• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.2977-2983
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• 2008

The combustion characteristics of a partially premixed flame in a dump combustor were studied to determine the effects of hydrogen enrichment in propane. Bluff-body was used for flame stabilization. Fuel mixtures containing a hydrogen mole fraction ranging from 0.1 to 0.5 were burnt at ambient pressure within a quartz chamber. Tests were carried out keeping the total reactant flow rate by adjusting the fuel and air flow rates. The fluctuations of pressure were measured by piezoelectric pressure sensor. The instantaneous flame structure and OH chemiluminescence images were described by High-speed Intensified Charged Coupled Device (HICCD) camera and Intensified Charged Coupled Device (ICCD) camera. The present results show that hydrogen enrichment in fuel changed the location of primary reaction zone from inner recirculation zone to turbulent shear layer and pressure signal. The reason is that chemical aspects take precedence over flow aspects in the hydrogen-enriched flame.

• 한국수소및신에너지학회논문집
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• 제21권1호
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• pp.42-49
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• 2010

Increasing environmental concerns regarding the use of fossil fuels and global wanning have prompted researcher to investigate alternative fuels. The purpose of this study is to investigate the syngas production by biogas reforming using a compression spark ignition engine. The parametric screening studies were carried out according to the variations of oxygen enrichment rate, biogas $CO_2$ ratio, intake gas temperature, and engine revolution. When the oxygen enrichment rate and input gas temperature increased, hydrogen and carbon monoxide were increased. But the biogas $CO_2$ ratio and engine revolution increased, the syngas were reduced. For the reforming of methane 100% only, generation of hydrogen and carbon monoxide was 58% and 17%, respectively. However when the biogas $CO_2$ ratio was 40%, hydrogen and carbon monoxide concentration were about 20% each.

• 한국수소및신에너지학회논문집
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• 제12권3호
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• pp.169-176
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• 2001

The purpose of study is to obtain low-emission and high-efficiency in LPG engine with hydrogen enrichment. The test engine was named heavy-duty variable compression ratio single cylinder engine (VCSCE). The fuel supply system provides LPG/hydrogen mixtures based on same heating value. Various sensors such as crank shaft position sensor (CPS) and hall sensor supply spark timing data to ignition controller. Displacement of VCSCE is $1858.2cm^3$. VCSCE was runned 1400rpm with compression ratio 8. Spark timing was set MBT without knocking. Relative air-fuel ratio(${\lambda}$) of this work was varied between 0.76 and 1.5. As a result, i) Maximum thermal efficiency occurred at ${\lambda}$ value 1.0. It was shown that thermal efficiency was increased approximately 5% with hydrogen enrichment at same ${\lambda}$ value. ii) Engine-out carbon monoxide (CO) emissions were decreased at a great rate under LPG/hydrogen mixture fuelling. iii) Total hydrocarbon (THC) emission was much exhausted in rich zone, same as CO. But THC was exhausted a little bit more in lean zone. iv) Finally, engine-out oxides of nitrogen (NOx) was increased with ${\lambda}$ value 1.0 zone at a greater rate with hydrogen enrichment due to high adiabatic flame temperature.

• 한국수소및신에너지학회논문집
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• 제26권2호
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• pp.164-169
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• 2015

Recent research has focused on alternative fuel to improve engine performance and to comply with emission regulation. Finding an alternative fuel and reducing environment pollution are the main goals for future internal combustion engines. The purpose of this study is to obtain low-emission and high-efficiency by hydrogen enriched CNG fuel in SI engine and is to clarify the effects of hydrogen enrichment in CNG fuelled engine on exhaust emission and performance. An experimental study was carried out to obtain fundamental data for performance and emission characteristics of hydrogen enrichment in SI engine. The experiment was conducted at 2500 rpm, bmep 2 bar, 4 bar conditions while CNG fuel was mixed with 10, 20 and 30% hydrogen blends. From the experimental results, combustion duration was shortened due to rapid flame propagation velocity of hydrogen and these were attributed to the burning velocity increasing exponentially with increasing hydrogen blending ratio. Hydrogen has much wider flammable limit than methane, gasoline and the minimum ignition energy is about an order of magnitude lower than for other combustion. By adding hydrogen, $CO_2$ and HC were reduced. However, $NO_X$ was increased dut to high rate of heat release for hydrogen substitutions.

• 한국수소및신에너지학회논문집
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• 제13권4호
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• pp.297-303
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• 2002

The purpose of study is obtaining low-emission and high-efficiency in LPi engine with hydrogen enrichment. The test engine was named variable compression ratio single cylinder engine (VACRE). The fuel supply system provides LPG/hydrogen mixtures based on same heating value. A varied sensors such as crank shaft position sensor (CPS) and hall sensor supplies spark timing data to ignition controller. Displacement of VACRE is $1858.2cm^3$. VACRE was runned 1400rpm with compression ratio 8. Spark timing was set MBT without knocking. Relative air-fuel ratio($\lambda$) of this work was varied between 0,8 and 1.5.

• 한국대기환경학회지
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• 제23권5호
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• pp.557-562
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• 2007

The purpose of this paper is to investigate the reforming characteristics and maximum operating condition for the hydrogen production by methane reforming using the compression ignition engine induced partial oxidation. An dedicated compression engine used for methane reforming was decided operating range. The partial oxidation reforming was investigated with oxygen enrichment which can improve hydrogen production, compared to general reforming. Parametric screening studies were achieved as $O_2/CH_4$ ratio, total flow rate, and intake temperature. When the variations of $O_2/CH_4$ ratio, total flow rate, and intake temperature were 1.24, 208.4 L/min, and $400^{\circ}C$, respectively, the maximum operating conditions were produced hydrogen and carbon monoxide. Under the condition mentioned above, synthetic gas were $H_2\;22.77{\sim}29.22%,\;CO\;21.11{\sim}23.59%$.

• 천문학회보
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• 제35권2호
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• pp.29.2-29.2
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• 2010

We present elemental abundances of 412 blue compact dwarf galaxies (BCDs) at z=0.2~0.5 using the Sloan Digital Sky Survey (SDSS) DR7. The gas-phase nitrogen to oxygen abundance ratios (N/O) of sample galaxies increase as the oxygen to hydrogen abundance ratios (O/H) decrease. This indicates that the nitrogen is more enriched than the oxygen. We found that there is a noticeable distinction between the merger candidates and the isolated galaxies. Merging candidates show more enrichment of nitrogen abundance compared to isolated galaxies. On the other hand, neon and oxygen abundances for merging candidates are slightly lower than the isolated systems. We discuss the main cause of these trends with internal mixing and mass loss by fast rotation of young massive stars. We also discuss the environmental effect to the relation between specific star formation rate and galaxy mass.

• 한국해양학회지:바다
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• 제8권4호
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• pp.380-391
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• 2003

광양만 및 여수해만의 중금속 오염과 저서환경에 대한 퇴적학적, 지화학적 특성을 평가하기위해 표층퇴적물을 채취하였다. 입도분석 결과 입도의 분포는 사질퇴적물과 점토질 퇴적물이 다양하게 분포하고 있는 것으로 나타났다. 사질퇴적물은 주로 POSCO 우측해역과 여수해만수로에 분포하고 있고 그 외 다른 지역에서는 니질퇴적물이 주로 분포하고 있다. 유기물(TOC) 함량은 약 0.2∼2.1%의 범위로 분포하고 있으며 유기물의 C/N비는 육지에서 공급된 유기물과 현장에서 생성된 유기물이 혼합되어 있음을 지시하고 있다. 또한 유기물의 C/S 비는 일부 지역에서 저서환경이 무산소 혹은 약한 저산소 상태에 있음을 지시하고 있다. 저질의 건강상태를 검토하기 위해 퇴적물중 황화수소 (H$_2$S) 함량을 측정한 결과 최고 301 ppm 에서 최소 0.7 ppm으로 나타났다. 전체적으로 묘도 안쪽지역에서 비교적 높은 값을 보이고 있어 일반적으로 오염된 저서환경을 지시하고 있다. 표층퇴적물에 대한 10종의 중금속 (Co, Ni, Cu, Cd, Pb, Li, Zn, V, Cr, Ba)에 대한 농축비(Ef)와 농집지수(Igeo)를 조사하였다. 그 결과 일부 지역에서는 평균퇴적 물의 농도에 비해 Pb, Ba는 최고 1∼7배정도 농축되어 있는 것으로 나타났으며, 그 외 금속 원소에 대해서도 0.8∼3.5 배 농축되어 있음이 나타났다. V와 Cd에 대한 농집지수는 조사지역 전역을 심하게 오염된 지역, 오염된 지역과 오염되지 않은 지역으로 대별할 수 있었다. 금속원소의 농축비 및 농집지수가 높은 곳은 유기물 및 황화수소 함량이 비교적 높게 나타나고 있으며 주로 세립질 퇴적물이 분포하는 지역으로 나타났다.

• 한국막학회:학술대회논문집
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• 한국막학회 1995년도 제3회 심포지움 (분리막 연구의 최신동향)
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• pp.21-22
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• 1995

Gas separation science and technology is among the most rapidly growing areas involving membrane-based processes. Nitrogen enrichment of air, hydrogen recovery from a broad array of stream types, and removal of acid gases from natural gases are typical of the applications in this field. Great progress has been made in the discovery of guidelines optimization of polymer structures with simultaneously high permeabilities and selectivities for these important gas pairs. The development of thin-skinned asymmetric hollow fibers have also provided structures with extremely high permeation fluxes. Especially in the case of O$_{2}$/N$_{2}$ separations, the rate of improvements in new polymeric materials for gas separations appears to be slowing to a halt. Evidence will be presented, however, that the practical tradeoff between membrane permeability and selectivity has not been reached.

• 대한환경공학회지
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• 제29권1호
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• pp.54-61
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• 2007

pH가 혐기성 수소 발효에 미치는 영향을 고찰하기 위해 배양기간 동안 pH를 $3\sim10$까지 일정하게 유지시킨 상태에서 수소생산 효율을 살펴보았다. 유입기질을 sucrose로 하여 생성된 가스는 이산화탄소와 수소였으며 메탄가스는 검출되지 않았다. 수정 Gompartz 방정식을 이용하여 수소가스 발생량$(P_h)$과 최대수소 생성율$(R_h)$을 회귀분석하였을 때 pH 5에서 수소가스 발생량$(P_h)$은 약 1182 mL이고 최대수소 생성율$(R_h)$은 112.46 mL/g dry wt biomass/hr이였다. 수소 전환율은 22.56%이였으며 butyrate/acetate 비가 pH 5에서는 1.63, pH 6에서는 0.38로 ratio값이 높은 pH 5에서 효율이 더 좋다는 것을 확인할 수 있었다. Haldane equation을 이용하여 비수소생산율을 산정해 본 결과 최대 비수소생산율은 119.61 mL/g VSS/hr이였고, 최대 비수소생산율을 나타내는 pH는 5.5로 판명되었다.