• Journal of the korean Society of Automotive Engineers
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• v.2 no.1
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• pp.9-20
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• 1980

디이젤기관의 냉시동성이 가솔린기관에 비하여 떨어지는 것은 이미 우리가 알고 있는 사실이다. 근년에는 소형트럭, 승용차, 소형건설기계 등의 분야에 있어서도 고속디이젤기관을 널리 사용하게 되었고 앞으로 디이젤연료의 중질화 및 세탄가 저하의 영향 등을 고려할 경우 시동성의 확보는 더욱 중요한 문제로 된다. 시동성에 영향을 미치는 인자 혹은 시동성개선의 방책으로서는 분 무의 착화에 직접 관련되는 것 외에 축전지의 저온특성 혹은 기관의 마찰토오크 등 여러가지에 걸쳐 있으나 이들 중에서 특히 분무의 착화에 직접 관련되는 방책에 관해서는 그것이 시동성에 미치는 영향에만 그치는 것이 아니고 시동개시직후에 있어서 배출가스, 혹은 출력성능 등에 미 치는 영향에 대해서도 함께 고려를 하여야 할 경우가 있다. 본고에 있어서는 냉시동시의 분무의 착화에 대하여 직접 관련하거나 그것을 촉진시킨다고 생각되는 몇개의 인자와 구체적인 방책을 취급하므로써 그것들이 시동성 및 시동직후의 청백연 혹은 출력성능 등에 대하여 미치는 영향에 대해서 기술하며 아래에서 취급되는 시동시의 착화를 촉진하기 위한 실제적인 인자 및 방책은 어느 것이나 기본적으로는 하나의 개념에 집약된다. 즉 그것은 연표와 효소로부터 이루어지는 연소계에 있어서 착화조건을 갖추어야함을 말할 것도 없다.

• Nuclear Engineering and Technology
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• v.27 no.4
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• pp.603-618
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• 1995

원자력 발전소 및 동위원소 사용기관에서 발생되는 가연성 고체 폐기물 및 유기폐액의 소각기술의 활용에 있어서 이의 안전성 확보를 위한 기술적 기준의 설정을 위한 고려인자들을 조사하였다. 국내외의 소각기술 활용현황을 알아보았고 본 기술의 국내 도입시 필요한 기술적 안전지침에 관한 외국의 사례를 조사하고 국내 관련 규정도 검토, 비교, 분석하여 주요 고려항목을 도출하였다. 안전성 확보를 위한 고려 항목을 크게 일반산업시설 적용항목, 원자력시설 상 안전조건, 소각시설의 기술적 요구사항, 기타 제반사항으로 나누어 제시할 수 있었다. 이들 내용은 기존 원자력 및 환경시설에 적용되는 안전성분석보고서 및 환경영향평가서로 작성될 수 있다고 보았으며 시설의 개요, 시설의 기술적 사항과 이에 따르는 안전을 위한 조건, 폐기물의 인수조건 등이 포함되며 기존 관련 법규의 적용 및 확인이 필요하였다. 기술적 사항에는 공정의 제염계수, 연소효율, 소각재의 형상, 배기가스의 방출농도, 작업자 및 인근주민의 피폭등이 확인되어야 하며 소각재의 처리방법 및 조건이 제시되어야 하고 소각재의 침출특성 등이 주요한 인자라고 보았다. 아울러 소각대상폐기물의 인수조건이 명시되어 소각성능에 따른 이의 안전성이 입증되어야 한다. 따라서 인허가 후 건설된 시설에서의 사용전 시험소각절차의 제시 및 이에 대한 관련 규제기관의 검사제도가 있어야 하며 품질보증절차 역시 관련지침에 따라 실시되어야 한다. 이와 같은 내용을 포함하는 안전기술지침의 설정이 절대적으로 필요하며 본 연구조사 결과의 활용이 기대된다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.8
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• pp.720-725
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• 2007

Cold acoustic tests have been performed to elucidate the effect of baffle gaps on the optimal damping characteristics in a liquid rocket combustor where coaxial injectors are installed. For several axial baffle lengths, an optimal acoustic damping capacitance has been achieved in a certain gap range. Cold acoustic tests for simulating fluid viscosity by changing the pressure in a model chamber have been done to study the main mechanism of optimal damping. Experimental data have shown that the optimal gap for high damping capacity exists mainly due to the viscosity near the gap of baffles. Therefore, axial baffle length can be reduced by using the optimal baffle gap, providing a possible solution of thermal cooling problems. Also, these optimum characteristics can be some guidelines for manufacturing and assembling injectors in full-scaled rocket combustors.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.82-85
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• 2009

In the development of Liquid Rocket Engine(LRE) systems, it is essential to understand the spray characteristics which influence mainly the performance and the stability of combustion. The injectors for this study have a recessed Liquid-swirl/Gas-centered jet coaxial type. For the similarity with actual conditions, the experimental conditions are calculated by using the momentum ratio as a matching parameter, and the stimulants of fuel and oxidizer are gaseous nitrogen and water respectively. The spray fields were measured by means of a photographic technique. Moreover, an effect of the momentum ratio has been investigated.

• 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.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.05a
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• pp.135-140
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• 2006

In the experimental study of $N_2$ purge cold flow test of impinging(FOOF) injector for determining of instability region, the whistling sound which has a specific frequency is generated. The frequency of whistling is proportional to the gas flow velocity in part of the oxidizer orifice and due to the coupling of the vibrating gas column and the natural frequency of pipe-orifice shape, the discontinuous jumping phenomena arises. The whistling phenomena have no effect on the combustion instability. Compared the damping factor of 1T1L mode with the hot fire test, the instability region of $N_2$ purge cold flow test is very much like that. It means that flow instability by impinging or mixing of jet is the main reason of combustion instability of impinging injector(FOOF) in the hot firing test.

• Journal of the Korean Institute of Gas
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• v.27 no.3
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• pp.1-10
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• 2023

Due to the development of the industrial revolution, regulations on exhaust emissions have been continuously strengthened to reduce the rapidly increasing greenhouse gas emissions. The use of environmentally friendly fuels is essential to meet these regulations. Hydrogen has been attracting attention as a future environmentally friendly fuel, but due to its material properties, it faces significant challenges in handling and storage. As an alternative, ammonia has been proposed. Ammonia can be easily liquefied at room temperature compared to hydrogen and has a high energy density. In order to examine the applicability of ammonia as an engine fuel, experiments were conducted to investigate the effects of changes in combustion control parameters in a direct injection ammonia combustion engine. The experiments were conducted by varying two variables: spark timing and excessive air ratio. Observations were made on combustion stability and the trends of exhaust emissions such as nitrogen oxides and unburned ammonia under the conditions of an engine speed of 1,500 rpm and medium to high loads (brake torque of 200 Nm). By optimizing the combustion control parameters, conditions for stable combustion even when using ammonia as the sole fuel were identified, and plans are underway to apply strategies for future expansion of the operating range.

• Journal of the Korean Institute of Gas
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• v.19 no.6
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• pp.8-14
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• 2015

Synthetic natural gas(SNG), acquired from coal, is regarded as an alternative to natural gas since a rise in natural gas due to high oil price can be coped with it. In the present study, 11-liter heavy duty compressed natural gas(CNG) engine was employed in order to examine the combustion and emission characteristics of SNG. The simulated SNG, made up 90.95% of methane, 6.05% propane and 3% hydrogen was used in the experiment. Power output, thermal efficiency, combustion stability and emission characteristics were compared to those with CNG at the same engine operating conditions. Knocking phenomenon was also analyzed at 1260 rpm, full load condition. Combustion with SNG was more stable than CNG. Nitrogen oxides emissions increased while Carbon dioxides emissions decreased. Anti-knocking characteristics were improved with SNG.

• Aerospace Engineering and Technology
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• v.8 no.1
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• pp.17-25
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• 2009

The precise calculation of gas absorption coefficient in the radiative transfer equation is very important to the prediction of radiative heat transfer induced from liquid engine plume in view of base insulation design. For this purpose, the WNB model for gas absorption coefficient is described with the selection of important parameters and then the calculated results are compared with those of SNB model for validation. Total emissivity, narrow band averaged intensity and total intensity are calculated and compared to the results of SNB model. As results, the total emissivity and the total intensity are well matched within 3.1% and roughly 5 % error, respectively. Moreover, the gas modeling database is constructed with estimation of the combustion gas composition of $CO_2$ and $H_2O$ for liquid engine plume.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.05a
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• pp.168-172
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• 2008

Hot firing tests of sub-scale combustors were carried out to study the characteristic velocity according to the variation of propellant mass flow and injector arrangement. Test results show that there exists an effective range of relative flow-rate density on the condition of similar combustion pressure and mixture ratio. Numerical analysis has also revealed that the increase of the distance between the outermost injector array and the cylindrical chamber wall with film cooling increases the region of low mixture ratio near combustion chamber wall and it decreases the characteristic velocity of the combustor. Thus, it was confirmed that these two factors play an important part in improving the performance of LRE combustor on a predetermined chamber pressure.