• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.27 no.3
• /
• pp.123-127
• /
• 2015

Thermochemical heat storage is a cutting-edge technology which can balance the energy usage between supplies and demands. Recent studies have suggested that thermochemical heat storage has significant advantages, compared to other storage methods such as latent heat storage or sensible heat storage. Nevertheless, ongoing research and development studies showed that the thermochemical heat storage has some serious problems. To bring the thermochemical heat storage method into market, we introduce experimental setup with composite material using perlite that supports calcium chloride sorbent. Also, to compare thermal properties with composite material, we used pure thermochemical material. Then, we found that the composite material has higher heat storage density by mass than pure calcium chloride. Moreover, it can be easily regenerated, which was impossible in the pure thermochemical materials.

• Applied Chemistry for Engineering
• /
• v.21 no.5
• /
• pp.522-526
• /
• 2010

Heat storage application techniques can be categorized into the sensible heat storage and the latent heat storage according to the method of heat storage. Heat storage is the way of saving remaining heat when heating and cooling loads are light, and then using it when the heating and cooling loads are heavy. Latent heat storage is defined as the method of saving heat by using substances which have high potential heat when phase change is in the range of a certain temperature and when heat storage space is small, compared to those of sensible heat storage and it is possible that absorption and emission of heat at a certain temperature. This study is conducted to save energy when either air-conditioning or heating is operated in a building. We have tried to find out the essential properties of matter and the optimum mixing rate about cement and gypsum for building materials, which have been widely used for proper phase change materials (PCM), when thermal environment property is applied. So we obtained the result of the cooling delay effect about 19% with heat storage mortar containing 3 wt% of PCM.

• Solar Energy
• /
• v.19 no.2
• /
• pp.29-36
• /
• 1999

Heat transfer characteristics of a low temperature latent heat storage system during the heat storage stage was examined for the circular finned tubes using fatty acid which shows the big density difference during melting as phase change materials. The heat storage vessel has the dimension of 530 mm height, 74 mm inside diameter and inner heat transfer tube is 480 mm in height and 13.5 mm outside diameter. Hot water was employed as the heat transfer fluid. During the heat storage stage, it was found that both conduction and natural convection were the major heat transfer mechanism. It was also found that the effect of natural convection on the heat transfer was more significant for the unfinned tube system than that for the finned tube system. The experimentally determined overall heat transfer coefficients were in the range of $50{\sim}250W/m^2K$ and the correlation for natural convection heat transfer as a function of Nusselt and Rayleigh number was proposed.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.4 no.3
• /
• pp.187-198
• /
• 1996

In this study, the performance of an automobile heat storage system using PCM is numerically simulated. For the analysis of system performance. The phase-change of the PCM and the transient forced convective heat transfer for the HTF are considered simultaneously as a conjugate problem. The phase-change behavior is effectively analyzed using a concept of thermal resistance. From the correlations of phase change rate and heat transfer due to the variations of flow rate of HTF around PCM, the automobile heat storage system performance is predicted. The present results amy be used as the fundamental information for the design of automobile heat storage system.

• Journal of the Korean Solar Energy Society
• /
• v.35 no.4
• /
• pp.17-24
• /
• 2015

The formation of heat islands causes high energy demand for space cooling and peak cooling loads in conditioned buildings. High-temperature fluctuations on a building roof may cause mechanical stress and increase surface deterioration. Thermal energy storage (TES) systems using microencapsulated phase-change materials (MPCMs) have been recognized as one of the most advanced energy technologies for enhancing the energy efficiency and sustainability of buildings. In this study, we prepared MPCM/paint composites for mitigating the heat island effect and reducing peak temperature. In addition, we carried out thermal and physical analysis of prepared MPCM composite samples by means of SEM, FTIR spectroscopy, DSC, and TGA. Further, we evaluated the dynamic heat transfer performance of heat-storage tiles painted with 10 g of heat-storage paint. From the obtained results, we deduced that MPCM/hydrophilic paint composites are more applicable to various fields, including the building sector, than MPCM/hydrophobic paint composites. On the basis of SEM and FTIR spectroscopy results, we concluded that materials with hydrophilic properties are more compatible with MPCMs than those with hydrophobic properties. In addition, DSC analysis results revealed that MPCM/hydrophilic paint composites have better compatibility, higher latent heat capacity, and better thermal properties than other composites. TGA results showed that hydrophilic-paint-based composites have higher thermal durability than hydrophobic-paint-based composites. Finally, a lot of MPCM-loaded heat-storage tiles showed lower peak temperatures at all measurement positions.

• 한국태양에너지학회:학술대회논문집
• /
• 2012.03a
• /
• pp.475-479
• /
• 2012

Thermal energy storage (TES) systems using Microencapsulated phase change material (MPCM) have been recognized as one of the most advanced energy technologies in enhancing the energy efficiency and sustainability of buildings. We examined a way to incorporate MPCMs with building materials through application for wood-based flooring. Wood-based flooring is commonly used for floor finish materials of residential buildings in Korea. However, wood-based flooring has not performed the characteristic of heat storage. This study is aimed at manufacturing high thermal efficiency wood flooring by increasing its heat storage using MPCM. As a result, this study confirmed that MPCM is dispersed well in adhesive through the scanning electron microscopy analysis. From the differential scanning calorimetry analysis, it can be confirmed that this composite has the characteristic of a thermal energy storage material. Also, we analyzed how this composition was formed by physical combination through the Fourier transform infrared analysis. Also, we confirmed the bonding strength of the material by using the universal testing machine.

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

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.12 no.2
• /
• pp.189-199
• /
• 2000

This paper investigates the thermodynamic performance of latent heat thermal energy storage system using two phase change materials(2-PCM system). The thermodynamic merit of using 2-PCM is clear in terms of exergetic efficiency, which is substantially higher than that of 1-PCM system. Optimum phase change temperature to maximize the exergetic efficiency exists for each case. The heat transfer area ratio of high temperature storage unit, X, becomes another important parameter for 2-PCM system if the phase change temperatures of given materials are different from those of optimum conditions. It is a good approximation for X$_{opt}$ to be 0.5 when optimum phase change temperatures are used. Otherwise X$_{opt}$ is determined differently as a function of given phase change temperatures.res.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.19 no.1
• /
• pp.202-211
• /
• 1995

Heat and hydrogen transfer characteristics have been experimentally investigated for a hydride reaction bed, in which hydride material LaN $i_{4,7}$A $l_{0.3}$ is contained for hydrogen storage. This problem is of particular interest in the design of metal hydride devices such as metal-hydride refrigerators, heat pumps, or metal-hydride storage units. Transient behavior of hydrogen transfer through the hydride materials as well as heat transfer is studied during absorption and desorption processes in detail. The experimental results obtained indicate that the mass flow of the hydrogen is strongly affected by the governing parameters, such as the initial pressure of the reaction bed, absorption or desorption period, and cooling or heating temperature. These mass transfer results are along with the heat transfer rate between hydride materials and heat transfer medium in the reaction bed.d.d.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.28 no.1
• /
• pp.15-20
• /
• 2016

Phase change materials (PCM) are able to store a large amount of latent heat, and can be applied to thermal energy storage systems. In a PCM, it takes a long time to store heat in the storage system because of the low thermal conductivity. In this study, a finned-tube-in-tank heat exchanger was applied to a PCM thermal energy storage system to increase heat transfer efficiency. The effects of geometric and operating parameters were investigated, and the results were compared with those of the tube-in-tank heat exchanger. The finned-tube-in-tank heat exchanger showed higher heat transfer effectiveness than the tube-in-tank heat exchanger. The heat exchange effectiveness of the storage tank was determined as a function of the average NTU.