• 한국해양공학회지
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• 제4권2호
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• pp.85-93
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• 1990

A numerical study on the cylindrical packed bed sensible heat storage unit was accomplished by finite difference method. Relation between the heat storage rate and the mechanical pumping energy and the characteristics of the heat storage were investigated for various in let velocities and porosities. In this study, the numerical results are as follows: 1) The temperature distributions of solid and fluid rapidly reached the steady state as the heat capacity ratio was increased. 2) The efficiency of the heat storage was increased as the heat capacity ratio was decreased. For constant heat capacity ratio, however, the efficiency of the heat storage was increased at lower porosity. 3) It is very profitable to design the heat storage system such that the porosity is larger for the large flow rate and samller for small flow rate.

• 한국해양공학회지
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• 제4권2호
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• pp.235-235
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• 1990

A numerical study on the cylindrical packed bed sensible heat storage unit was accomplished by finite difference method. Relation between the heat storage rate and the mechanical pumping energy and the characteristics of the heat storage were investigated for various in let velocities and porosities. In this study, the numerical results are as follows: 1) The temperature distributions of solid and fluid rapidly reached the steady state as the heat capacity ratio was increased. 2) The efficiency of the heat storage was increased as the heat capacity ratio was decreased. For constant heat capacity ratio, however, the efficiency of the heat storage was increased at lower porosity. 3) It is very profitable to design the heat storage system such that the porosity is larger for the large flow rate and samller for small flow rate.

• 한국해양공학회지
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• 제2권1호
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• pp.176-182
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• 1988

The exergy analysis on the heat storage performance of the senible heat storage unit which consists of the heat storage material in the concentric annulus and the hot fluid flowing through the inner tube is performed. Heat transfer characteristics which are necessary for the performance of the exergy analysis is obtained from the energy balance equations and the second law of thermodynamics. As the index of heat storage performance, the exergy lossnumber $N_{s}$, and exergy storage ratio from the concepts of the second law of thermodynamics are defined. Results are ovtained for the grometry of the storage unit, the Biot number Bi, ambient temperature $T_{o}$ as parameters. From these results the exergy storage ratio can be considered as the efficiency of the hat storage unit and is introduced as a guide to design.

• 설비공학논문집
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• 제29권8호
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• pp.429-436
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• 2017

There are three main methods to store heat energy; sensible heat storage, latent heat storage, and thermochemical heat storage. Thermochemical heat storage has the highest storage density among the three methods, so this study focused on the thermochemical heat storage method. Experiments were conducted in this study with Zeolite 13x as thermochemical material in a large-scale reactor with 8 kg of Zeolite 13x. Experiments analyzed storage density of Zeolite 13x with respect to four different heating temperatures ($50^{\circ}C$, $100^{\circ}C$, $150^{\circ}C$, $200^{\circ}C$) in heat storage process. As a result, they showed 40~50 percent of storage efficiency in the experiment. Experiments also revealed that reactions between Zeolite 13x and water vapor were reversible and stable, but efficiency of the system was low, compared with sensible heat storage systems or latent heat storage systems.

• 대기
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• 제22권4호
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• pp.429-436
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• 2012

The performances of the Seoul National University Urban Canopy Model (SNUUCM) under different meteorological conditions (clear, cloudy, and rainy conditions) in summertime are compared using observation dataset obtained at an urban site. The daily-averaged net radiation, sensible heat flux, and storage heat flux are largest in clear days and smallest in rainy days, but the daily-averaged latent heat flux is similar among clear, cloudy, and rainy days. That is, the ratio of latent heat flux to net radiation increases in order of clear, cloudy, and rainy conditions. In general, the performance of the SNUUCM is better in clear days than in cloudy or rainy days. However, the performance in simulating sensible heat flux in clear days is as poor as that in rainy days. For all the meteorological conditions, the performance in simulating latent heat flux is worst among the performances in simulating net radiation, sensible heat flux, and latent heat flux. The normalized mean error for latent heat flux is largest in rainy days in which the relative importance of latent heat flux in the surface energy balance becomes greatest among the three conditions. This study suggests that improvements to the parameterization of processes that are related to latent heat flux are particularly needed.

• 한국환경과학회지
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• 제24권6호
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• pp.721-729
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• 2015

Surface heat balance of the Gangjeong-Goryung Reservoir is analyzed for 12-17 August 2013. Each flux elements at the water surface is derived from the special field observations with application of an aerodynamical bulk method for the turbulent heat fluxes and empirical formulae for the radiation heat fluxes. The rate of heat storage in the reservoir is estimated by using estimated by surface heating rate and the vertical water temperature data. The flux divergence of heat transport is estimated as a residual. The features of the surface heat balance are almost decided by the latent heat flux and the solar radiation flux. On average for 12-17 August 2014 in the Gangjeong- Goryung Reservoir, if one defines the insolation at the water surface as 100 %, 94 % is absorbed in the reservoir; thereafter the reservoir loses about 30~50% by sensible heat, latent heat and net long-wave radiation. The residue of 50~80 % raises the water temperature in the reservoir or transported away by the river flow during the daytime.

• 태양에너지
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• 제9권2호
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• pp.22-30
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• 1989

Since the energy storage method by means of the thermochemical reaction has no heat loss by separating the reactants under the storage period, it is remarked as one of promising means particularly for long-term heat storage. In this study, the heat-storage/-release characteristics of the reversible chemical reaction cycle, $Ca(OH)_2/CaO$, is numerically analysed by a mathematical modelling. As a result, the effectiveness of the heat exchanger by the chemical heat storage method is considerably higher than that by the sensible heat storage method. It is found that the major parameters, which determines the effectiveness of the heat exchanger, are the mass flow rate and inlet temperature of fluid, the residence time, etc.. The heat-storage/-release period can be controlled by changing the operation conditions. It is expected that the results obtained here will supply useful informations in designing a regenerative heat exchanger utilizing the thermochemical reaction.

• 한국에너지공학회:학술대회논문집
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• 한국에너지공학회 1995년도 춘계학술발표회 초록집
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• pp.213-222
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• 1995

Korean traditional Ondol with the sensible heat storage medium has been for a long time used as residential heating system, in these days the concrete Ondol without the heat storage medium was realized as the heating system in the private houses and the apartments. This floor heating system is good for our health. But the concrete Ondol is not desirable for the energy saving and for the maintenance of comfortable room temperature because the heat storage medium is not employed in the concrete Ondol. And as the hot water circulating pipes ate buried under the the concrete floor, the concrete Ondol system has some kind of problems to be improved. Therefore the new type of Ondol system was developed in this study. And the new Ondol was consisted of latent heat storage material as heat storage medium with a great heat capacity and bioceramics as medium to maintain comfortable room temperature. In this study, the heat transfer characteristics of latent heat storage-bioceramic Ondol was analyzed theoretically.

• 태양에너지
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• 제15권1호
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• pp.13-28
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• 1995

온돌의 효시인 화덕은 바닥에 자갈을 깔고 그 위에 진흙을 덮었으며, 주위에 큰돌을 놓아 불을 피워 돌과 흙에 열을 저장하여 이용하였으며, 이는 열저장 측면에서 주시할만한 난방법이었다. 현재의 한국식 주거용 난방시설은 연탄, 석유 및 가스 보일러를 이용한 온수순환온돌로서 전통온돌에서 사용한 돌과 흙같은 축열매체가 사용되고 있지 않다. 축열매체를 사용하고 있지 않기 때문에 온돌바닥면과 난방공간과의 온도차가 심하게 되어 쾌적도가 떨어지므로 난방열을 지속적으로 공급해야 하는 어려움이 있다. 이와 같은 현재의 난방법을 개선기 위하여, 본 연구에서는 잠열축열재와 바이오세라믹으로 구성된 온돌을 개발하였고, 그 난방특성을 실험적으로 분석하였다.

• 한국환경과학회지
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• 제4권3호
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• pp.197-206
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• 1995

Surface heat balance of the northern sea of Cheju Island for summer in 1993 and 1994 is analyzed using the observation data obtained by Marine Research Institute, Cheju National University. Each flux elements at the sea surface is derived from the marine meteorological reports with application of an aerodynamical bulk method for the turbulent heat fluxes, and empirical formulae for the long-wave radiation heat fluxes. The flux divergence of oceanic heat transport and the rate of heat storage in the ocean are estimated as residual. The features of the surface heat balance are mainly decided by the solar radiation flux and the latent heat flux for 199B. But the Bowen Ratios were large for 1993. This means that the sensible heat fluxes were nearly equal to the latent heat fluxes for 1993. In this period, mean flux divergence of oceanic heat transport is about 130 W/$m^2$.