Thermal Conductivity Enhancement and Shape Stabilization of Phase-Change Materials Using Three-Dimensional Graphene and Graphene Powder

Abstract

The porous interconnected structure of three-dimensional graphene (3DC) combines the excellent thermal conductivity of graphene with an interconnected architecture, thereby creating a thermal network within composites infused with 3DC. In this study, improvements in thermal conductivity, latent heat of fusion (Hf) and shape-stability of paraffin were compared between paraffin phase change materials (PCM) infused with 3DC and with discrete graphene flakes (GP) at the same filler loading to quantify the advantage of the interconnected structure. Paraffin infused with a 3DC of higher bulk density (3DCH) was also compared to identify the effects of increasing filler density. Thermal conductivity of the PCM composites was measured using the hot-disk method and shape-stabilization was compared through thermal cycling in an environment chamber. We found that the interconnected architecture of 3DC improved the properties of the paraffin matrix in multiple ways. 3DC improved the solidification process for paraffin with heterogeneous nucleation, helped to retain the shape of the PCM composite over thermal cycling, reduced void formation within the PCM and induced a large increase in thermal conductivity at 7.4 times and 5.2 times that of neat paraffin for composites infused with 3DCH and regular 3DC respectively, with only a small trade-off in Hf.

CuO Nanoparticle@Polystyrene Hierarchical Porous Foam for the Effective Encapsulation of Octadecanol as a Phase Changing Thermal Energy Storage Material

“…Poor heat transfer characteristic because of low thermal conductivity is a drawback for an organic PCM because it leads to a longer phase change time and hence a reduction in heat storage capacity. Various practices have been pursued to deal with these obstacles such as adding conductive phases like metallic nanoparticles, use of PCM mixtures, changing composition, encapsulation, and extended surface. − On the other hand, the overcooling behavior, limits to the encapsulation capacity of PCM, thermal instability, and the leakage phenomenon occurring during phase transition are still major disadvantages that limit the applications of PCMs . To overcome these limitations, in addition to PCM microcapsules, − the application of shape-stable porous materials as a PCM carrier has received great interest in the literature. − To date, porous clay, mineral-based materials, metallic foams, porous carbon, and porous polymers , are the most commonly used framework materials for shape-stabilized PCM.…”

Fly Ash/Octadecane Shape-Stabilized Composite PCMs Doped with Carbon-Based Nanoadditives for Thermal Regulation Applications

“…3−5 Still, the leakage issue which emerged throughout the solid−liquid phase transition and low thermal conductivity are the most important deficiencies that restrict their usage in passive solar TES activites. 6,7 The first problem can be overcome via shape stabilization of PCMs. In this context, several porous supporter materials have been handled for easy and cheap production of shape-stable composites, some of which are attapulgite, 8,9 diatomite, 10−12 natural clay, 13 perlite, 14−16 silica fume, 17,18 vermiculite, 19−22 and bentonite.…”

“…Because of such features, the usage of PCMs with construction elements in buildings has become an important approach in increasing energy efficiency, ensuring indoor comfort, protecting the environment, and balancing the issue of energy supply/demand. , Among the various PCMs, organic ones (like paraffin, fatty acids, etc.) are the pioneer materials because of some of their superior properties such as high LHTES properties, cycling stability, nontoxicity, negligible super cooling, and low vapour pressure. − Still, the leakage issue which emerged throughout the solid–liquid phase transition and low thermal conductivity are the most important deficiencies that restrict their usage in passive solar TES activites. , The first problem can be overcome via shape stabilization of PCMs. In this context, several porous supporter materials have been handled for easy and cheap production of shape-stable composites, some of which are attapulgite, , diatomite, − natural clay, perlite, − silica fume, , vermiculite, − and bentonite. , On the other hand, fly ash (FA) composed of mainly silica and alumina is a good candidate for the production of shape-stabilized composite PCMs (SSC-PCMs) as a lightweight supporter porous material.…”

Polyethylene Glycol–Calcium Chloride Phase Change Materials with High Thermal Conductivity and Excellent Shape Stability by Introducing Three-Dimensional Carbon/Carbon Fiber Felt

“…The heat can quickly transfer on the three-dimensional network structure so as to achieve the situation of low filler content and high thermal conductivity. At present, the methods of forming the high thermal conductivity path in polymer composites mainly include the freeze-drying orientation method, , self-assembly molding, metal foam method, , carbon foam method, , ceramic foam, 3D skeleton network method, , interfacial polyelectrolyte complex spinning, in situ reduction of metal ions, electrophoretic deposition method (EPD), electrostatic flocking, and so on. These methods make the thermal conductivities of polymer materials increase several times or even dozens of times, which are good methods to quickly improve the thermal conductivity.…”