• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2008년도 추계학술대회 논문집
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• pp.196-199
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• 2008

In this study, gas hydrate production has been followed using swapping method to investigate the effect of injection rate of flue gas and soaking period in unconsolidated artificial sand sample. The results shows that recovery factor of methane gas decreases with increasing the injection rate of flue gas. This indicates that the velocity of flue gas in porous media may act as kinds of inhibitor for production of hydrate. Also recovery factor increases with increasing the soaking time.

• Asian-Australasian Journal of Animal Sciences
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• 제18권7호
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• pp.990-996
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• 2005

The effect of diets varying in level and source of nitrogen (N) and fermentable organic matter on dynamic characteristics of microbial populations in rumen liquor and their impact on substrate fermentation in vitro was studied. The diets tested were straw alone, straw+concentrate mixture and straw+urea molasses mineral block (UMMB) lick. The same diets were taken as substrates and tested on each inoculum collected from the diets. Diet had no effect on the amino acid (AA) composition of either bacteria or protozoa. Differences among the diets in intake, source of N and OM affected bacterial and protozoal characteristics in the rumen. Upper asymptote of gas production (Y$\alpha$) had a higher correlation with bacterial pool size and production rate than with protozoal pool size and production rate. Among the parameters of the gas production model, Y$\alpha$ and lag time in total gas has showed significant (p<0.01) correlation with bacterial characteristics. Though the rate constant of gas production significantly differed (p<0.01) between diet and type of straw, it was least influenced by the microbial characteristics. The regression coefficient of diet and type of straw for Y$\alpha$ indicated that the effect of diet on Y$\alpha$ was threefold higher than that of the straw. As microbial characteristics showed higher correlation with Y$\alpha$, and diet had more influence on the microbial characteristics, gas production on a straw diet could be used effectively to understand the microbial characteristics.

• Asian Journal of Atmospheric Environment
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• 제2권2호
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• pp.116-124
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• 2008

In this study, the Tier 2 method recommended by the Intergovernmental Panel on Climate Change (IPCC) was used to predict the methane generation rate at two landfill sites, designated as Y and C for purposes of this study, in South Korea. Factors such as the average annual waste disposal, methane emissions ($L_0$) and methane gas generation rate constant (k) were estimated by analyses of waste and the historical data for the landfills. The value of k was estimated by field experiments and then the changes in the methane generation rate were predicted through the year 2050, based on the value of k. The Y landfill site, which was in operation until the year 2008, will generate a total of 17, 198.7 tons by the end of 2018, according to our estimations. At the C landfill site, which will not be closed until the end of 2011, the amount of methane gas generated in 2011 will be 3,316 tons and the total amount of gas generated by 2029 will be 61,200 tons. The total production rate of methane gas at the C landfill is higher than that of the Y landfill. This indicates that the capacity of a landfill site affects the production rate of methane gas. However, the interrelation between the generation rate of methane and the value of k is weak. In addition, the generation of methane gas does not cease even when the operations at a landfill site come to a close and the methane gas production rate is at its highest at end of the operating life of a landfill site.

• 한국가스학회지
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• 제19권3호
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• pp.54-59
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• 2015

가스하이드레이트(GH: Gas Hydrate)는 전 세계적으로 약 10조 톤에 이르는 엄청난 양이 대부분 해양의 대륙사면에 부존되어 있으나(동토 지역 : 2 %, 해양 대륙사면 98 %), 현재까지 가스하이드레이트 저류층으로부터 상업화할 수 있을 만큼 가스를 회수하는 기술이 개발되어 있지 않은 실정이다. 일반적으로 회수하는 방법은 감압법, 열자극법, 억제재 주입법 및 치환법 등으로 크게 나누어 볼 수 있으며, 본 연구에서는 가스하이드레이트 포화율과 감압률에 따라서 가스하이드레이트 해리시간 및 가스생산이 어떻게 달라지는 지, 그에 대한 특성을 분석하고자 하였다. 연구분석 결과 감압률과 해리시간의 상관 관계식을 도출($Y=0.0004X^2-0.499X+176.86$)할 수 있었고, 또한 감압률이 클수록 메탄생산량이 좋다는 것을 알 수 있었지만(감압률 40% 대비 50%에서 메탄가스생산량이 46.2% 향상), 감압률이 60%에서는 오히려 생산량이 줄어드는데, 이는 가스하이드레이트 재형성에 기인한 것으로 판단된다.

• 한국수소및신에너지학회논문집
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• 제20권5호
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• pp.416-423
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• 2009

High-temperature steam electrolysis (HTSE) using solid oxide cell is a challenging method for highly efficient large-scale hydrogen production as a reversible process of solid oxide fuel cell (SOFC). The overall efficiency of the HTSE hydrogen and synthesis gas production system was analyzed thermo-electrochemically. A thermo-electrochemical model for the hydrogen and synthesis gas production system with solid oxide electrolysis cell (SOEC) and very high temperature gas-cooled reactor (VHTR) was established. Sensitivity analyses with regard to the system were performed to investigate the quantitative effects of key parameters on the overall efficiency of the production system. The overall efficiency with SOEC and VHTR was expected to reach a maximum of 58% for the hydrogen production system and to 62% for synthesis gas production system by improving electrical efficiency, steam utilization rate, waste heat recovery rate, electrolysis efficiency, and thermal efficiency. Therefore, overall efficiency of the synthesis production system has higher efficiency than that of the hydrogen production system.

• 한국환경보건학회지
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• 제16권2호
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• pp.89-95
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• 1990

This study was investigated to the energy recovery by the pyrolysis of waste tyre. the pyrolysis of the waste tyre was made by using the pyrolysis chamber for the gasification and the combustion chamber for the combustion of the pyrolysis gas. In batch system, the amount of waste tyre was put 150kg in the pyrolysis chamber and the proper air flow rate for the stable production of the pyrolysis gas was 0.95Nm$^{3}$ /min. the production time of the pyrolysis gas was stable above 210minutes, and the stable production rate was above 3.8Nm$^{3}$ /min. The production temperature of pyrolysis gas was 170$^{\circ}$C and combustion temperature of pyrolysis gas was 1,000$^{\circ}$C. The combustible component of washing gas in pyrolysis gas of waste tyre was CO, CH$_{4}$, $C_{2}H_{6}$ and $C_{3}H_{8}$, and total amount was 22.7%. Heat value of condensed material was 9,804Kcal/kg. The average concentration of air pollutants between cyclone and scrubber was CO 420.4ppm, SO$_{x}$ 349.8ppm. NO$_{x}$ 68.Sppm, HCl 24.4ppm and Dust 240.0g / Nm$^{3}$, respectively.

• 한국농공학회지
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• 제32권3호
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• pp.102-115
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• 1990

Importance of anaerobic digestion as an energy generating device has been increased as fuel shortage becomes serieous. Several modification methods on the conventional digesters including Powdered Activated Carbon (PAC) addition and two-phase digestion were studied to enhance the gas production. This study investigated the effects of PAC on anaerobic digestion of chicken manure in terms of gas production and sludge stabilization. As a first experiment, an optimum PAC dose for efficient gas production was determined in a batch test. In semi-continuous experiments, an optimum Sludge Retention Time (SRT) at that PAC concentration and an overall substate utilization rate coefficient were investigated. A portion of gas increased by PAC addition was estimated using a substrate utilization rate coefficient of microorganisms attached on PAC. This test was performed in batch experiments using acetic acid as a substrate. The digesters for all experiments were kept 35${\pm}$ 1˚C in a heated water bath. Mixing was performed manually once a day and the produced gas was collected for daily reading. The following conclusions were made for this study. 1. Cptimum PAC concentration was 5% total solids, where gas production rate was increased by 20 percents. 2. Optimum SRT was 7.5 days. 3. Substrate utilization rate coefficient of microorganisms attached on PAC was about twice as much as that of suspended ones.

• 대한기계학회논문집
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• 제19권3호
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• pp.858-867
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• 1995

Characteristics of premixed flames in counter-flow system are numerically studied using a detailed chemical reaction mechanism including gas phase radiation. Without radiation effect accounted, low CO and high NO$_{x}$ emission indices are observed, when strain rate decreases, due to increased residence time and higher flame temperature. Higher NO$_{2}$ production has been also observed when two premixed flames are interacting or cold air stream is mixed with burned gas. The rate of NO$_{x}$ production and destruction is dependent upon the diffusional strength of H and OH radicals, the existence of NO and the concentration of HO$_{2}$. For radiating flames, the peak temperature and NO$_{x}$ production rate decreases as the strain rate decreases. At high strain rate, it is found that the effect of radiation on flame is little due to its negligible radiating volume. It is also found that NO$_{x}$ production from the interacting premixed flame is reduced due to reduced temperature resulting from radiation heat loss. It is concluded that the radiation from gas has significant effect of flame structure and on emission characteristics.ristics.

• Asian-Australasian Journal of Animal Sciences
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• 제13권8호
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• pp.1084-1093
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• 2000

An in vitro gas production system was used to investigate the influence of various substrate mixtures on a natural mix of rumen microbes by measurement of fermentation end-products. The treatments were combinations of cassava (15.0, 30.0 and 45.0%) with different roughage sources (ruzi grass, rice straw or urea treated rice straw). Microbial biomass, net $^{15}N$ incorporation into cells, volatile fatty acid production, gas volume and rate of gas production increased linearly with increasing levels of cassava inclusion. There was also an effect of roughage source, with rice straw being associated with the lowest values for most parameters whilst similar values were obtained for ruzi grass and urea treated rice straw. The results suggest that microbial growth and fermentation rate increase as a function of readily available carbohydrate in the substrate mixture. A strong linear relationship between $^{15}N$ enrichment, total volatile fatty acid production and gas production kinetics support the suggestion of the use of the in vitro gas production system as a tool for screening feedstuffs as an initial stage of feed evaluation.

• 한국가스학회지
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• 제22권6호
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• pp.90-103
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• 2018

본 연구에서는 초크크기와 가스주입량을 조절함으로써 일반 유정이나 가스리프트가 적용된 유정에서 최적생산량을 산출할 수 있는 두 가지 인공신경망 모델을 개발하였다. 개발된 모델들의 입력자료는 용해가스-오일비, 물 생산 비율, 저류층압력, 초크크기 또는 가스주입량이고 출력자료는 정두압력과 오일 생산량으로 구성하였다. 먼저 육상 유정 시스템에 대하여 입력자료의 민감도 분석을 통해 각 변수의 범위를 결정하였고, 노달분석을 수행하여 초크크기 선정 모델에 1,715개, 가스주입량 선정 모델에 1,225개의 훈련자료를 각각 생성하였다. 동일한 저류층 자료에 대해 노달분석과 인공신경망 모델 결과를 비교해보면 두 모델 모두 결정계수 값이 0.99 이상으로 상관관계가 매우 높은 것으로 확인되었다. 또한 초크크기 선정 모델의 정두압력과 오일 생산량의 평균절대백분율오차는 각각 0.55%, 1.05%이고, 가스주입량 선정 모델의 정두압력과 오일 생산량의 평균절대백분율오차는 각각 1.23%, 2.67%로 개발된 모델의 정확도가 높은 것으로 확인되었다.