열전달 특성에 따른 전기용해로 내부 온도예측에 관한 수치적 연구

한동식(Dong-Sik Han),전충환(Chung-Hwan Jeon),장영준(Young-June Chang),송주헌(Ju-Hun Song) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5

The main objective of this study is to analyze the heat transfer characteristics in the electric furnace. Local temperatures are measured at various locations in the furnace using the B-type thermocouples. In this paper, mathematical heat transfer model has been developed predict temperature distribution by considering the thermal radiation and transient conduction effect on heating element, crucible and furnace walls. The numerical simulation was performed using the ANSYS-Workbench software, and its results were compared with experimental data. The computational results show that the temperature distributions agreed well with experimental results. Finally, a difference in temperature behavior of the crucible was investigated as some heat transfer parameters change.

층류 순산소 연소에서 CO₂몰분율에 따른 매연 배출 특성에 관한 연구

최도욱(Do Wook Choi),김규보(Gyu Bo Kim),전충환(Chung Hwan Jeon),장영준(Youg June Chang),송주헌(Ju Hun Song) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.11

Oxy-fuel combustion is a reliable way for the reduction of pollutants, the higher combustion efficiency and the separation of carbon dioxide. In this study, An experimental study was performed to investigate the influence of soot emission in laboratory-scale oxy-fuel burner. The experimental conditions are fixed up fuel(CH₄) and oxidizer(O₂) rate. But inert gas(CO₂) rate was changed. Also the study was performed in the laminar diffusion flame. As an optical method, laser induced incandescence is useful to get the information for spatial and temporal soot emission. Therefore, Soot emission measurements were performed to the technique of laser induced incandescence(LII) and 2D image was detected by ICCD camera. As a result of this experimental study, confirmed to Characteristic of soot emission in Oxy-fuel combustion.

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.5

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.

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.

고온 예열 공기에 의한 난류 비예혼합 화염의 연소 특성

곽지현,전충환,장영준,Kwark, Ji-Hyun,Jeon, Chung-Hwan,Chang, Young-June 대한기계학회 2003 大韓機械學會論文集B Vol.27 No.5

An experiment using high preheated air in a turbulent non-premixed flame was performed to investigate the effects of high preheated air on the combustion characteristics. Combustion using high preheated and diluted air with flue gas is a new technology which enables NO emission to be reduced. In this study, Na was used as diluent and propane as fuel. Combustion characteristics, especially the distributions of the flame temperature, NO concentration and OH radical intensity were examined under the condition of 300 K, 600 K, 1000 K in terms of the combustion air temperature, and also under the condition of the dilution level from 21% to 13% in terms of oxygen concentration. As the preheated air temperature increased, it appeared that the flame length became shorter, maximum flame temperature increased, the reaction region moved to upstream, and NO concentration increased, but the flame temperature's fluctuation was reduced. In opposite, it was shown with decrement of oxygen concentration at the maximum temperature that both maximum value and the gradient of the flame temperature decreased, and NO emission also decreased considerably, but its fluctuation became larger, being inclined to be unstable.

IDI 디젤기관의 개선된 단일영역 열발생량 계산

김규보,전충환,장영준,이석영,Kim Gyu-Bo,Jeon Choung-Hwan,Chang Young-Jun,Lee Suk-Young 한국마린엔지니어링학회 2004 한국마린엔지니어링학회지 Vol.28 No.7

An one-zone heat release analysis was applied to a 4 cylinder indirect injection diesel engine. The objective of the study is to calculate heat release accurately considering the effect of specific heat ratio. heat transfer and crevice model and to find out combustion characteristics of an indirect diesel engine considering the effect of the pressures in main and swirl chambers. Especially specific heat ratio indicating combustion characteristics is adapted. instead of that indicating matter properties, which has been used in former studies Moreover by adaption of blowby model, cylinder gas mass became accurately calculated. Therefore, with ideal gas equation, calculating cylinder gas temperature, it was found to affect heat transfer loss and heat release. Determining heat transfer constants $C_1$. $C_2$ as 0.6 respectively. the integrated gross heat release values were predicted well for the measured value at various engine speed, full load operating conditions. The curve of heat release rate was similar to SI engine rather than DI engine. That is originated from that swirl chamber reduce an instant combustion which occurs in DI engine due to ignition delay on early stage of combustion.

SCV 가솔린 엔진의 운전조건에 따른 희박연소 특성

최수진,전충환,장영준,Choi, Su-Jin,Jeon, Chung-Hwan,Chang, Young-June 대한기계학회 2000 大韓機械學會論文集B Vol.24 No.2

Lean combustion in a SI engine is one of the best solution for the improvement of fuel economy and reduction of pollutant emission. In order to access a lean combustion engine, stable combustion at lean AlF ratio is needed. In this paper, the effect of fuel injection timing on lean misfire limit has been investigated in an MPI engine. To investigate the interaction of injection timing and intake flow characteristics, three different swirl generating SCV(swirl control valve) configurations were considered, and investigated their effects on lean misfire limit and torque at full load operation. Also the effects of spark timing on lean combustion has been investigated. Lean combustion has been examined and the results are reported in this paper. SCV B has been developed to satisfy the requirements of sufficient swirl generation to improve lean combustion and stable performance. It is found that injection timing, spark timing and intake air motion govern the stable lean combustion.

메탄/공기 층류 부분예혼합화염의 상세 라디칼(OH*, CH* 그리고 C₂*) 정보와 배기매출물에 관한 실험적 연구

정용기,오정석,전충환,장영준,Jeong Yong Ki,Oh Jeong Seog,Jeon Chung Hwan,Chang Young June 대한기계학회 2005 大韓機械學會論文集B Vol.29 No.2

An experimental study was performed to investigate the effects of partially premixing, varying the equivalence ratios from $0.79{\sim}{\infty}$, on NOx emissions and chemiluminescence of excited $OH^{\ast},\;CH^{ast}\;C_2^{\ast}$ radicals in laminar partially premixed flames. the signal from the electronically excited state of $OH^{\ast},\;CH^{ast}\;C_2^{\ast}$ was detected through a band pass filter with a photo multiplier tube, which are processed to the intensity ratio ($C_2^{\ast}/CH^{\ast},\;C_2^{\ast}/OH^{\ast},\;and\;CH^{\ast}/OH^{\ast}$) to reveal the correlation with local equivalence ratio. And measurements of NOx emission were made to investigate the relationship between visible flame appearance, chemiluminescence, and EINOX. The results demonstrated that (1) the flames at ${\phi}<1.59$ exhibited classical double flame structure, at ${\phi}>4.76$, the flames exhibited diffusion flame structure, and the intermediate flames at $1.59<{\phi}<4.76$ was a merged flame, (2) the $OH^{\ast}$ peak was located inside the $CH^{\ast}\;and\;C_2^{\ast}$ radical for all measured conditions and the emission intensity ratio of $C_2^{\ast}/CH^{\ast}\;and\;C_2^{\ast}/OH^{\ast}$ were identified as good marker for local equivalence ratio over a range of ${\phi}=0.79{\sim}1.2\;and\;CH^{\ast}/OH^{\ast}\;is\;0.79<{\phi}<1.9$. However, it was difficult to predict the equivalence ratio in partially premixed flames using this system for ${\phi}>2.38$, (3) the minimum NOX emission index (EINOx) is obtained for a equivalence ratio of 3.19 in the intermediate flames.

이차전지 양극활물질 제조용 소성로의 열화학적 해석

황민영,김용균,전충환,송주헌,김용태,장윤한,Hwang, Min-Young,Kim, Yong-Gyun,Jeon, Chung-Hwan,Song, Ju-Hun,Kim, Yong-Tae,Chang, Youn-Han 한국전기화학회 2009 한국전기화학회지 Vol.12 No.2

리튬 2차전지는 휴대용 전자기기의 전원으로 사용되어 왔다. 최근 하이브리드 자동차, 전기자동차의 에너지 저장매체로써 적용으로 인해 시장 확대가 기대되고 있다. 양극 활물질은 리튬2차전지의 성능, 수명, 용량을 결정하는 물질이며, 급증하는 시장의 수요에 따라 양극 활물질을 대량으로 생산할 수 있는 기술을 개발하는 것이 시급하다. 본 연구에서 실제 양극 활물질($LiCoO_2$) 생산라인에서 가동 중인 소성로를 3D 모델링하였고, 수치적 해석을 통해 소성로 내부의 온도와 유동의 방향, 화학적 거동을 밝혀내었다. 결과로써, 생산량 증가로 인해 소성로에서 생성되는 $CO_2$ 농도가 증가하며 정체되는 지점을 확인하였고, TGA-DSC 실험을 통해 $CO_2$가 몰분율 15%이상에선 $LiCoO_2$의 적절한 형성에 영향을 주는 현상을 확인하였다. 또한 소성로의 형상변화와 공정조건의 변화를 통해 문제되는 $CO_2$를 원활히 배출할 수 있는 해결책을 제안하였다. Lithium secondary batteries have been widely used in the portable electric devices as power source. Recently it is expected that the realm of its applications expands to the markets such as energy storage medium of hybrid electric vehicle(HEV), electric vehicle(EV). Cathode active material is crucial in terms of performance, durability, capacity of lithium secondary batteries. It is urgent to develope the technology for mass production of cathode material to cope with the markets' demands in the near future. In this study, a calcination furnace running in real production line is modelled in 3D, and the thermal flow and gas flow after chemical reaction in the furnace is analyzed through numerical computations. Based on the results, it is shown that large volume of $CO_2$ gas is generated from chemical reaction. High concentration of $CO_2$ gas and it's stagnation is clearly found from the reactant containers in which the reaction occur to the bottom area of the furnace. It is also studied that 15% or more $CO_2$ mol fraction could affect to proper formation of $LiCoO_2$ through TGA-DSC analysis. The solutions to evacuate carbon dioxide from the furnace are suggested through the change of furnace design and operating condition as well.