• 한국연소학회:학술대회논문집
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• 한국연소학회 2000년도 제21회 KOSCO SYMPOSIUM 논문집
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• pp.67-76
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• 2000

Experimental and numerical investigation on NOx emission characteristics with equivalence ratios, fuel flow rates and nozzle diameters were studied in CH4 Jet flames. Emission indices of NOx were measured by chemiluminescent method with carbon converter. Numerical analyses were carried out with GRl-2.11 mechanism that includes C2-chemistry and all of NO reaction mechanisims. The roles of thermal NO and prompt NO mechanism on each flame's NOx emission index were investigated. The results of this study show that the numerical results represent well the trends of ElNOx experimentally observed. The numerical analyses clarified the trends of EINOx with equivalence ratios, fuel flow rates and nozzle diameters.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2000년도 제20회 KOSCO SYMPOSIUM 논문집
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• pp.35-44
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• 2000

It was numerically studied that NOx emission characteristics of confined $CH_{4}$ jet flames with the variation of the diameter of inner fuel nozzle, the flow rate of $CH_{4}$ and equivalence ratio. Parabolic type equations were adopted in the calculation and GRI-2.1I mechanism was used for the chemical reaction. NOx emission index (EINOx) was introduced to evaluate NOx emission quantitatively in parametrically varied flames and the contribution of Thermal and Prompt NO mechanism was discussed. The results showed that Total EINOx varied sensitively with the variation of the flow rate of$CH_{4}$ but it was not sensitive to the variation of the diameter of inner fuel nozzle. Thermal EINOx showed the similar tendency to total EINOx and Prompt EINOx showed insensitivity to the variation of the diameter of inner fuel nozzle and the flow rate of $CH_{4}$.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2006년 제4회 한국유체공학학술대회 논문집
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• pp.569-572
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• 2006

In present study, the influence of changing combustor pressure on flame stabilization and nitrogen oxide (NOX) emission in the swirl flame with secondary fuel injection was investigated. The combustor pressure was controlled by suction at combustor exit. Pressure index ($P^*=Pabs/Patm$), where Pabs and Patm indicated the absolute pressure and atmosphere pressure, was controlled in the range of 0.7~1.15 for each equivalence ratio conditions. It could be observed that flame stable region became narrower with decreasing equivalence ratio and pressure index. In this combustion system, stable flames were formed until $P^*=\;0.7$. Emission index decreased with decreasing pressure index for overall equivalence ratio conditions and NOx reduction rates were almost identical for $P^*<1$ regardless of equivalence ratio though EINOx values showed different level with change of equivalence ratio for $P^*{\geq}1$. It is also observed that EINOx decreased with increasing secondary fuel injection ratio. Emission index of nitric oxide was controllable by adjusting the changing combustor pressure and injecting secondary fuel and this NOx reduction technology is applicable to industrial furnaces and air conditioning system.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2006년도 제33회 KOSCO SYMPOSIUM 논문집
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• pp.128-133
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• 2006

Influence of changing combustor pressure on flame stabilization and nitrogen oxide (NOx) emission in the swirl-stabilized flame with secondary fuel injection was investigated. The combustor pressure was controlled by suction at combustor exit. Pressure index ($P{\ast}=P_{abs}/P_{atm}$), where $P_{abs}$ and $P_{atm}$ indicated the absolute pressure and atmosphere pressure, was controlled in the range of $0.7{\sim}1.3$ for each equivalence ratio conditions. The flammable limits of swirl flames were largely influenced by changing combustor pressure and they showed different tendency compared with laminar flames. Emission index showed maximum value near atmospheric condition and decreased with decreasing pressure index for overall equivalence ratio conditions. R.m.s of pressure fluctuations also showed similar tendency with nitric oxide emission. By injecting secondary fuel into flame zone, the flammable limits were extended significantly. Emission index of nitric oxide and r.m.s. of pressure fluctuations were also controlled by injecting secondary fuel. The swirl flames were somewhat lifted by secondary fuel with high momentum, hence low nitric oxide emission. This NOx reduction technology is applicable to industrial furnaces and air conditioning system by adopting secondary fuel injection.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2001년도 제22회 KOSCI SYMPOSIUM 논문집
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• pp.147-155
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• 2001

The NOx emission characteristics of jet flames fueled with $H_2$ and $CH_4$ were studied. Experimental and numerical investigations were carried out for various flames with varying equivalence ratio, fuel flow rate and nozzle diameter. The Emission indices of NOx(EINOx) were measured by chemiluminescent method and calculated by simulation using detailed chemistry. The results show that EINOx of $CH_4$ and $H_2$ flames have different trends in terms of equivalence ratio and fuel flow rate but have the same trends in terms of nozzle diameter. These differences can be explained by the following Thermal and Prompt trends in both flames. Thermal EINOx trends can be describe in function of residence time in the high-temperature region weighted by the maximum flame temperature and Prompt EINOx trends can be described in function of flame surface area of each combustion conditions.

• 한국연소학회지
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• 제6권1호
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• pp.36-43
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• 2001

The NOx emission characteristics of jet flames fueled with $H_2\;and\;CH_4$ were studied. Experimental and numerical investigations were carried out for various flames with varying equivalence ratio, fuel flow rate and nozzle diameter. The Emission indices of NOx(EINOx) were measured by chemiluminescent method and calculated by numerical model based on detailed chemistry. The results show that EINOx of $CH_4\;and\;H_2$ flames have different trends in terms of equivalence ratio and fuel flow rate but have the same trends in terms of nozzle diameter. These differences can be explained by the following Thermal and Prompt trends in both flames. Thermal EINOx is quite sensitive to the residence time in the high-temperature region weighted by the maximum flame temperature. Prompt EINOx is mainly influenced by flame surface area of each combustion conditions.

• 대한기계학회논문집B
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• 제26권11호
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• pp.1531-1541
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• 2002

The NOx emission characteristics of C$H_4$-Air coflow jet flames were numerically and experimentally investigated. NOx was measured using a chemiluminescent detection and calculated by the parabolic -type equation solver with a detatiled NOx chemistry. The fuel flow rate( $Q_{F}$), the diameter of mixture nozzle and the equivalence rate(Ф) were varied to discuss the EINOx of each flames at the various combustion conditions. The NOx emission index(EINOx) was introduced to quantify the NOx emission from the parametrically varied flames. The results show that Prompt EINOx increases on a logarithmic profile with increasing ${\Phi}$ and keeps nearly constant for the variation of $Q_{F}$. Thermal EINOx reaches the maximum value at around ${\Phi}$ =1.5 and then slowly decrease for ${\Phi}$ >1.5. In addition, Thermal EINOx increases with increasing $Q_{F}$, but nearly indifferent to the variation of the mixture nozzle diameter. Total EINOx also shows a peak at around ${\Phi}$ =1.5, followed by a relatively sharp decrease for 1.5< ${\Phi}$ <2.5 and increase slowly for 2.5 < ${\Phi}$ < $\infty$ The present Total EINOx trend is well explained by a combination of above Thermal and Prompt EINOx trend with the variation of ${\Phi}$ n of ${\Phi}$.

• 한국안전학회지
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• 제16권4호
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• pp.82-87
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• 2001

The NOx emission characteristics of jet flames fueled with It was studied. Experimental and numerical investigations were carried out for various flames with varying equivalence ratio, fuel flow rate and nozzle diameter. The Emission indices of NOx(EINOx) were measured by chemiluminescent method and calculated by simulation using detailed chemistry. The results show that the numerical results represent well the trends of EINOx experimentally observed. EINOx of H$_2$ flame steeply increase at small equivalence ratio, gently increase and steady at more than equivalence ratio is 4.0. EINOx trends of H$_2$ flame can be describe in function of residence time in the high-temperature region weighted by the maximum flame temperature.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2001년도 제22회 KOSCI SYMPOSIUM 논문집
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• pp.156-162
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• 2001

The effects of co-flow and the variation of the equivalence ratio on NOx emission were investigated experimentally for unconfined and confined partially premixed flames. The shape, length, temperature of flames and the concentration of burnt gas were measured. Two types of co-flow (parallel and swirling co-flow) were considered. For unconfined flames, flame with parallel co-flow is the longest and the next is flame without co-flow. Flame with swirl is the shortest. The length of swirling flame increases suddenly under certain value of equivalence ratio. EINOx is diminished by the decrease of equivalence ratio. It is found that the unconfining of flame enhances the emission of NOx. The EINOx of unconfined flame with parallel co-flow is less than that of flame without co-flow.

• 에너지공학
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• 제25권1호
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• pp.100-107
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• 2016

본 연구에서는 예혼합 화염과 비예혼합 화염을 동시에 구현하는 하이브리드 연소시스템에 배기가스 재순환 방법(FI-EGR and FPI-EGR)을 적용하여 공해물질 저감 효과를 확인하였다. 그 결과, 배기가스 재순환을 적용한 경우 상당량의 NOx 배출지수가 감소하는 것을 확인 할 수 있었으며, 추가적으로 배기가스 재순환을 적용한 하이브리드 연소시스템의 배출성능이 동일한 배기가스 재순환율을 가지는 비예혼합 화염의 배출성능보다 우수함을 확인하였다. 특히, 비예혼합 화염과 예혼합 화염의 비율이 50: 50인 하이브리드 연소시스템의 연료 측에 25% 까지 배기가스를 재순환 시킬 경우(FI-EGR), 배기가스 재순환을 적용하지 않은 비예혼합 화염에 비해 NOx 배출지수가 59% 저감되는 것을 확인하였으며, 혼합비율이 70:30인 하이브리드 연소시스템의 예혼합기와 연료측에 15%까지 배기가스를 재순환 시킬 경우(FPI-EGR), 배기가스를 재순환하지 않은 하이브리드 화염에 비해 NOx 배출지수가 48% 저감되는 것을 확인하였다.