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.

Direct antiviral agents in advanced liver disease (Waiting for or candidate for liver transplantation)

전충환 ( Chung-hwan Jun ) 대한간학회 2016 간학회 싱글토픽 심포지움 Vol.2016 No.1

The prevalence of end-stage liver disease resulting from HCV infection and end-stage renal disease is increasing worldwide. However, there are no approved treatments for these very ill patients, who cannot tolerate the harsh adverse effect associated with interferon. In the last year, the approval of the first interferon-free regimens for the treatment of chronic hepatitis C has been a major step forward in hepatology. The safety and efficacy of the combination of several direct-acting antivirals (DAAs), compared to interferon containing regimens, has opened hope for groups of patients in whom interferon-based regimens were contraindicated or in whom these regimens had a very limited efficacy and poor tolerance. Despite the recent approval of the first interferon-free regimen, data in patients with advanced cirrhosis, end stage renal disease and hepatitis C after liver transplantation are still limited. Some trials were therefore designed to investigate the effect of viral suppression on clinical outcomes in patients with hepatic decompensation and severe chronic kidney disease. In this chapter, data about advanced cirrhotic patients with peri-transplant setting and end stage renal disease will be discussed.

밀폐 연소실 내의 메탄-공기 예혼합기의 연소 및 라디칼 특성에 관한 연구(II)

최수진,전충환,장영준,Choe, Su-Jin,Jeon, Chung-Hwan,Jang, Yeong-Jun 대한기계학회 1997 大韓機械學會論文集B Vol.21 No.5

In order to evaluate the effects of equivalence ratio, initial pressure and temperature on the laminar flame propagation process, and combustion radicals characteristics, experimental approaches are carried out in methane-air premixture using a constant volume chamber. Local and average radical intensities were measured to determine the time and spatial correlations between each radicals; C $H^{*}$(431 nm), $C_{2}$$^{*}$ (517 nm) and O $H^{*}$(309 nm) . The results are showed that two kinds of equation were proposed for the cases of continuous flame and intermittent flame type to evaluate actual equivalence ratio using relative intensities with each radicals. Both equations were agreed with actual equivalence ratio within 10% errors range. And schlieren photo and CCD image were compared with flame sizes at equivalence ratio 1.0.o 1.0.

연속 연료공급으로 작동하는 직접 탄소 연료전지

장군(Jun Zhang),김종필(Jong-Pil Kim),전충환(Chung-Hwan Jeon) 대한기계학회 2012 대한기계학회 춘추학술대회 Vol.2012 No.5-3

?;?;A direct carbon fuel cell (DCFC) is a promising power generation system that directly converts the chemical energy stored in solid carbon into electricity. In this study, graphite is employed in a tubular solid-oxide-electrolyte DCFC with continuous fuel-feeding equipment and it is ground to power form (with particle size < 32 ㎛). The graphite power is fed with a feeding rate of 0.1g min<;SUP>;-1<;/SUP>; regularly. CO₂ at a flow rate of 400 standard cubic centimeters per minute (sccm) transports the graphite power to the anode side of the cell. The tubular single cell is comprised of a 1.5 ㎛ yttria-stabilized zirconia (YSZ) electrolyte, a 10 um NiO-YSZ cermet anode, and a 10 um strontium-doped lanthanum manganite and YSZ (LSM-YSZ) composite cathode. The reaction area on the anode is approx. 3.92 ㎠. Cell voltage and power density is measured as the current is increased at temperatures of 600-900 ℃ at 50 ℃ intervals. The performance stability test is conformed at 900 ℃ over a period of some 24 h.

SCV를 장착한 2밸브 Sl 가시화기관의 연소특성에 관한 연구

정구섭,전충환,장영준,Jeong, Gu-Seop,Jeon, Chung-Hwan,Jang, Yeong-Jun 대한기계학회 2001 大韓機械學會論文集B Vol.25 No.12

This study describes the combustion characteristics under various condition of air excess ratio and ignition timing in a 2-valve SI optically accessible engine with swirl control valve(SCV). It adapted three different types of SCV(open ratio 72.5%, 78%, 59%) to strengthen a swirl flow. Pressure data were acquired using pressure sensor to investigate the effect of swirl flow on combustion, and from these pressure data, IMEP(indicated mean effective pressure) and MFB(mass fraction burnt) were calculated to explain burn rate and flame speed. From acquired flame images, we inspected the flame propagation direction, flame area, and flame centroid. Flame propagation direction showed different tendency between with/without SCV, and flame area with SCV was faster and larger than that of conventional engine. Finally, the representative flame images at each crank angle were acquired by PDF method to verify flame growth process. It is found that strengthened swirl flow is more beneficial for faster and stable combustion.

동축 확산 부상화염의 Blow-off와 연소 특성

곽지현,전충환,장영준,Kwark, Ji-Hyun,Jun, Chung-Hwan,Jang, Young-June 대한기계학회 2003 大韓機械學會論文集B Vol.27 No.8

An experiment was performed to investigate lift-off, blow-off and combustion characteristics of a lifted coaxial diffusion flame according to fuel jet and air velocity. A jet diffusion flame which is attached on the nozzle rim begins to be lifted with increase of air velocity, and finally becomes blow-off at higher air velocity. In experiment, blow-off limit increased with increase of fuel jet velocity, however lift-off occurred at lower air velocity. Flame structure and combustion characteristics were examined by schlieren photos, temperature distributions and emission concentration distributions. Flame temperature became higher at midstream and its RMS became larger at up and downstream with increase of air velocity. Local NO concentration decreased but $CO_2$concentration increased with increase of air velocity, which shows combustion reaction becomes close to be stoichiometric at higher air velocity in spite of lift-off.

모형가스터빈 연소기내 연소불안정성에 대한 연구

이종호,이연주,전충환,장영준,Lee, Jong-Ho,Lee, Yeon-Ju,Jeon, Chung-Hwan,Jang, Yeong-Jun 대한기계학회 2002 大韓機械學會論文集B Vol.26 No.9

Combustion instabilities are an important concern associated with lean premixed combustion. Laboratory-scale dump combustor was used to understand the underlying mechanisms causing combustion instabilities. Experiments were conducted at atmospheric pressure and sound level meter was used to track the pressure fluctuations inside the combustor. Instability maps and phase-resolved OH chemiluminescence images were obtained at several conditions to investigate the mechanism of combustion instability and relations between pressure wave and heat release rate. It showed that combustion instability was susceptible to occur at higher value of equivalence ratio (>0.6) as the mean velocity was decreased. Instabilities exhibited a longitudinal mode with a dominant frequency of ∼341.8 Hz, which corresponded to a quarter wave mode of combustor. Heat release and pressure waves were in-phase when instabilities occurred. Rayleigh index distribution gave a hint about the location where the strong coherence of pressure and heat release existed. These results also give an insight to the control scheme of combustion instabilities. Emission test revealed that NOx emissions were affected by not only equivalence ratio but also combustion instability.

소결 버너에서 설계인자에 따른 연소특성 연구

이영준(Young-Jun Lee),황민영(Min-Young Hwang),송주헌(Ju-Hun Song),장영준(Young-June Chang),전충환(Chung-Hwan Jeon) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11

The objective of this study was to investigate the combustion characteristics of a sintering burner in the various design factors which were distance and angle of each injection hole. To analyze the characteristics, the numerical study was conducted y 3 cases of differential hole distance and 4 types of hole angle which were 40, 45°, 50°, 55° at each case. To validate the numerical study, an experimental study was performed in a unit of the sintering burner at same conditions of the iron ore sintering process. Throughout the results, some difference was existed in the combustion characteristics about the design factors.

난류 비예혼합 평면화염의 유동과 연소 특성

곽지현,정용기,전충환,장영준,Kwark, Ji-Hyun,Jung, Yong-Ki,Jun, Chung-Hwan,Chang, Young-June 대한기계학회 2003 大韓機械學會論文集B Vol.27 No.4

An experiment in a turbulent non-premixed flat flame was carried out in order to investigate the effect of swirl number on the flow and combustion characteristics. First. stream lines and velocity distribution in the flow field were obtained using PIV method. In contrast with the axial flow without swirl, highly swirled air induced stream lines along the burner tile. and backward flow was caused by recirculation in the center zone of the flow field. In the combustion. the flame with swirled air also became flat and stable along the burner tile with increment of the swirl number. Flame structure by measuring OH and CH radicals intensity and by calculating Damkohler number(Da) and turbulence Reynolds number(Re$_{T}$) was examined. It appeared to be comprised in the wrinkled laminar-flame regime. Backward flow by recirculation of the burned gas decreased the flame temperature and emissions concentrations as NO and CO. Consequently, the stable flat flame with low NO concentration was achieved.d.

선회도가 평면화염버너의 유동과 연소 특성에 미치는 영향

정용기,김경천,전충환,장영준,Jeong, Yong-Gi,Kim, Gyeong-Cheon,Jeon, Chung-Hwan,Jang, Yeong-Jun 대한기계학회 2002 大韓機械學會論文集B Vol.26 No.2

In this study, the flow and combustion characteristics of flat flame burner with twirler were investigated. There are several factors that define the characteristics of burner. Among them, the experiments was focused on swirl effect by four types of twirler in terms of flow structure, distribution of temperature and emission characteristics. In PIV(Particle Image Velocimetry) experiment, the less of swirl number, axial flow is dominant at the center. As swirl number increases, the flow develops along the burner tile and backward flow becomes stronger at center. From the combustion characteristics, as long as combustion load increases, blow-off limit was improved. But at the higher swirl number, the limit is decreased. At swirl number 0, the temperature is shown typical distribution of long flame burner. but swirl number increases, the temperature distribution is uniform in front of round tile. Therefore, the temperature distribution is coincided with flow structure. As excess air ratio increases, NO concentrations are high. But high swirl number gives rise to become low NO concentrations. The flame characteristics are comprised in wrinkled laminar-flame regime according to turbulence Reynolds number(Rel) and Damkohler number(Da).