• Title/Summary/Keyword: Thermal storage material

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Study on the Characteristics of Thermal Output and Thermal Storage in a Thermally Activated Building System with Phase Change Material (PCM을 활용한 구체축열시스템의 축열 및 방열 특성 연구)

  • Lee, Hyunhwa;Lee, Soojin;Song, Jinhee;Kim, Sumin;Lim, Jaehan;Song, Seung-Yeong
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.25 no.12
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    • pp.647-653
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    • 2013
  • TABS (Thermally Activated Building System) has recently applied by huge commercial buildings, airports, and convention centers in Europe. TABS provides night-time thermal storage by heating or cooling. The embedded water-based heating and cooling system uses the high thermal inertia of concrete in the building construction, in which a heating or cooling pipe is embedded. The aim of this study is to analyze the thermal storage and thermal output of TABS applied with PCM (Phase Change Material). To achieve this, prototypes of TABS and the thermal properties of various PCMs were investigated. By using the simulation program Physibel Voltra 6.0 W, the thermal storage and thermal output were evaluated according to a heating and cooling operation schedule.

A Study on the Characteristic of Heat Transfer of PCM(Phase Change Material) at the Simultaneous Charging and Discharging Condition (동시 축·방열 조건에서 PCM의 열전달 특성에 관한 연구)

  • Lee, Donggyu;Park, Sechang;Chung, Dong-yeol;Kang, Cheadong
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.28 no.8
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    • pp.305-310
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    • 2016
  • A thermal storage systems was designed to correspond to the temporal or quantitative variation in the thermal energy demand, and most of its heat is stored using the latent and sensible heat of the heat storage material. The heat storage method using latent heat has a very complex phenomenon for heat transfer and thermal behavior because it is accompanied by a phase change in the course of heating/cooling of the heat storage material. Therefore, many studies have been conducted to produce an experimentally accessible as well as numerical approach to confirm the heat transfer and thermal behavior of phase change materials. The purpose of this study was to investigate the problems encountered during the actual heat transfer from an internal storage tank through simulation of the process of storing and utilizing thermal energy from the thermal storage tank containing charged PCM. This study used analysis methods to investigate the heat transfer characteristics of the PCM with simultaneous heating/cooling conditions in the rectangular space simulating the thermal storage tank. A numerical analysis was carried out in a state considering natural convection using the ANSYS FLUENT(R) program. The result indicates that the slope of the liquid-solid interface in the analysis field changed according to the temperature difference between the heating surface and cooling surface.

Thermal performance of the spherical capsule system using paraffin as the thermal storage material (파라핀 축열재를 사용한 구형캡슐 시스템의 전열성능)

  • Cho, K.N.;Choi, S.H.
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.9 no.3
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    • pp.354-363
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    • 1997
  • The purpose of the present work is to show the best thermal storage material and the sensitivity of the parameters on the thermal performance by experimentally investigating the effects of the parameters on the thermal performance of the spherical capsule system using paraffins superior to the commercial one. The paraffins were n-Tetradecane and the mixture of n-Tetradecane 40% and n-Hexadecane 60%. The experimental parameters were the Reynolds number of 8, 12, and 16 and the inlet temperature of-7, -4, -1, and $2^{\circ}C$. The charging and the discharing time, the dimensionless thermal storage amount, and the averge heat transfer coefficient in the tank were obtained by utilizing the local temperature variation in the tank. The local charging and discharging time in the tank was axially and radially different a lot. The effects of the inlet temperature on the charging and the discharging time were larger during the charging process than during the discharging process, but the effects of the Reynolds number on the charging and the discharging time were in reverse order. The paraffins were better by 11~72% than the water with the inorganic material in the charging time aspect, but no difference in the discharging time aspect. The effects of the Reynolds number on the dimensionless thermal storage amount were smaller than the effects of the inlet temperature during the charging process, but in reverse order during the discharging process within the working range of the experimental parameters. The effects of the inlet temperature and the Reynolds number on the average heat transfer coefficient were larger during the discharging process than during the charging process. The average heat transfer coefficient for the paraffins was larger by 40% maximum than that for the commercial material during the charing and the discharging process.

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Performance Simulation and Analysis of the Solar Thermal Storage System Using Heat Pipe (히트파이프를 사용한 태양열 축열시스템의 성능모사 및 해석)

  • Jung, Eui-Guk;Boo, Joon-Hong;Kim, Jong-Kyu;Kang, Yong-Heack
    • 한국태양에너지학회:학술대회논문집
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    • 2009.11a
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    • pp.80-85
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    • 2009
  • Mathematical modeling and performance simulation results were shown for the solar thermal storage system which used heat pipe. The thermal storage system was composed of thermal storage tank and charging/discharging heat exchanger with one by the heat pipes. Heat pipe heat exchanger was attached to system, and could carry out charging and discharging to thermal storage tank at the same time. Height of the thermal storage tank was 600 mm, and that of the charging/discharging heat exchanger was 400 mm. Length of the heat pipe was the same as the total height of thermal storage system, and outer and inner diameter were 25.4 mm(O.D.) and 21.4 mm(I.D.) respectively. Diameter of the circular was 43 mm(O.D.), and fin geometries were considered as the design parameters. High temperature phase change material(PCM), $KNO_3$ and low temperature PCM, $LINO_3$ were charged to storage tank to adjust working temperature. Total size of thermal storage system able to get heat capacity more than 500 kW was calculated and the results were shown in this study. Number of heat pipe was required more than maximum 500, and total length of thermal storage system was calculated to the more than maximum 3 m at various condition.

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Design of type 316L stainless steel 700 ℃ high-temperature piping

  • Hyeong-Yeon Lee;Hyeonil Kim;Jaehyuk Eoh
    • Nuclear Engineering and Technology
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    • v.55 no.10
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    • pp.3581-3590
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    • 2023
  • High-temperature design evaluations were conducted on Type 316L stainless steel piping for a 700 ℃ large-capacity thermal energy storage verification test loop (TESET) under construction at KAERI. The hot leg piping with sodium coolant at 700 ℃ connects the main components of the loop heater, hot storage tank, and air-to-sodium heat exchanger. Currently, the design rules of ASME B31.1 and RCC-MRx provide design procedures for high-temperature piping in the creep range for Type 316L stainless steel. However, the design material properties around 700 ℃ are not available in those rules. Therefore, a number of material tests, including creep tests at various temperatures, were conducted to determine the insufficient material properties and relevant design coefficients so that high-temperature design on the 700 ℃ piping may be possible. It was shown that Type 316L stainless steel can be used in a 700 ℃ high-temperature piping system of Generation IV reactor systems or a renewable energy systems, such as thermal energy storage systems, for a limited operation time.

Analysis of PCM Wallboards Design Parameters using Dynamic Energy Simulation (동적 에너지 시뮬레이션을 이용한 PCM보드의 설계변수 분석에 관한 연구)

  • Lee, Jin-Uk;An, Sang-Min;Kim, Taeyeon;Lee, Seung-Bok
    • KIEAE Journal
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    • v.12 no.4
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    • pp.97-104
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    • 2012
  • A phase-change material is a substance with a high heat of fusion which, melting and freezing at a certain temperature, is capable of storing and releasing large amounts of energy. Heat is absorbed or released when the material changes from solid to liquid. Therefore, PCMs are classified as latent heat storage (LHS) units. The purpose of this study is to analyze PCM wallboard design parameters using dynamic energy simulation. Among the factors of PCM, melting temperature, latent heat, phase change range, thermal conductivity are very important element to maximize thermal energy storage. In order to analyze these factors, EnergyPlus which is building energy simulation provided by department of energy from the U.S is used. heat balance algorithm of energy simulation is conduction finite difference and enthalpy-temperature function is used for analyzing latent heat of PCM. The results show that in the case of melting temperature, the thermal energy storage could be improved when the melting temperature is equal to indoor surface temperature. It seems that when the phase change range is wide, PCM can store heat at a wide temperature, but the performance of heat storage is languished.

A promising form-stable phase change material prepared using cost effective Jute stick Biochar as the matrix of stearic acid for thermal energy storage (황마 바이오차를 사용한 에너지 저장용 상변화 물질의 제조 및 성능평가에 관한 연구)

  • Adnin, Raihana Jannat;Mandal, Soumen;Lee, Han-Seung
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2022.11a
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    • pp.169-170
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    • 2022
  • Due to the higher use of nonrenewable fossil fuel energy, environment friendly sustainable energy from waste materials is attracting attention of the researchers. Considering that, jute stick (JS) biochar has been considered for this study for ecofriendly and sustainable thermal energy storage application. Waste jute sticks (JS), which are being mainly used as a fuel for cooking purpose, have been pyrolyzed to produce porous biochar and have been used for shape stabilization of stearic acid (SA) as phase change material (PCM). SA at 1:1 ratio has been incorporated into the activated JS biochar to concoct shape-stabilized phase change composite (SAJS). The SAJS has been evaluated by different techniques such as Fourier transform-infrared spectroscope (FT-IR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The obtained composite PCM has shown excellent shape stability with a high latent heat storage, suggesting its suitability for thermal energy storage applications.

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The Effects of Additives on the Thermal Properties of a Clathrate Compound(I) -The Case of Ethanol- (포접화합물의 열물성에 미치는 첨가제의 효과(I) -TMA 물계 포접화합물에 Ethanol을 첨가한 경우-)

  • 김진흥;정낙규;김석현;김창오;강승현
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.16 no.3
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    • pp.258-264
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    • 2004
  • The ice thermal storage system is to use consolation latent heat of water. But, supercooling phenomenon of water during phase change is to increase the cooling capacity and to decrease COP of the refrigerator. Furthermore, this causes the operation cost of system to increase and the efficiency of energy to decrease. Therefore, the better thermal storage material than the water is required. The purpose of this study is to improve supercooling characteristics and thermal properties of TMA 30wt% clathrate by using Ethanol.

Synthesis of Almond Shell Biochar-Based Shape-Stable Composite Phase Change Material Using Capric Acid for Thermal Energy Storage (열 에너지 저장용 카프르산을 이용한 아몬드 껍질 바이오차 기반의 안정화 형태 상변이 물질의 성능)

  • Adnin Raihana Jannat;Soumen, Mandal;Lee, Han Seung
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2023.05a
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    • pp.51-52
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    • 2023
  • A new shape-stable composite phase change material (PCM) have been produced via an easy and simple vacuum impregnation method. The composite PCM have been derived from almond shell biochar (ASB) as supporting material and capric acid (CA) as phase change material. Cost effective waste almond shells (AS) are renewable, eco-friendly, and rich in pores which enhance the possibility of CA impregnation. Therefore, in this study, three different ratios of CA (1:1, 1:2 and 1:3) have been incorporated in ASB to produce shape-stabilized phase change composites (ASCAs). Different techniques such as scanning electron microscopy (SEM), Fourier transform-infrared spectroscope (FT-IR), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA) have been applied to evaluate the characteristics of ASCAs. The attained composite PCMs have exhibited shape stability with high latent heat storage, that makes it suitable for thermal energy storage applications.

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Thermal properties of latent heat storage microcapsule-water slurry

  • Mun, Soo-Beom
    • Journal of Advanced Marine Engineering and Technology
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    • v.39 no.8
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    • pp.807-812
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    • 2015
  • A microcapsule water slurry is a latent heat-storage material having a low melting point. In this study, the thermal properties of a microcapsule water slurry are measured. The physical properties of the test microcapsule water slurry, i.e., thermal conductivity, specific heat, latent heat, and density, are measured, and the results are discussed for the temperature region of solid and liquid phases of the dispersion material (paraffin). It is clarified that Eucken's equation can be applied to the estimation of the thermal conductivity of the microcapsule water slurry. Useful correlation equations of the thermal properties of the microcapsule water slurry are proposed in terms of the temperature and concentration ratio of the microcapsule water slurry constituents.