• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.11a
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• pp.150-153
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• 2006

Gas generator should be adopted either fuel rich or oxidizer rich combustion because of the temperature restriction to avoid any possible thermal damages to turbine blade. This study focuses to model the non-equilibrium chemical reaction of kerosene/LOx with detailed kinetics developed by Dagaut using Perfectly stirred reactor(PSR) assumption. To predict more reliable species fraction and other gas properties, Frenklach's soot model was added to Dagaut's detailed kinetics.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.4
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• pp.365-373
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• 2010

A chemical reactor model (CRM) was developed for a jet stirred reactor (JSR) to predict the emission of exhaust such as NOx. In this study, a two-PSR model was chosen as the chemical reactor model for the JSR. The predictions of NO formation in lean premixed methane-air combustion in the JSR were carried out by using CHEMKIN and GRI 3.0 methane-air combustion mechanism which include the four NO formation mechanisms. The calculated results were compared with Rutar's experimental data for the validation of the model. The effects of important parameters on NO formation and the contributions of the four NO pathways were investigated. In the flame region, the major pathway is the prompt mechanism, and in the post flame region, the major pathway is the Zelodovich mechanism. Under the lean premixed condition, the N2O mechanism is the important pathway in both flame and postflame regions.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2012.04a
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• pp.34-37
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• 2012

환기부족 구획화재에서 CO의 생성은 온도 및 조성에 큰 영향을 받으며, 구획 내의 체류시간 및 이동경로에 따라 복잡한 현상을 경험하게 된다. 그 결과 구획 내부의 CO 생성특성을 실험을 통해 상세하게 규명하는 것은 많은 한계가 있다. 이러한 배경 하에 본 연구에서는 환기부족 구획화재의 조건에서 총괄당량비에 따른 CO의 생성특성에 관한 수치해석 연구를 수행하였다. PSR(완전혼합반응기) code와 헵탄연료의 상세화학반응기구가 사용되었다. 주요 변수로서 체류시간, 온도, 반응물과 생성물의 혼합정도 그리고 열손실 등이 CO의 생성에 미치는 독립적 영향을 검토하였다. 추가로 주요반응에 의한 CO의 몰 생성률 및 소모율과 CO의 반응경로 분석을 통해 환기부족 구획화재의 조건에서 구체적인 CO 생성특성에 관한 이해가 시도되었다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.7
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• pp.89-96
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• 2006

The combustion temperature in gas generator should be kept below around 1,000K to avoid any possible thermal damages to turbine blade by adopting either fuel rich or oxidizer rich combustion. Thus, non-equilibrium chemical reaction dominates in the gas generator. Meanwhile, Kerosene is a compounded fuel mixed with various types of hydrocarbon elements and difficult to model the chemical kinetics. This study focus to model the non-equilibrium chemical reaction of kerosene/LOX with detailed kinetics developed by Dagaut using PSR(Perfectly stirred reactor) assumption. Also, droplet evaporation time is taken into account by calculating for the residence time of droplet and by decoupling reaction temperature from the reactor temperature. In Dagaut’s surrogate model for kerosene, chemical kinetics of kerosene consists of 1592 reaction steps with 207 chemical species. The comparison of calculation results with experimental data could provide very reliable and accurate numbers in the prediction of combustion gas temperature, species fraction and other gas properties.

• Journal of Korea Soil Environment Society
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• v.2 no.3
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• pp.23-30
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• 1997

The purpose of this study was to evaluate effects of solids content and mixing speed in treatment of petroleum hydrocarbon contaminated soils using a slurry-phase bioreactor. Performance results on slurry-phase bioremediation of diesel fuel contaminated soil were generated at the bench-scale level. The fate of TPH(Total Petroleum Hydrocarbon) was evaluated in combination with biological treatment. Abiotic and biotic fate of the TPH were determined using soil not previously exposed to compounds in diesel fuel. The reactor volume for given throughput can be reduced by maximizing the solids content. Applications of 50% and 20% solids content(dry weight basis) were showed a little difference(57.5% : 61.6%) in biological TPH removal rate each other. Mixing and particle suspension are critical to desorption and biological degradation. In this standpoint, this study was performed using two mixing speed. When the reactor was operated at 70rpm, it had a better result in the particle suspension and TPH removal rate than the reactor with mixer rotated at 20rpm. In the reactor applied 20rpm, it was resulted in failure of particle suspension.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.2
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• pp.225-232
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• 2012

A chemical reactor network (CRN) was developed for a lean premixed gas turbine combustor to predict the emission of pollutants such as NOx and CO. In this study, the predictions of NOx and CO emissions from lean premixed methane-air combustion in the gas turbine were carried out using CHEMKIN and a GRI 3.0 methane-air combustion mechanism, which includes the four NO formation mechanisms for various load conditions. The calculated results were compared with experimental data obtained from a modified test combustor to validate the model. The contributions of the four NO pathways were investigated for various load conditions. The effects of nonuniformity of the mass flux and of the equivalence ratio of the injector on the NOx formation were investigated, and a method of reducing the pollutant formation was suggested for the development of a sub-10 ppm gas turbine combustor.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.7
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• pp.1465-1472
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• 2009

The effect of heat loss rate on NOx formation of $CH_4/air$premixed flame were examined numerically in a perfectly stirred reactor. The following conclusions were drawn. Under the adiabatic wall condition, an increase in the residence time causes a remarkable increases in NOx emission. Under the heat loss conditions, however, NOx decreases significantly as the heat transfer coefficient and residence time increase. As the heat loss rate increases, Thermal NO mechanism and Re-burning NO mechanism play an important role in the NOx reduction, but Prompt NO mechanism and $N_2O$-intermediate NO mechanism lead to the increase in NOx production. Although the NOx formation is actually related to complex NOx mechanism with the changes in the heat transfer coefficient and residence time, it was found that NOx concentration can be represented by independent Thermal NO mechanism. From these results, new NOx correlation combined with the heat loss rate and residence time was suggested for predicting the NOx concentration in a practical $CH_4/air$premixed combustor.

• Journal of Energy Engineering
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• v.23 no.3
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• pp.125-131
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• 2014

In order to increase landfill gas (LFG) production with food waste leachate, this study was confirmed to be acidogenetic conditions for landfill site injection. Thereby, it was conducted for acidogenetic treatments to determine the decrease in viscosity and VFA production. After acidogenesis treatments, solubility of food waste leachate increased approximately 15%, and as a result, UASB and CSTR were similar by reactor type using the change of retention time. Based on the result of the change in viscosity by reactor type, efficiency of UASB showed approximately 11.38% of higher decrease in viscosity as $76.95{\pm}3.27%$ vs. CSTR. Also, VFA production showed the higher increase of 2.01 times (UASB) and 1.76 times (CSTR) respectively at the point of increasing retention time from 3 to 5 days. From the above results, efficiency of UASB in a reactor was relatively higher because large molecular lead to longer retention time than small molecular due to having screen effect in the fixed media.

• Journal of Aquaculture
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• v.7 no.4
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• pp.239-249
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• 1994

This study was conducted to elucidate mixing characteristics of the media to dertermine hydraulic model parameters of the three phase fluidized bed for the water quality management of aquaculture. The volume and H/D ratio of the reactor were 1.76 Liter and 10.9, respectively. The experimental results showed that variance $(\sigma^2)$ and dispersion number $(D/{\mu}L)$ were above 0.47 and $0.35\~\infty$, respectively. Therefore, the condition of the reactor was almost ideal complete mixing. The dependence of the overall oxygen-transfer coefficient $(K_{La})$ on each experimental variables through a multple linear regression was given by the following equation ; $$K_{La}\;=\;44.9(D_i/D_c)^{-0.4611}\;A_f^{0.8622}\;C_m^{-0.0746}\;d_p^{-0.4302}$$

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.3
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• pp.74-79
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• 2005

The Homogeneous Charge Compression Ignition(HCCI) combustion is currently under intensive investigation because of its potential to increase thermal efficiency while greatly decreasing NOx and p.M. In order to account for the thermal boundary layer effects, the two-zone model has been developed to analyze the combustion characteristics of HCCI engine. The detailed chemistry are represented by the GRI mechanism 3.0 involving 53 species and 325reactions. The present combustion model has been validated against the experimental results. Computations are also made for the wide-range operating conditions of HCCI engine.