scholarly journals A newly designed paraffin@VO2 phase change material with the combination of high latent heat and large thermal conductivity

2020 ◽  
Vol 559 ◽  
pp. 226-235 ◽  
Author(s):  
Tianshu Cheng ◽  
Ning Wang ◽  
Haixu Wang ◽  
Rong Sun ◽  
Ching-Ping Wong
Keyword(s):  
Thermal Conductivity ◽  
Phase Change ◽  
Phase Change Material ◽  
Latent Heat ◽  
Change Material ◽  
High Latent Heat

Thermal Conductivity and Latent Heat Properties of Microencapsulated Phase Change Material (μPCM)/Multiwall Carbon Nanotube (MWCNT) Composites for EVs Application

2016 ◽  
Vol 1133 ◽  
pp. 131-135
Author(s):  
Adli Zil Ikram Abdullah ◽  
Mohd Fadzli bin Abdollah ◽  
Boon Tuan Tee ◽  
Hilmi Amiruddin ◽  
Ahmad Kamal Mat Yamin ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Carbon Nanotube ◽  
Phase Change ◽  
Phase Change Material ◽  
Latent Heat ◽  
Mass Fraction ◽  
Multiwall Carbon Nanotube ◽  
Microencapsulated Phase Change Material ◽  
Change Material ◽  
Multiwall Carbon

The aim of this study is to investigate the thermal properties of microencapsulated phase change material (μPCM) / multiwall carbon nanotube (MWCNT) composites. Several disc samples with 30mm diameter x 5mm width of μPCM/MWCNT composites were prepared with different mass fractions of MWCNT of 2, 4, 7 and 10 wt% using a compaction method. The thermal conductivity test was performed according to ASTM standard, while the latent heat property was calculated based on the theoretical equations. It was found that the thermal conductivity increase with mass fraction of MWCNT. However, the latent heat decreases with mass fraction of MWCNT. From these results, the optimized mass fraction of MWCNT approximately 5%, could be selected due it stable-form in thermal conductivity and latent heat capacity for electric vehicles (EVs) application. Furthermore, the reducing in melting time with increasing of MWCNT is accordance with the improvement of thermal conductivity.

Optimization of Graphite Composite Latent Heat Storage Systems

2017 ◽  
Author(s):  
Anne Mallow ◽  
Kyle Gluesenkamp ◽  
Omar Abdelaziz ◽  
Samuel Graham
Keyword(s):  
Thermal Conductivity ◽  
Energy Density ◽  
Phase Change ◽  
Phase Change Material ◽  
Power Density ◽  
Latent Heat ◽  
Heat Storage ◽  
Storage Systems ◽  
Junction Temperature ◽  
Change Material

The energy density and power density are critical properties of thermal energy storage systems. Use of a phase change material as the storage medium provides high energy density due to the ability to store energy as latent heat during the phase transition; however, the power density is limited by the low thermal conductivity. Insertion of a highly conductive graphite foam within the material can increase the rate of thermal response of the phase change material. As the graphite bulk density increases, the thermal conductivity increases, but the composite latent heat decreases due to displacement of the phase change material. This introduces a trade-off between energy density and power density of the composite. In this work, a validated numerical model is used to study the trade-off between energy density and power density with respect to graphite bulk density under various imposed heat fluxes. Comparisons are made based on the melting time, junction temperature between the composite and the heat source, and the volumetric energy density. To simplify the complicated relationship between composite thermophysical properties and charging response, two non-dimensional numbers are used. The Fourier number provides a comparison between the heat storage and heat diffusion by considering the thermal conductivity, latent heat, sensible heat, density, melting time, and volume. A dimensionless temperature compares the junction temperature (temperature between the heat source and the composite) when the sample is fully melted to the melt onset temperature. These non-dimensional numbers can assist in the design of latent heat storage systems where some parameters are fixed (such as heat flux, junction temperature, mass, operating time, or required energy storage) and others must be determined by the design (such as required thermal conductivity or height).

Paraffin/graphene sponge composite as a shape-stabilized phase change material for thermal energy storage

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Pengyang Li ◽  
Qiang Chen ◽  
Qingyu Peng ◽  
Xiaodong He
Keyword(s):  
Thermal Conductivity ◽  
Graphene Oxide ◽  
Phase Change ◽  
Phase Change Material ◽  
Latent Heat ◽  
Impregnation Method ◽  
Shape Stability ◽  
Content Type ◽  
Graphene Sponge ◽  
Change Material

Purpose This paper aims to study the synergistic effect of graphene sponge on the thermal properties and shape stability of composite phase change material (PCM). Design/methodology/approach Graphene oxide sponge is first prepared from an aqueous solution of graphene oxide by freeze-drying method. The oxidized graphene sponge is reduced by hydrazine hydrate. Finally, use vacuum impregnation method to introduce paraffin into graphene sponge to prepare composite PCM. Findings Graphene sponge is used to improve the shape stability of paraffin wax and improves the thermal conductivity and latent heat of the composite PCM. The thermal conductivity increases by 200 per cent and the composite PCM has excellent reliability in 100 melt-freezing cycles. Research limitations/implications A simple way for fabricating composite PCM with high thermal conductivity and latent heat which has the potential to be used as thermal storage materials without container encapsulation has been developed by using graphene sponge and paraffin. Originality/value The materials and preparation methods with special structure and properties in this paper provide a new idea for the research of PCM, which can be widely used in the fields of energy conversion and storage.

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