• Transactions of the Korean hydrogen and new energy society
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• v.23 no.3
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• pp.227-235
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• 2012

Finding an alternative fuel and reducing environmental pollution are the main goals for future internal combustion engines. The purpose of this study is to obtain low-emission and high-efficiency by hydrogen enriched LPG fuel in constant volume chamber. An experimental study was carried out to obtain fundamental data for the combustion and emission characteristics of pre-mixed hydrogen and LPG in a constant volume chamber (CVC) with various fractions of hydrogen-LPG blends. To maintain equal heating value of fuel blend, the amount of LPG was decreased as hydrogen was gradually added. Exhaust emissions were measured using a HORIBA exhaust gas analyzer for various fractions of hydrogen-LPG blends. The results showed that the rapid combustion duration was shortened, and the rate of heat release elevated as the hydrogen fraction in the fuel blend was increased. Moreover, the maximum rate of pressure rise also increased. These phenomena were attributed to the burning velocity which increased exponentially with the increased hydrogen fraction in the $H_2$-LPG fuel blend. Exhaust HC and $CO_2$ concentrations decreased, while NOX emission increased with an increase in the hydrogen fraction in the fuel blend. Our results could facilitate the application of hydrogen and LPG as a fuel in the current fossil hydrocarbon-based economy and the strict emission regulations in internal combustion engines.

• Journal of the Korean Society of Propulsion Engineers
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• v.6 no.2
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• pp.29-36
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• 2002

Experiments have been performed to investigate the effect of secondary venturi tip angle on flow and spray characteristics in gas turbine combustor with a swirl cup assembly. Three variations of secondary venturi tip angle are made: converging, straight and diverging angles. It is found that the variation of venturi tip angle results in the significant changes of flow and spray characteristics in gas turbine combustors, such as the size and location of recirculation zones. drop size and mass distribution affecting combustion efficiency and NOx emissions. In diverge case, central toroidal recirculation zone(CTRZ) exists near the exit, which is known to be beneficial for flame stability. But in converge case, the finest SMD distribution and uniform mass distribution are found and CTRZ is longer than other cases. Consequently, high combustion efficiency and low pollutant emission are expected in converge case.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.11a
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• pp.449-452
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• 2008

Flow difference between reacting and non-reacting case in a swirl stabilized annular combustor is investigated using 3D Large Eddy Simulation with flamelet turbulent combustion model. The combustor of concern is the LM6000, lean premixed dry low-NOx annular combustor, developed by GEAE. Boundary conditions are based on experimental data. Heat release as a result of combustion put the dilatation of density in primary combustion zone highly increased so that the main swirl stream behind of a swirl cup stretched further downstream than that of non-reacting case. The oval shape of core flow in cross-section to flow direction, which clearly observed in non-reacting case, tends to be circle, and small vorticities in wide range in non-reacting case disappears, but the size of iso-vorticity increase in reacting case.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.04a
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• pp.439-444
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• 2011

Doosan Heavy Industries & Construction Co., Ltd. has been recently developing the gas turbine engine using the biogas as fuel. This paper describes the non-reacting and reacting flow analysis of the combustor which is one of the main components in gas turbine engine. Through CFD analysis, investigation has been performed to evaluate the primary factors for aerodynamic design and to predict combustor behaviors during operation with various fuel distribution ratios. The calculation results are compared with rig test data, which reveals that CFD predictions such as pressure loss, air distribution ratio, and recirculation flow are quite reliable. The trend of NO formation was similar with the test, except the low fuel distribution ratio.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.3
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• pp.451-458
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• 2022

In Korea, five major ports have been designated as sulfur oxide emission control areas to reduce air pollutant emissions, in accordance with Article 10 of the "Special Act on Port Air Quality" and Article 32 of the "Ship Pollution Prevention Regulations". As regulations against vessel-originated air pollutants (such as PM, CO2, NOx, and SOx) have been strengthened, the Ministry of Oceans and Fisheries(MOF) enacted rules that newly built public ships should adopt eco-friendly propulsion systems. However, particularly in diesel-electric hybrid propulsion systems,the demand for precise control schemes continues to grow as the fuel saving rate significantly varies depending on the control strategy applied. The conventional Power Take In-Power Take Off(PTI - PTO) mode control adopts a rule-based strategy, but this strategy is applied only in the low-load range and PTI mode; thus, an additional method is required to determine the optimal fuel consumption point. The proposed control method is designed to optimize fuel consumption by applying the equivalent consumption minimization strategy(ECMS) to the PTI - PTO mode by considering the characteristics of the specific fuel oil consumption(SFOC) of the engine in a diesel-electric hybrid propulsion system. To apply this method, a specific fishing vessel model operating on the Korean coast was selected to simulate the load operation environment of the ship. In this study, a 10.2% reduction was achieved in the MATLAB/SimDrive and SimElectric simulation by comparing the fuel consumption and CO2 emissions of the ship to which the conventional rule-based strategy was applied and that to which the ECMS was applied.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.7
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• pp.692-698
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• 2020

This paper examines the effects of a multi-stage pilot split injection strategy on combustion and exhaust emission factors in a single-cylinder diesel engine. One analysis noted that in the single-injection condition, the maximum in-cylinder pressure and rate of heat release were highest. The pilot injection quantity was evenly divided, showing a tendency to decrease as the number of injections increased. In another injection condition, when the multi-stage pilot split injection strategy was applied, IMEP, engine torque, and combustion increased. The COV_IMEP was greatest with the lowest combustion efficiency. The combustion ability was poor. In a single injection condition, the O₂ concentration in the exhaust gas was the lowest and the CO₂ was the highest. When the multi-stage split injection strategy was applied, the low temperature combustion process proceeded, and the oxidation rate of CO₂ decreased while the emission level increased. In a single injection condition in which a locally rich mixture was formed, the HC emission level showed the highest results. A 55.6% reduction of NOx emission occurred under a three-stage pilot injection condition while conducting a multi-stage pilot split injection strategy.

• Korean Chemical Engineering Research
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• v.49 no.6
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• pp.857-864
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• 2011

Oxy-fuel combustion with many advantages such as high combustion efficiency, low flue gas flow rate and low NOx emission has emerged as a promising CCS technology for coal combustion facilities. In this study, the effects of the direct sulfation reaction on $SO_2$ removal efficiency were evaluated in a drop tube furnace under typical oxy-fuel combustion conditions represented by high concentrations of $CO_2$ and $SO_2$ formed by gas recirculation to control furnace combustion temperature. The effects of the operating parameters including the reaction temperature, $CO_2$ concentration, $SO_2$ concentration, Ca/S ratio and humidity on $SO_2$ removal efficiency were investigated experimentally. $SO_2$ removal efficiency increased with reaction temperature up to 1,200 due to promoted calcination of limestone reagent particles. And $SO_2$ removal efficiency increased with $SO_2$ concentrations and the humidity of the bulk gas. The increase of $SO_2$ removal efficiency with $CO_2$ concentrations showed that $SO_2$ removal by limestone was mainly done by the direct sulfation reaction under oxy-fuel combustion conditions. From the impact assessment of operation parameters, it was shown that these parameters have an effects on the desulfurization reaction by the order of the Ca/S ratio > residence time > $O_2$ concentration > reaction temperature > $SO_2$ concentration > $CO_2$ concentration > water vapor. The semi-empirical model equation for to evaluate the effect of the operating parameters on the performance of in-furnace desulfurization for oxy-fuel combustion was established.

• Journal of Energy Engineering
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• v.23 no.2
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• pp.42-48
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• 2014

Soot and tar which were derived from combustion or pyrolysis processes in Puverized Coal(PC) furnace or boiler have been significantly dealing in a radiative heat transfer and an additional source of NOx. Furthermore, the increasing for the use of a coal with low caloric value gives rise to a lot of tar-soot yield and LOI in a recycled ash for using cement materials. So, the ash with higher tar-soot yield and LOI can not recycle due to decreased strength of concrete. In this study, tar-soot yields and flame structures were investigated using the LFR for a blending combustion with bituminous coal and sub-bituminous coal. Also, The investigation were conducted as each single coals and blending ratio. The coals are used in a doestic power plant. In the experimental results, sub-bituminous coal with high volatile contents shows longer soot cloud length than bituminous coal, but overall flame length was shorter than bituminous coal. Tar-soot yields of sub-bituminous coal is lower than those of bituminous coal. Combustion characteristics are different between single coal and blended coal. Therefore, finding an optimal coal blending ratio according to coal rank effects on tar-soot yields.

• Journal of the Korean Society of Urban Environment
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• v.18 no.4
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• pp.511-521
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• 2018

Despite the limitations and difficulty in the application of CALINE3 model for air dispersion prediction of roads and tunnels construction businesses in South Korea, the model is being used in all roads construction projects. This study compared the predicted values of CALINE3 and AERMOD model that is suggested by the US EPA, to the values of GRAL model, a Lagrangian particle tracking model developed in Europe, by applying the models to the existing roads of the urban areas. The result showed low relevance to the actual measurement value in the case of CALINE3 model, thus displaying a low trusted value when applying to the urban areas. In the case of using AERMOD model, the predicted values were overly expressed compared to the actual measurement value, thus leading to the need of adding a No2 conversion method to the model in the future. In the case of GRAL model, a Lagrangian particle tracking model, the relevance between the actual and predicted values were high as the model considers the surrounding topography and the buildings all together, thus confirming that the model can be used for air dispersion prediction of the roads in the urban areas. Lastly, the result of this study testing the air prediction models in Jeongneung Measuring Station points that it is necessary for the future studies to expand the testing areas and test the validity of the models continuously.

• Journal of Korean Medicine Rehabilitation
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• v.33 no.2
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• pp.1-18
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• 2023

Objectives The purpose of this study was to evaluate the antioxidant, anti-inflammatory and wound healing effects of Samul-tang-ga-dansam water extract (SD) in wound-induced mice. Methods The mice were divided into five groups (n=7): the normal group, the control group, the positive control group, the low-dose SD group and the high-dose SD group. The normal group had no wounds and the other groups were wounded on the back with a leather punch. Distilled water was administered to the control group, 200 mg/kg of vitamin E was administered to the positive control group. In the low-dose SD group and the high-dose SD group, 1.23 g/kg and 2.47 g/kg of SD were administered, respectively. Antioxidant and anti-inflammatory protein levels were evaluated using western blot analysis. Skin tissue was analyzed by H&E, Masson's trichrome staining method. Results Oral administration of the SD significantly reduced the visible skin damage and decreased the reactive oxygen species and ONOO^- activity of the serum. It significantly increased heme oxygenase-1, superoxide dismutase, catalase, GPx-1/2, Nrf2 and Keap-1 which are antioxidant-related factors in skin tissue and reduced NF-κB p65, inducible nitric oxide synthase, cyclooxygenase-2, tumor necrosis factor α, interleukin (IL)-1β, IL-6 which are inflammation-related factors. Also, SD significantly decreased NOX2, p22^phox and p47^phox and increased α-smooth muscle actin and COL1A1 protein expression in fibroblasts involved in connective tissue repair. According to histological examination, the thickened epithelial layer was thinned and collagen fibers were increased to accelerate wound healing. Conclusions It is suggested that Samul-tang-ga-dansam has antioxidant and anti-inflammatory effects and promotes wound tissue repair.