• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2008년도 추계학술발표대회 논문집
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• pp.178-183
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• 2008

The purpose of this study is to compare the effect on the thermal stratification under various aspect ratios in the solar storage tank using FLUENT. Numerical calculations of three designs with different aspect ratio were carried out to show the behaviour of stratification in a solar storage tank. The calculation results show that the thermal stratification of the 2.5:1 aspect ratio solar storage tank can be 6.22% higher then that of the 1.5:1 aspect ratio solar storage tank and 2.68% higher then that of the 2:1 aspect ratio solar storage tank.

• 한국태양에너지학회 논문집
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• 제22권2호
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• pp.11-17
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• 2002

This paper is concerned with the development of a new method for making, separating ice and storage floated ice by installing an evaporation plate at under-water within a storage tank. In a conventional harvest-type ice storage system, a tank saves ice by separating an ice from an installed evaporation plate, which is located above an ice storage tank as an ice storage system. Developed new harvest-type method shows good heat transfer efficiency than a convectional method. It is because the evaporation panel is directly contacted with water in a storage tank. Also, at a conventional system a circulating pump, a circulating water distributor and a piping are installed, however these components are not necessary in a new method. In this study ice storage systems are experimentally investigated to study the charge and discharge of thermal energy. The results show the applicable possibility and performance enhancement of a new type.

• 한국태양에너지학회 논문집
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• 제38권5호
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• pp.63-74
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• 2018

The heating performance of a solar thermal seasonal storage system applied to a 1,320 m2 glass greenhouse was analyzed numerically, and the economic feasibility depending upon the number of boreholes was evaluated. For this study, the gardening 16th and 19th zucchini greenhouse of Jeollanam-do agricultural research & extension services was selected. And the heating load of the glass greenhouse selected was 1,147 GJ. BTES(Borehole Thermal Energy Storage) was considered as a seasonal storage, which is relatively economical. The number of boreholes was selected from 25 to 150. The TRNSYS was used to predict and analyze the dynamic performance of the solar thermal system. Numerical simulation was performed by modelling the solar thermal seasonal storage system consisting of flat plate solar collector, BTES system, short-term storage tank, boiler, heat exchanger, pump and controller. As a result of the analysis, when the number of boreholes was from 25 to 50, the thermal efficiency of BTES system and the solar fraction was the highest. When the number of boreholes was from 25 to 50, it was analyzed that the payback period was from 5.2 years to 6.2 years. Therefore it was judged to be the number of boreholes of the proposed system was from 25 to 50, which is the most efficient and economical.

• 한국수소및신에너지학회논문집
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• 제31권6호
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• pp.564-570
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• 2020

Metal hydride is suitable for safe storage of hydrogen. The hydrogen storage kinetics of the metal hydride are highly dependent on its heat transfer characteristics. This study presents a metal hydride-expended graphite composite with improved thermal conductivity and its hydrogen storage kinetics. To improve the heat transfer characteristics, a metal hydride was mixed and compacted with a high thermal conductivity additive. As the hydrogen storage material, AB5 type metal hydride La0.9Ce0.1Ni5 was used. As an additive, flakes-type expended graphite was used. With improved heat transfer characteristics, the metal hydride-expended graphite composite stores hydrogen four times faster than metal hydride powder.

• 에너지공학
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• 제16권4호
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• pp.164-169
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• 2007

우리나라에서 여름철 피크전력부하의 감소는 매우 중요하다. 정부는 피크전력부하를 저감하기 위하여 많은 지원 정책과 법률을 제정하여 시행하고 있다. 그리고 빙축열시스템은 이런 대안 중의 하나로서 알려지고 있다. 이 논문의 목적은 축열운전, 병렬운전과 축열조 단독운전이 수행된 밀폐식 빙축열시스템의 축열조 성능과 전체 효율을 평가하는 것이다. 설계조건에서 운전된 빙축열시스템의 자료를 이용하여 축열조의 축열밀도와 방냉효율 그리고 시스템의 총괄에너지 이용효율을 계산하면 $18.4\;USRT-h/m^3$, 96.2% 그리고 2028.7 kcal/kWh이다. 빙축열시스템의 축열조에 공급되는 에너지를 설계조건보다 많게 공급하면 과냉각효과에 의해 설계조건보다 시스템 효율이 낮게 평가되어진다.

• 터널과지하공간
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• 제25권2호
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• pp.115-124
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• 2015

열에너지 저장은 고온 또는 저온의 잉여 열에너지를 저장하여 수요 발생 시 사용하기 위한 기술로서 에너지의 수요와 공급 사이의 불균형을 해소하고, 이를 통해 에너지 시스템의 효율을 향상시킬 수 있다. 특히 간헐적인 신재생에너지 자원을 열에너지 형태로 변환하거나 저장함으로써 에너지 믹스에서 신재생에너지의 비중을 제고할 수 있으며, 이를 위해서는 열에너지 저장 장치와의 조합이 반드시 필요하다. 지하 암반공동을 이용한 열에너지 저장은 높은 건설비용이 수반되어 그 활용이 제한적이지만, 대규모의 열에너지를 장기간 저장할 수 있는 가장 현실적인 방법이다. 또한 기후조건에 따라 외부로의 열손실이 영향을 받는 지상의 열저장소와는 달리, 열저장 지하 암반공동은 장기 운영 시 주변 암반의 히팅에 따른 열손실의 감소를 기대할 수 있다. 본고에서는 열저장 암반공동의 형상 및 다중배치 설계 시 고려해야 할 주요 인자들을 소개하고, 저장공간의 설계에 대한 가이드라인을 제안하였다.

• 설비공학논문집
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• 제22권10호
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• pp.719-726
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• 2010

In this paper, the appropriate thermal storage time of an air-conditioning system with slab thermal storage was considered by use of summer measurement values. Two standards of heat extraction rate and criterion function were established as the standard that evaluates appropriateness. When heat extraction rate was a standard, zero hour and seven hours were obtained as appropriate thermal storage time, in the case of evaluation by energy consumption and running cost individually. Also, when criterion function was a standard, the difference between energy consumption and running cost was small, it was because the weight function to room air temperature deviation was much bigger than heat extraction rate.

• Journal of Biosystems Engineering
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• 제15권2호
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• pp.123-133
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• 1990

Thermal performance of a solar heating plastic greenhouse designed for a hydroponic system was studied. The system was constructed with the air-water heat exchanger and thermal storage tank that were combined with hydroponic water beds. Experiments were carried out to investigate the daily average heat stored and released in thermal storage tank, average solar energy collection efficiency, average coefficient of performance, average oil reduction factor of thermal storage system, and the heat transfer coefficient during the nighttime in plastic greenhouse. The results obtained in the present study are summarized as follows. 1. Daily average heat stored in thermal storage tank and released from the thermal storage tank was 1,259 and $797KJ/m^2$ day, respectively. 2. The average solar energy collection efficiency of thermal storage tank was 0.125 during the experiment period. And the average coefficient of performance of thermal storage system in plastic greenhouse was 3.6. 3. The average oil reduction factor of thermal storage system and the heat transfer coefficient during the nighttime in plastic greenhouse were found to be 0.52 and $4.3W/m^2\;hr\;^{\circ}C$, respectively.

• 태양에너지
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• 제19권4호
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• pp.11-20
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• 1999

The study on ice thermal storage system is to improve total system performance and increase the economical efficiency in actual air-conditioning facilities. To obtain the high charging and discharging efficiencies in ice thermal storage system, the improvement of thermal stratification is essential, therefore the process flow must be piston flow in the cylindrical type. In the influence of the inlet port type, the inflowing water in the distributor type diffuses through the whole storage tank more than in the slot type. In case of the flow process in the ice storage tank, the upward flow type in the charging process and the downward flow type in the discharging process make the stratification well, thereby the loss of energy wored be smaller. The influence of the inlet temperature difference and the change of the inlet flow rate is intensive when the temperature difference is larger, the flow rate is smaller in case of charging and the results are opposite in case of discharging with the reason that the good coduction condition. The total effeciency of the ice thermal storge system is 73% on condition that the porosity in the thermal storage tank is 0.55. This result shows that cylinderical ice storage tank has better storage capacity than rectangular type in case of the same porosity.

• 설비공학논문집
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• 제26권6호
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• pp.247-256
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• 2014

The regulations to reduce energy consumption and carbon dioxide emission in building sectors are being developed and promoted all over the world. However, in Korea, as balcony extension of the apartments has been legally allowed, it became prevalent and resulted in excessive energy consumption. This study derived the possibility of PCM application to the thermal storage wall system through theoretical consideration and investigated the problems occurring when the balcony space has been extended to the diverted space. In addition, this study aims at the possibility of verifying the installation and confirming the cooling energy reduction effect, by conducting measuring tests with the actual installation of PCM applied thermal storage wall system. As a result of theoretical consideration, it is determined that the disadvantages with the existing thermal storage wall system can be complemented by applying PCM, and this study suggests the PCM applied Thermal Storage Wall System. The study was conducted on 1/6 of a miniature inner room of a domestic apartment with 84 $m^2$ of exclusive area. From the results of actual measurements, it is confirmed that the balcony extension structure can gain 11.3% of more calories than the existing balcony structure, resulting in the increase in cooling energy usage. It is determined that the installation of the PCM applied Thermal Storage Wall System may gain 25.2% of less calories to reduce cooling energy usage.