• 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.

• Journal of Institute of Convergence Technology
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• v.5 no.1
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• pp.1-5
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• 2015

SI thermochemical hydrogen production process achieves water splitting into hydrogen and oxygen through three chemical reactions. The process is comprised of three sections and one of them is HI decomposition into $H_2$ and $I_2$ called as Section III. The production of $H_2$ included processes involving EED for concentrating a product stream from Section I. Additionally an $I_2$ crystallization would be considered to reduce burden on EED by removing certain amount of $I_2$ out of a process stream prior to EED. In this study, the current thermodynamic model of SI process was briefly described and the calculation results of the applied Electrolytes NRTL model for phase equilibrium calculations was illustrated for ternary systems of Section III. We calculated temperature and heat duty of an $I_2$ crystallizer and heat duty of heaters using UVa model and heat balance equation of simulation tool. The results were expected to be used as operation information in optimizing HI decomposition process and setting up material balance throughout SI process.

• Transactions of the Korean hydrogen and new energy society
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• v.26 no.6
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• pp.567-580
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• 2015

In order to select an optimum gasifier for specific low rank coal, evaluation elements were studied by analyzing characteristics of low rank coal compared with those of high rank coal and the effects of each gasifier type in accordance with the characteristics. And syngas composition calculation model was made on the basis of thermochemical equilibrium to quantify some of the evaluation elements. And then the suitable gasifier was selected for a kind of Indonesian low rank coal through this syngas composition calculation model and the evaluation elements of selecting gasifier.

• Journal of The Korean Society of Agricultural Engineers
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• v.57 no.1
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• pp.79-87
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• 2015

A thermochemical equilibrium model was constructed for predicting composition of synthesis gas in biomass gasification. The model included estimation of equilibrium constants using Gibbs free energy. After constructing the model, the results were compared with the experimental values and predictions from a previous model. Gas compositions were reasonably well agreed with them and showed effects of operational and fuel condition. When the reaction temperature increased, the lower heating values decreased due to the decrease in CH4 concentrations. The methane concentrations were lower than those observed in experimental results. The model was used to predict the gas composition and heating values for the cases of mixed fuel of charcoal and un-dry woodchips. Although downdraft gasifiers require fuels less than 15% of moisture contents, the model results indicated that the mixed fuel with charcoal and woodchips which had over 25% of moisture contents could be used in the downdraft gasifiers. It might be explained by increase in energy density resulting from mixing charcoal. The results imply that the efforts and costs for drying biomass fuels could be reduced by mixing charcoal or fuels with higher calorific values.

• Mass Spectrometry Letters
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• v.12 no.4
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• pp.131-136
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• 2021

Collision-induced dissociation of peptides involves a series of proton-transfer reactions in the activated peptide. To describe the kinetics of energy-variable dissociation, we considered the heat capacity of the peptide and the Marcus-theory-type proton-transfer rate. The peptide ion was activated to the high internal energy states by collision with a target gas in the collision cell. The mobile proton in the activated peptide then migrated from the most stable site to the amide oxygen and subsequently to the amide nitrogen (N-protonated) of the peptide bond to be broken. The N-protonated intermediate proceeded to the product-like complex that dissociated to products. Previous studies have suggested that the proton-transfer equilibria in the activated peptide affect the dissociation kinetics. To take the extent of collisional activation into account, we assumed a soft-sphere collision model, where the relative collision energy was fully available to the internal excitation of a collision complex. In addition, we employed a Marcus-theory-type rate equation to account for the proton-transfer equilibria. Herein, we present results from the integrated thermochemical approach using a tryptic peptide of ubiquitin.

• Resources Recycling
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• v.31 no.2
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• pp.33-39
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• 2022

In this study, analytical thermochemical modeling factors that contribute to maintaining a specific temperature range during vanadium roasting as a pretreatment using a rotary kiln are investigated. The model-related mechanisms include thermochemical reaction rates, heat balance, and heat transfer, through which the resultant temperature can be estimated intuitively. Ultimately, by optimizing these parameters, the ideal roasting temperature in the kiln is ≈1000 ℃ (or ≈1273 K) for long-term operation. Therefore, the heat generated from hydrocarbon (natural gas) fuel combustion and ore oxidation reactions, as well as the radiant heat transferred to ores, are assessed. In addition, thermochemical methods for relieving the temperature gradient in order to maintain the optimum temperature range of the rotary kiln are suggested.

• Journal of Advanced Navigation Technology
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• v.22 no.2
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• pp.90-95
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• 2018

In the solid rocket motor (SRM), a thrust of rocket is generated by a nozzle so it is very important device. The nozzle of SRM is a condition of high temperature and high pressure so occurs the erosion by combustion gas. The liquid rocket propulsion systems (LRPSs) cools the nozzle by the fuel and oxidizer but SRM does not cool the nozzle. This paper deal with the development of the oxy-acetylene torch tester and investigate the thermochemical erosion properties for the thermal insulation materials of the graphite rocket nozzle throat through the experiment. The results of experiments are compared with the results of Theoretical model and identify the key factors affecting of erosion. The results is in good agreement with the experimental data.

• International Journal of Aerospace System Engineering
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• v.2 no.1
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• pp.12-17
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• 2015

Aero-optical effects induced by the flow around the optical window degrade the performance of the IR seeker, especially for the hypersonic flow. For the thermochemical non-equilibrium flow, index of refraction model and optical transmission calculation method are developed to predict the aero-optical effects. The optical distortion is discussed for the typical optical widow shape and flow condition. The influence on aero-optical effects is analyzed.

• Transactions of the Korean Society of Automotive Engineers
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• v.1 no.1
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• pp.80-89
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• 1993

Performance simulation for a Spark Ignition Wankel rotary Engine is presented in this paper. The volume of chamber at each eccentric shaft angle is evaluated by using geometric models of housing and rotor. A thermodynamic model which includes the first law of thermodynamics, combustion and convective heat transfer from chamber contents to surroundings is imployed. A thermochemical equilibrium model which considers 10 species(CO, $CO_2$, $O_2$, $H_2$, $H_2O$, OH, O, NO, $N_2$) in the burned gas region, is also employed. Four processes of gas exchange, compression, combustion and expansion are considered and the pressure, temperature and composition of chamber gas at each eccentric shaft angle in each process are computed in this performance simulation. This performance simulation must be useful for optimal design of Spark Ignition Wankel Rotray Engine with parametric study for various design parameters and operating conditions.