Latent Heat Storage Capacity Research Articles

Preparation of hierarchical porous microspheres composite phase change material for thermal energy storage concrete in buildings

Phase change materials with high latent heat significantly reduce building energy consumption. However, the serious leakage issue, low thermal conductivity, and the poor photothermal response utterly hinder their wide application in architecture. We reported an effective strategy for constructing hierarchical porous composite microspheres (PCN) through spray drying, calcination, and acid activation, using palygorskite (Pal) as the raw material. PCN presented a spherical hierarchical porous structure constructed by crosslinking Pal nanofibers and cellulose nanocrystals in a particular proportion. Paraffin-PCN (P-PCN) composite phase change materials (PCMs) with high shape stability, excellent photothermal conversion ability and latent heat storage capacity were synthesized. The heat preservation time of the P-PCN natural cooling from 35 °C to 30 °C is approximately twice that of the P-Pal. The P-PCN indicates obvious advantages in building thermal management, with the melting enthalpy promoted to 130.2 J/g. Further, the P-PCN-based building materials (P-PCN-B) with the P-PCN and the building aggregate maintain superior light-thermal energy conversion and thermal properties after multiple cycles. The P-PCN-B indicates outstanding mechanical properties (compression strength reaching 14.2 MPa) and flame-retarded properties. This work provides an innovative design strategy for developing multifunctional intelligent energy storage concrete and paves the way for the sustainable utilization of energy storage materials.

High thermal storage ability and photothermal conversion capacity phase change capsule with graphene oxide covalently grafted silica shell

Preparation of phase change materials with energy collection, conversion and storage functions is considered to be an important way to solve the energy shortage problem. Hence, a novel phase change capsule (EP@MGO) with photothermal conversion function was innovatively designed. In the process of preparing EP@MGO, the modified graphene oxide (MGO) layer was covalently anchored on the surface of the phase change capsule encapsulated by silica shell (EP) through Si-O-Si bonds, in which MGO was obtained by modifying GO nanosheets with isocyanate propyl triethoxysilane. The as-prepared EP@MGO microcapsule presents favorable latent heat storage capacity, with enthalpy of 139.8 J/g and high encapsulation efficiency of 83.6%. Besides, the thermal stability, leakage-proof property, durability, and thermal reliability of EP@MGO were enhanced significantly due to the physical protection effect provided by the SiO2-MGO double-layer shell. Moreover, the covalently MGO-grafted silica shell endows EP@MGO with high thermal conductivity (1.603 W/m·K), which improves its thermal management efficiency. More importantly, EP@MGO exhibits the potential ability to effectively utilize ultraviolet and visible light. In detail, the absorbance of EP@MGO increased by ∼192% in the ultraviolet and visible light region (200–800 nm), and the photothermal conversion efficiency under near infrared (NIR) region as high as 64.4%, which has negligible change (64.2%) even after 50 times heating-cooling cycle. Therefore, the phase change capsule EP@MGO provides a new idea for realizing efficient utilization of solar energy, and exhibits the application potential in biomedical treatment, smart textiles, and solar thermal collector.

Design of a graphene oxide@melamine foam/polyaniline@erythritol composite phase change material for thermal energy storage

At present, only a single modification method is adopted to improve the shortcomings of erythritol (ET) as a phase change material (PCM). Compared with a single modification method, the synergistic effect of multiple modification methods can endow ET with comprehensive performance to meet the purpose of package, supercooling reduction, and enhancement of thermal conductivity. In this work, we innovatively combine graphene oxide (GO) nanosheet modified melamine foam (MF) and polyaniline (PANI) to construct a novel ET-based PCM by blending and porous material adsorption modification. PANI as the nucleation center can enhance the crystallization rate, thereby reducing the supercooling of ET. Meanwhile, GO@MF foam can not only be used as a porous support material to encapsulate ET but also as a heat conduction reinforcement to improve heat storage and release rate. As a result, the supercooling of GO@MF/PANI@ET (GMPET) composite PCM decreases from 91.2 °C of pure ET to 57.9 °C and its thermal conductivity (1.58 W⋅m−1⋅K−1) is about three times higher than that of pure ET (0.57 W⋅m−1⋅K−1). Moreover, after being placed at 140 °C for 2 h, there is almost no ET leakage in the GMPET composite PCM, and the mass loss ratio is less than 0.75%. In addition, the GMPET composite PCM displays a high melting enthalpy of about 259 J⋅g−1 and a high initial mass loss temperature of about 198 °C. Even after the 200th cycling test, the phase transition temperature and the latent heat storage capacity of the GMPET PCM all remain stable. This work offers an effective and promising strategy to design ET-based composite PCM for the field of energy storage.

Phase change material infused recycled brick aggregate in 3D printed concrete

In this paper the effects of the addition of a paraffin phase change material on the strength and printability of 3D printed concrete are studied. Phase change materials are latent heat storing materials, which garner and release large amounts of energy as they change phase. The addition of phase change materials to concrete produces a composite material with maximised latent and sensible heat storage capacity. Used in buildings, this composite material has the ability to minimise unwanted heat transfer across the building envelope.An existing mix design (RBA-3DPC), in which 64% of the natural aggregate in a 3D printable concrete (3DPC) had been replaced with recycled brick aggregate, is adjusted by adding phase change material to the pores of the recycled brick aggregate by vacuum impregnation, creating PCM-3DPC. Rheological characterisation tests are performed on reference mix designs (3DPC and RBA-3DPC) and the PCM-3DPC mix design, and used in a buildability model to validate the number of printable layers. Mechanical characterisation tests including cube strength tests, direct tensile tests and uniaxial compressive tests are performed on cast and printed specimens of the mix designs. There is no existing research on the effects of the combined addition of recycled brick aggregate and phase change material in 3D printed concrete.It is concluded that the PCM-3DPC has the highest number of printable layers predicted by the model and realised by a cylindrical column print and overall, PCM-3DPC has greater strength compared to RBA-3DPC, and lower strength compared to 3DPC. The PCM-3DPC exceeds the RBA-3DPC interlayer tensile strength by 6%, intralayer compressive strength by 43% and interlayer compressive strength by 9%, and subceeds the 3DPC interlayer tensile strength by 15% and interlayer compressive strength by 13%.

Phase-change composites for bimodal solar/electromagnetic energy storage based on magnetite-modified cellulose microfibers

• Cellulose microfibers were modified with Fe 3 O 4 nanoparticles in a tunable way. • Adsorption of lauric acid onto Fe 3 O 4 -modified fibers leads to shape-stable PCM. • Magnetic PCM composites can store thermal energy under alternating magnetic field. • Magnetite nanoparticles improves light-to-thermal conversion of PCM composites. Fe 3 O 4 -modified cellulose microfibers containing 7, 16, and 31 wt% of magnetite were prepared via co-precipitation of Fe 2+ and Fe 3+ salts. The magnetic phase-change composites were synthesized by adsorption of lauric acid onto the modified fibers with the highest saturation magnetization (23 emu/g) and magnetic-to-thermal conversion. The resulted composites demonstrated the saturation magnetization of 11.2 emu/g and latent heat storage capacity of 90 J/g corresponding to the loading efficiency of lauric acid of 49–51 wt%. The IR-imaging revealed the efficient accumulation of latent heat in the phase-change composite under the simulated sunlight and high frequency alternating magnetic field along with the excellent shape stability of the composites during the melting of lauric acid.

Nanosilver modified navel orange peel foam/polyethylene glycol composite phase change materials with improved thermal conductivity and photo-thermal conversion efficiency

Porous carbon-based composite phase change materials (CPCMs) have received widespread attention from researchers for their stable shape and considerable latent heat storage capacity. Here, using navel orange peel-based porous carbon (BPC) as the support carrier, nano-Ag as the surface modification material and polyethylene glycol (PEG) for the phase change medium, a novel PEG/BPC-Ag (Ag@CPCM) was fabricated by vacuum impregnation. Surprisingly, the experimental results indicated that nano-Ag modified the BPC could make the Ag@CPCM have stronger photo-thermal conversion ability, higher thermal conductivity and better thermal reliability. Significantly, the addition of nano-Ag increased the thermal conductivity of navel orange peel-based CPCMs to 0.639 W/m K (Ag@CPCM) from 0.313 W/m K (PEG/BPC), and its relative enthalpy efficiency η raised to 107.2 % from 104.8 %, and its photo-thermal conversion efficiency θ increased to 94.7 % from 77.2 %. Furthermore, the prepared novel CPCMs maintained its original phase change properties after 100 thermal cycles of testing, which demonstrated that the prepared CPCMs possessed favorable thermal stability and reusability. Overall, the Ag@CPCM materials have great potential for applications such as thermal management and solar energy storage.

A thermodynamic framework to identify apposite refrigerant former for hydrate-based applications

High latent heat storage capacity with naturally assisted salt rejection makes the clathrate compounds appropriate for applications towards load management and desalination processes. Adding to these energy savings are the ease of operations provided by water and the mild conditions at which the refrigerant hydrates are occurred. A direct comparison between these hydrates becomes unfeasible due to the scattered experimental data. Though thermodynamics can streamline this dispersed data, they are currently limited to being a proof of concept most accurately representing the experimental observations. We address this critical deficit of phase assessment and identify, from among R13, R14, R22, R23, R125, R134a and R152a, the most suitable hydrate former for the concerned application. An approach based on van der Waals and Platteeuw model is undertaken and the estimates are quantified in terms of percent average absolute relative deviations (% AARD). An average AARD of 1.75% and 2.68% is observed in pure and aqueous electrolytic phase of NaCl, KCl, CaCl2 and MgCl2, respectively. The model predictions are then estimated at temperature/salinity of 281 K/0 wt% and 284 K/3.5 wt%. Together with the qualitative assessment of the hydrate phase, viz, vapor pressure, compressibility and dissociation enthalpy, R152a refrigerant is observed to be the appropriate former for applications to both load management and desalination.

Novel properties of stearic acid / MXene - Graphene oxide shape - Stabilized phase change material: Ascended phase transition temperature and hierarchical transition

To develop novel materials with active photothermal conversion and latent heat storage properties, the shape-stabilized phase change material was fabricated via self-assembly method employing stearic acid (SA) as heat storage medium, graphene oxide and MXene as hybrid matrix (GM) and photothermal conversion agent. The morphology, structure, properties and phase transition behavior were investigated by various techniques. The results shown that SA/GM has sandwich-like structure and SA is confined between matrix nanosheets in multiple crystallographic forms. Due to the superposition of host-guest interaction and intrinsic van der Waals force between nanosheets, the primary melting temperature of SA/GM climbs 27.7 °C approximately than that of SA, as well as the total latent heat decreases by 28.55%–30.85% compared with theoretical values. The confinement effect increases the crystallization activation energy of confined SA, and leads to the formation of non-phase transition layer, transitional confinement layer and proximate bulk layer. However, the above observations are applicable to fatty acids/GM, only the suppressed latent heat occurs in all GM-matrix composites. In addition, the SA/GM7 has excellent photothermal conversion efficiency, as high as 93.34%, and gradient latent heat storage capacity, 45.96 J g −1 at 74.43 °C and 91.19 J g −1 at 92.37 °C. Stearic acid/Mxene - graphene oxide (SA/GM) composite was fabricated though self-assembly method. The confined SA exists in multiple crystal forms and shows abnormal properties, including the ascended phase transition temperature, hierarchical phase transition and the formation of confined layer. The SA/GM presents excellent photothermal conversion efficiency and gradient heat storage/release performances. • SA/GM was self-assembled by the inherent forces of matrix nanosheets and host-guest interaction. • The main melting temperature of SA/GM increased by 27.7 °C approximately. • Non-phase change layer, transitional confinement layer and proximate bulk layer exist in SA/GM. • Ascended transition temperature and stratified phase transition are applicable to fatty acids/GM.

Promising palmitic acid/poly(allyl methacrylate) microcapsules for thermal management applications

This study aimed to develop a promising thermal energy storage material based on poly(allyl methacrylate (AMA))-based palmitic acid (PA) microencapsulation using emulsion polymerization. Poly(AMA) and PA were chosen as the capsule shell and core materials, respectively. The synthesized microcapsules exhibited a good latent heat storage capacity of 143–188 J/g. This study also aimed to evaluate the effect of the core material ratio of the microcapsules on the thermal, structural, and chemical properties of PA microcapsules. To determine the thermal performance of the prepared microcapsules, mortar-based composite materials containing PA microcapsules were prepared at a ratio of 90/10 (wt% mortar/micro phase change material) and analyzed during heating and cooling using infrared techniques. The analysis showed that the temperature of the composite materials containing PA microcapsules was 6.6 °C lower than that of the reference composite after 60 min of heating. This indicates that mortar composites containing PA microcapsules are less affected by heating and cooling and can therefore be applied as promising energy storage materials for thermal management applications, particularly in buildings.

Supercooled sodium acetate aqueous solution for long-term heat storage to support heating decarbonisation

Heating decarbonisation through electrification requires the development of novel heat batteries. They should be suitable for the specific application and match the operation conditions of domestic renewable energy sources. Supercooled liquids, often considered a drawback of phase change materials, are among the most promising technologies supporting heating decarbonisation. Although some studies have shed light on stable supercooling, the fundamentals and stability remain open problems not always accompanied by relevant experimental investigations. This research critically analyses the physic and chemistry of sodium acetate (SA, NaCH3COO) aqueous solution, a low-cost, non-toxic, and abundant compound with stable supercooling for long-term heat storage. It has an appropriate phase change temperature for high-density heat storage using heat pumps or solar thermal technologies in residential applications. The existing discrepancies in literature are critically discussed through a systematic experimental evaluation, providing novel insights into efficient material design and appropriate boundary conditions for reliable material use in long-term heat batteries. Despite previous studies showing that the thermal reliability and stability of sodium acetate aqueous solution as a supercooled liquid for heat storage cannot be guaranteed, this study demonstrates that through an appropriate encapsulation and sealing method, the peritectic composition of sodium acetate solution (p-SA 58 wt%) can be used as a supercooled liquid for long-term heat storage with a stable melting temperature of 57 °C, appropriate for domestic heat technologies. It is demonstrated that energy storage efficiency can be maintained under cycling, with a constant latent heat storage capacity of 245 kJ/kg and a volumetric storage density of 314 MJ/m3. It was confirmed that the material should achieve a fully-melted state for stable supercooling. Finally, local cooling and retaining seed crystals through high pressure were highlighted as the most suitable basic principles for successful crystallization and heat release. This promising material can store energy for long periods without latent heat losses due to its stable subcooling. Latent heat can be released when required at any selected time and temperature just by a simple activation process.

Cenosphere-based PCM microcapsules with bio-inspired coating for thermal energy storage in cementitious materials

Phase change materials (PCMs) provide passive storage of thermal energy in buildings to flatten heating and cooling load profiles and minimize peak energy demands. After microencapsulated into a protective shell, they can be directly added to cementitious materials to add thermal energy storage capacity to the material. However, existing studies show that the strength of the produced materials can be drastically reduced by the added PCM microcapsules. To overcome this drawback, this study develops a novel PCM microcapsule using the cenosphere as the protective shell, together with a bio-inspired dopamine coating. As hollow fly ash particles, cenosphere shells are much harder and stronger than commonly used polymer based protective shells. While the strong binding ability of dopamine to diverse surfaces through covalent and non-covalent interactions provides better bonding between the PCM microcapsule and the surrounding cement paste. For these reasons, the strength of the produced cement mortar can be greatly improved by this microcapsule. An experimental study shows that a 35% increase in compressive strength has been achieved by adding 10 wt% of the new PCM microcapsule into the cement mortar. Microstructure examination and hydration products analysis revealed that the dopamine coating facilitates the hydration of the cement and produces a denser and stronger interface between the microcapsule and the cement paste. As a result, a novel PCM microcapsule is developed which not only integrates latent heat storage capacity to the cement mortar but also enhance the compressive strength of the mortar, which cannot be achieved by any other PCM microcapsules.

Fabrication and investigation on influence of metal oxide nanoparticles on thermal, flammability and UV characteristics of polyethylene glycol based phase change materials

The current study is aimed at the fabrication and property evaluation of form-stable phase change material (PCMs) nanocomposites films made by solvent casting method using Polyethylene Glycol (PEG) as working PCM and Polyvinyl Alcohol (PVA) as a supporting matrix, reinforced with Titanium Dioxide Nanoparticles (NTO). The influence of the incorporated metal oxide nanoparticles in varying concentrations (0.25–1 %) on the chemical, thermal, microstructural, UV resistance, and flammability characteristics for the developed nanocomposites has been thoroughly investigated. The resultant form-stable PCMs are characterized by FTIR and FE-SEM. Phase change behaviours and thermal stability of the prepared PCMs are determined by DSC and TGA analysis. T-History and thermal cycling tests have been carried out to access the charging-discharging time as well as the thermal reliability of the form-stable PCMs. The addition of the varying loadings of NTO particles to the optimized PEG/PVA composition significantly improves the phase change parameters, such as latent heat storage capacities from 65.59 J/g to 73.02 J/g and degree of supercooling from 18.93 to 17.03 respectively; along with the thermal stability of the nanocomposites with increasing order of nanoparticles concentrations. The presence of NTO particles in nanocomposites has proved to be effective in successfully reducing the UV transmittance across the films. The metal oxide filler also enhances the flame-retardant behaviour of the form-stable PCMs.

A solid–solid phase change filler with enhanced thermal properties for cooling asphalt mastic

The goal of this work is to improve the latent heat storage capacity and the thermal response rate of a polyurethane solid–solid phase change material (PUSSPCM) for evaluating its applicability as an alternative filler to cool an asphalt mastic. For this purpose, graphite/PUSSPCM (GPCM) structures with various mesh values and contents of graphite were synthesized. The latent heat was initially increased and then decreased with the increasing graphite content. By selecting the optimum content, a GPCM with a larger mesh can possess a higher latent heat. The existence of a relatively large content and mesh of graphite could lead to a higher thermal conductivity for GPCM. The latent heat storage capacity and the thermal conductivity of the synthesized GPCM-8000–1 were 23.2 % and 254.7 % higher than those of PUSSPCM, respectively. Meanwhile, the GPCM-8000–1 material configuration with excellent thermal stability at 200 °C can withstand the high-temperature construction environment of asphalt pavement without liquid leakage and decomposition. As a result, it is recommended as a solid–solid phase change filler to fabricate phase change asphalt mastics. The extracted outcomes from the rheological test results show that the high-temperature deformation resistance, low-temperature cracking resistance and fatigue resistance of the phase change asphalt mastics are improved in contrast to the traditional asphalt mastic. Finally, the cooling effect of the phase change asphalt mastics was evaluated, with the maximum cooling amplitude reaching the value of 5.6 °C.

N-eicosane@TiO2/TiN composite phase change microcapsules: Efficient visible light-driven reversible solid-liquid phase transition

Organic phase change materials (PCMs) promise remarkable latent heat storage capacity but suffer from weak visible-light absorption capability and ultralow thermal conductivity for harvesting and conversion of clean solar energy. Herein, we design and synthesize a new core@shell structured n-eicosane@TiO2/TiN composite microcapsules which can realize 98.08 % of thermal energy storage capacity. By making use of the localized surface plasmon resonance of high-thermal-conductivity TiN, the prepared composite microcapsules possess a remarkable photo-thermal conversion efficiency up to 78.4 %. Plasmonics TiN can not only efficiently adsorb visible light and convert the optical energy into heat but also enhance thermal conductivity of the composite microcapsules, resulting in ultra-low supercooling degree of 1.02 oC. In addition, the composite microcapsules exhibit excellent phase change reversibility and thermal durability during the 100-cyclic scans. Our work offers new insights into designing high-performance microcapsuled PCMs in solar thermal applications, bringing great potential for renewable energy utilization beyond traditional fossil energy sources.

Two-dimensional lamellar phosphogypsum/polyethylene glycol composite PCM: Fabrication and characterization

In this work, a nanocomposite phase change material (PCM) has been designed by combining two-dimensional lamellar anhydrous calcium sulfate with polyethylene glycol (PEG). We report a facile strategy to controllably fabricate two-dimensional lamellar anhydrous calcium sulfate (LAH) with the average thickness of 28.63 nm from phosphogypsum (PG) through ethylenediamine tetraacetic acid disodium (Na2EDTA) induction in glycerol and ethylene glycol solutions at 98 °C. The obtained 2D lamellar CaSO4 was a slit-type mesoporous material stacked by the nanosheet of calcium sulfate. It has a specific surface area of 70.02 m2/g, which is 10 times larger than phosphogypsum. Na2EDTA acts as a crystal habit-directing agent to regulate crystal morphology through nonclassical nanoparticle-mediated crystallization processes, resulting in the crystalline morphology tending to be lamellar. Lamellar anhydrous calcium sulfate phase change composites (LAHPCMs) were prepared with 2D lamellar anhydrous nano-CaSO4 and polyethylene glycol (PEG). The LAHPCMs had a high latent heat storage capacity (92.99 J/g). Lamellar anhydrous calcium sulfate phase change composites have good thermal stability and durability, structure stability, and good liquid leakage resistance. These results provide the possibility for phosphogypsum to be used for energy storage and thermal insulation.

A Novel Layered Double Hydroxide and Dodecyl Alcohol Assisted PCM Composite with High Latent Heat Storage Capacity and Thermal Conductivity

A Novel Layered Double Hydroxide and Dodecyl Alcohol Assisted PCM Composite with High Latent Heat Storage Capacity and Thermal Conductivity

Phase-change materials reinforced intelligent paint for efficient daytime radiative cooling

SummaryPassive cooling of buildings has become increasingly important for green and low-carbon development, especially in the near decade where daytime radiative cooling technology (DRCT) has drawn attention with big breakthroughs. However, irresistibly importing heat from sunlight and surroundings results in notable temperature rise, thus limiting the cooling effect. Here, we report a radiative paint with latent heat storage capacity to store imported heat by coupling randomly-distributed phase-change materials (PCMs) based microcapsules with acrylic resin to enhance cooling performance. The bifunctional paint shows good performance in selected-suitable phase transition temperature, high enthalpy, high reflectivity in the sunlight region and strong emissivity in the atmospheric window region. The temperature measurements demonstrate that the paint possesses enhanced cooling performance of temperature drop and time buffering effect compared with the pure radiative cooling paint. This work offers the potential to broaden the applications of PCMs and DRCT for energy saving and environment protection.

Use of Low Melting Point Metals and Alloys (Tm < 420 °C) as Phase Change Materials: A Review

Phase Change Materials (PCMs) are materials that release or absorb sufficient latent heat at a constant temperature or a relatively narrow temperature range during their solid/liquid transformation to be used for heating or cooling purposes. Although the use of PCMs has increased significantly in recent years, their major applications are limited to Latent Heat Storage (LHS) applications, especially in solar energy systems and buildings. PCMs can be classified according to their composition, working temperature and application. Metallic PCMs appear to be the best alternative to salts and organic materials due to their high conductivity, high latent heat storage capacity and wide-ranging phase change temperature, i.e., melting temperature and chemical compatibility with their containers. This paper reviews the latest achievements in the field of low-melting point metallic PCMs (LMPM-PCMs), i.e., those with melting temperatures of less than 420 °C, based on Zn, Ga, Bi, In and Sn. Pure LMPM-PCMs, alloy LMPM-PCMs and Miscibility Gap Alloy (MGA) LMPM-PCMs are considered. Criteria for the selection of PCMs and their containers are evaluated. The physical properties and chemical stability of metallic PCMs, as well as their applications, are listed, and new application potentials are presented or suggested. In particular, the novel application of metallic PCMs in casting design is demonstrated and suggested.

Novel shape-stabilized phase change materials: Insights into the thermal energy storage of 1-octadecanol/fumed silica composites

Here, novel C18OH/FS shape-stabilized phase change materials (SSPCMs) were simply prepared by incorporating 1-octadecanol (C18OH) into a porous fumed silica (FS). Given the high porosity (88%), FS provided sufficient inner space for the impregnation of a large C18OH amount up to 75% of the total mass. It was found that C18OH was effectively stabilized in the FS porous network, which could be due to physical interactions such as capillary force, surface tension, and hydrogen bonding at the interfacial region. C18OH PCM was infiltrated into FS porous network by initial adsorption onto particle surfaces and subsequent filling micropores, mesopores, and finally macropores of the support FS. The resultant C18OH/FS SSPCM (75 wt% of C18OH) showed an excellent leakage resistance, high crystallinity of 92.7% and latent heat storage capacity of 160.3 J/g. In addition, the C18OH/FS SSPCM provided excellent thermal reliability with a test of 500 accelerated thermal cycles. The solid 13C NMR, DSC, and XRD analyses successfully characterized the formation of non-freezable layer during the infiltration of C18OH into the pores by forming hydrogen bonding between C18OH and surface silanol groups. This non-freezable layer negatively affected the crystallinity of C18OH and lowered the heat storage capacity, which could be minimized at a large content of impregnated C18OH. Overall, these results suggest that the C18OH/FS SSPCMs have great latent heat storage capacity with good thermal reliability, simple fabrication, and cost-effectiveness that would be potential for large-scale applications in thermal energy storage.

Fabrication and Thermal Performance of 3D Copper-Mesh-Sintered Foam/Paraffin Phase Change Materials for Solar Thermal Energy Storage

Due to its large latent heat and high energy storage capacity, paraffin as one of the phase change materials (PCMs) has been widely applied in many energy-related applications in recent years. The current applications of paraffin, however, are limited by the low thermal conductivity and the leakage problem. To address these issues, we designed and fabricated form-stable composite PCMs by impregnating organic paraffin within graphite-coated copper foams. The graphite-coated copper foam was prepared by sintering multilayer copper meshes, and graphite nanoparticles were deposited on the surface of the porous copper foam. Graphite nanoparticles could directly absorb and convert solar energy into thermal energy, and the converted thermal energy was stored in the paraffin PCMs through phase change heat transfer. The graphite-coated copper foam not only effectively enhanced the thermal conductivity of paraffin PCMs, but also its porous structure and superhydrophobic surface prevented the paraffin leakage during the charging process. The experimental results showed that the composite PCMs had a thermal conductivity of 2.97 W/(m·K), and no leakage occurred during the charging and discharging process. Finally, we demonstrated the composite PCMs can be readily integrated with solar thermoelectric systems to serve as the energy sources for generating electricity by using abundant clean solar-thermal energy.