Accommodating volume change and imparting thermal conductivity by encapsulation of phase change materials in carbon nanoparticles

2018 ◽  
Vol 6 (6) ◽  
pp. 2461-2467 ◽  
Author(s):  
P. A. Advincula ◽  
A. C. de Leon ◽  
B. J. Rodier ◽  
J. Kwon ◽  
R. C. Advincula ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Graphene Oxide ◽  
Stearic Acid ◽  
Phase Change ◽  
Phase Change Material ◽  
Volume Change ◽  
Carbon Nanoparticles ◽  
Phase Change Materials ◽  
Graphene Oxide Nanosheets ◽  
Change Material

A Pickering-type emulsion is used as a template to encapsulate the phase change material stearic acid (SA) using graphene oxide nanosheets stitched together.

scholarly journals Enhancement of heat transfer in phase change material using graphite-paraffin composites

2018 ◽  
Vol 172 ◽  
pp. 02001
Author(s):  
R Sathiyaraj. ◽  
R Rakesh. ◽  
N Mithran. ◽  
M Venkatesan.
Keyword(s):  
Thermal Conductivity ◽  
Energy Storage ◽  
Phase Change ◽  
Phase Change Material ◽  
Phase Change Materials ◽  
Thermal Environment ◽  
Graphite Powder ◽  
Energy Storage Materials ◽  
Melting Period ◽  
Change Material

Phase change materials (PCMs) are energy storage materials which can be used for maintaining a controlled thermal environment for various applications in earth and space. PCMs are used in advanced technologies in aerospace cooling applications like heat exchangers and heat pipes for re-entry vehicles and spacecraft. Paraffin is a phase change material (PCM) commonly used for energy storage-related applications. Paraffin wax exhibits slow thermal response due to low thermal conductivity value (~0.2 W/m K for most paraffin waxes). In the present work, an attempt is made to fabricate a composite PCM using graphite powder. Such a composite material has enhanced thermal conductivity along with reduced melting period which are desirable properties of a PCM during solid to liquid phase change process. The reduction in melting period is indicated by the difference in change in temperature measured by the thermocouples during a specified time. The temperature variation and solid-liquid interface formation during the melting process are experimentally studied. The results showed that composite graphite powder with paraffin can improve the total phase transition time.

scholarly journals Graphene Modified Montmorillonite Based Phase Change Material for Thermal Energy Storage with Enhanced Interfacial Thermal Transfer

2020 ◽  
Author(s):  
Kang Peng ◽  
Hongjie Wang ◽  
Pengfei wan ◽  
Jianwei Wang ◽  
Hua Luo ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Energy Storage ◽  
Stearic Acid ◽  
Phase Change ◽  
Phase Change Material ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Thermal Transfer ◽  
Modified Montmorillonite ◽  
Change Material

Abstract Thermal energy storage technology plays a crucial role in the thermal management system. Clay based organic phase change material has considerable advantages in the application of thermal energy storage due to low cost and high energy storage capacity. However, the low thermal conductivity of clay, especially poor interfacial thermal transfer, limits its thermal energy storage efficiency. Herein, stearic acid/reduced graphene oxide modified montmorillonite composites (SA/RGO-MMT) were prepared by the vacuum impregnation of stearic acid into graphene modified montmorillonite matrix, which was obtained via the in situ reduction of graphene oxide on the surface of montmorillonite. Stearic acid is assembled in the porous structures of RGO-MMT with the physical interactions. SA/RGO-MMT possesses high melting enthalpy of 159 J/g, low extent of supercooling of 1.4 oC and excellent thermal reliability after 100 thermal cycling. Energy storage and release rates of SA/RGO-MMT were significantly improved due to the enhanced interfacial thermal transfer by graphene. Therefore, SA/RGO-MMT is a promising form-stable phase change material for applications in solar heat storage fields. The strategy in this study highlights the importance of enhancing interfacial thermal transfer for the efficient thermal energy storage materials.

The Investigation of Phase Change Emulsion (PCE): Fabrication, Thermal Conductivity and Utilization of Nanoparticles

2013 ◽  
Vol 860-863 ◽  
pp. 862-866 ◽  
Author(s):  
Yi Fei Zheng ◽  
Zhong Zhu Qiu ◽  
Jie Chen
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Energy Storage ◽  
Phase Change ◽  
Phase Change Material ◽  
Phase Change Materials ◽  
Heat Storage ◽  
Change Material

Phase change materials in the form of emulsion (PCE) is a category of novel phase change fluid used as heat storage and transfer media. It plays an important role in commercially viable applications (energy storage, particularly).The emulsion is made of microparticles of a phase change wax (a kind of paraffin or mixture ) as a phase change material (PCM), mixed paraffin directly with water. This paper presents information on the different PCM emulsions by different researchers. It gives the method of preparation of the PCE, and makes a special effort to investigate the heat transfer phenomena and the method of enhancing the thermal conductivity of the emulsion.

scholarly journals Silver microsphere doping porous-carbon inspired shape-stable phase change material with excellent thermal properties: preparation, optimization, and mechanism

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Junwei Zhang ◽  
Yan Chen ◽  
Zeguang Nie ◽  
Zhengshou Chen ◽  
Junkai Gao
Keyword(s):  
Thermal Conductivity ◽  
Phase Change ◽  
Phase Change Material ◽  
Porous Carbon ◽  
Phase Change Materials ◽  
Agricultural Waste ◽  
Raw Material ◽  
Stable Phase ◽  
Cotton Stalk ◽  
Change Material

AbstractIn this study, silver microspheres (SMS) were introduced into cotton stalk porous-carbon (CSP) to prepare silver microsphere doping porous-carbon (SMS-CSP), and then SMS-CSP was used as the matrix of polyethylene glycol (PEG) to synthesize shape-stable phase change material of PEG/SMS-CSP. It was found that the introduction of SMS into CSP could not only greatly improve the loading capacity of the porous-carbon for PEG, but also could increase the thermal conductivity of PEG/SMS-CSP. Additionally, the method of introducing SMS into porous-carbon had the advantages of environmental protection and simple operation. Moreover, the raw material of cotton stalk is a kind of agricultural waste, which has the merits of wide source, low price and easy to obtain. Furthermore, in the preparation of cotton stalk porous-carbon, with the increase of pyrolysis temperature the thermal conductivity of PEG/SMS-CSP could be enhanced significantly. The mechanism about the enhancement of thermal conductivity was clarified, which could provide more basic theory for the study about the thermal conductivity of shape-stable phase change materials (ss-PCMs) based on porous-carbon.

scholarly journals Preparation of Stearic acid/Diatomite Composite Phase Change Material

2021 ◽  
Vol 245 ◽  
pp. 03070
Author(s):  
Jianping Zong ◽  
Defu Wang ◽  
Yanlin Jin ◽  
Xing Gao ◽  
Xinxin Wang
Keyword(s):  
Stearic Acid ◽  
Phase Change ◽  
Phase Change Material ◽  
Phase Change Materials ◽  
Intermolecular Forces ◽  
Impregnation Method ◽  
Vacuum Degree ◽  
Composite Phase Change Materials ◽  
Composite Phase Change Material ◽  
Change Material

The composite phase change material was prepared via the impregnation method using diatomaceous as the carrier and stearic acid as the phase change material. The effects of diatomite content, temperature, immersion time and pressure on the mass ratio of stearic acid and diatomaceous earth in the composite phase change materials were discussed. The experimental results showed that the optimum conditions for preparing stearic acid/diatomite composite phase change material were immersion temperature of 80℃, socking time of 2 h, diatomite mass fraction of 23.04%, and vacuum degree of 0.03 MPa. Finally, the infrared spectroscopy analysis of stearic acid/diatomite composite phase change energy storage material showed that there is no chemical reaction between stearic acid and diatomite. And they are held together by intermolecular forces.

scholarly journals Enhancing Thermal Conductivity and Photo-Driven Thermal Energy Charging/Discharging Rate of Annealed CMK-3 Based Phase Change Material

Nanomaterials ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 364 ◽  
Author(s):  
Yanfeng Chen ◽  
Cuiyin Liu ◽  
Yue Situ ◽  
Jian Liu ◽  
Hong Huang
Keyword(s):  
Thermal Conductivity ◽  
Thermal Stability ◽  
Phase Change ◽  
Phase Change Material ◽  
Phase Change Materials ◽  
Solar Spectrum ◽  
Heating System ◽  
Visible Range ◽  
Good Thermal Stability ◽  
Change Material

In this work, the CMK-3 is successfully prepared with SBA-15 as the template and first annealed to 2000 °C to improve thermal conductivity. The annealed CMK-3 has a thermal conductivity of 6.981 W m−1 K−1 higher than un-annealed CMK-3. The annealed CMK-3 is used to encapsulate the RT44HC, and RT44HC/annealed CMK-3 has 10-fold of thermal conductivity and enhanced thermal stability than RT44HC. The RT44HC/annealed CMK-3 has a large melting enthalpy of 177.8 J g−1 and good thermal stability. The RT44HC/annealed CMK-3 has optical absorptive coefficient of visible range of solar spectrum, which identify seven-fold higher than RT44HC. The RT44HC/annealed CMK-3 has great photo-thermal performance, and the photo-driven energy charging and discharging rate of RT44HC/annealed CMK-3 is almost 30-fold larger than the RT44HC. The results show that the annealed CMK-3 is a great mesoporous carbon nanomaterial for phase change materials and the annealed CMK-3 based phase change material has great potential in solar thermal utilizations such as solar water heating system and solar heating building systems.

scholarly journals The Effect of Hydroxylated Multi-Walled Carbon Nanotubes on the Properties of Peg-Cacl2 Form-Stable Phase Change Materials

Energies ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1403
Author(s):  
Lingyu Zheng ◽  
Xuelai Zhang ◽  
Weisan Hua ◽  
Xinfeng Wu ◽  
Fa Mao
Keyword(s):  
Thermal Conductivity ◽  
Carbon Nanotubes ◽  
Phase Change ◽  
Phase Change Material ◽  
Phase Change Materials ◽  
Interfacial Thermal Resistance ◽  
Stable Phase ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes ◽  
Change Material

Calcium ions can react with polyethylene glycol (PEG) to form a form-stable phase change material, but the low thermal conductivity hinders its practical application. In this paper, hydroxylated multi-walled carbon nanotubes (MWCNTs) with different mass are introduced into PEG1500·CaCl2 form-stable phase change material to prepare a new type of energy storage material. Carbon nanotubes increased the mean free path (MFP) of phonons and effectively reduced the interfacial thermal resistance between pure PEG and PEG1500·CaCl2 3D skeleton structure. Thermal conductivity was significant improved after increasing MWCNTs mass, while the latent heat decreases. At 1.5 wt%, composite material shows the highest phase change temperature of 42 °C, and its thermal conductivity is 291.30% higher than pure PEG1500·CaCl2. This article can provide some suggestions for the preparation and application of high thermal conductivity form-stable phase change materials.

Effects of carbon nanotubes additive on thermal conductivity and thermal energy storage properties of a novel composite phase change material

2018 ◽  
Vol 53 (21) ◽  
pp. 2967-2980 ◽  
Author(s):  
Ahmet Sarı ◽  
Alper Biçer ◽  
Gökhan Hekimoğlu
Keyword(s):  
Thermal Conductivity ◽  
Carbon Nanotubes ◽  
Differential Scanning Calorimetry ◽  
Phase Change ◽  
Phase Change Material ◽  
Phase Change Materials ◽  
Scanning Calorimetry ◽  
Composite Phase Change Materials ◽  
Composite Phase Change Material ◽  
Change Material

Fatty acids are commonly preferred as phase change materials for passive solar thermoregulation due to their several advantageous latent heat thermal energy storage (LHTES) properties. However, further storage container requirement of fatty acids against leakage problem during heating period and also low thermal conductivity significantly limit their application fields. To overcome these drawbacks of capric acid–stearic acid eutectic mixture as phase change material, it was first impregnated with expanded vermiculite clay by melting/blending method and then doped with carbon nanotubes. The effects of carbon nanotubes additive on the chemical/morphological structures and LHTES properties of the composite phase change material and thermal enhanced change phase change materials were investigated by scanning electron microscope, Fourier transform infrared spectroscopy, X-ray diffraction, differential scanning calorimetry and thermogravimetric analysis analysis techniques. The differential scanning calorimetry results showed that the form-stable composite phase change materials and thermal enhanced composite phase change materials have melting temperatures in the range of 24.35–24.64℃ and latent heat capacities between 76.32 and 73.13 J/g. Thermal conductivity of the composite phase change materials was increased as 83.3, 125.0 and 258.3% by carbon nanotubes doping 1, 3 and 5 wt%. The heat charging and discharging times of the thermal enhanced -composite phase change materials were reduced appreciably due to the enhanced thermal conductivity without notably influencing their LHTES properties. Furthermore, the thermal cycling test and thermogravimetric analysis findings proved that all fabricated composites had admirable thermal durability, cycling LHTES performance and chemical stability.

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