• 멤브레인
• /
• 제27권6호
• /
• pp.477-486
• /
• 2017

수소는 산업용 전력생산, 자동차용 연료 등을 위한 대체가능한 에너지 담체로 인식되고 있다. 미래 저탄소 에너지 시스템에서 에너지 저장은 전력 수요에 유연하지 않거나 간헐적인 공급의 균형을 이루기 위한 중추적인 역할을 담당할 수 있을 것이다. 수소는 에너지 담체로서 전기에너지를 화학에너지로, 화학에너지를 전기에너지로 변환할 수 있는 에너지 저장 방법 중의 하나이다. 수소제조 방법 중에서, 특히, 물의 전기분해를 이용한 방법은 신재생 에너지원과의 접목을 고려할 때 가장 효율적이고 실용적인 방법으로 여겨지고 있다. 물 전기분해 수소제조 기술은 전기를 이용하여 수소를 물로부터 직접 제조하는 방법으로, 화석연료 이용 제조방법과 비교하여 수소를 제조할 때 지구환경 오염물질인 이산화탄소의 배출이 없다. 수소제조 방법 중의 하나인 물 전기분해의 원리와 물 전기분해의 종류인 알칼리 수전해(AWE, alkaline water electrolysis), 고분자 전해질막 수전해(PEMWE, polymer electrolyte membrane water electrolysis), 고온 수증기 전기분해(HTSE, high temperature steam electrolysis)에 대하여 분석하고자 하였다. 물 전기분해는 수소제조 방법의 하나로 연구가 진행되고 있으며, 최근에는 PTG (power to gas)와 PTL (power to liquid) 시스템의 요소기술로도 주목을 받고 있다. 본 총설에서는 물 전기분해에 대한 원리와 종류, 특히 알칼리 수전해에 대한 최근 연구동향에 대해 설명하였다.

• Journal of Electrochemical Science and Technology
• /
• 제10권3호
• /
• pp.302-312
• /
• 2019

The voltage produced from the salinity gradient in reverse electrodialysis (RED) increases proportionally with the number of cell pairs of alternating cation and anion exchange membranes. Large-scale RED systems consisting of hundreds of cell pairs exhibit high voltage of more than 10 V, which is sufficient to utilize water electrolysis as the electrode reaction even though there is no specific strategy for minimizing the overpotential of water electrolysis. Moreover, hydrogen gas can be simultaneously obtained as surplus energy from the electrochemical reduction of water at the cathode if the RED system is equipped with proper venting and collecting facilities. Therefore, RED-driven water electrolysis system can be a promising solution not only for sustainable electric power but also for eco-friendly hydrogen production with high purity without $CO_2$ emission. The RED system in this study includes a high membrane voltage from more than 50 cells, neutral-pH water as the electrolyte, and an artificial NaCl solution as the feed water, which are more universal, economical, and eco-friendly conditions than previous studies on RED with hydrogen production. We measure the amount of hydrogen produced at maximum power of the RED system using a batch-type electrode chamber with a gas bag and evaluate the interrelation between the electric power and hydrogen energy with varied cell pairs. A hydrogen production rate of $1.1{\times}10^{-4}mol\;cm^{-2}h^{-1}$ is obtained, which is larger than previously reported values for RED system with simultaneous hydrogen production.

• Bulletin of the Korean Chemical Society
• /
• 제24권6호
• /
• pp.802-804
• /
• 2003

The relative stabilities of weak binding clusters are sensitive to temperature due to the entropy effect. Thus, here we report significant changes in relative stabilities between two low-energy electron-water trimer structures and those between three low-energy electron-water pentamer structures, as the temperature increases. The trimer and pentamer show structural changes around 200 K.

• 에너지공학
• /
• 제25권1호
• /
• pp.29-42
• /
• 2016

본 연구는 최근 정부의 에너지신산업 정책 중 하나인 발전소 온배수열 활용사업의 경제성을 분석하고, 동 사업의 활성화를 위한 정부의 경제적 유인 제도를 재구성하였다. LCOE 산출방법을 이용하여 발전소 온배수열 시스템의 경제성을 분석한 결과 현 수준에서는 기름보일러, 바이오매스, 발전소 보조증기보다 LCOE값이 높지만 지열 시스템과는 유사한 것으로 나타났다. 또한 온배수열 시스템의 LCOE 구성요인의 민감도를 측정한 결과, 열공급 거리에 가장 민감하게 반응하는 것으로 나타났다. 따라서 온배수열 활용사업을 확대시키기 위한 정부의 경제적 유인제도 구성 시 REC 가중치를 열공급 거리별로 차등 적용하는 것이 필요한 것으로 분석되었다.

• Journal of Advanced Marine Engineering and Technology
• /
• 제22권4호
• /
• pp.529-537
• /
• 1998

Currently as due to the rapid development of industry and increase in population we meet serious problems concerning the shortage and pollution of water. In the country many experts predict a shortage of water approaching 450 million tons by the year 2006. To cope with this serious problem it is necessary to construct desalination plants. In the adoption of a desalination system the most important factor is the cost of fresh water production,. In general LNG is stored in a tank as a liquid state below $-162^{\circ}C$. When it is serviced, however the LNG absorbs energy from a heat source and transforms to a high pressure gaseous state. During this process a huge amount of cold energy accumulated in cooling LNG is wasted. This wasted cold energy can be utilized to produce fresh water by using a sea water freezing desalination system. In order to develop a sea water freezing desalination system and to establish its design technique qualitative and quantitative data regarding the freezing behavior of sea water is required in advance, The goals of this study are to reveal the freezing behavior of sea water is required in advance. The goals of this study are to reveal the freezing mechanisms of sea water to measure the freezing rate and to investigate the freezing heat-transfer characteristics,. The experimental results will provide a general understanding of sea water freezing behavior in a rectangular vessel cooled from above.

• 한국태양에너지학회 논문집
• /
• 제32권6호
• /
• pp.53-59
• /
• 2012

This study was carried out to evaluate thermal performance of the renewable hybrid heat supply system with solar thermal system and wood pellet boiler for Zero Carbon Green home of apartment houses. The hybrid heat supply system was set up at Korea Institute Energy Research in 2011. The system was comprised of the wood pellet boiler unit with heat capacity designed as 20,000kcal/hr, a $0.15m^3$ hot water storage tank for space heating, a evacuated tubular solar collector $3.74m^2$ of aperture area at the $20^{\circ}$ install angle, a $0.3m^3$ hot water storage tank. Thermal performance tests for one-house of apartment house were carried out by hot water load and heating load in winter season through the hybrid heat supply system. As a result, hot water energy supplied by the hybrid heat supply system was 11kWh in a day. Solar thermal energy portion was 2.99kWh which is 27% of the total hot water energy supply. wood pellet boiler supply portion was 8.017kWh which is 73% of the total hot water energy supply.

• 한국전산유체공학회지
• /
• 제21권2호
• /
• pp.106-111
• /
• 2016

Waste-to-energy facilities including incinerators are known as an efficient method to reduce wastes. In waste-to-energy facilities, more efficient cooling system is still needed for grates as the energy density of waste increased. For better cooling performance with the water-cooled grates, optimal design of cooling water pathways is highly beneficial. We performed numerical investigation on fluid flow and residence time of cooling water with change of the geometry of the cooling water pathway. With addition of round shaped guide vanes in the water pathway, the maximum residence time of flow is reduced(from 4.3 sec. to 2.4 sec.), but there is no significant difference in pressure drop between inlet and outlet, and average residence time at the outlet. Furthermore the flow stagnation region moves to the outlet, as the position of the round shaped guide vanes is located to the neck point of pathways.

• 대한설비공학회:학술대회논문집
• /
• 대한설비공학회 2009년도 하계학술발표대회 논문집
• /
• pp.357-362
• /
• 2009

As a unutilized energy, treated sewage water locates widespread near urban areas. From the previous survey, the sewage water is reported to hold energy potential up to 36,000 Tcal/year, which was 2.1% of the total domestic energy consumption and 9.7% of the energy usage in the household and business sector in 2006. Temperature of the sewage water differs locally, but its range is observed in a range of $20{\sim}25^{\circ}C$ in summer and $8{\sim}13^{\circ}C$ in winter. Since the temperature range of the sewage water has a better seasonal distribution about $5{\sim}10^{\circ}C$ compared to ambient air, it is a promising heat sink for summer or heat source for winter. The sewage water is also a high quality heat source from its abundant quantity and uniform temperature. Considering the ambient temperature of Korea is very low in winter, a heat pump system using the sewage water can be an alternative to prevent problems of capacity deficiency and frost formation.

• 한국원자력학회:학술대회논문집
• /
• 한국원자력학회 2005년도 춘계학술발표회
• /
• pp.105-106
• /
• 2005

• 동력기계공학회지
• /
• 제20권2호
• /
• pp.79-84
• /
• 2016

The thermodynamic performance of ocean thermal energy conversion with 1 kg/s geothermal water flow rate as a heat source was evaluated to obtain the basic data for the optimal design of cycle with respect to the classification of the working fluid. The basic thermodynamic model for cycle is rankine cycle and the geothermal water and deep seawater were adapted for the heat source of evaporator and condenser, respectively. R245fa, R134a are better to use as a working fluid than others in view of the use of geothermal water. It is important to select the proper working fluid to operate the ocean thermal energy conversion. So, this paper can be used as the basic data for the design of ocean thermal energy conversion with geothermal water and deep seawater.