Leakage-proof phase change composites supported by biomass carbon aerogels from succulents

2018 ◽  
Vol 20 (8) ◽  
pp. 1858-1865 ◽  
Author(s):  
Yanhong Wei ◽  
Juanjuan Li ◽  
Furong Sun ◽  
Jinrong Wu ◽  
Lijuan Zhao
Keyword(s):  
Thermal Conductivity ◽  
Phase Change ◽  
Organic Phase ◽  
Phase Change Materials ◽  
Carbon Aerogels ◽  
Biomass Carbon ◽  
Low Thermal Conductivity ◽  
Practical Applications ◽  
Phase Change Composites

The practical applications of organic phase change materials (PCM) are greatly limited, due to their leakage in the melted state and unacceptably low thermal conductivity.

Latent Heat Storage: Container Geometry, Enhancement Techniques, and Applications—A Review

2019 ◽  
Vol 141 (5) ◽  
Author(s):  
S. Arunachalam
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Energy Storage ◽  
Phase Change ◽  
Latent Heat ◽  
Thermal Energy ◽  
Heat Exchangers ◽  
Phase Change Materials ◽  
Heat Storage ◽  
Low Thermal Conductivity

Energy storage helps in waste management, environmental protection, saving of fossil fuels, cost effectiveness, and sustainable growth. Phase change material (PCM) is a substance which undergoes simultaneous melting and solidification at certain temperature and pressure and can thereby absorb and release thermal energy. Phase change materials are also called thermal batteries which have the ability to store large amount of heat at fixed temperature. Effective integration of the latent heat thermal energy storage system with solar thermal collectors depends on heat storage materials and heat exchangers. The practical limitation of the latent heat thermal energy system for successful implementation in various applications is mainly from its low thermal conductivity. Low thermal conductivity leads to low heat transfer coefficient, and thereby, the phase change process is prolonged which signifies the requirement of heat transfer enhancement techniques. Typically, for salt hydrates and organic PCMs, the thermal conductivity range varies between 0.4–0.7 W/m K and 0.15–0.3 W/m K which increases the thermal resistance within phase change materials during operation, seriously affecting efficiency and thermal response. This paper reviews the different geometry of commercial heat exchangers that can be used to address the problem of low thermal conductivity, like use of fins, additives with high thermal conductivity materials like metal strips, microencapsulated PCM, composite PCM, porous metals, porous metal foam matrix, carbon nanofibers and nanotubes, etc. Finally, different solar thermal applications and potential PCMs for low-temperature thermal energy storage were also discussed.

scholarly journals Characterization of MgCl2·6H2O-Based Eutectic/Expanded Perlite Composite Phase Change Material with Low Thermal Conductivity

Materials ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 2369 ◽  
Author(s):  
Chao Zhang ◽  
Zeyu Zhang ◽  
Rongda Ye ◽  
Xuenong Gao ◽  
Ziye Ling
Keyword(s):  
Thermal Conductivity ◽  
Phase Separation ◽  
Phase Change ◽  
Phase Change Materials ◽  
Impregnation Method ◽  
Expanded Perlite ◽  
Thermal Reliability ◽  
Low Thermal Conductivity ◽  
Human Thermal Comfort ◽  
Save Energy

The melting points of the phase change materials (PCMs) incorporated into the walls of buildings should be within the human thermal comfort temperature range. In this paper, 15 wt.% of MgCl2·6H2O was mixed with CaCl2·6H2O to obtain the eutectic with a melting point of 23.9 °C. SrCl2·6H2O suppresses the supecooling of the eutectic. The combination with expanded perlite (EP) via the impregnation method overcomes the phase separation and liquid leakage of the CaCl2∙6H2O-MgCl2∙6H2O mixture. The composite PCM is form-stable with the maximum loading mass fraction up to 50 wt.% and latent heat of 73.55 J/g. EP also significantly reduces the thermal conductivity of the CaCl2∙6H2O-MgCl2∙6H2O from 0.732 to 0.144 W/(m·K). The heating-cooling cycling test reveals that the composite PCM is thermally stable. The cheap eutectic salt hydrate, with little supercooling, no phase separation and liquid leakage, low thermal conductivity and good thermal reliability, show great potential as envelope materials to save energy consumption in buildings.

Thermal properties of nano-graphite-embedded magnesium chloride hexahydrate phase change composites

2017 ◽  
Vol 28 (7) ◽  
pp. 651-660 ◽  
Author(s):  
Apurv Yadav ◽  
Bidyut Barman ◽  
Abhishek Kardam ◽  
S Shankara Narayanan ◽  
Abhishek Verma ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Phase Change ◽  
Phase Change Materials ◽  
Heat Storage ◽  
Melting Time ◽  
Chloride Hexahydrate ◽  
Large Heat ◽  
Phase Change Composites ◽  
Change Material

Phase change materials can provide large heat storage density with low volume. But their low thermal conductivity limits their heat transfer capabilities. Since carbonaceous nanoparticles have a good thermal conductivity they can be applied as an additive to phase change materials to increase their heat transfer rate. In this study, nano-graphite is used as an additive and the influences of its various concentrations on the thermal conductivity and melting and freezing rate for the nanoparticle-enhanced phase change materials is experimentally investigated. Experimental results indicates a reduction of 22% in melting time and a reduction of 75% in solidification time of 0.5% nano-graphite-embedded phase change material.

Biomass carbon aerogels based shape-stable phase change composites with high light-to-thermal efficiency for energy storage

2020 ◽  
Vol 153 ◽  
pp. 182-192 ◽  
Author(s):  
Chengjun Wang ◽  
Weidong Liang ◽  
Yueyue Yang ◽  
Fang Liu ◽  
Hanxue Sun ◽  
...  
Keyword(s):  
Energy Storage ◽  
Phase Change ◽  
Thermal Efficiency ◽  
High Light ◽  
Carbon Aerogels ◽  
Stable Phase ◽  
Biomass Carbon ◽  
Phase Change Composites

scholarly journals Thermoplastic Elastomer based Phase Change Materials with Enhanced Mechanical Property, Thermal Conductivity and Photo-thermal Performance

2019 ◽  
Author(s):  
Fuxian Wang ◽  
Xuelin Zou ◽  
Yanfeng Chen ◽  
Jian Liu
Keyword(s):  
Thermal Conductivity ◽  
Mechanical Property ◽  
Phase Change ◽  
Thermal Energy ◽  
Phase Change Materials ◽  
Expanded Graphite ◽  
Thermoplastic Elastomer ◽  
Solar Thermal Energy ◽  
Phase Change Composites ◽  
New Phase

Traditional phase change composites usually suffer poor mechanical property and easy collapsing in the phase changing process. Herein, a highly flexible phase change composite is fabricated using thermoplastic elastomer as the basic gel and the expanded graphite/paraffin as the filler. This new phase change composite shows a tensile strength of 2.1 MPa and a breaking elongation of 220%. It has a melting enthalpy of 145.4 J•g-1 and a thermal conductivity of 2.2 W•m-1•K-1 with 70% of expanded graphite/paraffin. The thermoplastic elastomer based phase change composite exhibits great reversible property after 200 heating/cooling cycles. This flexible phase change composite demonstrates good photo-thermal energy charging/discharging property and shows great potential to be applied in the solar thermal energy systems.

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