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류봉우(Bong Woo Ryu),연인모(In Mo Youn),박성욱(Sung Wook Park),이창식(Chang Sik Lee) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.5
The combustion characteristics of dimethyl ether (DME) were investigated using the experimental and numerical methods. For the numerical approach, the combustion characteristics of DME fueled engine were predicted by 3D-CFD code, KIVA code coupled with the CHEMKIN (KIVA-CHEMKN) and the spray calculation was conducted by considering the thermo-chemical properties of DME. In order to calculate the fuel oxidation and emission formation (NOx), a detailed chemical kinetic mechanism which was composed of 83 species and 360 reaction paths was considered. The pressure of combustion chamber from the calculation agrees well with the measurements from the test engine. The amount of NOx emission has a good agreement to experiments.
디젤 기관의 분사 조건이 DME 연료의 분사특성에 미치는 영향
류봉우(Bong Woo Ryu),방승환(Seung Hwan Bang),서현규(Hyun Kyu Suh),이창식(Chang Sik Lee) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
The purpose of this work is to investigate the injection rate of dimethyl ether (DME) fuel by using injection rate system and compare it with diesel fuel. In order to analyze the injection rate of DME fuel, an injection rate system composed of a piezoelectric sensor, injection line, the adapter tilled with fuel. and relief valve. For the acquisition of fuel pressure wave variation, a piezoelectric sensor was installed in the injection chamber tilled with fuel and relief valve was utilized to keep the constant pressure in the injection line. The experiments are performed at various injection pressure and energizing duration to analyze their effects on injection rate. It was found that DME fuel was higher injection rate than diesel fuel according to various experimental condition. In the case of injection quantities, DME fuel was larger than diesel fuel before 0.5 ㎳ of time after start of energizing and then reverse tendency was shown after 0.5 ㎳. It can be said that DME fuel was a shorter injection delay and longer actual injection delay than diesel fuel because of a lower kinetic viscosity.
축소반응기구를 이용한 DME 엔진의 연소 및 배기 특성에 관한 수치 해석
류봉우(Bong Woo Ryu),오윤중(Yun Jung Oh),박성욱(Sung Wook Park),이창식(Chang Sik Lee) 한국연소학회 2010 KOSCOSYMPOSIUM논문집 Vol.- No.41
This study performed the numerical simulation of chemical reaction mechanism for ignition and combustion phenomena of dimethyl ehter (DME) in a diesel engine using KIVA-CHEMKIN code. The reduced reaction mechanism which was consisted of 44 species and 166 reactions was obtained from the base detailed reaction mechanism which was composed of 79 species and 351 reaction steps. The spray combustion and emission characteristics when applying the reduced reaction mechanism were validated by comparing with applying the detailed reaction mechanism and the calculation time reduction ratio was also evaluated. The calculation accuracy of the reduced reaction mechanism was good agreement with that of the detailed reaction mechanism for combustion and emission characteristics under various injection timings and the calculation time was reduced about 45% at the conditions that the chemical reaction was frequently generated.
류봉우(Bong Woo Ryu),방승환(Seung Hwan Bang),이창식(Chang Sik Lee) 한국자동차공학회 2007 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
The purpose of this study is to investigate the injection and spray characteristics of dimethyl ether (DME) compared with diesel fuel that were injected through a common-rail injection system in a diesel engine. In order to analyze the spray behavior of DME and diesel, injection rate profiles and spray development process were obtained by using an injection rate measuring system and a spray visualization system. For the analysis of injection and spray characteristics of both fuels. experiments were conducted at various injection parameters such as injection pressure, injection angle and energizing duration. The results showed that the DME spray had shorter injection delay, longer injection duration, and lower maximum injection rate than diesel under identical experiment conditions due to the difference of fuel properties. In addition, spray development of DME had evaporating characteristics and shorter spray tip penetration than that of diesel owing to lower density of fuel.
디젤엔진에서 분사조건이 연소 및 배기 특성에 미치는 영향 예측
류봉우(Bong Woo Ryu),김형준(Hyung Jun Kim),이제형(Je-Hyung Lee),이창식(Chang Sik Lee) 한국자동차공학회 2008 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
This study numerically investigated the combustion and emission characteristics in accordance with single and split injection conditions. Numerical analysis was performed by using the AVL-FIRE code with the ECFM-3Z combustion model. In-cylinder pressure profiles of calculation results had good agreement with experimental results. In case of early injection (40° BTDC), the combustion and emission characteristics of single injection were deteriorated due to the occurrence of the wall wetting at both the piston head and cylinder liner. However the split injection led to lower the amount of wall wetting and increase the combustion pressure and indicated mean effective pressure (IMEP) through the wide distribution of air-fuel mixture in the cylinder.
류봉우(Bong Woo Ryu),박성욱(Sung Wook Park),이창식(Chang Sik Lee) 대한기계학회 2011 大韓機械學會論文集B Vol.35 No.1
디젤의 대체연료인 디메틸 에테르의 반응기구 축소에 관한 수치해석을 수행하였다. 상세반응기구(79 개의 화학종과 351 개의 반응단계)를 기초로, 최대몰농도 해석과 민감도 해석을 균질반응기 모델에 적용하였다. 축소반응기구는 상세반응기구의 착화지연기간과 비교하여 구축하였는데, 기준값으로 7.5×10?? 을 적용했을 때 44 개의 화학종과 166 개의 반응단계로 구성된다. 축소반응기구의 계산 정확도를 검증하기 위하여 두 반응기구를 단일영역 균일예혼합 압축착화 엔진모델에 적용하였고, 축소반응기구의 계산결과는 상세반응기구의 결과와 일치하였다. 따라서 본 연구의 축소반응기구는 계산의 정확도의 손실 없이 DME 를 연료로 사용하는 압축착화엔진의 착화 및 연소 과정을 모사하는데 이용될 수 있다. The numerical analysis of the reduction of reaction mechanism for the ignition of dimethyl ether (DME) was performed. On the basis of a detailed reaction mechanism involving 79 species and 351 reactions, the peak molar concentration and sensitivity analysis were conducted in a homogeneous reactor model. The reduced reaction mechanism involving 44 species and 166 reactions at the threshold value 7.5 × 10?? of the molar peak concentration was established by comparing the ignition delays the reduced mechanism with those the detailed mechanism. The predicted results of the reduced mechanism applied to the single-zone homogeneous charge compression ignition (HCCI) engine model were in agreement with those of the detailed mechanism. Therefore, this reduced mechanism can be used to accurately simulate the ignition and combustion process of compression ignition engine using DME fuel.
류봉우(Bong Woo Ryu),박성욱(Sung Wook Park),이창식(Chang Sik Lee) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.5
본 연구는 단열, 정적 상태의 반응기 모델을 이용하여 디메틸 에테르 연료의 축소반응기구를 개발하고, 압축착화엔진의 운전조건과 유사한 초기압력과 초기온도, 당량비의 계산조건에서 상세반응기구와의 착화지연기간에 대한 비교를 통해 축소반응기구의 정확성을 검증하였다. 현존하는 상세반응기구(78 개의 화학종과 351 개로 구성)를 기초로 최대몰농도해석, 반응율해석, 민감도해석 등을 통해 44 개의 화학종과 166 개의 반응단계로 구성된 축소반응기구를 구성하였다. 본 연구방법은 반응단계의 형태나 반응상수의 변화없이 반응식을 축소시키는 골격화 방법을 기초로 하고 있기 때문에 착화지연기간에 대한 정확도의 손실을 최소화할 수 있다. In the present study the reduced reaction mechanism for dimethyl ether (DME) fuel was developed by using 0-D homogeneous reactor model and was validated by comparison of the ignition delay data for the reduced reaction mechanism with those for the detailed reduced reaction under the various initial pressures, initial temperatures, and equivalence ratios such a similar operating conditions of compression ignition engine. The peak molar concentration analysis, reaction flux analysis, and sensitivity analysis was conducted from the basis of the existing comprehensive reaction mechanism that consisted of 79 species and 351 reactions, the reduced reaction mechanism was therefore generated as it contained 44 species and 166 reaction steps. The reduction process of this paper largely based on the skelatalization method, in which is the methodology to reduce the master mechanism without changing the form of reactions or constants of reaction rate, can minimize the loss of accuracy of ignition delay predictions.