• 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.

• Transactions of the Korean hydrogen and new energy society
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• v.34 no.6
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• pp.650-656
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• 2023

In order to efficiently control boil-off rate of a liquefied hydrogen tank, the important thing is to maintain an appropriate vacuum level. however, compared to small and medium-sized storage tank, it is very difficult to create and maintain vacuum in large-capacity storage tanks. In this study, we aim to determine the target level of future large-capacity storage tank technology development and secure basic data on performance test methods by analyzing the corelation between evaporation gas and thermal conductivity of liquefied hydrogen storage tanks.

• 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 Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.1
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• pp.67-74
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• 2000

One of the important application of a contact melting process is a latent thermal energy storage owing to its high heat flux. In some previous works, the split fins have been employed in order to enhance the melting speed. In the present work, the close contact melting was experimentally investigated using an ice as specimen for both split and non-split fins. It was shown that the contact melting by split fins increases the melting rate compared to that of non-split ones.

• Journal of the Korean Solar Energy Society
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• v.33 no.1
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• pp.73-78
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• 2013

Hexadecane and exfoliated graphite nanoplate (xGnP)composite was prepared as a shape-stabilized phase change material (SSPCM) in a vacuum to develope thermal energy storage. The Hexadecane as an organic phase change material (PCM) is very stable against phase separation of PCM and has a melting point at $18^{\circ}C$ that is under the thermally comfortable temperature range in buildings. The xGnP is a porous carbon nanotube material with high thermal conductivity. Scanning electron microscope (SEM) and Fourier transformation infrared spectrophotometer (FT-IR)were used to confirm the chemical and physical stability of Hexadecane/xGnP SSPCM. In addition, thermal properties were determined by Deferential scanning calorimeter(DSC) and Thermogravimetric analysis (TGA). The specific heat of Hexadecane/xGnPSSPCM was $10.0J/g{\cdot}K$ at $21.8^{\circ}C$. The melting temperature range of melting and freezing were found to be $16-25^{\circ}C$ and $17-12^{\circ}C$. At this time, the laten heats of melting and freezing were 96.4J/g and 94.8J/g. The Hexadecane was impregnated into xGnP as much about 48.8% of Hexadecane/xGnP SSPCM's mass fraction.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.5
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• pp.105-110
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• 2020

The global battery market is rapidly growing due to the development of vehicles(EV) and wireless electronic products. In particular logistics robots, which hielp to produce EVs, have attracted much interest in research in Korea Because logistics sites and factories operate continuously for 24 hours, the technology that can dramatically increase the operation time of the logistics equipment is rapidly developing, and various high-level technologies are required for the batteries used in. for example, logistics robots. These required technologies include those that enable rapid battery charging as well wireless charging to charge batteries while moving. The development of these technologies, however, result in increasing explosions and topical accidents involving rapid charging batteries These accidents due to the thermal shock caused by the heat generated during the charging of the battery cell. In this study, a performance evaluation of a heat dissipation design using infrared thermal imaging was performed on an energy storage systrm(Ess) applied with an internal heat conduction cooling method using a heating plate.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2020.06a
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• pp.66-67
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• 2020

The synthesis of stearic acid composite phase change material (PCM) was investigated and the samples produced were characterized for use in latent heat storage, using a simple chemical sol-gel process. The PCM was encapsulated to tetraethyl orthosilicate by various preparation ratios of stearic acid (5, 10, 15, 20, 30 and 50%). Fourier transformation infrared spectroscope (FT-IR) and X-Ray diffraction (XRD) were performed to determine the chemical structure and crystalloid phase of the microencapsulated PCM. SATEOS1 (5%) shows the best proportion for the PCM. With the presence of stearic acid as core materials and SiO2 as the supporting materials, it does not show any chemical reaction between both of them. SATEOS1 shows promising potential for thermal energy storage as it shows a better encapsulation efficiency and good thermal stability.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.3-8
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• 2006

The heat pump system is attractive alternatives to conventional heating and cooling systems owing to their higher energy utilization efficiency. The thermal loads of commercial and institutional buildings are generally cooling-dominated. In this study have been developed ice storage type heat pump system for cooling and heating by heat pipe. This system was practiced performance test on evaluation criteria for heat storage systems. Accomplished the actual proof examination and looked into the performance of the system. In this study, measurement and analysis of ice storage type heat pump system for cooling and heating by heat pipe. The heat pump unit COP appears 3.05 for cooling and 4.20 for heating. As a result, the method to energy saving and to using a substitute energy actively that is heat pump cooling & heating system is expected by heat pipe. Thermal storage capacity appears $19.5RTH/m^3$ for cooling.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.1
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• pp.214-220
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• 2011

This paper studies about the assessment of thermal performance between wet ondol system and electric ondol system. Electrical ondol systems shows faster warm-up time, higher floor surface temperature distribution and lower power consumption than wet ondol system. However, if we provide heat regularly wet ondol system which has more heat capacity shows greater thermal storage than electric ondol system. Therefore, we could conclude that wet ondol system which keeps temperature regularly by the thermal storage show better energy-efficiency in case of using the central heating and district heating system. However, Electrical ondol system shows better efficiency in case of using the space during short time or individual heating systems which needs to heat quickly. The Experiment says that electric ondol system has more benefits on timing to reach the set temperature and energy-efficiency than wet ondol system.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.34 no.5
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• pp.293-300
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• 2021

In this study, the microstructure and thermal conductivity correlation was investigated for concrete materials used in concrete thermal energy storage (CTES) among real-time energy storage devices. Graphite was used as admixture to increase the thermal conductivity performance of the CTES. Concrete specimens of 10% and 15% substitution of cement by mass with graphite, as well as ordinary portland cement (OPC) specimens were prepared, and the microstructural changes and effects on thermal conductivity were analyzed. Porosities of OPC and concrete with graphite were compared using micro-CT, and the microstructural characteristics were quantified using probability functions. Three-dimensional virtual specimens were constructed for thermal analysis, to confirm the effect of microstructural characteristics on thermal conductivity, and the results were compared with the measured conductivity obtained using the hot-disc method. To identify thermal conductivity of graphite for thermal analysis, solid phase conductivity was inversely determined based on simulation and experimental results, and the effect of graphite on thermal conductivity was analyzed.