scholarly journals The Impact of Additives on the Main Properties of Phase Change Materials

Energies ◽  
2020 ◽  
Vol 13 (12) ◽  
pp. 3064 ◽  
Author(s):  
Ewelina Radomska ◽  
Lukasz Mika ◽  
Karol Sztekler
Keyword(s):  
Thermal Conductivity ◽  
Phase Change ◽  
Latent Heat ◽  
Phase Change Materials ◽  
High Thermal Conductivity ◽  
Liquid Transition ◽  
Supercooling Degree ◽  
Wide Range ◽  
Solid Liquid ◽  
The Impact

The main drawback of phase change materials (PCMs) is their low thermal conductivity, which limits the possibilities of a wide range of implementations. Therefore, the researchers, as found in the literature, proposed several methods to improve the thermal conductivity of PCMs, including inserting high thermal conductivity materials in nano-, micro-, and macro-scales, as well as encapsulation of PCMs. However, these inserts impact the other properties of PCMs like latent heat, melting temperature, thermal stability, and cycling stability. Hence, this paper aims to review the available in the open literature research on the main properties of enhanced PCMs that undergo solid–liquid transition. It is found that inserting high thermal conductivity materials and encapsulation results in improved thermal conductivity of PCMs, but it decreases their latent heat. Moreover, the insertions can act as nucleating agents, and the supercooling degree can be reduced. Some of the thermal conductivity enhancers (TCEs) may prevent PCMs from leakage. However, some test results are inconsistent and some seem to be questionable. Therefore, this review indicates these discrepancies and gaps in knowledge and points out possible directions for further research.

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.

Composite phase change materials improve the photo-thermal effects of cotton fabrics

2020 ◽  
pp. 004051752097561
Author(s):  
Wei Zhang ◽  
Shang Hao ◽  
Jiali Weng ◽  
Yibo Zhang ◽  
Jiming Yao ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Surface Temperature ◽  
Ambient Temperature ◽  
Phase Change ◽  
Latent Heat ◽  
Thermal Effects ◽  
Phase Change Materials ◽  
Thermal Storage ◽  
Cotton Fabrics ◽  
Composite Phase Change Materials

We report on the impregnation-based preparation of composite phase change materials (CPCMs) with thermal storage properties, using paraffin wax and multi-walled carbon nanotubes (MWCNTs). We coated the CPCMs on the fabric by scraper coating, then evaluated their shape stability, latent heat, thermal conductivity, thermal storage stability and photo-thermal effects. Results show that CPCMs with 10% acid-oxidized MWCNTs introduce only a small phase leakage when heated at 50℃ for 900 s; their latent heat energy reduces by 16.5%, while their thermal conductivity increases by 131.9% compared to pure paraffin. When exposed to sunlight at an ambient temperature of 12.5℃, the cotton fabrics coated with CPCMs record a 12.8℃ higher surface temperature than the pristine fabric, while their heat dissipation is delayed by 120–180 s. The fabric surface temperature increases to twice the ambient temperature during daytime. Overall, these findings indicate that the coated fabric has excellent thermal stability, affirming its potential as photo-thermal functional material.

Extending Die-Attachment Fatigue Life of Power Electronics Using Phase Change Materials

2016 ◽  
Author(s):  
Levi J. Elston
Keyword(s):  
Phase Change ◽  
Power Electronics ◽  
Phase Change Materials ◽  
Operating Conditions ◽  
Device Structure ◽  
Die Attachment ◽  
Advanced Packaging ◽  
Life Improvement ◽  
Solid Liquid ◽  
The Impact

The ever-increasing power throughput and ever-decreasing size of modern electronics, specifically power electronics, requires more advanced packaging techniques and materials to maintain thermal limits and sustain mechanical life. Specific applications with known operating conditions for these components can realize added benefits through a tailored thermal-mechanical-electrical optimized assembly, potentially utilizing niche material classes. Without losing any expected functionality, solid-liquid phase change materials could be incorporated into the device structure to reduce peak temperature and/or suppress high-cycle fatigue problems commonly found at die-attachment interfaces. The purpose of this study was to investigate, through model-based design and analysis, the impact of using organic phase-change materials (PCMs) at two strategic locations in the standard device stack. The results suggest noteworthy life improvement (40%) is possible when optimizing for a given melt point material. Additionally, further improvements were predicted through future material enhancements, namely thermal conductivity and latent heat.

scholarly journals Hierarchical macro-nanoporous metals for leakage-free high-thermal conductivity shape-stabilized phase change materials

2020 ◽  
Vol 269 ◽  
pp. 115088 ◽  
Author(s):  
Yaroslav Grosu ◽  
Yanqi Zhao ◽  
Alberto Giacomello ◽  
Simone Meloni ◽  
Jean-Luc Dauvergne ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Phase Change ◽  
Phase Change Materials ◽  
High Thermal Conductivity ◽  
Nanoporous Metals
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