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메탄 공기 층류 부분 예혼합화염에서 예혼합 정도에 따른 화염구조와 질소산화물의 배출에 미치는 영향에 관한 연구
오정석(Jeong Seog Oh),정용기(Yong Ki Jeong),전층환(Chung Hwan Jeon),장영준(Young June Chang) 대한기계학회 2003 대한기계학회 춘추학술대회 Vol.2003 No.11
It is shown that the effect of variable parameters on flame structures and NOx emissions in the laminar<br/> partially premixed methane-air flames with a co-axial Bunsen burner. Objectives of this paper is to<br/> understand the effects of flow variables on NOx emissions and the flame structure with OH<br/> chemiluminescence, including reconstructed image by abel inversion processing at each conditions. A fuel<br/> flowrate of 200 [cc/min] was fixed and the amount of air was varied from 400 to 1200 [cc/min]. The<br/> experimental variables were equivalence ratio( ), fuel split percentage( ) and inner tube recess(x/D). Flow<br/> conditions were ranged from 1.36~4.76(equivalence ratio), 50~100(fuel split percentage) and 0~20(inner<br/> tube recess). NOx analyzer and ICCD camera with a OH filter were used as a main experimental<br/> apparatus. In addition, Abel inversion, which is a kind of tomography and valuable to estimate a<br/> two-dimensional structure of co-axial flames from cubical information, was employed for combustion<br/> diagnostics. Results from this study indicate that the main effects depend on equivalence ratio and next<br/> sigma, x/D for NOx production and OH formation. Throughout Abel inversion, we could affirm the<br/> maximum position and the tendency of OH radical intensity by variants at five axial heights above the<br/> burner exit.
이중동축 메탄/공기 층류 부분 예혼합화염에서의 화염구조와 자발광 배출 특성 안쪽관 연료주입의 영향
오정석(Jeong Seog Oh),정용기(Yong Ki Jeong),전충환(Chung Hwan Jeon),장영준(Young June Chang) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.11
In this study, the effect of central fuel injection on a coaxial laminar CH₄/air flame was experimented at the defined premixing condition(φ=1.90, σ=50/75/100%, x/D=10). The partial premixing parameter are the equivalence ratio that total fuel is fixed at 200cc/min, the fuel split degree which means the percentage of fuel entering the outer tube to the total amount, and the mixing distance indicating the nonreactant mixture's homogeneity between inner tube top and burner exit. The object is to investigate the flame structure and chemiluminescence characteristics of laminar partial premixed flame as changing mixing parameters. The radical signal was acquired from ICCD camera and PMT. Each intensity was compared with Abel inverted value for measuring the effect of background light on the peak signal location and the intensity at central preheat zone. The results show that the peak location of each radical was broaden as the fuel split degree increasing because the mixing quality was enhanced. and OH* is a good indicator for flame front between reaction and preheat zone. At last C₂* has the same tendency with CH* but a thinner reaction zone than CH* due to a rapid decay on the burned gas side.
메탄/공기 층류 부분예혼합화염의 상세 라디칼(OH*, CH* 그리고 C<sub>2</sub>*) 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.
초본계 펠릿 보일러 보급 및 확산을 위한 초본계 펠릿과 목재 펠릿 열분해 특성 비교 연구
오정석(Jeong-Seog Oh),강새별(Sae-Byul Kang),이현희(Hyun-Hee Lee),최규성(Kyu-Sung Choi) 대한기계학회 2020 대한기계학회 논문집. Transactions of the KSME. C, 산업기술과 혁신 Vol.8 No.2
한국에너지기술연구원에서는 바이오 자원 중의 하나인 농업 생산 부산물을 활용할 수 있는 200㎾th급 초본계 펠릿(rice husk pellet including farming wastes) 보일러를 산업계와 함께 연구 개발하고 있다. 본 논문에서는 펠릿 보일러를 연구 개발하는 과정에서 도출된 초본계 펠릿 열분해 특성 실험 결과를 소개하고자 한다. 실험 장치로 초본계 시료를 질소 분위기에서 500℃까지 열분해할 수 있는 열중량 분석기(TGA)를 사용하였다. 또한 연료로서 시료의 특성을 분석하기 위해 공업 분석(proximate analysis)과 원소 분석(ultimate analysis)을 수행하였다. 실험 결과로 원소 분석, 열중량 분석 이외에도 반크라벨렌 선도(Van Kravelen diagram), 연소성 지수(CI : Combustability Index), 온도 증가에 따른 질량 감소율(DTA : Derivative Thermogravimetric Analysis), 활성화 에너지 선도 기울기를 구하였고 이를 목재 펠릿과 비교 분석하였다. A 200 ㎾ industrial boiler for rice husk pellet combustion is under developing in the Korea Institute of Energy Research (KIER) with a pellet boiler company. In the current study, the pyrolysis characteristics of rice husk pellets was investigated as a fundamental research and compared with that of wood pellets. A thermogravimetric analyser (TGA) was used to heat up rice husk pellets to 500 ℃ in nitrogen atmosphere. Experimental results were plotted in the Van Kravelen diagram and analyzed as a form of combustability index (CI), derivative thermogravimetric analysis (DTA), and gradient in activation energy (Ea) plot.
보일러 열에너지 이용 및 시스템 효율 향상을 위한 습식 분무 응축 열교환 개념 적용 가능성 연구
오정석(Jeong-Seog Oh),강새별(Sae-Byul Kang),이현희(Hyun-Hee Lee),최규성(Kyu-Sung Choi) 대한기계학회 2019 대한기계학회 논문집. Transactions of the KSME. C, 산업기술과 혁신 Vol.7 No.2
대표적인 에너지 다소비기기인 보일러 시스템에 습식분무 응축열교환 개념을 적용하여 열에너지 이용효율 향상 및 온실가스배출 저감 가능성을 실험적으로 연구하였다. 실험장치로 약 10만 ㎉-H₂O/hr급 온수 보일러를 사용하였으며 배기가스 후단에 직경 약 0.5 ㎜의 중공 원뿔형 물 분사 시스템을 설치하였다. 물 분사량과 배기가스 배출조건을 고정한 상태에서 배기관 단열 유무, 배기가스 온도, 응축열교환기 냉각유량에 따른 응축수량을 측정하였다. 실험결과 응축 시작온도가 배기관 단열전에는 약 80 ℃였으나 배기관 단열시 약 60 ℃로 낮아졌다. 배기가스로 물을 분사할 경우 응축수량이 증가하였으며 배가스 온도도 감소하였다. 배기가스 온도를 낮추거나 응축열교환기의 냉각 수량을 증가할 경우 응축수량 역시 증가하였다. The concept of condensing heat exchange with water spray (CHEWS) into a flue gas was experimentally investigated to confirm the possibility of application to conventional boiler system. An 100,000 ㎉ scale hot-water boiler was used and installed with a hollow-cone type water spray system in the current study. As a experimental results, the gas-phase water began to be condensed about 60 ℃ in case of vent pipe insulation. The amount of condensed water increased with a decrease in flue gas temperature while decreased with a decrease in cooling water in a heat exchanger.
부상된 동축공기 수소 난류확산화염에서의 화염안정화 특성
오정석(Jeong-Seog Oh),김문기(Mun-ki Kim),윤영빈(Young-bin Yoon) 한국항공우주학회 2008 韓國航空宇宙學會誌 Vol.36 No.4
수소제트와 동축공기를 사용한 본 연구에서, 난류확산화염의 화염안정성 특정을 실험적으로 수행하였다. 목적은 연료속도 증가에 따라 감소하는 부상화염길이의 경향을 보고하고, 부상 메커니즘을 포함한 화염구조를 분석하는 것이다. 수소연료는 100에서 300 ㎧ 사이에서 조절되었으며, 이때 동축공기는 16 ㎧ 고정되고, 주위류는 0.1 ㎧ 이하로 유지되었다. 유동장과 연소장 동시측정을 위하여, 두 대의 Nd:Yag 레이저와 CCD 카메라를 이용하여 PIV와 OH PLIF 기법이 사용되었다. 결론적으로 난류화염전파속도는 난류강도에 비례하였으며, 제트 레이놀즈수의 0.017승에 비례하였다. In this study of lifted hydrogen jet with coaxial air, we have experimentally studied the characteristics of stabilization point in turbulent diffusion flames. The objectives are to present the phenomenon of a liftoff height decreasing as increasing fuel velocity and to analyse the flame structure and behavior including liftoff mechanisms. The fuel jet exit velocity was changed from 100 up to 300 ㎧ and a coaxial air velocity was fixed at 16 ㎧ with a coflow air less than 0.1 ㎧. For the simultaneous measurement of velocity field and reaction zone, PIV and OH PLIF technique was used with two Nd:Yag lasers and CCD cameras. It has been suggested that the stabilization of lifted hydrogen diffusion flames was correlated with a turbulent intensity, S<SUB>t</SUB>~u′, and jet Reynolds number, S<SUB>t</SUB>~Re<SUB>jet</SUB><SUP>0.017</SUP>.
윤상욱(Sangwook Yun),오정석(Jeong seog Oh),김문기(Munki Kim),윤영빈(Youngbin Yoon) 한국연소학회 2006 KOSCOSYMPOSIUM논문집 Vol.- No.-
Many previous works have been performed to provide correlations of flame length, theoretically and experimentally. Most of these results studied were conducted in vertical turbulent flame with no coaxial air condition. The present study analyzes the flame length scaling with coaxial air. In turbulent hydrogen non-premixed jet flames with coaxial air, flame length scaling theoretically proposed so far has been related with the concept of a far-field equivalent source. At high coaxial air to fuel velocity ratio, UA/UF, however, this scaling theory has some difference with experimental flame length data. This difference is understood to be due to the fact that the theory is based on far-field notion, while the effect of coaxial air on jet flame occurs in the region near the nozzle exit. Therefore, we define effective jet density Peff involving the concept of near-field so that effective jet diameter can be extended to the near field region. In this condition, we modify the correlation and compare with experimental data.
송진관(Jinkwan Song),안규복(Kyubok Ahn),오정석(Jeong-seog Oh),윤영빈(Youngbin Yoon) 한국유체기계학회 2006 유체기계 연구개발 발표회 논문집 Vol.- No.-
The effect of internal liquid flow on spray plume characteristics was performed experimentally in subsonic crossflows. The injector internal flow was classified as three modes such as a normal, cavitation, and hydraulic flip. The objectives of the research are to investigate the effect of internal liquid flow on the spray plume characteristics and compare the trajectory of spray plume with previous works. The results suggest that the trajectory of spray plume can be correlated as a function of liquid/air momentum flux ratio(q), injector diameter and normalized distance from the injector exit(x/d). It’s also found that the injector internal turbulence influences the spray plume characteristics significantly.