• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 춘계학술대회 초록집
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• pp.158.2-158.2
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• 2011

DME is acronym of dimethyl ether, which is spotlighted as an ideal fuel to produce hydrogen due to its high hydrogen/carbon ratio, high energy density and easiness to carry. In this research, we calculated thermodynamic hydrogen (or syngas) yield from DME autothermal reforming and compared to other fuels. The reforming efficiency was about 80% above $700^{\circ}C$. Lower OCR has higher reforming efficiency but, it requires additional heat supply since the reactions are endothermic. SCR has no significant effect on the reforming efficiency. The optimized condition is $700^{\circ}C$, SCR 1.5, OCR 0.45 without additional heat supply. Comparing to other commercial gaseous fuels (methane and propane), DME has higher selectivity of $H_2O$ and $CO_2$ than the others due to the oxygen atom in the molecule. To apply DME autothermal reforming to real system, a proper catalyst is required. Therefore, it is performed the experiment comparing various novel metal catalysts based on CGO. Experiments were performed at calculated condition. The composition of product was measured and reforming efficiency was calculated. The catalysts have similar efficiency at high temperature(${\sim}800^{\circ}C$) but, CGO-Ru has the highest efficiency at low temperature ($600^{\circ}C$).

• 한국환경농학회지
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• 제35권2호
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• pp.121-127
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• 2016

BACKGROUND: Anaerobic digestion is the most feasible technology because not only the energy embedded in organic matters can be recovered, but also they are stabilized while being degraded. This study carried out to improve methane yield of slaughterhouse wastewater treatment sludge cake by the thermal pre-treatment prior to anaerobic digestion.METHODS AND RESULTS: Slaughterhouse wastewater treatment sludge cake was pre-treated by the closed hydrothermal reactor at reaction temperature of 190℃. BMPs (Biochemical methane potential) of the thermal hydrolysate was tested in the different S(Substrate)/I(Inoculum) ratio conditions. COD(Chemical oxygen demand) and SCOD(Soluble chemical oxygen demand) contents of thermal hydrolysate were 10.99% and 10.55%, respectively, then, the 96.00% of COD was remained as a soluble form. The theoretical methane potential of thermal hydrolysate was 0.51 Nm³ kg^-1-VS_added. And BMPs were decreased from 0.56 to 0.22 Nm³ kg^-1-VS_added when S/I ratio were increased from 0.1 to 2.0 in the VS content basis. Those were decreased from 0.32 to 0.13 Nm³ kg^-1-COD_added when S/I ratio were increased from 0.1 to 2.0 based on COD content. The anaerobic degradability of VS basis have showed 196.9%, 102.2%, 80.7%, 67.4%, and 39.4% in S/I ratios of 0.1, 0.3, 0.5, 1.0, and 2.0, respectively. Also the COD of 119.6%, 76.3%, 70.1%, 69.0%, and 43.1% were degraded anaerobically in S/I ratios of 0.1, 0.3, 0.5, 1.0, and 2.0, respectively.CONCLUSION: BMPs obtained in the S/I ratios of 0.1 and 0.3 was overestimated by the residual organic matters remaining at the inoculum. And inhibitory effect was observed in the highest S/I ratio of 2.0. The optimum S/I ratios giving reasonable BMPs might be in the range of 0.5 and 1.0 in S/I ratio. Therefore VS biodegradability of thermal hydrolysate was in 67.4-80.7% and COD biodegradability showed 69.0-70.1%.

• 한국수소및신에너지학회논문집
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• 제32권4호
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• pp.197-204
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• 2021

Pressure swing adsorption is a purification process which can get pure hydrogen. The purification process is composed of four process: compression, adsorption, desorption and discharge. In this study the adsorption process was simulated by using the Fluent and validated with experimental results. A gas used in experiment is composed of H₂, CO₂, CH₄, and CO. Adsorption process conducted under 313 kelvin and 3 bar and bituminous-coal-based (BPL) activated carbon was used as the adsorbent. Langmuir model was applied to explain the gas adsorption. And diffusion of all the gases was controlled by micro-pore resistances. The result shows that, the most adsorbed gas was carbon dioxide, followed by methane and carbon monoxide. And carbon monoxide took the least amount of time to reach the maximum adsorption amount. The molar fraction of the off-gas became the same as the molar fraction of the gas supplied from the inlet after adsorption reached the equilibrium.

• Journal of Animal Science and Technology
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• 제54권1호
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• pp.15-22
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• 2012

본 연구는 거세 한우의 비육 기간에 보리나 옥수수 위주의 농후 사료를 일당 증체량 0.7 kg/일에 필요한 TDN량 6.9 kg씩 급여하였을 때 장내 발효과정에 생성되는 메탄가스를 측정하는데 그 목적이 있다. 보리나 옥수수 급여구의 건물 섭취량은 차이가 없었으나 영양소별 섭취량은 보리와 옥수수의 영양성분의 차이에 의해서 보리 위주의 농후사료 급여구가 조단백질, 조섬유, 가용무질소물, 유기물, Neutral detergent fiber와 Acid detergent fiber의 섭취량이 유의적으로 섭취량이 높았고(p<0.05), 조지방과 조회분 섭취량은 옥수수 위주의 농후사료 급여구가 유의적으로 높았다(p<0.05). 각 영양소별 소화율은 보리나 옥수수 위주의 농후사료 급여 구 모두 건물, 조단백질, 조지방, 조회분 소화율에서 차이가 없었으나 조섬유, Neutral detergent fiber와 Acid detergent fiber 소화율은 보리 위주의 농후사료 급여 구에서 유의적으로 높았다(p<0.05). 호흡가스 발생량은 옥수수 위주의 농후사료를 급여했을 때가 산소 소모량 6.4% (p=0.32), 이산화탄소와 메탄생성량은 각각 15.4% (p=0.09)와 16.8% (p=0.09) 높은 경향이 나타났고, 메탄 배출계수는 보리나 옥수수 위주의 농후사료 급여 시 각각 43.6 (kg/Head/Year)과 50.9 (kg/Head/Year)로 산출되었다. 메탄전환계수는 보리와 옥수수 위주의 농후사료를 급여하였을 때 총에너지 섭취량은 각각 35.9 Mcal/d와 35.5 Mcal/d씩 섭취했고 메탄으로 손실된 에너지는 12.2 Mcal/d와 14.9 Mcal/d로 메탄가스 생성에 의한 메탄전환계수는 보리 위주의 농후사료 급여 구에서 4% (0.04 Ym)이었고, 옥수수 위주의 농후사료 급여 구에서 5% (0.05 Ym)로 나타났다. 따라서 위의 결과는 우리나라 한우의 사양 실정에 맞게 적용한 실험으로 향후 축산분야의 온실가스 저감을 위한 사양체계 및 메탄배출계수 산출연구에 대한 기초자료로 활용될 수 있을 것으로 판단된다.

• 한국산학기술학회:학술대회논문집
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• 한국산학기술학회 2010년도 춘계학술발표논문집 2부
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• pp.961-964
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• 2010

A semi-empirical fluctuation term is presented to improve a classical equation of state (EOS) for volumetric properties in the critical region. The term is based on the two assumptions: (1) The Helmholtz energy is individually divided into classical and long-range density fluctuation contribution (2) All molecules form cluster near the critical region due to long-range density fluctuation. To formulate such molecular cluster, we extended the Veytsman statistics originally developed for the cluster due to hydrogen bonding. The probability function in the statistics is modified to represent the characteristics of long-range density fluctuation vanishing far from critical region. The proposed fluctuation contribution was incorporated into the Sanchez-Lacombe EOS and the combined model with 6 adjustable parameters has been tested against experimental VLE data. The combined model is found to well represent flatten critical isotherm for methane and top of the coexistence curve for the tested components. The prediction results for caloric data are in good agreement with the experimental data.

• 에너지공학
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• 제22권4호
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• pp.347-354
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• 2013

생물학적방법으로 이산화탄소를 에너지원인 메탄으로 전환하고자 hydrogenotrophic methanogen이 우점화된 실험실규모의 연속운전 반응기를 이용하여 수소의 주입비율과 EBCT에 따른 실험을 진행하였다. 수소와 이산화탄소의 주입비율을 4:1과 5:1(mol/mol)로 달리한 실험결과 두 조건 모두 주입된 수소가 대부분 소모되며 99% 이상의 전환율을 보였다. 이산화탄소의 경우 4:1에서는 $74.45{\pm}0.33$%, 5:1에서는 $95.8{\pm}10.7%$의 전환율로 이산화탄소를 모두 전환시키기 위해서는 양론식에 비해 더 많은 양의 수소가 필요한 것으로 확인되었다. 이는 hydrogenotrophic methanogen의 생장유지에 필요한 에너지원인 수소가 사용된 것에 기인한 것으로 사료된다. 체류시간별로 처리효율을 확인한 결과, 임계처리용량은 EBCT 3.3시간에서 수소(99.9%)와 이산화탄소(96.23%)의 안정적인 전환율을 보이며 $1.15{\pm}0.02m^3{\cdot}m^{-3}{\cdot}day^{-1}$의 메탄생산속도와 $2.01{\pm}0.04kg{\cdot}m^{-3}{\cdot}day^{-1}$의 이산화탄소 고정화속도를 나타내었다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 춘계학술대회 초록집
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• pp.174.1-174.1
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• 2011

Biogas production and utilisation is an emerging alternative energy technology. Biogas is produced from the biological breakdown of organic matter through anaerobic digestion. Biogas can be utilized for various energy services such as heating, electricity generation and vehicle fuel. Especially, to be utilized as vehicle fuel, raw biogas needs to be upgraded, that is, mainly the removal of carbon dioxide to increase the methane content, up to more than 95% in some cases, similar to the composition of fossil-based natural gas. Biogas fuelled vehicles can reduce $CO_2$ emission by between 75% and 200% compared with fossil fuels. Biomethane development is largely driven by national initiative and predominately by concerns for national air pollution and waste management. Recently, biogas projects for vehicle fuels by some companies are ongoing and Korea government also announced investment to develop biogas as a transport fuel. Therefore, the aim of this study is to examine the feasibility of biomethane as a transport fuel in Korea. In this study, we investigated quality characteristics, quality standard and upgrading technology to use vehicle fuel of transport sector in Korea.

• 한국경영과학회지
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• 제15권1호
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• pp.37-46
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• 1990

Biomass to methane production is a good supply of substitutable energy resources. The economic viability of these systems depends a great deal on cost effective production methods and facilities. The operational problem is to determine the time eto allocate to each batch of several feedstocks for each digester and to determine the number of batches for each digester so as to maximize biogas production for two identical digesters over a fixed planning horizon. This paper provides an efficient approximation procedure which is based on decomposition of the problem and the analysis of incremental gas production function for each feedstock. The computational experience for the heuristic procedure was also reported.

• 한국안전학회지
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• 제27권4호
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• pp.26-32
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• 2012

With a progress of electrical and electronic technology, radio-frequency including high frequency components are widely to various industrial installations. Some of them are used in hazardous locations where explosive or flammable gases exist. As a result, ignition of such gases may be induced by a spark discharge when the radio frequency circuits are switched on or off. The purpose of this study is to investigate the ignition hazards of some kind of flammable mixtures based on the IEC 60079-11 publication. In this experiment, we used a high frequency resistive circuit which consists of a co-axial cable, a 20 ${\Omega}$, 30 ${\Omega}$, 40 ${\Omega}$ and 50 ${\Omega}$ resistor and two kind of power amplifier with frequency range up to almost 1 MHz and 50 MHz. Experimental results show that the ignition of the acetyleneair, ethylene-air mixtures and methane-air mixtures due to spark discharge depends primarily on the frequency of the power source in the resistive circuit the minimum ignition voltage increases gradually with the increase of the frequency.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2002년도 추계학술발표대회 논문집
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• pp.265-268
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• 2002

In this work, the blend system of epoxy and PMR-15 polyimide is investigated in terms of the cure behaviors and thermal stabilities. The cure behaviors are studied in DSC measurements and thermal stabilities are also carried out by TGA analysis. DDM (4, 4'-diamino diphenyl methane) is used as curing agent for EP and the content of PMR-15 is varied within 0, 5, 10, 35, and 20 phr to neat EP. As a result, the cure activation energy ($E_a$) is increased at 10 phr of PMR-15, compared with that of neat EP. From the TGA results of EP/PMR-15 blend system, the thermal stabilities based in the initial decomposed temperature (IDT) and integral procedural decomposition temperature (IPDT) are increased with increasing the PMR-15 content. The fracture toughness, measured in the context of critical stress intensity factor ($K_{IC}$) and critical strain energy release rate ($G_{IC}$), shows a similar behavior with $E_a$. This result is probably due to the crosslinking developed by the interactions between intermolecules in the polymer chains.