• 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 Solar Energy Society
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• v.35 no.1
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• pp.89-96
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• 2015

n-octadecnae based shape stabilized phase change material (SSPCM) was prepared by using vacuum impregnation method. And an exfoliated graphite nanoplate (xGnP) which has high thermal conductivity properties is used as a PCM container. And then we made heat storage concretes which contains SSPCM for reducing heating and cooling load in buildings. In the prepararion process, the SSPCM was mixed to a concrete as 10, 20 and 30wt% of cement weight. The thermal properties and chemical properties of heat storage concrete were analyzed from Scanning electron microscope (SEM), Fourier transformation infrared spectrophotometer (FT-IR), Deferential scanning calorimeter (DSC), Thermogravimetric analysis (TGA) and TCi thermal conductivity analyzer. And we conducted surface temperature analysis of SSPCM and xGnP by using heat plate and insulation mold.

• Solar Energy
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• v.11 no.3
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• pp.53-61
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• 1991

In this research, Octacosane($C_{28}H_{58}$) and Sodium Acetate Trihydrate($CH_3COONa{\cdot}3H_2O$) were selected as latent heat storage materials to store off-peak electricity or waste heat of an industrial plant. Experimental analyses were performed in terms of the variation of phase change temperature and latent heat, phase change stability for the long term utilization. The results were as follows. 1. The phase change temperatures of industrial grade Octacosane and Sodium Acetate Trihydrate were $60.7^{\circ}C$ and $57.4^{\circ}C$, the latent heat were 60.6kcal/kg and 51.1kcal/kg respectively. 2. The latent heat quantity of Octacosane was decreased with the increasing number of phase change cycles. It decreased from 60.6kcal/kg to 47.2kcal/kg upto 200 cycles and then no variation was observed after 200 cycles. 3. To prevent the supercooling of Sodium Acetate Trihydrate, the nucleating agent, Sodium Pyrophosphate Decahydrate of 3 wt% was added, and then the supercooling temperature (Tm-Tsc) was decreased from $25.7^{\circ}C$ to $1^{\circ}C$. The phase separation was disappeared by the addition of CMC-Na of 3 wt% as a thickener. It was found that the optimal quantity of nucleating agent and thickener was 4wt% considering the stability of SAT as a latent heat storage material. 4. The phase change temperature of Sodium Acetate Trihydrate($CH_3COONa{\cdot}3H_2O$) was adjusted from 57.4 to $46.2^{\circ}C$ by the addition of UREA. And then the latent heat quantity was decreased from 51.1 to 38.3kcal/kg. 5. When the heat storage capacities between the sensible and latent heat storage materials were analyzed and compared in heating process from 30 to $90^{\circ}C$, the heat storage capacity of Octacosane was 2.45 times larger than water and 12.5 times than granite at $60.7^{\circ}C$, and the heat storage capacity of Sodium Acetate Trihydrate was 2.53 times larger than water and 12.91 times than granite at $57.4^{\circ}C$.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.2
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• pp.173-178
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• 2010

The ice storage system uses water for low temperature latent heat storage. However, a refrigerator capacity are increased and COP are decreased due to supercooling of water in the course of phase change from liquid to solid. This study investigates the cooling characteristics of the TMA-water clathrate compound including TMA (Tri-methyl-amine, $(CH_3)_3N$) of 20~25 wt% as a low temperature latent heat storage material. The results showed that the phase change temperature are increased and the supercooling degree and the specific heat are decreased according to the weight concentration of TMA increased. Especially, the clathrate compound containing TMA 25wt% has the average phase change temperature of $5.8^{\circ}C$ and the supercooling degree of $8.0^{\circ}C$, retention time of liquid phase for 651sec and specific heat of 3.499 kJ/kgK in the cooling process. This expressed good than different concentration of TMA cooling characteristic. Like this, to apply TMA 25wt%-water clathrate compound is determined by advantageous as the low temperature latent heat storage material.

• Solar Energy
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• v.16 no.2
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• pp.113-122
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• 1996

This study presents experimental results of heat transfer characteristics of P.C.M. during outward melting process in a vertical cylinder. The experiment was carried out in six conditions, i. e., three different inlet temperature($7^{\circ}C,\;4^{\circ}C\;and\;1^{\circ}C$) and two directions of working fluid(upward and downward). Melting P.C.M. produced a bell-shaped phase change interface. When the inlet temperature was $7^{\circ}C$, the lower region remained at $4^{\circ}C$ until the temperature of upper region reached $4^{\circ}C$. This was due to the state of maximum density of the lower region. When the direction of the working fluid in the case of $7^{\circ}C$, inlet temperature, was upward, the rate of melting and the total melting energy were higher than when it's direction was downward. But the rate of melting and the total melting energy appeared higher value as it's direction was downward when the inlet temperature is $4^{\circ}C$ and $1^{\circ}C$.

• Journal of the Korea Institute of Building Construction
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• v.11 no.5
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• pp.435-441
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• 2011

The life cycle assessment on greenhouse gas emission of reinforced concrete buildings shows that more than 70 percent of greenhouse gas that is discharged by a building is discharged in the building maintenance stage, including cooling and heating. To reduce the greenhouse gas emission, maintenance planning to minimize the energy consumption is necessary in the design stage. In this paper, two heat storage rooms are tested to save the air cooling energy of the buildings. The specimens are essentially identical, except that chamber A contained paraffin sheets as the finishing material, while the other, chamber B, served as a control. The test results show that chamber A with the paraffin sheets exhibited less temperature change than chamber B without the sheets when temperature was increased outside of the specimens. The heating energy was probably consumed in the phase change of the paraffin sheets, which can be useful for reducing energy consumption related to air cooling during the summer.

• Solar Energy
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• v.13 no.2_3
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• pp.53-64
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• 1993

This study investigated heat transfer phenomena during the freezing of an initially superheated or non-superheated liquid in a cooled cylinder tube. Numerical and experimental method were performed to obtatin the temperature and velocity distribution, the shape of interface. Natural convection effects in the superheated liquid were confined and moderated a short freezing time. After natural convection ceases, heat conduction dominated in the whole paraffin, so Crystal and much-zone were found out in PCM. Initial superheating of liquid tended to morderatly diminish the frozen layer thickness at short freezing times but little effect on the these quantities at longer times. On the amount of frozen mass, Iintial liquid superheating is less affected than tube wall subcooling.

• Journal of the Korea Concrete Institute
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• v.23 no.4
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• pp.521-528
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• 2011

Recently, environmental concerns and issues have become great concerns for the public. Therefore, this study is conducted with the objective of preventing energy depletion and $CO_2$ emission. PCM (Phase Change Materials) having latent heat characteristic is mixed in mortar to find a proper mix proportion. Also, the mortar properties and performances as well as a melting point of PCM when applied to air conditioning and heating conditions in at building environments were obtained by performing experiments. Also, latent heat and heat transfer characteristics were obtained from experiments by test of thermal performance to formulate temperature gradient about amount of heat transfer of PCM content using the Fourier's thermal equation. The study results can be used in the application of PCM in buildings and expected effect of air conditioning and heating energy.

• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.3
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• pp.24-29
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• 2013

An automotive cooling system is designed sufficiently large enough to endure the excessive heat load. In general driving condition, the cooling systems are too large to operate optimally. An experimental study was performed to evaluate a novel automotive cooling strategy using the latent heat of a phase change material (PCM). The strategy is expected to reduce the cooling system size up to around 35% and the engine warm-up time around 60%. The strategy will help improve fuel economy and emissions characteristics of vehicles as a result of reduced total body weight and shortened engine warm-up time by a smaller radiator, as well as more stable combustion mode due to constantly maintained coolant temperature.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.3 no.2
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• pp.87-96
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• 1991

A two-phase closed thermosyphon is applied to an ice storage system. The thermosyphon is used to freeze the water in a storage tank. The experiment has been performed to investigate the effects of the important parameters such as the quantity of the fluid filled with, the ratio of the length of the evaporator to the condenser, and the temperature and the mass flow rate of the brine. It is found that the higher thermal performance of the thermosyphon is obtained as the ratio of the length of the evaporator section to that of the condenser section is decreased and the temperature of the brine is lowered. The increase of the quantity of the working fluid also favors the performance of the system. The experimental data can be utilized for the basic design of ice storage systems with thermosyphons.