• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.122-125
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• 2006

This paper deals with the Ondol, Korean under-floor heating system using latent heat storage materials. It has been recognized that the heating system using the latent heat storage materials are economically efficient and comfortable. For the comparison and analysis to the data of the existing experiment, a repetitive experiment makes sure the ability of Ondol panel.

• Solar Energy
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• v.19 no.3
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• pp.23-28
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• 1999

The thermal performance of storage brick, containing microencapsulated PCM(phase change material), was investigated for utilization as a floor heating system. Sodium acetate trihydrate($CH_3COONa{\cdot}3H_2O$) was selected for the PCM and was encapsulated. The thermal storage brick was manufactured with mixing cement mortar having 10%, 20% PCM contents, respectively. Four different flow rates and three different cooling temperatures was used in this work for analyzing the heat charging and discharging characteristics of the thermal storage brick. The result showed that cycle time was shortened as the PCM content was increased and as the mass flow rate was increased. The same effect was obtained when the cooling temperature was decreased. For each thermal storage brick the overall heat transfer coefficient(U-value) was constant for a 0% brick, but was increased with time for the bricks containing microencapsulated PCM.

• Journal of the Korean Society of Clothing and Textiles
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• v.32 no.6
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• pp.991-998
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• 2008

This study is to determine the effects of PCM concentration on the temperature changes of the air layers of a garment when the environmental temperature changes. The selected PCM was Nonadecane and coated on cotton fabrics with PCM concentrations 10%, 20%, and 30%. The temperature changes of the air layers between fabrics were measured by Human-Clothing-Environment Simulator which measure a dynamic heat transfer. After stabilizing at $34^{\circ}C$ for 1 hour, the multi layered garment system were exposed to $5^{\circ}C$ or $10^{\circ}C$ for 30 minutes and then, exposed to $34^{\circ}C$ for 30minutes. The results like following could be obtained. When the environmental temperature changed high to low, temperature of the air layer increased by heating effect of PCM. In the contrast, when the environmental temperature changed low to high, the temperature increase of the air layer was delayed because of cooling effect by PCM. Also, the more concentration of PCM, the bigger the heating effect. Cooling effect showed more clearly at PCM concentration 20%. The temperature differences of the air layers between with PCM fabrics and with non-PCM fabrics were bigger at $10^{\circ}C$ than at $5^{\circ}C$. Consequently, though PCM has influenced on the temperature of the air layer by heating and cooling effect, those effects haven't shown in all layers equally. It was shown that the effect of PCM varied according to the layer in the case of multi layered garment system and heat gain as well as heat loss in the outermost layer had to be taken into account.

• Fibers and Polymers
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• v.7 no.1
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• pp.12-19
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• 2006

For thermal adaptable fabrics, the polyurethane-urea microcapsules containing phase-change materials (PCMs: hexadecane, octadecane and eicosane) were successfully synthesized by interfacial polycondensation using 2,4-toluene diisocyanate (TDI)/poly(ethylene glycol) (PEG400)/ethylene diamine (EDA) as shell monomers and nonionic surfactant NP-12 in an emulsion system under stirring rates of $3,000{\sim}13,000$ rpm. The mean particle size of microcapsule decreased significantly with increasing the stirring rate up to 11,000 rpm, and then leveled off. The mean particle size increased with increasing the content and molecular weight (eicosane > octadecane > hexadecane) of PCMs at the same stirring rate. The mean particle sizes of microcapsules were found to decrease with increasing the NP-12 content up to 1.5 wt%, and thereafter increased a little. It was found that the melting temperature ($T_m$) and crystallization temperature ($T_c$) of three kinds of encapsulated PCMs and their enthalpy changes (${\Delta}H_m,{\Delta}H_c$) increased with increasing PCM contents. The encapsulation efficiencies (Ee) of hexadecane microcapsule linearly increased with increasing the content of hexadecane. It was found that the stable microcapsule containing 50 wt% of hexadecane could be obtained in this study. However, Ee of octadecane and eicosane microcapsules increased with increasing PCM's contents up to 40 wt%, and then decreased a little. By considering the encapsulation efficiency, it was found that the maximum/optimum contents of octadecane and eicosane microcapsules were about 40 wt%. By the dynamic thermal performance test, it was found that the maximum buffering levels of Nylon fabrics coated with hexadecane, octadecane, and eicosane microcapsules were about $-2.4/+2.9^{\circ}C,\;-3.6/+3.6^{\circ}C\;and\;-4.0/+4.7^{\circ}C$, respectively.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.26 no.2
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• pp.72-78
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• 2014

In a cold chain, the refrigerator is also employed for defrosting, by using an electric heater, which consumes 15% of the power for the system operation. In this study, the condensation heat of the refrigerant was suggested as the heat source of defrosting heat, instead of that from an electric defrost heater. The heat for defrosting was stored to a phase change material (PCM, NMP : $52^{\circ}C$) in thermal storage, and was periodically supplied to the evaporator by a circulation loop of brine. As a result, a defrost time by the PCM was obtained that was less than or equal to that by the electric heater. Moreover, power consumption during defrosting was saved by up to 99% of that of the electric heater.

• Applied Chemistry for Engineering
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• v.21 no.5
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• pp.570-574
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• 2010

The main function of conventional insulation materials is only to block the heat transfer and reduce heat loss from the building. On the other hand, thermal storage materials can work as an energy saver by absorbing or emitting heat within a specific temperature range. Thermal storage materials for building can maintain a constant temperature by effectively regulating the cycle of indoor temperature. As a result, we can enhance the performance of a cooling and heating system efficiently. In this study, phase change materials (PCMs) were added as thermal storage materials into gypsum boards which are extensively used for building material and we found out the thermal environmental characteristics. In addition, we checked out some problems when applying the thermal storage materials to buildings. Finally, This study set out to examine the degree of environmental-friendly characteristics of thermal storage building materials by analyzing the amount of TVOC and HCHO contents with the possibility of pollutants emission.

• 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.

• Journal of Biosystems Engineering
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• v.31 no.3 s.116
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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.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.55 no.6
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• pp.297-301
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• 2006

In the present work, we investigate the characteristics of new composition material, chalcogenide $Ge_1Se_1Te_2$ material in order to overcome the problems of conventional PRAM devices. The Tc of $Ge_1Se_1Te_2$ bulk was measured $231.503^{\circ}C$ with DSC analysis. For static DC test mode, at low voltage, two different resistances are observed. depending on the crystalline state of the phase-change resistor. In the first sweep, the as-deposited amorphous $Ge_1Se_1Te_2$ showed very high resistance. However when it reached the threshold voltage(about 11.8 V), the electrical resistance of device was drastically reduced through the formation of an electrically conducting path. The phase transition between the low conductive amorphous state and the high conductive crystal]me state was caused by the set and reset pulses respectively which fed through electrical signal. Set pulse has 4.3 V. 200 ns. then sample resistance is $80\sim100{\Omega}$. Reset pulse has 8.6 V 80 ns, then the sample resistance is $50{\sim}100K{\Omega}$. For such high resistance ratio of $R_{reset}/R_{set}$, we can expect high sensing margin reading the recorded data. We have confirmed that phase change properties of $Ge_1Se_1Te_2$ materials are closely related with the structure through the experiment of self-heating layers.

• Proceedings of the KSME Conference
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• 2001.06d
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• pp.226-231
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• 2001

The purpose of this paper is to propose the experimental method of thermal properties of Phase Change Materials (PCMs) by using T-history method. As far, in order to measure the heat of fusion and specific heat of PCMs, conventional thermal analysis methods such as DSC and DTA have been used. Because these methods test very small samples, thermal properties of samples are usually different from those of materials consisting of several components. For these reasons, T-history method, the simple measurement method of the heat of fusion and specific heat of PCMs have been performed. In this paper, we investigated the thermal properties of low temperature PCMs(below $0^{\circ}C$) under the charging process by using T-history method. The results are compared to those of DSC method. The T-history method will be useful for selection of the best PCM from lots of candidates and development of new PCMs.