• 한국연소학회:학술대회논문집
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• 2014.11a
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• pp.37-40
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• 2014

Capturing the carbon dioxide emitted from coal-fired power plants will be necessary if targeted reduction in carbon emissions is to be achieved. Modelling and simulation are the base for optimal operation and control in thermal power plant and also play an important role in energy savings. This study aims to analyze the performance of supercritical coal fired power plant through steady and dynamic simulation using a commercial software gCCS. A whole power plant has been modeled and validated with design data of 500 MWe power plant, base and part load operations of the plant were also evaluated, consequently it had been proven that the simulated result had a good agreement with actual operating data. In addition, the effect of co-firng on the plant efficiency and flue gases were investigated using gCCS simulator.

• International Journal of Aeronautical and Space Sciences
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• v.18 no.1
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• pp.28-37
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• 2017

Recent modeling of thermal nonequilibrium processes in simple molecules like hydrogen and nitrogen has indicated that rotational nonequilibrium becomes as important as vibrational nonequilibrium at high temperatures. In the present work, in order to analyze rovibrational nonequilibrium, the rotational mode is separated from the translational-rotational mode that is usually considered as an equilibrium mode in two- and multi-temperature models. Then, the translational, rotational, and electron-electronic-vibrational modes are considered separately in describing the thermochemical nonequilibrium of nitrogen behind a strong normal shock wave. The energy transfer for each energy mode is described by recently evaluated relaxation time parameters including the rotational-to-vibrational energy transfer. One-dimensional post-normal shock flow equations are constructed with these thermochemical models, and post-normal shock flow calculations are performed for the conditions of existing shock-tube experiments. In comparisons with the experimental measurements, it is shown that the present thermochemical model is able to describe the rotational and electron-electronic-vibrational relaxation processes of nitrogen behind a strong shock wave.

• Journal of Institute of Convergence Technology
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• v.2 no.2
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• pp.30-34
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• 2012

The SI thermochemical cycle process accomplishes water splitting through distinctive three chemical reactions. We focused on thermodynamic models applicable to the process. Recently, remarkable models based on the assumed ionic species have been developed to describe highly nonideal behavior on the liquid phase reactions. ElecNRTL models with ionic reactions were proposed in order to provide reliable process simulation results for phase equilibrium calculations in Section II and III. In this study, the current thermodynamic models of SI thermochemical cycle process were briefly described and the calculation results of the applied ElecNRTL models for phase equilibrium calculations were illustrated for binary systems.

• Transactions of the Korean hydrogen and new energy society
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• v.13 no.3
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• pp.204-213
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• 2002

In this work, hydrogen production by a 2-step water-spritting thermochemical cycle based on metal oxides redox pairs was investigated on the bases of the thermodynamics and technical feasibility. Also, a 2nd-law analysis performed on the closed cyclic process indicates a maximum exergy conversion efficiency of 7.1% when using a solar cavity-receiver operated at 2300K and air/Fe3O4 molar ratio = 10.

• Transactions of the Korean hydrogen and new energy society
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• v.34 no.3
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• pp.316-326
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• 2023

Development of carbon-neutral fuel production technologies to solve climate change issues is progressing worldwide. Among them, methane can be produced through the synthesis of hydrogen produced by renewable energy and carbon dioxide captured through a CO₂ methanation reaction, and the fuel produced in this way is called synthetic methane or e-methane. The CO₂ methanation reaction can be conducted via biological or thermochemical methods. In this study, a 30 Nm³/h thermochemical CO₂ methanation process consisting of an isothermal reactor and an adiabatic reactor was used. The CO₂ conversion rate and methane concentration according to the temperature measurement results at the center and outside of the adiabatic reactor were analyzed. The gas flow into the adiabatic reactor was found to reach equilibrium after about 1.10 seconds or more by evaluating the residence time. Furthermore, experimental and analysis results were compared to evaluate performance of the reactor.

• Nuclear Engineering and Technology
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• v.39 no.2
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• pp.111-122
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• 2007

The current energy supply system is burdened by environmental and supply problems. The concept of a hydrogen economy has been actively discussed worldwide. KAERI has set up a plan to demonstrate massive production of hydrogen using a VHTR by the early 2020s. The technological gap to meet this goal was identified during the past few years. The hydrogen production process, a process heat exchanger, the efficiency of an I/S thermochemical cycle, the manufacturing of components, the analysis tools of VHTR, and a coated particle fuel are key areas that require urgent development. Candidate NHDD plant designs based on a 200 MWth VHTR core and I/S thermochemical process have been studied and some of analysis results are presented in this paper.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.1
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• pp.85-96
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• 2003

For a design of rocket engine nozzle, chemical equilibrium analysis which shares the same numerical characteristics with frozen flow analysis can be used as an efficient design tool for predicting maximum thermodynamic performance of the nozzle. 10 this study, a chemical equilibrium flow analysis code was developed for the design of hydrocarbon fueled rocket engines. 10 oder to understand the thermochemical characteristics occurring in a nozzle through the expansion process, such as recombination of chemical components and the accompanying energy recovery, chemical equilibrium flow analysis was carried out for the KSR-III rocket engine nozzles together with frozen flow and non-equilibrium flow analyses. The performance evaluation based on the present KSR-III nozzle flow analyses has provided an understanding of the thermochemical process in the nozzle and additionally, it has confirmed that the newly designed nozzle shape modified to have a reduced exit area ratio is an adequate design for obtaining an increased ground thrust.

• Transactions of the Korean hydrogen and new energy society
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• v.18 no.2
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• pp.109-115
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• 2007

Solar energy conversion to hydrogen was carried out via a two-step thermochemical water splitting using metal oxide redox pair. To simulate the solar radiation, a 7 kW short arc Xe-lamp was used. Partially reduced iron oxide and cerium oxide have the water splitting ability, respectively. So, $Fe_3O_4$ supported on $CeO_2$ was selected as the active material. $Fe_3O_4/CeO_2$(20 wt/80 wt%) was prepared by impregnation method, then the active material was washcoated on the ceramic honeycomb monolith made of mullite and cordierite. Oxygen was released at the reduction step($1673{\sim}1823\;K$) and hydrogen was produced from water at lower temperature($873{\sim}1273\;K$). The result demonstrate the possibility of the 2-step thermochemical water splitting hydrogen production by the active material washcoated monolith. And hydrogen and oxygen was produced separately without any separation process in a monolith installed reactor. But the SEM and EDX analysis results revealed that the support used in this experiment is not suitable due to the thermal instability and coating material migration.

• Journal of the Korean Institute of Gas
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• v.24 no.5
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• pp.29-38
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• 2020

It is practically difficult to accurately measure the temperature and concentration of a large combustion systems at industrial sites in real time. Temperature measurement using thermocouple, which are mainly used, is a point-measuring method that is less accurate and less reliable to analyze the wide area range of inner combustion system, and has limitations to internal accessibility. In terms of concentration analysis, most measurement methods use sampling method, which are limited by the difficulty of real-time measurement. As a way to overcome these limitations, laser-based measurement methods have been developed continuously. Laser-based measurement are line-average measurement methods with high representation and precision, which are beneficial for the application of large combustion systems. In this study the temperature and concentration were measured in real time by water vapor and oxygen generated during combustion using Tunable Diode Laser Absorption Spectroscopy (TDLAS). The results showed that the average temperature inside the combustion system was 1330℃ and the mean oxygen concentration was 3.3 %, which showed similar tendency with plant monitoring data.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.12 no.4
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• pp.215-221
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• 2002

Epitaxial Si layers were deposited on (100) Si substrates by hot-wall chemical vapor deposition (CVD) technique using the $SiH_2Cl_2/H_2$chemistry. Thermochemical calculations of the Si-H-Cl system were carried out to predict the window of actual Si deposition process and to investigate the effects of process variables (i.e., deposition temperature, reactor pressure, and input gas molar ratio ($H_2/SiH_2Cl_2$)) on the epitaxial growth. The calculated results were in good agreement with the experiment. Optimum process conditions were found to be the deposition temperature of 850~$950^{\circ}C$, the reactor pressure of 2~5 Torr, and the input gas molar ratio ($H_2/SiH_2Cl_2$) of 30~70, providing device-quality epitaxial layers.