• Journal of the Korean Solar Energy Society
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• v.24 no.1
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• pp.7-12
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• 2004

Mixtures type PCM, $H_2O$-NaOH that has relatively large capacity of the latent heat and long duration of phase change temperature was developed and experimentally analyzed for the low temperature storage of the food and medical products. The results could be summarized as follows; 1. Borax as nucleating agent and acrylic polymer as thickening agent were added to $H_2O$ to prevent the supercooling and phase separation. 2. Phase change (solid$\leftrightarrows$liquid) duration of $H_2O$ added with NaOH was prolonged longer 50% than that of pure $H_2O$. 3. Phase change temperature of the latent heat material, $H_2O$-NaOH was $1.5\sim2^{\circ}C$ the maximum latent Heat was 279 kJ/kg at the NaOH addition of 1.3 wt.%. 4. The specific heat of $H_2O$-NaOH at the solid and liquid state was increased in proportion to the wt.% of NaOH, when NaOH of $1.15\sim1.60$ wt.% was added to $H_2O$, the specific heat of the solid state was increased from 3.19 kJ/kg to 5.84 kJ/kg and that of liquid state from 7.8 kJ/kg to 10.28 kJ/kg. 5. When NaOH of $1.15\sim1.60$ wt.% was added to $H_2O$, the total heat storage capacity composed of sensible and latent heat was $313\sim331.3$ kJ/kg and the maximum heat storage capacity was occurred at NaOH addition of 1.30 wt. %.

• Proceedings of the KIPE Conference
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• 2011.11a
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• pp.275-276
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• 2011

본 논문은 풍력과 태양광 등의 신재생 에너지 전력저장뿐만 아니라 계통 안정화 및 전력품질 관리에 적용 가능한 BESS(Battery Energy Storage System)에서 대용량 에너지를 안정적으로 충전하고 방전할 수 있는 BCS(Battery Conditioning System) 개발에 대해 기술하였다. 충 방전시 배터리 냉각을 고려한 열유동 해석, 외부 환경조건 및 국내외 운송을 고려한 구조해석 등의 과정을 거쳐 설계 제작하였으며, 충 방전 성능시험을 수행하였다.

• Journal of Energy Engineering
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• v.26 no.2
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• pp.99-120
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• 2017

In SS branch of Korea District Heating Corporation, Combined Heat & Power power plant with 99MW capacity and 98Gcal / h capacity is operated as a district electricity business. In this region, it is difficult to operate the generator due to the problem of surplus heat treatment between June and September due to the economic recession and the decrease in demand, so it is urgent to develop an economical energy new business model. In this study, we will develop an optimized operation model by introducing a renewable energy hybrid system based on actual operation data of this site. In particular, among renewable energy sources, fuel cell (Fuel Cell) power generation which can generate heat and electricity at the same time with limited location constraints, photovoltaic power generation which is representative renewable energy, ESS (Energy Storage System). HOMER (Hybrid Optimization of Multiple Energy Resources) program was used to select the optimal model. As a result of the economic analysis, 99MW CHP combined cycle power generation is the most economical in terms of net present cost (NPC), but 99MW CHP in terms of carbon emission trading and renewable energy certificate And 5MW fuel cells, and 521kW of solar power to supply electricity and heat than the supply of electricity and heat by 99MW CHP cogeneration power, it was shown that it is economically up to 247.5 billion won. we confirmed the results of the improvement of the zone electricity business condition by introducing the fuel cell and the renewable energy hybrid system as the optimization process model.

• Solar Energy
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• v.7 no.2
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• pp.22-29
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• 1987

This paper dealed with thickness variation of bottom heat sotrage zone due to salinity and flow rate of extration hot brine in small test solar pond (0.5m wide, 0.5m high, 1.0m long). Testing apparatus and situation were follows: 7.1 cm of height of suction diffuser and 1.8cm of height of discharge diffuser above the test pond respectively, 0.3cm of slot size of suction diffuser, 1.0cm of slot size of discharge diffuser, 47cm of length of the slot; heating of hot water ($75^{\circ}C$) through separated hot water tank, discharge of the brine into storage zone through discharge diffuser, the extration of the brine through suction diffuser, circulation of the extracted brine through a heat exchanger (cooler). Following results were obtained through the experiments. 1. In small test solar pond, the typical three zone which showed up in real solar pond were established. 2. Richardson Number was used more effectively to confirm hydrodynamic stability of the stratified flow. 3. The thickness of non convective layer had a great effect on the heat storage of the bottom convective layer, then the temperature of bottom convective layer had a relation to that of upper convective layer. 4. Optimum operating condition in the test pond was on 10%-15% of salt concentration and $0.05m^3/hr$ of flow rate of extraction hot brine. 5. Following thickness of 3 zones were available to obtain under optimum operation condition: o bottom storage zone: $30%{\pm}10%$ of total pond depth o non-convective zone: $40%{\pm}10%$ of total pond depth o Upper surface zone: $20%{\pm}10%$ of total pond depth.

• Journal of the Korean Solar Energy Society
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• v.39 no.6
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• pp.93-112
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• 2019

In this paper, a very new web-based software for renewable energy system (RES) design and economic evaluation was introduced. This solution would provide the precise RES estimation service including not only photovoltaic (PV), wind turbine (WT) and fuel cell (FC) individually but also energy storage system (ESS) as combined forms with PV or WT. The three reasons why we ought to develop it are: First, the standardized tool suitable to the domestic environment for estimating power generation from RES facilities and economic evaluation is required. Secondly, the standardized tool is needed to spread domestic RES supply policy and to promote the new industry in the micro-grid field. The last, the reliability of economic evaluation should be enhanced more for new facilities. To achieve those aims, the weather database of one hundred locations have established and the RES facility database has also constructed. For the energy management, mathematical models for PV, WT, ESS and FC were developed. As a final phase, the analytical process to evaluate economics has performed with field data verification.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.151-151
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• 2011

오늘날 에너지문제는 인류가 직면한 가장 중요한 당면과제 중 하나이다. 석유, 석탄과 같은 화석에너지는 점점 고갈되어 가고 있으며, 이산화탄소 배출로 인한 기후변화도 해결이 시급한 문제이다. 이러한 문제들을 해결하기 위한 방안으로 신재생에너지의 중요성이 부각되고 있다. 특히 신재생에너지 기술 중 태양전지는 미국, 일본, 유럽, 중국 등 많은 국가에서 기술개발 및 보급에 앞장서고 있으며, 시장선점을 위한 기술개발 경쟁이 치열하다. 또한 연료전지의 경우 전기와 열을 동시에 생산 가능하며, 다른 에너지 변환기보다 훨씬 높은 효율을 가지고 있어 신에너지원으로서 주목받고 있다. 이와 함께 기후변화에 실질적인 해결책으로 세계는 CCS에 기대하고 있으며, 기술개발 및 실증을 위한 국제공동연구도 활발하게 진행 중이다. 본 논문에서는 이러한 중요성을 인식하여 태양전지, 연료전지 그리고 CCS에 대하여 국내외 에너지기술 활용도를 분석하였다. 활용도 분석을 위하여 특허등록건수, 특허의 피인용 정보와 이를 활용한 CPP지수를 산출하였다. 오늘날 특허는 국가나 기업 등 특정 주체에 대한 기술력 또는 혁신성을 측정하거나, 기술개발 동향을 파악하기 위한 중요한 정보로 사용된다. 특히 CPP지수(특허당 피인용지수)는 분석대상(국가, 기업 등)의 특허가 이후의 기술혁신 활동에 어느 정도의 활용되어 영향을 미쳤는가를 보여주는 지표로써, 특정 국가나 기업의 기술혁신 활동의 수준 및 혁신성과의 가치를 살펴 볼 수 있다. 이를 통하여 국내의 에너지기술 경쟁력을 살펴보고 시사점을 도출하였다. 우선 특허데이터 수집을 위하여 톰슨 이노베이션을 활용하여 2001년부터 2010년까지 미국, 일본, 유럽, 한국에 등록된 특허를 검색하였으며, 특허등록번호를 중심으로 중복데이터를 제거하였다. 또한 특허명칭, 요약정보를 통하여 노이즈를 제거하였다. 노이즈가 제거된 특허를 활용하여 기술별, 국가별 기술개발 동향을 살펴보았으며, CPP지수를 통하여 기술별, 국가별 활용도를 분석하였다. 분석 결과, 태양전지의 경우 대부분의 국가에서 특허건수가 매년 증가함에 따라, 지속적으로 기술경쟁이 심화되고 있는 것으로 분석되었다. 또한 한국의 CPP지수는 미국, 일본 등 주요 경쟁국가에 비해 상당히 낮게 나타나 기술 활용 수준이 낮은 것으로 분석되었다. 따라서 핵심기술 개발과 같은 에너지기술의 질적수준을 높이기 위한 대책마련이 필요한 실정이다. 본 논문의 결과를 통하여 특허를 위한 기술개발이 아닌 보다 활용성이 높은 기술개발이 이루어지기를 바라며, 나아가 국가에너지기술 경쟁력을 높이는데 기여할 것으로 기대한다.

• Journal of the Korean Solar Energy Society
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• v.21 no.4
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• pp.37-46
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• 2001

This study describes the experimental study that focuses on the effects that distributor shapes and flow rate variations have an influence on the stratification in a rectangular thermal storage tank. Experiments were carried out under the conditions that the flow rates of working fluid are 20, 10 and $5\ell$/min. The storage tank is initially filled with chilled water of $1^{\circ}C$, and is extracted through the bottom at the same rate as the return warm water from load is entered through the distributor at the top of the tank. The thermo-cline forms at the top of the storage tank as the warm water enters the tank from the load through the distributor and the thermo-cline thickness increases with time. Emphasis is given to the effects of mixing at the inlet that increases the thermo-cline decay Flow rate variation and inlet distributor shapes are the important parameters in deciding the performance of a storage system. Stratification degree increases with decreasing in inlet flow rate under $10\ell$/min. Experiments shows that better thermal stratification can be obtain using the distributor to limit momentum mixing at the inlets and outlets. Also, 12% of improvement in the thermal energy usage has been achieved using the modified distributor discharging same flow rate in each lateral ports.

• Korean Chemical Engineering Research
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• v.43 no.3
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• pp.331-343
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• 2005

Development of hydrogen station system is an important technology to commercialize fuel cells and fuel cell powered vehicles. Generally, hydrogen station consists of hydrogen production process including desulfurizer, reformer, water gas shift (WGS) reactor and pressure swing adsorption (PSA) apparatus, and post-treatment process including compressor, storage and distributer. In this review, we investigate the R&D trends and prospects of hydrogen station in domestic and foreign countries for opening the hydrogen economy society. Indeed, the reforming of fossil fuels for hydrogen production will be essential technology until the ultimate process that may be water hydrolysis using renewable energy source such as solar energy, wind force etc, will be commercialized in the future. Hence, we also review the research trends on unit technologies such as the desulfurization, reforming reaction of fossil fuels, water gas shift reaction and hydrogen separation for hydrogen station applications.

• Journal of The Korean Society of Agricultural Engineers
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• v.51 no.2
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• pp.1-6
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• 2009

Acetogen과 같은 일부 혐기성미생물은 소위 acetyl-CoA 경로에 의해 아세트산, 에탄올, 그리고 몇 가지 생화학 물질을 생산한다. 이 경로에서는 일산화탄소를 기질로 이용할 수 있다. 일산화탄소 이외에 수소가 이용될 수 있다. 즉 이들 미생물은 독립영양생물로서 이산화탄소와 태양광에너지를 이용하는 녹색식물과 비유될 수 있으며, 일산화탄소는 탄소원으로서 동시에 에너지원으로서 이용된다. 본 연구에서는 혐기성 소화액 중 아세트산을 생성하는 미생물이 존재한다고 가정하고, 일산화탄소와 수소가 주 가연성분인 합성가스를 공급하면 추가의 메탄이 생성가능성을 평가하였다. 혐기성 소화과정에서 발생되는 메탄은 주로 아세트산으로부터 만들어지므로 일산화탄소를 공급하는 경우 추가로 메탄이 생성될 것으로 추측할 수 있기 때문이다. 이를 확인하기 위하여 현재 운영중인 바이오가스 생산 설비로부터 얻은 혐기성 소화액을 생물반응조에 넣은 후, 합성가스를 순환-공급하여 가스 생산량의 변화 및 조성을 분석하였다. 질소가스를 공급한 대조구와는 달리 일산화탄소 또는 합성가스를 공급한 경우에는 메탄가스가 생산되는 것을 확인하였다. 질소가스를 공급한 대조구와는 달리 일산화탄소 또는 합성가스를 공급한 경우에는 메탄가스가 생산되는 것을 확인하였다. 일산화탄소만을 공급했을 때에는 이산화탄소의 생성으로 가스 생산량이 증가하였으나, 수소가 포함된 합성가스를 공급하였을 때에는 이산화탄소가 탄소원이로 소비되어 가스 저장도 내의 가스량이 감소하는 것을 확인할 수 있었다. 가스화공정에 으해 얻어지는 합성가스는 온도와 가스 조성을 고러할 때, 바이오가스 생산을 위한 혐기성 소화조와 연계하면 소화조의 가온에 필요한 열을 공급할 수 있고 바이오가스 중 이산화탄소 농도를 낮추어 발열량을 개선할 수 있을 것으로 판단된다.

• Solar Energy
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• v.13 no.2_3
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• pp.65-78
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• 1993

An overdose of fossil fuel for greenhouse heating causes not only the high cost and low quality of agricultural products, but also the environmental pollution of farm village. To solve these problems it is desirable to maximize the solar energy utilization for the heating of greenhouse in winter season. In this study phase change materials were selected to store solar energy concentratively for heating the greenhouse and their characteristics of thermal energy storage were analyzed. The results were summarized as follows. The organic $C_{28}H_{58}$, and the inorganic $CH_3COONa{\cdot}3H_2O\;and\;Na_2SO_4{\cdot}10H_2O$ were selected as low temperature latent heat storage materials. The equation of critical radius was derived to define the generating mechanism of the maximum latent heat of phase change materials. The melting point of $C_{28}H_{58}$ was $62^{\circ}C$, and the latent heat was $50.0{\sim}52.0kcal/kg$. The specific heat of liquid and solid phase was $0.54{\sim}0.69kcal/kg^{\circ}C$ and $0.57{\sim}0.75kcal/kg^{\circ}C$ respectively. The melting point of $CH_3COONa{\cdot}3H_2O$ was $61{\sim}62^{\circ}C$, the latent heat was $64.9{\sim}65.8$ kcal/kg and the specific heat of liquid and solid phase was respectively $0.83kcal/kg^{\circ}C$ and $0.51{\sim}0.52kcal/kg^{\circ}C$. The melting point of $Na_2SO_4{\cdot}10H_2O$ was $30{\sim}30.9^{\circ}C$, the latent heat was 53.0 kcal/kg and the specific heat of liquid and solid phase was respectively $0.78{\sim}0.89kcal/kg^{\circ}C$ and $0.50{\sim}0.7kcal/kg^{\circ}C$ When the urea of 21.85% was added to control the melting point of $Na_2SO_4{\cdot}10H_2O$ and the phase change cycles were repeated from 0 to 600, the melting point was $16.7{\sim}16.0^{\circ}C$ and the latent heat was $36.0{\sim}28.0kcal/kg^{\circ}C$.