systematic design and energy management of a power-to-methane system integrated with power cycle
    (2025-12-01)
    Saebea, Dang
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    Arpornwichanop, Amornchai
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    The methanation process transforms CO<inf>2</inf> into green methane by combining it with hydrogen from solid oxide electrolysis cells (SOECs). Efficient energy management of the integrated system, along with effective heat utilization from methanation for power generation, enhances system efficiency. This study compares four configurations of a system incorporating SOECs, methanation, and the Rankine cycle, focusing on energetic, economic, and environmental performance. The impact of gas recycling in the adiabatic methanator on system performance was also investigated. Key findings reveal that incorporating a water separation unit and increasing the gas recycle ratio significantly improve methane yield and CO<inf>2</inf> utilization. Systems with water removal through heat integration achieve overall efficiencies of 50.17 to 52.27%. The levelized product cost of the system with water removal is lower, ranging from 195.27 to 223.05 $/MWh, and it produces the lowest CO<inf>2</inf> emission intensity at 119.91 kgCO<inf>2</inf> per MWhCH<inf>4</inf>.
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    Effect of Flow Pattern on Single and Multi-stage High Temperature Proton Exchange Membrane Fuel Cell Stack Performance
    (2014-01-01)
    Authayanun, Suthida
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    Patniboon, Artitaya
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    Saebea, Dang
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    Arpronwichanop, Amornchai
    A high-temperature proton exchange membrane fuel cell (HT-PEMFC) is a promising clean and effective technology for power generation because of its simplified water and heat management as well as high CO tolerance. Therefore, it could be possible to directly use a reformate gas for HT-PEMFC without the need for sophisticated purification processes. Due to the non-uniform of H<inf>2</inf> and CO distributions within fuel cells, the stack design is one of the key factors to enhance the performance and efficiency of HT-PEMFC. In this study, a single HT-PEMFC stack is investigated by considering the CO poisoning effect. The mathematical model of HT-PEMFC based on the electrochemical reaction model coupled with the diffusion model of a gas diffusion layer and electrolyte film layer is used for simulation studies. At high fuel utilization, hydrogen is highly consumed and CO concentration increases, having a significant impact on cell performance. The multi-stack HT-PEMFC is designed to minimize the CO poisoning effect and to maximize its efficiency. The power output that is obtained from each cell stack is presented and the overall power output is compared with single cell stack. Effect of different flow patterns, i.e., co-current and counter-current flow, on the HT-PEMFC stack performance is also presented. © 2014 Elsevier B.V.
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    Thermodynamic analysis of hydrogen production from the adsorption-enhanced steam reforming of biogas
    (2014-01-01)
    Saebea, Dang
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    Authayanun, Suthida
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    Arpornwichanop, Amornchai
    Biogas is considered a potential, renewable fuel to be used as a hydrogen source. At present, a steam reforming is widely used process in hydrogen production, but it needs to be operated at high temperature to achieve high hydrogen yield. Because biogas consists of mostly CO<inf>2</inf>, the hydrogen purification of a reformate gas obtained is another important issue, especially for fuel cell applications. In this study, an enhanced-adsorption steam reforming process in which steam reforming reaction and CO<inf>2</inf> adsorption are occurred in a single unit is investigated. A thermodynamic analysis is performed to study effects of important operating parameters on hydrogen yield and product distribution. It is found that a biogas processor should be operated at high temperatures and inlet steam-T o-methane ratio. The content of CO in the reformate gas increases with increased operating temperature. The steam reforming of biogas coupled with a CO<inf>2</inf> adsorption gives a higher hydrogen product with considerable low CO content, compared to the conventional steam reforming of biogas.