무기성 상전이 물질의 활성탄 세공 내 담지 기술 개발

백소영(Soyoung Baek),야사만 가파리(Yasaman Ghaffari),배지열(Jiyeol Bae),김광수(Kwang Soo Kim) 대한환경공학회 2021 대한환경공학회지 Vol.43 No.12

목적: 최근 에너지 관련 연구는 대체에너지 개발에서 나아가, 생산된 에너지의 효율적 관리 기술 개발로 변화하고 있다. 이에 대해 에너지 저장 및 방출 기능을 가진 상전이 물질을 에너지 매체로 사용하는 연구가 꾸준히 진행되고 있다. 본 연구에서는 활성탄을 상전이 물질의 충진매체로 사용하여 보다 효율적인 열저장매체를 개발하고자 하며 동시에 활성탄 세공 내에 상전이 물질을 효율적으로 충진시키는 방법을 개발하고자 한다. 방법: 본 실험에 사용한 활성탄은 목탄계 분말 활성탄(250-350 mesh)과 입상활성탄을 이용하였으며 실험에 사용한 무기성 상전이 물질로는 Manganese nitrate hexahydrate을 사용하였다. 상전이 물질의 세공내 충진 방법은 가압방식과 희석방식을 이용하였으며 개발 소재의 열 흡수/방출 능력은 10-50℃ 범위 내의 온도에서 관찰하였다. 결과 및 토의: 가압식 및 희석식 충진 방법에 따른 상전이 물질의 활성탄 충진 여부는 SEM, TEM-EDX 및 bulk density 분석을 통해 확인하였다. 가압식 방법으로 상전이 물질을 충진 하였을 경우 Manganese nitrate hexahydrate의 물질 특성이 그대로 반영되어 각각의 상전이 온도에서 열의 흡수와 방출이 발생되어 온도변화가 지연되는 구간을 보였다. 희석 방식을 이용한 상전이 물질 충진연구에서 최적 용매 선정 실험결과 에탄올을 용매로 사용하였을 경우 상전이 물질 담지 후에도 열 흡수/방출이 뚜렷하게 관찰되었다. 최적 희석 배율 선정 실험을 통해 부유하는 활성탄이 가장 최소량에 되게 하면서 에탄올의 비율이 낮은 희석 비(1:1)를 도출하였다. 용매 제거 실험결과 85℃ 온도에서 기화하여 에탄올을 제거하였을 때의 조건이 최적으로 나타났으며, 온도변화에 따른 열 흡수/방출 특성을 평가한 결과 열 흡수/방출 현상이 관찰됨을 확인하였다. 결론: 1) 가압방식 및 희석방식 모두 무기성 상전이 물질이 활성탄 내부에 고정시킬 수 있는 상전이 충진 방식이며 담지 이후에도 열 흡수/방출 특성이 유지된다. 2) 희석방식 사용 시, 에탄올이 용매로써 적합하며 최적 희석비율은 1:1임을 확인하였다. 3) 희석용매 제거 방법에 있어 기화방식이 가장 적합함을 확인하였다. Objectives : Recently, energy-related research has shifted from developing alternative energy to the efficient management technology of the produced energy. As an alternative, research on phase change materials (PCMs) capable of absorbing and releasing heat as an energy medium has been conducted. This study developed a more efficient heat storage medium using activated carbon as a medium for the phase change material. At the same time, we developed a method for efficiently impregnating the phase change material into the activated carbon pores. Methods : The activated carbon used in this experiment was charcoal powder activated carbon (250-350 mesh) and granular activated carbon. The inorganic phase change materials used in the experiment was manganese nitrate hexahydrate. The method for impregnating the phase change material was pressurization method and dilution method. The heat absorption / emission capacity of the developed material was examined within the range of 10℃ to 50℃. Results and Discussion : The Scanning electron microscope (SEM) and Transmission electron microscopy energy-dispersive X-ray spectroscopy (TEM-EDX) analysis showed that the phase change material was filled in the pore of activated carbon. When the phase change material is filled by the pressurized method, the material properties of manganese nitrate hexahydrate are reflected, resulting in absorption and release of heat at each phase change temperature. As a result of experiments for the selection of the optimum solvent in the phase change material filling study using the dilution method, when ethanol was used as the solvent, the heat absorption was clearly observed even after the phase change material was loaded. As a result of selecting the optimal dilution ratio, the ratio of ethanol was determined to be 1:1 as the dilution ratio with the lowest amount of floating activated carbon. The optimal solvent removal method experimental results show that the heat absorption/release section occurred when the ethanol was removed by evaporation at 85℃ temperature. Conclusions : 1) Both the pressurization method and the dilution method are filling methods in which inorganic phase change materials can be immobilized inside activated carbon, and heat absorption and release characteristics are maintained even after loading. 2) The heat absorption release was maintained for ethanol and the optimal dilution ratio was 1:1. 3) In case of the dilute solvent removal method, the heat absorption/release capacity was maintained when the solvent was removed using only the vaporization method.

알케인류 상변화물질의 열적 특성 해석

崔恩洙,鄭東柱 明知大學校 産業技術硏究所 2003 産業技術硏究所論文集 Vol.22 No.-

Abstract - The objective of the present study is to reveal thermal characteristics of various alkane phase-change-material which have high latent heat during phase change from solid to liquid. In order to analysis thermal characteristics of various phase-change-material, phase-change temperature and energy of various phase-change-material were measured by using differential scanning calorimeter. The phase-change-material slurries which are used in this study were paraffin particle, microcapsulated octadecane and microcapsulated lauric acid. The heating rate of differential scanning calorimeter and the size of phase-change-material were changed during phase-change temperature and energy measurement.

여러 가지 상변화물질 슬러리의 원형관내 대류 열전달에 관한 연구

崔恩洙,鄭東柱 明知大學校 産業技術硏究所 2003 産業技術硏究所論文集 Vol.22 No.-

To investigate convective heat transfer of various the phase-change-material slurries in a circular tube, paraffin slurry, MC-lauric acid slurry, MC-octadecane slurry and ice slurry were tested in two kinds of heat transfer experimental apparatus with constant heat flux test section. Nusslet numbers of the phase-change-material slurries were found to increase when the phase-change- material melted. Nusselt number of the phase-change material slurry increased, as the size and fraction of the phase-change material increased. The effective thermal capacities of the phase-change-material slurries were higher than those of water. As fraction and fusion energy of the phase-change-material increased, the effective thermal capacity increased.

Phase Change Material (PCM) 소재 적용 소방보호복의 화상발생 억제효과에 관한 연구

이준경 한국화재소방학회 2016 한국화재소방학회논문지 Vol.30 No.3

Fire fighters rely on fire fighter protective clothing (FFPC) to provide adequate protection in the various hazardousenvironments. To enhance its protection performance, the FFPC material must be thick and thus it is difficult to achieveweight reduction. One of the methods of overcoming this problem, the addition of phase change material (PCM) to FFPC,is a new technology. In previous studies, the researches was mostly related to the temperature characteristics of the fibersincorporating PCM, but little information is available about its effect on burn injuries. Thus, in this study, the inhibitoryeffects of adding PCM to FFPC on second degree burns were investigated through numerical calculations. Thermal analysesof biological tissues and FFPC with embedded PCM exposed to several fire conditions causing severe tissue damagewere studied by using a finite difference method based on the Pennes bio-heat equation. FFPC with embedded PCM wasfound to provide significantly greater protection than conventional fire fighting clothing, because the heat of absorptiondue to the phase change within the material is used to limit the heat conduction of the material. 소방공무원의 화상방지를 위해 소방보호복의 개발이 이루어지고 있으나, 보호 성능을 높이기 위해서 소재의 두께가 증가하고, 그럼으로 경량화 달성이 어려워지는 단점이 존재한다. 이를 극복하기 위한 여러 가지 방법 중 Phase ChangeMaterial(PCM, 상변화 물질)을 적용한 섬유를 소방보호복 안감에 적용하는 연구가 진행되고 있다. 기존 연구의 경우, 고온노출시 PCM 적용 섬유의 온도 특성에 대한 연구가 일부 있었으나, 화상 발생과의 직접적인 연관성을 살펴볼 수가없다는 큰 단점이 존재한다. 본 연구에서는 짧은 시간 고열유속 상태의 돌발화염조건에 대해 현재 사용되고 있는 소방보호복 안감에 대한 PCM 적용 여부에 따라 2도 화상 발생 억제 효과를 수치계산을 통해 살펴보았다. 피부의 화상 해석을 위해 생체 열전달 방정식(Bio-heat transfer)을 이용하여 지배방정식을 유도하였으며, 유한차분법(Finite DifferenceMethod)을 활용하여 화상에 대한 예측을 수행하는 수치해석 접근법을 사용하였다. 시간에 따른 온도 및 손상함수 결과분석을 통해 PCM 소재의 열흡수가 열전달을 지연시키는 효과가 큼을 확인할 수 있었고, 그에 의해 화상발생을 방지하는 매우 유효한 방법임을 확인할 수 있었다.

상변화물질 저장 탱크 내 핀-관 열 교환기 유량 변화에 따른 수치해석적 연구

허승민(Seung-Min Heo),윤재형(Jae-Hyeong Yoon),신동호(Dong-Ho Shin) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.11

As the crisis of climate change escalates, research on renewable energy is being conducted very actively in all countries. Korea also revised the Enforcement Decree of the Framework Act on Low Carbon Green Growth and reduced carbon dioxide emissions by 37% compared to the 2030 forecast. Recently, Phase change material storage, which uses phase change material to store heat studied a lot. However, the thermal conductivity of phase-change substances are normally less than 0.1, that brings disadvantage of low heat exchange rate. To improve the heat exchange rate of PCM, a new type of pin-pipe was studied numerically in the storage tank of phase change material, and the cross-cutting technique was used to investigate the heat transfer according to shape.

Latent heat storage biocomposites of phase change material-biochar as feasible eco-friendly building materials

Jeon, Jisoo,Park, Ji Hun,Wi, Seunghwan,Yang, Sungwoong,Ok, Yong Sik,Kim, Sumin Academic Press 2019 Environmental research Vol.172 No.-

<P><B>Abstract</B></P> <P>One approach to enhance the energy efficiency of buildings is the integration of construction materials of latent heat storage biocomposites, which are prepared by vacuum impregnating the phase change material into biochar. Biochar is used because it is highly utilized and environmentally-friendly, and the selected phase change materials are fatty acid type which are bio-based material and have a low risk of depletion. Experimental results showed that latent heat storage biocomposite possesses excellent exudation and thermal stability as characterized by 0.1727 W/mK of thermal conductivity comparable to that for a gypsum board, and good chemical compatibility as its amount of latent heat tends to decrease as compared with that of pure phase change material. Results of the numerical analysis showed further that latent heat storage biocomposite efficiently reduced the maximum energy consumption of reference building models by 531.31 kWh per year. Thus, both results validate the claim that latent heat storage biocomposite is a promising building material.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Latent heat storage biocomposite was prepared from eco-friendly biochar and bio-based phase change materials. </LI> <LI> Experiments and numerical analyses were performed. </LI> <LI> Integration of latent heat storage biocomposite into building walls reduced annual building energy consumption. </LI> <LI> Latent heat storage biocomposites can be used as sustainable building materials. </LI> </UL> </P>

Structurally Reinforced Phase Changing Films Fabricated by Layer-by-Layer Deposition of Pickering Emulsions with Cellulose Nanofibers

배지우,서혜민,조영식,김진웅 한국공업화학회 2020 한국공업화학회 연구논문 초록집 Vol.2020 No.-

This study introduces a phase changing emulsion films system (PCEFs) with controllable thermal energy storage. Basically, tetradecanol as a phase change material was emulsified with aid of amphiphilically modified silica nanoplatelets (ASNPs). The ASNP-armored Pickering emulsion was highly stable while improving the interfacial adhesion. Then, we fabricated the structurally reinforced PCEFs consisting of phase change emulsion drops and cellulose nanofibers (CNFs) by using LbL deposition. The melting point and heat capacity of the PCEFs could be regulated depending on the type of phase changing materials. Finally, we expect that the PCEFs fabricated in this study would have great applicability for development of organic-inorganic hybid film-based architectural materials.

Modification of Graphene Aerogel Embedded Form-Stable Phase Change Materials for High Energy Harvesting Efficiency

유정빈,송영석 한국고분자학회 2022 Macromolecular Research Vol.30 No.3

While porous graphene aerogel can hold plenty of pure phase change material (PCM) in the internal space, its volume shrinkage is a serious problem to decrease the weight of working material. Since the thermal energy storage (TES) capacity of PCM composite, however, depends on the mass ratio of pure PCM during the phase transition process, graphene aerogel filled PCM composite is an appropriate material for high latent heat thermal energy storage (LHTES). In this work, polydimethylsiloxane (PDMS) is embedded into the graphene aerogel by using a spraying method. The PDMS-embedded graphene aerogel exhibits higher mechanical property and flexibility than pristine aerogel. It reduces the volume shrinkage effectively and sustains the initial 3D porous structure to infiltrate pure PCM into the internal space, which can lead to an increase in the efficiency of thermo-electric energy harvesting due to the increase of PCM weight. A PN junction of thermo-electric power generator (PN TEG) is connected to the modified PCM composites, and a temperature difference between two sides of device occurs under the change of external conditions. The modified PCM composites constructed PN TEG generates stable and continuous thermo-electric energy during heating and cooling processes. In addition, finite element method (FEM) is employed to verify the experimental measurement.

기포 구동 흐름과 이산화티타늄 나노파티클이 융합된 상변화물질의 열전달 강화 연구

최성호(Sung Ho Choi),장수진(Jang Su Jin),손동기(Dong Kee Sohn),고한서(Han Seo Ko) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.11

Phase-change materials using latent heat energy and isothermal characteristics in phase change period are applied to thermal energy storage devices, thermal management devices, etc. However, low heat transfer performance of phase change materials is evaluated as a disadvantage for various applications. To overcome these shortcomings, various studies have been conducted to enhance the heat transfer performance of phase change materials. In this study, we propose the convergence of bubble-driven flow and TiO2 nanoparticles to enhance the heat transfer of phase-change materials. Physical properties of phase change materials and heat transfer mechanisms are analyzed using visualization experiments.

Numerical model and simulation of a vehicular heat storage system with phase-change material

Park, Sangki,Woo, Seungchul,Shon, Jungwook,Lee, Kihyung Elsevier 2017 Applied Thermal Engineering Vol.113 No.-

<P><B>Abstract</B></P> <P>For heat storage applications designed to recover and recycle waste heat energy, it is usually advantageous to store heat in a phase-change material. One-dimensional numerical analysis and evaluation of a heat storage system that uses a phase-change material to store latent heat in addition to sensible heat was carried out, and it was found that up to 30% of the total heat energy generated by the fuel and subsequently lost to cooling can be recovered. A heat storage system was installed to reduce warm-up time by releasing heat directly into the engine coolant during cold start, and the corresponding reduction in fuel consumption was measured. With the addition of a heat storage device, the warm-up time to 95°C was reduced by between 18.1% and 27.1%. A numerical simulation of the New European Driving Cycle was carried out for a vehicle equipped with a 1.6-L diesel engine and a heat storage system. Analytical results showed that the warm-up time was reduced by 40.5% and the fuel consumption was reduced by 2.71% compared to a vehicle without a heat storage system installed.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Numerical analysis and evaluation of a heat storage system with a phase-change material. </LI> <LI> Numerical simulation of the New European Driving Cycle was carried out for a vehicle. </LI> <LI> The warm-up time was reduced by 40.5% and the fuel consumption was reduced by 2.71%. </LI> </UL> </P>