• Journal of the Korean Solar Energy Society
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• v.30 no.2
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• pp.10-15
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• 2010

The experimental study was conducted to optimize the system dissipating properly heat from the in-situ solar panel installed on the roof. For this purpose, six 12-Watt panels, which were consisted of the different design conditions such as containing phase change material(PCM), changing the array of the aluminum fin and honeycomb at the back of the panel, were tested. PCM, which had $44^{\circ}C$ melting point, was chosen in this study. In order to enhance absorbing and expelling heatin PCM, profiled aluminum fin was placed either inward oroutward from the panel. Furthermore, Aluminum honeycomb is imbedded in the back container to find if it would improve the thermal conductivity of PCM. During the experiment, there were ranged to $26^{\circ}C\sim32^{\circ}C$ for outdoor temperature and $700W/m^2\sim1000W/m^2$ for irradiance. As a result, the solar panel, combined with honeycomb and outward fins with PCM instead of placing the fins inward, is showing the best performance in terms of controling panel temperature and its efficiency.

• Journal of Institute of Convergence Technology
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• v.4 no.2
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• pp.51-54
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• 2014

Energy storage not only reduces the mismatch between supply and demand but also improves the performance and reliability of energy systems. The different forms of energy that can be stored, including mechanical, electrical and thermal energy. Phase change materials (PCM) are latent heat storage materials. A large number of phase change materials (organic, inorganic and eutectic) are available in any required temperature range. We concentrated on eutectic materials and made a eutectic by mixing urea and choline chloride. Heat capacity ($C_p$) is one of the most important properties to be considered when a process is developed using the eutectic and currently DSC (Differential Scanning Calorimetry) has been proved as an effective technique to measure the heat capacity. This study focused on measuring heat capacity ($C_p$) of the mixing urea and choline chloride by DSC.

• Polymer(Korea)
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• v.29 no.1
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• pp.8-13
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• 2005

Polystyrene (PS) particles containing the phase change material (PCM) were synthesized by miniemulsion polymerization. The polymer particles prepared with different parameters were investigated in terms of average particle size, particle distribution, and latent heat storage of encapsulated paraffin wax (PW) as PCM. The morphology and particle features of PS particles were analyzed by scanning electron microscope and particle size analyzer, respectively. As a result, the diameters of PS particles were adjusted with manufacturing conditions. The stable and spherical PS particles of nanosize were obtained by miniemulsion polymerization, which could be attributed to the prevention of Ostwald ripening by cosurfactant. Thermal properties of PS particle containing PCM were studied by differential scanning calorimetry. From DSC freeze-thaw cycle, PCM coated with PS exhibited the thermal energy storage and release behaviors, and the latent heat was found to be a maximum 145 J/g. It was noted that PS particles containing PCM showed a good potential as a thermal energy storage medium.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.11 no.4
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• pp.549-559
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• 1999

An experimental study was peformed to measure the viscosity of microencapsulated PCM slurries as the functions of its concentration and temperature, and also influence to its fluid dynamics. For the viscosity measurement, a rotary type viscometer, which was equipped with temperature control system, was adopted. The slurry was mixed with water and Sodium Lauryl Sulphate as a surfactant by which its suspended particles were dispersed well without the segregation of particles during the experiment. The viscosity was increased as the concentration of MicroPCM particle added. The surfactant increased 5% of the viscosity over the working fluid without particles. Experiments were proceeded by changing parameters such as PCM particles'concentration as well as the temperature of working fluid. As a result, a model to the functions of temperature for the working fluid and its particle concentration is proposed. The proposed model, for which its standard deviation shows 0.8068, is agreed well with the reference's data. The pressure drop was measured by U-tube manometer, and then the friction factor was obtained. It was noted that the pressure drop was not influenced by the state of PCM phase, that is solid or liquid in its core materials at their same concentration. On the other hand, it was described that the pressure drop of the slurry was much increased over the working fluid without particles. A friction factor was placed on a straight line in all working fluids of the laminar flow regardless of existing particles as we expected.

• International Journal of Air-Conditioning and Refrigeration
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• v.10 no.1
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• pp.31-39
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• 2002

Microencapsulated pcm (MPCM) particles are mixed with distilled water and utilized to evaluate its characteristics and performance as a thermal storage medium transporting heat. For the present study, tetradecane ($C_14$$H_30$, $T_m$=5.5$^{\circ}C$) is capsulated in the core, coated with the melamine for their surface. The size of particles is well-controlled under 10$\mu$m in the process of in-situ polymerization with melamine-formaldehyde resin. For the experiment, the concentractions of slurries are prepared for 20 wt%, 30 wt%, and 40 wt%. The results are compared with those of water and 100% tetradecane oil. The pure water and tetradecane start solidifying within 20 minutes after introducing cooling water into the thermal storage tank whose flow rates are varied by 125 cc/min, 250 cc/min, and 500 cc/min. However, MPCM slurries are required relatively longer period of time for their phase change than pure phase change materials. That is, the entrained MPCM particles restrict their heat transfer in terms of natural convection and conduction to them.

• Journal of Advanced Marine Engineering and Technology
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• v.26 no.1
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• pp.23-29
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• 2002

Solid-liquid phase change (i.e. melting or solidification) occurs in a number of situations of practical interest. Some common examples include the melting of edible oil, metallurgical process such as casting and welding, and materials science applications such as crystal growth. Therefore, due to the practical importance of the subject, there have been a large number of experimental and numerical studies of problems involving phase change during the past few decades. Also, this study presented the effective way to enhance phase change heat transfer.

• 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.

• Transactions of the Korean hydrogen and new energy society
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• v.31 no.6
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• pp.622-629
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• 2020

The performance and cost of electric vehicles (EVs) are much influenced by the performance and service life of the Li-ion battery system. In particular, the cell performance and reliability of Li-ion battery packs are highly dependent on their operating temperature. Therefore, a novel battery thermal management is crucial for Li-ion batteries owing to heat dissipation effects on their performance. Among various types of battery thermal management systems (BTMS'), the phase change material (PCM) based BTMS is considered to be a promising cooling system in terms of guaranteeing the performance and reliability of Li-ion batteries. This work is mainly concerned with the basic research on PCM based BTMS. In this paper, a basic experimental study on PCM based battery cooling system was performed. The main purpose of the present study is to present a comparison of two PCM-based cooling systems (n-Eicosane and n-Docosane) of the unit 18650 battery module. To this end, the simplified PCM-based Li-ion battery module with two 18650 batteries was designed and fabricated. The thermal behavior (such as temperature rise of the battery pack) with various discharge rates (c-rate) was mainly investigated and compared for two types of battery systems employing PCM-based cooling. It is considered that the results obtained from this study provide good fundamental data on screening the appropriate PCMs for future research on PCM based BTMS for EV applications.

• KIEAE Journal
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• v.17 no.3
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• pp.107-112
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• 2017

Purpose: Both silica gel and activated carbon black particles were adopted for use as PCM absorbed porous media applicable as construction materials. To investigate usable methods for absorbing PCM into the media, they were soaked into PCM and also tested for enhancement of PCM absorption into them. Method: To test PCM absorption into some porous media such as both ${\varphi}1{\sim}2mm$ and $10{\mu}m$ silica gels, and $50{\mu}m$ activated carbon black, $43^{\circ}C$ PCM was used as a laten heat material. The method, soaking into PCM was applied to this study, and the media were moderately rotated by centrifuge to have the extra PCM flow out. DSC analysis was conducted to investigate the melting and solidifying of the PCM absorbed into the porous media. Result: It was found that PCM was absorbed into the porous media by over 85 wt% of all particles. In addition, it was noted that the ultrasonic vibrator was accelerating the PCM absorption into the particles to three times higher speed than simple soaking. Centrifuge was adopted to remove extra PCM sticking on the particle surfaces and extra PCM was moderately removed from the surfaces of the particles. DSC analysis indicated that the latent heat of the absorbed PCM particles was 160 J/g, and the melting temperature was approximately $40^{\circ}C{\sim}50^{\circ}C$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.32 no.6
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• pp.448-453
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• 2019

This work reports the electrical characteristics of and temperature distribution in chalcogenide phase change memory (PCM) devices that have a self-aligned structure. GST (Ge-Sb-Te) chalcogenide alloy films were formed in a self-aligned manner by interdiffusion between sputter-deposited Ge and $Sb_2Te_3$ films during thermal annealing. A transmission electron microscopy-energy dispersive X-ray spectroscopy (TEM-EDS) analysis demonstrated that the local composition of the GST alloy differed significantly and that a $Ge_2Sb_2Te_5$ intermediate layer was formed near the $Ge/Sb_2Te_3$ interface. The programming current and threshold switching voltage of the PCM device were much smaller than those of a control device; this implies that a phase transition occurred only in the $Ge_2Sb_2Te_5$ intermediate layer and not in the entire thickness of the GST alloy. It was confirmed by computer simulation, that the localized phase transition and heat loss suppression of the GST alloy promoted a temperature rise in the PCM device.