• 한국태양에너지학회 논문집
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• 제30권1호
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• pp.42-49
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• 2010

The IIS(Internal Insulation System) is applied in most Korean apartment buildings which are the most common type of residential buildings. Consequently, there are many cases in which the layer of insulation is disconnected by the structural components at the wall-slab and wall-wall joints in the envelope. These joints become thermal bridges where the risk of heat loss increases. It is expected that the EIFS(External Insulation and Finish System) is the solution to this problem. In this study, annual heating and cooling loads of apartment buildings with IIS and EIFS were compared using Design Builder program in order to evaluate the thermal storage effect of EIFS where the concrete thermal mass is located inside of the insulation material. As results, the apartment building with EIFS could reduce annual heating and cooling loads by 2.4% and 4.1%, respectively.

• 설비공학논문집
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• 제26권7호
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• pp.322-328
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• 2014

Return piping is used in a solar combi-system for heating and hot water supply. When the temperature of the lower side of a storage tank is low due to hot water usage, the returned hot water after heating is mixed with the lower side cold water of the tank, and the useful energy is reduced. We studied the degree of thermal stratification in the tank, using either a diffuser or a manifold to prevent mixing. Using the diffuser, mixing starts from the bottom of the storage tank. On the other hand, the manifold has the marked effect of preventing mixing. As a result of experiments with changing the diameter and number of holes in the manifold, the optimum condition is 8.5 mm diameter and 96 holes, under the condition of 0.3 lpm.

• 신재생에너지
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• 제17권1호
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• pp.33-39
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• 2021

The energy use is increasing as the quality of human life improves. and research on the efficient use of energy in ESS (Energy Storage System) is ongoing. An air conditioner is required for the efficient use of an ESS, as are data on the distribution of the temperature of the latter based on the capacity of the air conditioner. In the absence of an air conditioner, the battery of the ESS reaches its maximum temperature of 40℃ after 2 h. When an air conditioner is present, the temperature of the battery stabilizes as the capacity of the former increases.

• 한국건설순환자원학회논문집
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• 제8권4호
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• pp.571-580
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• 2020

본 연구에서는 열에너지 저장시스템의 중요한 요소인 저장 매체에 관한 연구를 수행하였다. 열에너지 저장 매체로써 콘크리트는 열적 및 역학적 특성이 우수하며 저렴한 비용으로 인해 다양한 이점을 갖는다. 또한, 강섬유가 혼입된 초고강도 콘크리트는 고인성 및 고강도 특성으로 인해 고온 노출에 우수한 내구성을 나타내며, 강섬유의 높은 열전도율은 축열 및 방열에 유리한 영향을 미친다. 초고강도 콘크리트의 온도분포 특성을 파악하기 위하여 콘크리트 블록을 제작하고 일정한 열사이클을 적용하여 가열실험을 수행하였다. 열유체 흐름에 의한 열전달을 위하여 열전달 파이프를 콘크리트 블록 중심부에 매립하였다. 또한, 열전달 파이프 형상에 따른 온도분포 특성을 비교하기 위하여 핀의 유무에 따라 원형 파이프 및 종방향 핀 부착 파이프를 설정하였다. 열사이클에 따른 온도분포 특성을 분석하고, 이를 토대로 시간에 따른 열에너지 및 누적 열에너지를 산정하여 비교 분석하였다. 열사이클이 반복될수록 강섬유 혼입 초고강도 콘크리트는 고온에 대하여 안정화를 나타내었다. 또한, 온도분포 및 열에너지 산정 결과를 통해 축열 성능을 보유한 것으로 판단되며, 열에너지 저장 매체 역할을 수행할 수 있는 재료로 기대된다.

• Journal of Biosystems Engineering
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• 제31권3호
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• pp.161-167
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• 2006

The purpose of this study is to find the optimal conditions of PCM slurry manufacturing equipment for saving the marketing cost and keeping the original quality of products. In addition, the characteristics of the movable container for shipping or distributing products is analysed. The major results are as follows. 1. PCM thermal storage system is designed with the conditions of temperature($-5{\sim}10^{\circ}C$), cold chain time(30 minutes), and one time usage(50 liter). This system includes tank, freezer, circulating pump, cycle type heat exchanger, swelling tank, equipment of supplying PCM supplying unit includes cold tank, cycle type heat exchanger, suction unit and control equipments, etc. 2. After ability test of PCM thermal storage system, it shows that the required freezing time of PCM thermal storage system is less than one of the previous system. The reason is that churn (top and bottom) and compulsion circulation are occurred simultaneously and unit cooler type method is better than chiller type method. 3. By the experiment of transportation latent heat container, it is decided that the best container is $K_1$ with latent heat temperature($0{\sim}5^{\circ}C$) and density(0.15%). However, for $K_l\;and\;K_2$, it is necessary more studies on latent heat thermal conditions and conditions of making method.

• 태양에너지
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• 제12권1호
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• pp.81-87
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• 1992

본 연구의 목적은 건물의 냉난방에 이용되는 현열이용형 축열조의 축열 특성을 규명하는데 있었다. 실험에 사용된 축열재는 자갈이었으며 일정한 온도조건하에서 축열재 사이를 통과하는 유체의 유동속도와 자갈의 크기별로 실험을 하였다. 자갈의 크기와 유속을 변화시켜 축열량과 축열효율을 실험적으로 구한 결과 축열재의 충진율이 72.5%이고 유속이 0.14m/s일 때가 최단시간 내에 최대축열량에 도달하였으며, 축열효율도 가장 높았다.

• Journal of Biosystems Engineering
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• 제37권1호
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• pp.19-27
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• 2012

Purpose: Utilizing air thermal energy during over-heated time in the greenhouse is a necessary component to save greenhouse heating costs for nighttime. However, there is no practical way to implement the related principles. Methods: In this study, a heating and cooling system which utilizes the surplus air thermal energy in a greenhouse was developed. Available air thermal energy and heating load for this experimental glasshouse were estimated based on temperature conditions of the plant growth and weather data. Results: Estimated values were 400 MJ/day for maximum surplus air thermal energy and 340 MJ/day for maximum heating energy which were target values of the design as well. The system consists of a heat pump, fan-coil units and heat storage tanks which are divided into low and high temperature tanks. Moreover, a new control logic was developed for surplus air thermal energy utilization. Conclusions: This paper explains the details of conceptual design process of the system. Results of test operations showed that the developed system performed the recovery and supply of the thermal energy according to design purposes.

• Journal of Biosystems Engineering
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• 제23권2호
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• pp.147-156
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• 1998

It is desirable to use the renewable energy for the greenhouse heating in winter season, it make possible not only to save fossil fuel and conserve green environment but also to promote the quality of agricultural products and reduce the agricultural production cost. In this study the heat pump - PCM latent heat storage system has been developed to use the natural energy as much as possible for the thermal environment control of greenhouse. The coefficient of performance (COP) of the heat pump system was 3~4 with the ambient temperature ranging from 8$^{\circ}C$ to -8$^{\circ}C$, and greenhouse heating effect of the heat pump-PCM latent heat storage system on the basis of the ambient temperature was about 12-15$^{\circ}C$.

• Journal of Biosystems Engineering
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• 제21권1호
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• pp.84-93
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• 1996

Several paraffins(CnH2n +2) can be used as the thermal energy storage medium because of their large amount of latent heat and their flexibility of phase change temperature. But they have not been used in the thermal energy storage system because their long term stability have not been verified. Paraffins(CnH2n+2) which the values of n are 23, 24, 26 and 28 were selected for this experimental research. And this research was peformed to apply them to the practical systems. The results were summarized as follows. (1) The increase of phase change cycles had no effect on their phase change temperatures. (2) According as the values of n increased from 23 to 28, the specific heats of paraffins(CnH2n+2) increased, and were in the range of 0.47 0.75 ㎉/$kg^circ C$. (3) Thermal conductivities of them were in the range of 0.14 0.17 W/$m^circ C$. and specific gravities of them were in the range of 765800 kg/m3. (4) The density of paraffins was in the range of 765 800 kg/$m^circ C$ , and the density of solid phase was larger than that of liquid phase. (5) When the number of phase change cycles was 1, 500 cycles, the latent heat of paraffins was 90% of the initial value.

• 한국수소및신에너지학회논문집
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• 제2권1호
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• pp.69-75
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• 1990

The effect of thermal cycling on the hydrogenation characteristics of the $Mg_2Cu-H$ system was investigated in order to study of intrinsic degradation of the system. The hydrogen storage capacity decreased with thermal cycling from $573^{\circ}K$ to $663^{\circ}K$. By the thermal analysis it is found that stable $MgH_2$ hydride is formed during thermal cycling. With a heat treatment at $693^{\circ}K$ at a hydrogen pressure of 16 atm, the hydrogenation rate drastically decreased. From these observation, it suggested that the intrinsic degradation of $Mg_2Cu$ system results from mainly the formation of stable $MgH_2$ hydride phase.