• 한국분말재료학회지
• /
• 제26권1호
• /
• pp.1-5
• /
• 2019

In this study, porous Mo-5 wt% Cu with unidirectionally aligned pores is prepared by freeze drying of camphene slurry with $MoO_3-CuO$ powders. Unidirectional freezing of camphene slurry with dispersion stability is conducted at $-25^{\circ}C$, and pores in the frozen specimens are generated by sublimation of the camphene crystals. The green bodies are hydrogen-reduced at $750^{\circ}C$ and sintered at $1000^{\circ}C$ for 1 h. X-ray diffraction analysis reveals that $MoO_3-CuO$ composite powders are completely converted to a Mo-and-Cu phase without any reaction phases by hydrogen reduction. The sintered bodies with the Mo-Cu phase show large and aligned parallel pores to the camphene growth direction as well as small pores in the internal walls of large pores. The pore size and porosity decrease with increasing composite powder content from 5 to 10 vol%. The change of pore characteristics is explained by the degree of powder rearrangement in slurry and the accumulation behavior of powders in the interdendritic spaces of solidified camphene.

• 한국산학기술학회논문지
• /
• 제17권8호
• /
• pp.502-507
• /
• 2016

화석연료에 기반을 둔 경제구조에서 수소경제로의 이행은 에너지 안보와 기후변화의 대응이라는 측면에서 중요한 과제이다. 이러한 경제구조의 변환과정에서 발생할 수 있는 파급효과를 사전적으로 분석하는 연구가 필요하다. 따라서 이 논문은 동태 연산일반균형모형을 이용하여 수소에너지 도입이 경제와 환경에 미치는 영향을 분석하였다. 첫째, 수소 에너지 도입은 투자증대와 생산비용의 감소를 통해 GDP 증대에 기여한다. 둘째, 수소에너지와 같은 신재생에너지 도입을 위한 정부보조의 경우 재원마련을 위한 세수증대로 인해 총수요가 감소하는 효과가 있다. 마지막으로 화석연료에서 수소경제로 전환시키는 수소에너지 도입은 이산화탄소 배출을 감소시키는 환경적 효과가 있다 온실가스 감소를 통한 기후변화에 보다 효과적으로 대응하기 위해서는 신재생에너지에 기반을 둔 수소에너지로의 전환이 필요하다. 즉 정부는 지속가능성에 기반을 둔 수소에너지 정책을 추진해야 하며, 향후 신재생에너지에 기반을 둔 수소에너지 도입의 경제적, 환경적 효과를 분석할 필요성이 있다.

• 한국수소및신에너지학회논문집
• /
• 제31권1호
• /
• pp.33-40
• /
• 2020

As hydrogen utilization becomes more active recently, a large amount of hydrogen should be supplied safely. Among the three supply methods, liquefied hydrogen, which is an optimal method of storage and transportation convenience and high safety, has a low temperature of -253℃, which is complicated by the liquefaction process and consumes a lot of electricity, resulting in high operating costs. In order to reduce the electrical energy required for liquefaction and to raise the efficiency, hydrogen is cooled by using a mixed refrigerant in a precooling step. The electricity required for the precooling process of the mixed refrigerant can be reduced by using the cold energy of LNG. Actually, LNG cold energy is used in refrigeration warehouse and air liquefaction separation process, and a lot of power reduction is achieved. The purpose of this study is to replace the electric power by using LNG cold energy instead of the electric air-cooler to lower the temperature of the hydrogen and refrigerant that are increased due to the compression in the hydrogen liquefaction process. The required energy was obtained by simulating mixed refrigerant (MR) hydrogen liquefaction system with LNG cold heat and electric system. In addition, the power replacement rate of the electric process were obtained with the pressure, the temperature of LNG, the rate of latent heat utilization, and the hydrogen liquefaction capacity, Therefore, optimization of the hydrogen liquefaction system using LNG cold energy was carried out.

• 한국분말야금학회:학술대회논문집
• /
• 한국분말야금학회 1995년도 춘계학술강연 및 발표대회 강연 및 발표논문 초록집
• /
• pp.17-17
• /
• 1995

• 한국수소및신에너지학회논문집
• /
• 제32권6호
• /
• pp.551-564
• /
• 2021

The use of clean energy based on the hydrogen economy is increasing rapidly due to the greenhouse gas reduction policies and the increase in the need for hydrogen. Currently, South Korea government have been considering a plan to construct hydrogen refueling stations at expressway service area for the purpose of supplying hydrogen vehicles. In the case of a hydrogen refueling stations, a quantitative risk assessment (QRA) must be performed because it includs and uses a high pressurized hydrogen storage tank. In this study, QRA was conducted using societal risk and F-N curve by the consequence assessment (CA) of jet fire and explosion according to the population density, capacity of the high pressurized hydrogen storage tank and frequency assessment (FA) data to the general hydrogen refueling stations systems in expressway service area. In the cases of jet with a leak diameter of 7.16 mm, regardless of expressway service area location, the societal risk was over 1E-04 that was acceptable for as Low As reasonably practicable (ALARP) region (workforce), but unacceptable for ALARP region (public). In the cases of gas explosion, all expressway service area satisfy ALARP region. In the case of the population density is over 0.0727, QRA for constructing the hydrogen refueling stations, must be conducted.

• 한국수소및신에너지학회논문집
• /
• 제31권4호
• /
• pp.351-362
• /
• 2020

Recently, renewable power is rapidly increasing globally due to extensive effort to mitigate climate change and conventional power generation industry faces new challenges. The gas turbine technology has potentials to expand its role in future power generation based on the intrinsic characteristics such as fuel diversity and fast load following ability. Hydrogen is one of the most promising fuel in terms of reducing emissions and storing variable renewable energy and replacing hydrocarbon fuel with hydrogen has become very popular. Therefore, this paper presents the core technologies to combust hydrogen added fuel efficiently in gas turbines and the analysis of domestic and international R&D trends.

• 한국수소및신에너지학회논문집
• /
• 제20권1호
• /
• pp.9-21
• /
• 2009

As one of the alternative solution for energy and environmental issues such as climate change, energy security, oil price, etc., hydrogen energy has been getting so much attentions these days. This paper analyzed the $CO_2$ emission, costs, and energy consumptions when the hydrogen energy was introduced to transportation, specifically in Sedan sector using the energy system model, MARKAL. As results, 21.5% of $CO_2$ emission in 2040 could be reduced and additional 76 billion dollars will be needed in the high energy price scenario. The amount of energy saving mainly due to the replacement of existing car to hydrogen vehicle was 16% of the final energy consumption in 2040.

• 한국태양에너지학회 논문집
• /
• 제37권5호
• /
• pp.27-37
• /
• 2017

In this study, an artificial solar simulator composed of a 2.5 kW Xe-Arc lamp and mirror reflector was used to carry out the solar thermal two step thermochemical water decomposition cycle which can produce high efficiency continuous hydrogen production. Through various operating conditions, the change of hydrogen production due to the possibility of a dual-zone reactor and heat recovery were experimentally analyzed. Based on the reaction temperature of Thermal-Reduction step and Water-Decomposition step at $1,400^{\circ}C$ and $1,000^{\circ}C$ respectively, the hydrogen production decreased by 23.2% under the power off condition, and as a result of experiments using heat recovery technology, the hydrogen production increased by 33.8%. Therefore, when a thermochemical two-step water decomposition cycle is conducted using a dual-zone reactor with heat recovery, it is expected that the cycle can be operated twice over a certain period of time and the hydrogen production amount is increased by at least 53.5% compared to a single reactor.

• 한국재료학회지
• /
• 제26권2호
• /
• pp.79-83
• /
• 2016

A commercial NiO (green nickel oxide, 86 wt% Ni) powder was reduced using a batch-type fluidized-bed reactor in a temperature range of 500 to $600^{\circ}C$ and in a residence time range of 5 to 90 min. The reduction rate increased with increases in temperature; however, agglomeration and sintering (sticking) of Ni particles noticeably took place at high temperatures above $600^{\circ}C$. An increasing tendency toward sticking was also observed at long residence times. In order to reduce the oxygen content in the powder to a level below 1% without any sticking problems, which can lead to defluidization, proper temperature and residence time for a stable fluidized-bed operation should be established. In this study, these values were found to be $550^{\circ}C$ and 60 min, respectively. Another important condition is the specific gas consumption rate, i.e. the volume amount ($Nm^3$) of hydrogen gas used to reduce 1 ton of Green NiO ore. The optimum gas consumption rate was found to be $5,000Nm^3/ton$-NiO for the complete reduction. The Avrami model was applied to this study; experimental data are most closely fitted with an exponent (m) of $0.6{\pm}0.01$ and with an overall rate constant (k) in the range of 0.35~0.45, depending on the temperature.

• 전기화학회지
• /
• 제18권2호
• /
• pp.81-85
• /
• 2015

A method for degradation of the perchlorate anion ($ClO{_4}^-$) has been studied using electrochemically generated zero-valent iron (ZVI) deposited on a porous carbon electrode. The first strategy of this study is to produce the ZVI via the electrochemical reduction of iron (II) on a porous carbon electrode coated with a conducting polymer, instead of employing expensive $NaBH_4$. The present method produced well distributed ZVI on conducting polymer (polypyrrole thin film) and increased surface area. ZVI surface can be regenerated easily for successive reduction. The second strategy is to apply a mild reducing condition (-0.3 V) to enhance the efficiency of the degradation of perchlorate with ZVI without the evolution of hydrogen. The electrochemically generated ZVI nanoparticles may offer an alternative means for the complete destruction perchlorate without evolution of hydrogen in water with high efficiency and at low cost.