Thermal, microstructural and numerical analysis of hempcrete-microencapsulated phase change material composites

Organic shell material and phase change material (PCM) have low thermal conductivity, which reduces the heat absorption and release rate of microencapsulated phase change materials (MEPCMs). Boron nitride nanosheets (BNNSs) with high thermal conductivity can not only stabilize the oil phase as the Pickering emulsifier but also improve the thermal conductivity of MEPCMs as one of the shell components, thus facilitating the heat conduction in the microcapsule system. Herein, MEPCM with paraffin wax (PW) as the core material and polystyrene (PS) modified by BNNSs as the shell material (PW@PS/BNNS MEPCMs) are synthesized via Pickering emulsion polymerization. The structure of PW@PS/BNNS MEPCMs can be regulated by tuning the PW and BNNS contents, to achieve high latent heat and thermal conductivity. In comparison to pure PW, the thermal conductivity of MEPCMs-5 wt % BNNSs increases by 63.76% at 25 °C. The PW@PS/BNNS powder possesses a latent heat capacity of 166.3 J/g, corresponding to a high encapsulation ratio of 80.77%. These properties endow the prepared MEPCMs with excellent thermal regulation properties. We also propose the formation mechanism of PW@PS/BNNS MEPCMs via Pickering emulsion polymerization for the first time, which will guide the MEPCM fabrication toward a reliable direction.

A novel measurement method of thermal performances for an improved thermal storage concrete with microencapsulated phase change materials

Modifications of microencapsulated phase change materials: Supercooling suppression, thermal conductivity enhancement and stability improvement

Construction of ammonium polyphosphate-modified halloysite nanotubes on phase change material microcapsules for the enhancement of thermophysical performance and flame retardant properties

Phase change materials (PCMs) have been extensively utilized in latent thermal energy storage (TES) and thermal management systems to bridge the gap between thermal energy supply and demand in time and space, which have received unprecedented attention in the past few years. To effectively address the undesirable inherent defects of pristine PCMs such as leakage, low thermal conductivity, supercooling, and corrosion, enormous efforts have been dedicated to developing various advanced microencapsulated PCMs (MEPCMs). In particular, the low-dimensional thermally conductive nanofillers with tailorable properties promise numerous opportunities for the preparation of high-performance MEPCMs. In this review, recent advances in this field are systematically summarized to deliver the readers a comprehensive understanding of the significant influence of low-dimensional nanofillers on the properties of various MEPCMs and thus provide meaningful enlightenment for the rational design and multifunction of advanced MEPCMs. The composition and preparation strategies of MEPCMs as well as their thermal management applications are also discussed. Finally, the future perspectives and challenges of low-dimensional thermally conductive nanofillers for constructing high performance MEPCMs are outlined.

Effects of in-situ acid dopants on the latent heat storage properties and morphology of palmitic acid @ polyaniline microencapsulated phase change materials

Modified preparation of Al2O3@Al microencapsulated phase change material with high durability for high-temperature thermal energy storage over 650 °C

Novel microencapsulated ternary eutectic alloy-based phase change material

Microencapsulation of high temperature metallic phase change materials with SiCN shell

Synthesis and properties of microencapsulated stearic acid/silica composites with graphene oxide for improving thermal conductivity as novel solar thermal storage materials

Nanofluid is a class of fluid that consists of metal nanoparticles such as aluminium oxide (Al2O3) and water solution. For effective heat removal, the concentration of these nanoparticles needs to be below 4%. It has been found that only if the concentration is below 4% that the heat removal is possible. The purpose of this paper is to enhance the heat removal effectiveness and the heat storage capacity of nanofluid with microencapsulated phase change material (MEPCM). When MEPCM particles are in the molten stage, it becomes favourable for heat removal and for storage. This paper demonstrates numerically the use of a ternary mixture of fluid containing MEPCM and Al2O3 nanoparticles. Both particles are at different concentrations, thus a set of different fluid/particles concentration is investigated. The fluid consists of Al2O3 nanoparticles and MEPCM particles in water. The effectiveness of these mixtures in heat storage is investigated for different concentrations of the two set of nanoparticles. Results reveal that this fluid can enhance the heat removal, and it has a good heat storage capability.

In the last decade, microencapsulated phase change material (MPCM) slurries have been proposed and studied as novel coolants for heat transfer applications. Such applications include electronics cooling, and secondary coolants in air conditioning systems among others. Experiments have shown that MPCM’s increase the overall thermal capacity of thermal systems by taking advantage of the phase change material’s latent heat of fusion. However, research has also shown that the overall heat transfer coefficient is diminished due to a reduction in the effective thermal conductivity and increased viscosity of the slurry. For this reason, there is an urgent need to modify the content of microcapsules containing phase change material to increase their effective thermal conductivity and the overall heat transport process. Our solution consists of increasing the thermal conductivity of MPCM by adding carbon nanotubes to the shell and core of the microcapsules. Carbon nanotubes have shown to increase the thermal conductivity of liquids by 40% or more in recent experiments. In this paper, MPCM slurry containing octadecane as phase change material and multi-wall carbon nanotubes (MWCNTs) embedded in the capsule material and core are compared with pure water as heat transfer fluid. Thermal and physical properties of MPCM slurry containing carbon nanotubes were determined using a differential scanning calorimeter and concentric viscometer, respectively. Experimental convective heat transfer coefficient data for MWCNT aqueous suspensions under laminar flow and constant heat flux were determined using a bench-top heat transfer loop. Experimental heat transfer results are presented.

MicroPCM-based phase change energy storage backfill materials: Application potential in geothermal exploitation

Microencapsulated phase change materials (MPCM) slurries with high heat transfer and great latent heat can serve as both the heat transfer fluids and energy storage medias. Studies showed that the effective specific heat and heat transfer rate increased by 28.1% and 23.6% respectively as using MPCM slurries. The rheological behavior of slurries do not change as adding MPCM with low concentration, can be characterized by Newtonian fluid feature with mass fraction <0.25. MPCM particles have flow drag reduction effect under turbulent situation, which was applied to building energy efficiency and refrigeration, obtained remarkable energy conservation effect.

Microencapsulated phase change materials (MPCMs) offer a promising way to enhance the thermal performance of cement-based materials; however, their incorporation often compromises mechanical properties and durability, limiting practical application. A mechanistic understanding of how MPCM particle size governs the coupled thermal, mechanical, and transport behavior of cementitious systems remains incomplete. In this paper, two organic MPCMs with identical core–shell chemistry but distinct particle sizes (mean diameters of 10.78 μm and 34.21 μm) were incorporated into mortar at dosages of 10 wt.% and 20 wt.% under w/b ratios of 0.35 and 0.45. The effects of MPCM particle size and content on hydration kinetics, rheology, strength development, pore transport behavior, and thermal conductivity were systematically investigated using isothermal calorimetry, flow spread testing, compressive strength measurements, capillary water absorption, thermal conductivity analysis, X-ray diffraction, and SEM–EDS characterization. Results show that MPCM incorporation delays early-age hydration and reduces peak hydration rates, with finer particles exerting a stronger inhibitory effect due to increased specific surface area and water adsorption. While all MPCM-modified mortars exhibit reduced compressive strength and increased capillary absorption, larger MPCM particles mitigate strength loss by limiting the total interfacial transition zone (ITZ) area and reducing ITZ connectivity. In contrast, smaller MPCM particles more effectively decrease thermal conductivity, achieving up to a 33% reduction, owing to enhanced interfacial thermal resistance. Microstructural observations confirm that MPCMs do not alter cement hydration products but influence performance through interfacial defects, porosity evolution, and particle-scale interactions. These findings demonstrate that MPCM particle size critically controls the trade-off between thermal regulation and structural integrity, providing quantitative guidance for designing PCM-modified concrete through optimizing particle-size.