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Characteristics of Non-premixed Edge Flames in a Counterflow Slot Burner
Cha, Min-Suk,Ronney, Paul D. The Korean Society of Combustion 2005 한국연소학회지 Vol.10 No.4
The propagation rates of advancing and retreating non-premixed edge flames in a slot-jet counterflow were measured as a function of strain rate for varying jet spacing, mixture strength, stoichiometric mixture fractions $(Z_{st})$ and Lewis numbers (Le). Methane and propane fuels were tested and nitrogen and carbon dioxide were used as inerts. As results, we could identify igniting fronts, retreating fronts, two total extinction limits, and short-length edge flames. A burner separation affected to a low extinction limit only. Regimes for advancing and retreating edges together with total extinction were mapped in terms of normalized flame thickness and heat loss factor for $CH_4/O_2/N_2$ mixtures. Edge flames for $Z_{st}$ > 0.5 behaved like a stronger mixture while for $Z_{st}$ < 0.5 showed deteriorated feature, because of relative locations of a non-premixed flame and intermediate species such as CO and $H_2$. Furthermore, due to the relative importance of heat loss, propagating speeds of edge flames were significantly enhanced in $CH_4/O_2/CO_2$ mixtures (Le < 1) demonstrating increasing stability limits. However $C_3H_8/O_2/N_2$ mixtures (Le > 1) showed opposite result.
폴리이미드 재질의 소형 플라스틱 연소기의 크기에 따른 특성 연구
신강창(Kangchang Sin),허환일(Hwanil Huh),Paul D. Ronney 한국추진공학회 2008 한국추진공학회 학술대회논문집 Vol.2008 No.11
MEMS 기술의 발전에 따라 마이크로 시스템이 개발되면서 마이크로 시스템이 요구하는 높은 에너지를 제공하는 에너지원으로 연소기반의 초소형 동력장치에 대한 연구가 진행되고 있다. 초소형 동력장치는 별도의 열원이 있어야 하기에 이와 연계되는 초소형 연소기가 필요하다. Swiss-roll 연소기는 연소기의 크기와 형상, 재질에 대한 연구들이 진행되어 왔다. 선행연구결과 연소기 재질의 열전도도가 낮고, 재질의 두께가 얇을수록 연소기의 성능이 좋아진다는 결론을 얻을 수 있었다. 본 연구에서는 낮은 작동온도를 요구하는 PEM형 연료전지에의 적용가능성을 검토하기 위해서 열전도율이 낮은 polyimide 연소기를 제작하여 성능분석을 수행하였다. Micro power generators have been studying to provide high power that micro systems require. Micro power generators need micro combustor. Swiss-roll combustor has been studied about scale, geometry, material. From previous study experiments have shown that swiss-roll combustors require thin walls with low thermal conductivity for maximum performance at small scales. In this work, polyimide combustors with low thermal conductivity and thin thickness are built and tested.
연료전지 개질기로 활용을 위한 스위스 롤 연소기의 크기와 연료의 종류에 따른 특성연구
김연호(Younho Kim),허환일(Hwanil Huh),Paul D. Ronney 한국추진공학회 2011 한국추진공학회지 Vol.15 No.1
The geometrically similar swiss roll reactors of different physical sizes were tested with the aim of independently determining the effects of Re and Da. It is found that the difference between catalytic and non-catalytic combustions extinction limits are narrowed as scale decreases. In addition to assess the importance of fuel chemistry, different families of fuels including alkanes and ethers were tested. From these results the effect of scale and fuel type on microscale reactor performance and implications for practical micro combustion devices are discussed.
마이크로 동력발생용 소형 스위스롤 연소기의 크기와 형상 효과에 대한 연구
오화영(Hwayoung Oh),허환일(Hwanil Huh),Paul D. Ronney 한국추진공학회 2011 한국추진공학회지 Vol.15 No.1
Combustion and extinction limits in heat-recirculating excess enthalpy reactors employing both gas-phase and catalytic reaction have been examined with an emphasis Reynolds number (Re) effects and possible application to microscale combustion devices. In this paper, geometrically similar reactors of different physical sizes and different numbers of turns were tested with the aim of estimating for combustor characteristics. Combustion efficiency is estimated by measuring exhausted gases through the gas chromatograph. From these results the effect of scale and number of turns are demonstrated and optimal operating conditions for Swiss roll combustors are identified.
연료전지에의 적용을 위한 소형 플라스틱 연소기의 크기에 따른 특성연구
신강창(Kangchang Shin),허환일(Hwanil Huh),Paul D. Ronney 한국연소학회 2008 KOSCOSYMPOSIUM논문집 Vol.- No.-
Micro power generators have been studying to provide high power that micro systems require. Micro power generators need micro combustor. Swiss-roll combustor has been studied about scale, geometry, material. From previous study experiments have shown that swiss-roll combustors require thin walls with low thermal conductivity for maximum performance at small scales. In this work, polyimide combustors with low thermal conductivity and thin thickness are built and tested.
오화영(Hwayoung Oh),김연호(Younho Kim),허환일(Hwannil Huh),Paul D. Ronney 한국연소학회 2006 KOSCOSYMPOSIUM논문집 Vol.- No.-
Extinction limits and combustion temperatures in heat-recirculating excess enthalpy reactors employing both gas-phase and catalytic reaction have been examined previously, with and emphasis Reynolds number (Re) effects and possible application to microscale combustion devices. However, Re is not the only parameter needed to characterize reactor operation. In particular, the use of a fixed reactor size implies that residence time and Re cannot be adjusted independently. To remedy this situation, in this work geometrically similar reactors of different physical sizes were tested with the aim of independently determining the effects of Re and Da. It is found that the difference between catalytic and non-catalytic combustion limits narrow as scale decreases. Moreover, to assess the importance of wall thermal conductivity, reactors of varying wall thickness were studied. From these results the effect of scale on microscale reactor performance and implications for practical microcombustion devices are discussed.
데이비드 클레이튼(David B. Clayton),차민석(Min Suk Cha),폴 로니(Paul D. Ronney) 한국연소학회 2009 한국연소학회지 Vol.14 No.1
Propagation rates (Uedge) of various premixed, twin edge-flames were measured as a function of global strain rate (σ), mixture strength, and Lewis number (Le). Using a counterflow slot-jet burner with electrical heaters at each end, both advancing (positive Uedge) and retreating (negative Uedge) edge-flames can be studied as they propagate along the long dimension of the burner. Experimental results are presented for premixed methane/air twin flames in terms of the effects of σ on Uedge. Both low-σ and high-σ extinction limits were discovered for all mixtures tested. As a result, the domain of edge-flame stability was obtained in terms of heat loss factor and normalized flame thickness, and comparison with the numerical result of other researchers was also made. For low (CH₄/O₂/CO₂) and high (C₃H?/air) Lewis number cases, propagation rates clearly show a strong dependence on Le.
Characteristics of Edge Flames for Premixed Flames in a Counterflow Slot Burner
David B. Clayton(데이비드 클레이튼),Min Suk Cha(차민석),Paul D. Ronney(폴 로니) 한국연소학회 2006 KOSCOSYMPOSIUM논문집 Vol.- No.-
The propagation rates (Uedge) of various premixed edge-flames were measured as a function of global strain rate (σ), mixture strength, and Lewis number (Le). Using a counterflow slot-jet burner with electrical heaters at each end, both advancing (positive Uedge) and retreating (negative Uedge) edges can be studied as they propagate along the long dimension of the burner. Preliminary results are presented for single and twin premixed hydrocarbon edge-flames in terms of the effects on Uedge. A low-σ extinction limit has been discovered for all mixtures tested but further analysis is necessary for full characterization since sufficiently high-σ leads to an apparent stability limit. Propagation rates clearly show a strong dependence on Le. Future work will focus on completing the premixed hydrocarbon edge-flame analysis and include investigations into non-premixed edge-flames and edge-flames composed of fuels such as hydrogen (H₂) with significantly lower Le.