• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.10
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• pp.1458-1464
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• 2002

$CO_2$ is well known greenhouse gas which is the major source of global warming. Reducing $CO_2$ emission in combustion process can be achieved by increasing combustion efficiency, oxygen enriched combustion and recirculation of the emitted $CO_2$ gas. Stability of non-premixed flame in oxygen enriched environment will be affected by the amount of oxygen, kind of diluents and fuel exit velocity. The effects of these parameters on flame liftoff and blowout are studied experimentally oxidizer coflowing burner. Experiments were divided into three cases according as where $CO_2$gas was supplied. - 1) to coflowing air, 2) to fuel with 0$_2$-$N_2$ coflow, 3) to coflowing oxygen. Flame in air coflowing case was lifted in turbulent region. Flame lift and blowout in laminar region with the increase in $CO_2$ volume fraction in $CO_2$-Air mixture makes flame lift and blowout in laminar region. Increase in oxygen volume fraction makes flame stable-i.e. flame liftoff and blowout occur at higher fuel flowrates. Liftoff height was non-linear function of nozzle exit velocity and affected by the $O_2$ volume fraction. It was found that the flame in $O_2$-$N_2$ coflow case was more stable than $O_2$-$CO_2$ case, Liftoff heights vs (nozzle exit velocity/laminar burning velocity)$^{3.8}$ has a good correlation in $O_2$-$CO_2$ oxidizer case.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.4
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• pp.555-560
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• 2002

Numerical simulations of freely propagating flames burning stoichiometric CH$_4$/O$_2$/$N_2$mixtures are performed at atmospheric pressure in order to understand the effect of the $O_2$enrichment level on CH$_4$/Air flame. A chemical kinetic mechanism is employed, the adopted scheme involving 54 gas-phase species and 632 forward reactions. The calculated flame speeds are compared with the experiments for the flames established at several $O_2$enrichment level, the results of which is in excellent agreement. As a result of the increased $O_2$enrichment level from 0.21 to 1, the mole fraction of CO in the burred gas is increased. The flame speed and the temperature in the burned gas are also increased, but the thickness of the flame is severely shrunken in the preheat region. The maximum of the calculated EINO is obtained around 0.6 and 0.7 of the $O_2$enrichment level in cases of flames for fuel-lean mixtures.

• Proceedings of the KSEEG Conference
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• 2005.04a
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• pp.285-289
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• 2005

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.5 s.236
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• pp.617-624
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• 2005

An analysis of the effects of $CO_{2}$ on fundamental combustion characteristics was performed in Oxygen enriched condition by comparing the laminar burning velocities, flame structures, fuel oxidation paths. Fictitious $CO_{2}$ was introduced to discriminate the chemical reaction effects of $CO_{2}$ from the thermal effects. PREMIX code was utilized to evaluate the laminar burning velocities. OPPDIF code was utilized to investigate the flame structure and fuel oxidation path variation. The contributions of thermal effects on laminar burning velocities are dominant at lowly oxygen-enriched condition but those of chemical reaction effects become dominant at highly oxygen-enriched condition. Chemical reaction effects caused the additional flame temperature decrease besides thermal effects and oxygen-leakage increase in non-premixed flame. Specific fuel oxidation path and CO production path is enhanced in spite of overall decrement of fuel consumption rate by chemical reaction effects of$CO_{2}$.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.2
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• pp.223-229
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• 2004

Combustion using oxygen enriched air is known as a technology which can increase thermal efficiency due to increase of the flame temperature. Flame shapes, schlieren photos, OH radical chemiluminescence and local flame temperature were examined as a function of OEC(Oxygen Enriched Concentration) in a coaxial non-premixed jet. With increase of OEC, flame length and width decreased, but its brightness increased significantly, and the size of vortices in the flame also increased. Especially, the reaction around the flame surface became active. The strong OH intensity appeared to be made and moved from middle stream to upper one with increase of OEC, which shows combustion reaction in the upper stream becomes more dominant In addition, the temperature distributions of the flames showed similar tendency with OH radical intensities. A flame with high temperature and strong stability was obtained with increasing OEC of the coflow.

• Proceedings of the KSME Conference
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• 2001.11b
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• pp.149-154
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• 2001

The emission characteristics, flame stability, the composition of the flame zone and temperature profile were studied experimentally. The compositions of oxydant were varied by substituting $N_2$ with $CO_2$ at the constant $O_2$ concentration. Results showed that flame became unstable due to the high heat capacity, low transport rate and strong radiation effect of $CO_2$ in comparison with those of $N_2$. The reaction zone was cooled, broadened, as the conversion ratio of $CO_2$ to $N_2$ was increased. Temperature has a large effect on the NOx emission. The concentration of NOx in flue gas decreased due to the decreased temperature of reaction zone. It was also shown that the reaction was delayed by the cooling effect. As the conversion ratio of $CO_2$ to $N_2$ was increased, the emission of CO and the higher temperature zone increased due to the decrease of reaction rate by the cooling effect.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.2
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• pp.207-214
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• 2004

The burning velocities of conventional and oxygen-enriched methane flame in various equivalence ratio were determined by experiments. The validity of existing reaction mechanisms was examined in oxygen-enriched flame on the basis of the experiment results. Modified reaction mechanism is suggested, which was able to predict burning velocity of oxygen enriched flame as well as methane-air flame. Complementary study on reaction mechanisms shows the following results : Present experiment data were found to be more reliable in comparison with existing ones in a oxygen-enrichment condition. It was found that some modification in existing reaction mechanisms is necessary, since discrepancy between measurements and predictions is increasing with oxygen enrichment ratio. The sensitivity analysis was performed to discriminate the dominantly affecting reactions on the burning velocity in various oxygen enrichment and equivalence ratio. A modified GRI 3.0 reaction mechanism based on our experiment results was suggested, in which reaction rate coefficients of (R38) H+O$_2$<=>O+OH in GRI 3.0 reaction mechanisms were corrected based on sensitivity analysis results. This mechanism showed a good agreement in predicting the burning velocity and number density of NO in oxygen-enriched flame and would provide proper reaction information of oxygen-enriched flame at this stage.

• Proceedings of the Membrane Society of Korea Conference
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• 1994.10a
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• pp.34-35
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• 1994

기체혼합물의 분리및 정제기술은 에너지 절약의 관점과 새로운 기능성 고분자의 개발로 고분자막에 의한 분리법이 관심을 끌게되었다. 공기로부터 산소부화, 방사성 크세논 및 크립론의 제거, 제련소 폐가스증의 수소분리, 천연가스로부터 헬륨의 회수분야등은 실제로 산업적으로 실용화되고 있다. 그러나 고분자막은 일반적으로 투과성과 선택성이 서로 상반되는 경향을 나타내므로, 투과성과 분리성이 좋은 기능성 고분자막의 개발에 다양한 연구가 필요로 하고있다. 본 연구에서 사용한 PTFE(polytetrafluoroethylene)는 결정성 고분자로서 넓은 온도범위에서 낮은 마찰계수, 우수한 전기적 절연특성, 강한 Carbon-fluorine 겹합에 기인한 높은 열적 안정성, 화확적 불활성때문에 공업용 고분자 재료로서 독특한 위치를 차지하고 있다. 최근에 미국과 일본을 주축으로 상용화딘 공기전지(Zinc-air battery)는 PTFE막의 뛰어난 소수성과 화학적 저항성으로 수은 전지의 대체품으로 주목받고 있는데, 장기 방전시 성능 저하가 따르므로 막을 통한 산소투과성을 방전에 필요한 최소값으로 감소시키는 것이 중요한 과제가 되고있다.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2001.05a
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• pp.344-345
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• 2001

담수산 rotifer, Braohionus calyciflorus의 내구란은 종의 유전적 보존, 환경 독성학의 실험재료뿐만 아니라, Artemia cyst처럼 간단하게 부화시켜 자어의 먹이로 공급할 수 있는 장점이 있다. 일반적으로 rotifer의 내구란 생산은 배양용기내의 rotifer 밀도가 증가하면서 유성생식 개체가 출현하며 이후 수컷의 수정으로 내구란이 형성되는 일련의 과정을 거친다. 그러나 이러한 과정에 있어서 rotifer의 유성생식 개체의 출현과 수컷의 수정에 영향을 미쳐 rotifer 개체수의 증가와 더불어 용존산소 감소 및 암모니아 증가 둥 배양수의 환경 악화로 내구란 생산과정이 중단되면서 효율적인 내구란 대량생산은 기대하기가 매우 어렵다. (중략)

• Environmental Analysis Health and Toxicology
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• v.24 no.2
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• pp.119-125
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• 2009

This study was carried out to investigate the toxic effect of WSF (water soluble fraction) in crude oil on the hatch, survival rate, abnormality and physiological activity of fertilized eggs and early larvae in Paralicthys olivaceus. The time required in hatching the fertilized eggs exposure to crude oil was 50.8${\sim}$53.2 hours both in control group and experimental group, showing no significant difference(p>0.05). The hatching rate in the control group was more than 80% in 1.9 ${\mu}g/mL$ WSF concentration, but hatching rate was less than 55.7% in below of 3.9 ${\mu}g/mL$ WSF concentration, showing significant difference (p<0.05). The survival rate on the 3rd day of early larval stage was 61.96% with 1.9 ${\mu}g/mL$ WSF, 11.1% with 3.9 ${\mu}g/mL$ WSF, and they all died with other concentration levels. The oxygen consumption rate in experimental groups was lower than control group. The heart rate (no./min) was 47.4${\sim}$52.8 before hatching and there was no significant difference between control group and experimental group, but heart rate reduced with the decrease of WSF concentration after hatching. The abnormality was 1.1% in the control group whereas 36.7% with 3.9${\mu}g/mL$ WSF, and abnormality was mostly comprised of incomplete spinal formation and spinal curvature. The results of this study suggest that even low concentration to WSF affects the early development of the flounder, Paralicthys olivaceus.