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밀폐 연소실내의 메탄-공기 예혼합기의 연소 및 라디칼 특성에 관한 연구 (1)
전충환,장영준,Jeon, Chung-Hwan,Jang, Yeong-Jun 대한기계학회 1996 大韓機械學會論文集B Vol.20 No.2
To clarify the effects of equivalence ratio, initial pressure and temperature on the flame propagation and radicals characteristics, a series of the experimental study were conducted in a quiescent methane-air premixture using a constant volume chamber. The development of the flame was visualized following the start of ignition using high speed schlieren photo and radical images by intensified CCD camera. Combustion pressure and ion current were recorded simultaneously according to the experimental conditions which were equivalence ratio with 0.7 to 1.2, initial pressure with 0.08 MPa to 0.40 MPa and initial premixture temperature with 3l3.2K to 403.2K. The results showed that the flame speed by ion current and mass fraction burned by combustion pressure characterized the effects of flame propagation very well. And increased combustion duration due to lean combustion condition that was below equivalence ratio, 0.8 caused cycle variation and decreasing the power of engine.
선박용 엔진의 텀블형상 및 내부유동 특성에 관한 수치 해석적 연구
전충환(Chung-Hwan Jeon),이병화(Byoung-Hwa Lee),김호성(Ho-Sung Kim) 한국마린엔지니어링학회 2007 한국마린엔지니어링학회 학술대회 논문집 Vol.2007 No.-
Many researches have been studied on in-cylinder flow as one of dominant effects for an engine combustion. Specially because the combustion flame speed is mainly determined by the turbulence at the end of compression process. Tumble and Turbulence ahead of combustion is changed according to combustion figure, compression ratio, RPM like this kind of operation condition, and it has much influence on combustion stability. As this phenomenon make research certainly, combustion stability and effectivity will be improve. This paper describes analytical results of the tumble flow, intensity, turbulence inside the cylinder of maritime engine. 3-D computation has been performed by using STAR-CD v3.26 solver and es-ice.
탈휘발화 과정에서 혼탄의 반응률과 열적 거동에 관한 연구
전충환 ( Chung Hwan Jeon ),유광일 ( Kwang Il Ryu ),김량균 ( Ryang Gyoon Kim ),이동방 ( Dong Fang Li ),오택림 ( Ze Lin Wu ) 한국화학공학회 2013 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.51 No.1
The objective of this research is to predict the TG curve of blends of bituminous coal and sub-bituminous coal during devolatilization. TSL (Thermal Shock Large) TGA was used for Experiments, and Coats-redfern method was used for reaction order calculation. Based on reaction order, sum method was verified to be suitable for a single coal, then, prediction and comparison of TG curve of coal blends was conducted using both of WSM (Weight Sum Method) and MWSM (Modified Weight Sum Method), where the latter was developed in this research. The presented experiment results and WSM & MWSM were showed to be reasonable using linear least square method. MWSM performed more accurately than WSM for the case that TG curve had different slopes and the case that sharp weight loss happened due to release of volatile matter. The results showed that it`s possible to predict the thermal behavior of coal blends during devolatilization based on the thermal behavior of single coals
LFR 장치를 이용한 입자 크기 변화에 따른 저열량 아역청 미분탄의 연소특성에 관한 실험적 연구
전충환(Chung-Hwan Jeon),김용균(Yong-Gyun Kim),김재동(Yong-Gyun Kim),김규보(Gyu-Bo Kim),송주헌(Ju-Hun Song) 대한기계학회 2010 大韓機械學會論文集B Vol.34 No.3
본 연구는 아역청탄의 미분탄 연소특성에 있어서, 입자크기가 미치는 영향을 알고자 실험을 통해 고찰한 것이다. 본 연구를 위하여, 온도 및 온도 상승률을 고려해 볼 때, 실제 미분탄 연소로의 환경을 잘 구현할 수 있는 층류반응기를 설계하고 이용하였다. 크기가 다른 미분탄 입자들이 탈 때 형성되는 화염구조 및 길이를 본 반응기를 이용해 조사하였다. 육안으로 관찰된 화염구조로부터 석탄연소과정들을 분명하게 구분할 수 있었다. 입자의 크기변동은 휘발분 점화개시점에 미치는 영향이 큰 반면, 휘발분의 연소시간에 미치는 영향은 가장 적었다. 입자의 크기가 커질수록 촤의 화염길이도 증가하였다. 화염불안정성 역시 입자가 커짐에 따라 증대되었다. 일정한 체류시간 간격내에서의 촤의 소비율은 거의 일정하였다. In this study, the effect of particle size on the combustion characteristics of pulverized sub-bituminous coal was experimentally investigated. A laminar-flow-entrained reactor was designed and implemented to realize the desired heating ratio and temperature corresponding to the combustion atmosphere of a pulverized-coal-fueled furnace. The flame length and structure of burning particles according to different sizes were investigated. Coal combustion processes were clearly distinguished by direct visual observation of the flame structure. The onset point of volatile ignition is greatly affected by changes in the particle size, and the burning time of the volatiles is least affected by changes in the particle size. The length and instability of char flame also increase with the increase of the particle size. However, the char consumption rate within the residential time remains nearly constant.
정적연소실내 메탄-공기 혼합기의 가연한계 및 연소특성에 관한 실험적 연구
전충환(Chung-hwan Jeon),양인규(In-gyu Yang),김현규(Hyunkyu Kim),송주헌(Ju-hun Song),장영준(Young-june Chang) 한국마린엔지니어링학회 2010 한국마린엔지니어링학회 학술대회 논문집 Vol.2010 No.4
Natural gas is a promising alternative fuel to meet strict engine emission regulations in many countries. The development of natural gas engines requires low emissions along with the demand for better fuel consumption and increased power ratings. In this study, a cylindrical Constant Volume Combustion Chamber(CVCC) was used to investigate the combustion characteristics under different ambient pressure and equivalence ratio. The maximum combustion pressure, heat release rate and mass fraction of burned gas was evaluated in particular by ambient pressure and equivalence ratio. It also show that variation of flammability limits according to existence of pre-chamber. This result could provide lean bum condition by analyzing combustion characteristics with ambient condition.
TMA를 이용한 국내 발전용 탄의 용융점 변화에 대한 연구
전충환 ( Chung Hwan Jeon ),이순호 ( Soon Ho Lee ),임호 ( Ho Lim ),김상도 ( Sang Do Kim ) 한국화학공학회 2014 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.52 No.2
The slagging which generated from ash deposition on furnace wall and tube in boiler reduces the heat transfer efficiency and damages to safety of boiler. The slag flow behavior in boiler is affected by melting temperature which is related to ash compositions. In this study, the behavior of slag is researched by using ash fusibility test, called TMA (Thermo-Mechanical Analysis). The technique measures the percentage shrinkage as the function of temperature, T25%, T50%, T75%, T90%. These temperatures indicate different stages of melting. Then, the effect of ash chemical compositions measured from XRF (X-ray Fluorescence Spectrometer) to ash fusion temperatures is discussed. Among the chemical compositions, refractory and fluxing influence on ash fusibility is described. High levels of refractory component and limited amount of fluxing components (Fe2O3, K2O, CaO) increase overall melting temperatures. High SiO2/Al2O3 ratio decrease high melting temperatures (T75%, T90%). Meanwhile, the presence of reasonable levels of fluxing components reduces overall melting temperature. A presence of fluxing component such as K2O and CaO is found to decrease the T25% values significantly. From this research, it is possible to make a reasonable explanation and prediction of ash fusion characteristic from analysis of TMA results and ash chemical compositions.
정적챔버에서 분위기 압력에 따른 비증발 디젤분무특성 연구
전충환(Chung-Hwan Jeon),정정훈(Jeong-Hoon Jeong),김현규(Hyun-Kyu Kim),송주헌(Ju-Hun Song),장영준(Young-June Chang) 한국마린엔지니어링학회 2010 한국마린엔지니어링학회지 Vol.34 No.4
본 연구의 목적은 다양한 분위기 압력 하에서 커먼레일 디젤인젝터를 통해 분사되는 비증발 디젤분무특성에 관한 연구이다. 디젤분무의 거시적 특성으로 분무관통거리와 분무각을 음영사진과 이미지프로세싱으로 연구하였다. 수치해석은 상용 CFD프로그램인 AVL-FIRE를 사용하였다. 분열모델은 WAVE모델을 사용하였으며 표준 k-ε난류모델을 적용하였다. 분무각과 Zeuch법을 적용한 연료 분사율을 수치해석의 입력값으로 사용하였다. 분무관통거리를 실험값과 비교하여 좋은 결과를 얻었고 수치해석을 통하여 노즐팁 하류방향으로 분무의 각 구간별 액적입경분포를 알아보았다. The aim of this investigation was study on the non-evaporation diesel spray characteristics injected through a common-rail diesel injector under various ambient pressure. The diesel spray was investigated with observation of macroscopic characteristics such as spray tip penetration and spray cone angle by the shadowgraph and the image processing method. The numerical study was conducted using a computational fluid dynamics code, AVL-FIRE. The breakup models used were WAVE model and standard k-ε turbulence model was applied. The numerical study used input data which spray cone angle and fuel injection rate was achieved by Zeuch's method. Comparison with experimental result such as spray tip penetration was good agreement. Distribution of droplet diameter were conducted on four planes where the axial distances were 5, 15, 39 and 49mm respectively downstream from the orifice exit.