Expanded Graphite Particles Research Articles

Thermal Performance Improvement of Composite Phase-Change Storage Material of Octanoic Acid–Tetradecanol by Modified Expanded Graphite

Phase-change cold storage technology is recommended as a solution for energy conservation and carbon neutrality in air conditioning systems of buildings. This study focuses on the development of binary composite phase-change materials comprising octanoic acid–tetradecanol (OA-TD). To enhance its thermal conductivity, expanded graphite (EG) was employed as an additive carrier, and the surface modification of EG particles using hexadecyltrimethoxysilane (HDTMOS) was attempted to make up for the instability and further to improve the performance of OA-TD/EG CPCMs. The OA-TD/EG-HDTMOS CPCMs were synthesized by EG mixed with EG-HDTMOS at a 1:1 mass ratio. The thermal performance and stability of the OA-TD/EG-HDTMOS CPCMs were thoroughly evaluated by multi-cycle melting–solidification and thermal conductivity measurements. The results revealed that the OA-TD mixture, when at a mass ratio of 77:23, exhibited a phase-transition temperature of 11.4 °C and a latent heat ranging from 150 to 155 J/g. Then, the OA-TD/EG-HDTMOS composite material, at a 12:1 mass ratio of OA-TD to EG-HDTMOS, solidified and melted at temperatures of 9.2 °C and 11.2 °C, with a latent heat ranging from 138 to 143 J/g, and significantly improved the thermal conductivity to 0.7 W/(m·K), representing a remarkable 133% increase compared to that of OA-TD alone. Even after undergoing 100 melting–solidification cycles, the OA-TD/EG-HDTMOS maintained superior phase-change thermal performance and stability, making it suitable for cold storage and energy conservation in air conditioning.

Potential application of wet-phase modified expandable graphite particles as a novel in-depth profile control agent in carbonate reservoirs

Novel wet-phase modified expandable graphite (WMEG) particles were developed for in-depth profile control in carbonate reservoirs. The harsh environment of carbonate reservoirs (≥ 130 °C, ≥ 22 × 104 mg/L) brings significant challenges for existing profile control agents. WMEG particles were developed to address this problem. WMEG particles were synthesized via intercalation with ultrasound irradiation and chemical oxidation. The critical expansion temperature of WMEG particles is 130 °C, and these particles can effectively expand 3–8 times under high temperature and high salinity water. The core flow experiments show that WMEG particles exhibit a good plugging capacity, profile control capacity, and a better-enhanced oil recovery (EOR) capacity in deep carbonate reservoirs. WMEG particles can be expanded in the formation and form larger particles that bridge the upper and lower end faces of the fracture. Then the high-permeability zones are effectively plugged, and the heterogeneity is improved, resulting in an obvious increase in oil recovery. This research provides a novel insight into future applications of profile control agents for in-depth profile control treatment in carbonate reservoirs.

Thermal and electrical properties of palmitic acid/expanded graphite composite phase change materials for thermal energy storage

Expanded graphite (EG) based phase change material (PCM) has attracted significant concern in thermal management systems. In this paper, a series of composite PCMs composing of EG with different sizes (50, 80, and 100 mesh) as the substrate, and palmitic acid (PA) as the PCM, were prepared by vacuum impregnation method. The results shown that the size of EG particles effect the adsorption capacity of PA. The mass fraction of PA in PA/EG-50 reached 83.6% and the enthalpy of melting and solidification of PA/EG-50 are 160.13 J/g and 159.75 J/g, respectively. The thermal conductivity decreased slightly as the particle size of EG increased, and the thermal conductivity of PA/EG-100 is the highest of 4.86 W/(m·K). The TGA results show that all composite PCMs present good thermal stability below 200 °C. The electro-thermal conversion efficiency increased with the particle size of EG increasing, and the electro-thermal conversion efficiency of PA/EG-100 reached up to 91.39% under low-voltage conditions (1.9 V). These results throw light on the potential application of EG-based composite PCM, especially for the electro-thermal conversion.

High-performance static formation of methane hydrate in fixed bed constructed by incorporating expanded graphite into polyimide foam

Hydrate has been endowed with great potential in energy storage and transportation. However, the kinetics of its formation process has been a challenge, often requiring dynamic mechanical processes that are energy-intensive and cumbersome to operate. Herein, a well-designed expanded graphite (EG)/polyimide (PI) foam was first explored as fixed bed for the formation of methane hydrate. The results demonstrate that the EG/PI fixed bed exhibits a remarkable performance in hydrate formation under static conditions, with a high gas storage capacity of 149 V/V, a short induction time and a rapid formation rate of 13.1 V·V−1·min−1 at 6 MPa and −2 °C, and excellent recyclability, which are attributed to its stable micro/macro structures. Thereinto, the pores of EG serves as gas adsorption and reaction sites, initialing the formation with extremely short induction time. The three-dimensional framework of PI foam supports the uniform dispersion of EG particles and enables the efficient formation of hydrate under static condition. The EG/PI fixed bed decreases the water freezing point and leads to a high supercooling that facilitates the rapid nucleation of hydrate. Meanwhile, the fixed bed provides extensive mass-transfer channels, sufficient growing space, and superior heat conductivity, which contribute to the hydrate growth under static condition. This work not only offers a novel strategy for fabricating high-performance fixed bed, but also provides an insight into its promotion mechanism in hydrate formation.

Fire performance, toxicity, and thermal diffusivity of wastepaper mixed with magnesium hydroxide, depending on the particle size of expandable graphite

As the construction of high-rise buildings increases to solve residential spaces caused by high density population concentration, the occurrence of fire accidents in high-rise buildings is also increasing. The primary cause of fire damage in high-rise buildings is the spread of fire caused by exterior wall finishes. Therefore, it is essential to develop semi-non-combustible finishes that can be applied to high-rise buildings to prevent the spread of fire due to exterior wall finishes. To address this issue, numerous studies are being conducted to develop flame retardant finishing materials that reduce heat release rate and total heat release. A double flame retardant mixed waste paper with expandable graphite and magnesium hydroxide was manufactured to improve the fire performance of cellulose building finishing materials. Total heat release (THR), CO, and CO2 Generation changes were measured using a cone calorimeter, and thermal diffusion rate was measured through the LFA 1000 experiment. The correlation of total heat release, CO generation, CO2 generation, and mass reduction rate by variation of expandable graphite's mesh size at double flame-retardant waste paper were secured through a cone calorimeter test. The thermal diffusion rate data of the specimen were secured through the LFA 1000 experiment. Through experiments, it has been confirmed that specimens using specific expandable graphite particles can be utilized as fire-resistant finishing materials in construction, ensuring fire resistance performance.

Correlating microstructure-property relationships in carbon fiber-expanded graphite hybrid composites for synergistic improvements in thermal and mechanical properties

Thermally conductive and structurally reinforcing polymer composites are in high demand for applications such as electric vehicles, rapid prototyping, and thermal interface materials. Including a single geometry (platelet or rod) filler is a common strategy to improve the performance of polymers. However, the thermal and mechanical properties follow an inverse dependence and often require high filler loadings that compromise the overall properties. Hybridization of filler geometries has effectively improved the thermal conductive network while retaining mechanical performance. The focus of this work is to understand the effect of microstructure and interactions of hybrid fillers in high strength thermally conductive composites. For this study, expanded graphite, and carbon fibers (CFs) were used as the hybrid filler system to improve the thermal conductivity and mechanical properties of polyamide-based thermoplastic composites. The detailed microstructural study revealed that at a lower normalized weight ratio of CFs, the fibers bridge the expanded graphite particles to create a filler-filler network which leads to synergistic effect on both the tensile strength (by 29%) and thermal conductivity (by 290%) compared to a single-filler expanded graphite-based system. Above a critical mass fraction of CF, the planar graphitic orientation led to a loss in thermal conductivity which is attributed to reduced exfoliation and packing density of fillers.

Phosphonitrile decorating expandable graphite as a high-efficient flame retardant for rigid polyurethane foams

Researchers have widely focused on the high flammability and releasing toxic gases of rigid polyurethane foam (RPUF) under fire attack. In this work, the hybrid expandable graphite (EG) intumescent flame retardant is designed and fabricated for the fire safety of RPUF. Hexachlorocyclotriphosphazene (HCCP) is self-assembled on the surface and interlamination of EG (HCCP@EG) via water bath method and incorporated into RPUF matrix to improve the flame retardant efficiency of EG and the interfacial adhesion between EG particles and RPUF matrix. The structural morphological characterization indicates that HCCP@EG is successfully synthesized. HCCP@EG also exhibits good thermal stability and high char residues. Compared with neat RPUF, RPUF composites with 15% HCCP@EG show excellent flame-retardant properties and achieve a UL-94 V-0 level and a limiting index higher than 27.0%, which is due to the construction of a network structure of HCCP in the graphite lamellas and its synergistic and barrier effect. In addition, compared with EG, the presence of HCCP enhances interface compatibility between EG and RPUF, resulting in improving the mechanical property of RPUF composites. In summary, this work provides a facile approach to manufacturing high-performance RPUF products with outstanding fire safety.

Flame retardancy of polypropylene filled with expandable graphite and magnesium hydroxide: The impact of particle size of expandable graphite and its mechanism

AbstractPolypropylene (PP) was modified by expandable graphite (EG) and magnesium hydroxide (MH) to enhance its flame retardancy. The impact of EG particle size on fire behavior of PP/MH/EG ternary composite was studied in detail. The results reveal that EG synergizes markedly with MH in flame‐retarding PP. The PP/MH/EG composite with larger EG particle size displays better flame retardancy, smoke inhibition, acid resistivity, processability, and less toxic gas release upon combustion. The striking contrast derives from differences of charring behavior in condensed phase. The composite with larger EG particle size can produce intumescent char with larger expansion volume and better compactness and continuity, which hinders heat transfer inside polymer composite. Owing to much smaller expansion volume, the composite containing smaller EG particle size cannot generate effective fireproof barrier. As a consequence, this composite exhibits worse fire retardance and smoke inhibition in contrast with the composite with larger EG particle size.

Thermal characteristics of expandable graphite as a burning rate enhancer in hybrid propulsion

AbstractHybrid propulsion, consisting of solid fuel and liquid oxidizer, exhibits major advantage regarding safety, development costs, energetic performance, and controllability. Hence, it has been considered for space and other propulsion programs. One of the characteristic features of hybrid motors, that may be of major disadvantage, is their relatively low thrust due to the characteristic low regression rate of the typical polymeric solid fuels. This research group had revealed that a small fraction of an expandable graphite (EG) additive could double the burning rate and thrust of hybrid motors. EG is an intercalated form of graphite, elongating and swelling, getting a worm‐like string shape at elevated temperatures. In an earlier work it was hypothesized that enhanced heat transfer via conduction through the EG strings protruding from the hot surface, is a significant parameter increasing the burning rate. In the present investigation, thermal analysis revealed that the ignition temperature of polyester fuel containing 5 wt% of EG, is substantially lower than that of the pure polymer, which may promote higher burning rate as well. High‐speed photography of the surface of EG‐containing solid fuels as well as that of individual EG particles during controlled heating, demonstrated the dynamic behavior resulting in the formation of EG strings longer by an order of magnitude compared to the original particles. The different phenomena were related to the observation of enhanced burning rate.

Achieving extraordinary thermal stability of salt hydrate eutectic composites by amending crystallization behaviour with thickener

Commercial thermal energy storage (TES) systems necessitate reliable thermal performance throughout their operational lifetime. Repeated volume changes of the phase change materials (PCMs) during thermal cycling disengages thermal contacts between the conductive fillers like expanded graphite (EG) in TES composites, causing unstable thermal conductivity (k) that fades with cycling. Our in-operando crystallization studies on eutectic PCM made of zinc nitrate hexahydrate (ZNH) and KNO3 revealed that the thermal stability of PCM composites can be considerably degraded by the formation of large and sharp-cornered PCM crystals during the freezing cycle. While the crystals can push EG particles, disengaging thermal contacts between them, we have newly discovered that carboxymethyl cellulose (CMC) can be used to retain the thermal contacts by forming networks of smaller PCM crystals. Furthermore, the scalable synthesis methodology of EG/ZNH eutectic composites was introduced. Here EG particles were strongly connected into a matrix via a stable, corrosion resistant polydimethylsiloxane (PDMS) binder, stabilizing thermal networks and thereby maintaining k up to 1000 melt/freeze cycles. The thermal conductivity of our 25 vol% EG sample (13.3 W m−1 K−1) is more than 48% higher than other salt hydrate eutectic composites reported in the literature. We expect this study to provide insights on cooperative interaction between different components of TES systems (PCM, filler, thickener, binder) for exceptionally robust thermal properties.

Preparation and Performance Analysis of Form-Stable Composite Phase Change Materials with Different EG Particle Sizes and Mass Fractions for Thermal Energy Storage.

The low thermal conductivity and leakage of paraffin (PA) limit its wide application in thermal energy storage. In this study, a series of form-stable composite phase change materials (CPCMs) composed of PA, olefin block copolymer (OBC), and expanded graphite (EG) with different particle sizes (50 mesh, 100 mesh, and 200 mesh) and mass fractions are prepared by melt blending. OBC as a support material could reduce PA leakage during melting, and EG as a thermally conductive filler can improve the thermal performance of PCMs. The microstructure characteristics and chemical and thermal properties of prepared CPCMs are tested and analyzed. The results show that PA/OBC and EG have good compatibility, and there is no chemical reaction with each other to generate new substances. Thermal conductivity can be significantly improved by adding EG, and it is greatly enhanced with the increase in EG particle size at the same EG mass fraction. Simultaneously, the addition of EG increased the melting temperature of CPCMs and decreased the solidification temperature as well; meanwhile, the values of melting temperature and solidification are also reversed for CPCMs compared to PA/OBC. There is an optimal content of EG to balance the thermal conductivity and heat storage capacity for CPCMs. The addition of OBC can provide a stable geometric construction, and the leakage will be further improved with the increase in EG content. Finally, the melting time of CPCMs containing EG-50, EG-100, and EG-200 with 4 wt % EG is shortened by 52.9, 41.1, and 37.5%, respectively, compared with PCMs without EG in the heat storage and release experiments. Also, the CPCMs with EG-50 have better thermal performance compared with the CPCMs of EG-100 and EG-200.

Thermal properties and application of a novel CaCl2·6H2O/expanded graphite shape-stabilized composite phase change material for electric radiant heating

In recent years, electric heating has been popularized and applied as a heating form of clean energy. In order to realize the peak shifting and valley filling of heating electricity to reduce heating cost and improve energy efficiency, phase-change heat storage electric heating system has become a hot topic of research and application. In this paper, using CaCl2·6H2O as phase change material (PCM), SrCl2·6H2O as nucleating agent and expanded graphite (EG) as porous supporting carrier, a novel shape-stabilized composite PCM was prepared by melt blending method. The thermal physical properties of shape-stabilized composite PCM with different prepared proportions were studied through experiments. The experimental results showed that 88%CaCl2·6H2O + 2%SrCl2·6H2O + 10%EG (50 mesh to 100 mesh) is the optimal prepared proportion of the shape-stabilized composite PCM. The composite PCM with a latent heat of 172.92 kJ/kg, a thermal conductivity of 3.85 W/m·K and a super-cooling degree less than 2 °C, has good shape stability and thermal reliability. A kind of novel electric heating module was fabricated with prepared composite PCM and carbon fiber heating wire. The heat storage and release characteristics of the module were studied through experiments, and the effects of different electric heating power, EG particle size and module size on its thermal performance were also studied. The experimental results showed that the internal temperature of the module was uniform and the module can maintain stable heat dissipation for a long time. The temperature fluctuation of the module surface is relatively small. In summary, the module can meet the heating requirements of buildings when applied to electric radiant heating in the building, and the CaCl2·6H2O/EG shape-stabilized composite PCM shows great promise in building energy saving.

Research on novel battery thermal management system coupling with shape memory PCM and molecular dynamics analysis

• A novel SCPCM with shape memory and shape stability is proposed. • The interaction of PA/SEBS was analyzed at the molecular level. • SCPCM shows good thermal stability at a temperature range higher than PA phase transition. • Under discharge conditions of 3C, the temperature difference in the PCM module is kept within 3℃. Traditional battery thermal management using phase change materials (PCM) is restricted by PCM’s leakage, low thermal conductivity and incompatibility. In this work, a shape memory composite PCM (SCPCM) composed of styrene-b-(ethylene-co-butylene)-b-styrene triblock copolymer (SEBS), paraffin (PA), expanded graphite (EG) and Fe 3 O 4 -modified graphene oxide (Fe 3 O 4 -MGO) was prepared. The thermal properties and shape stability of the composite material were studied. The compatibility between the phase change matrix and the support material was investigated. The results show that reducing the size of EG particles can effectively reduce the thermal conduction “percolation point”. The Fe 3 O 4 -MGO particles loaded on EG can effectively reduce the interfacial thermal resistance between EG and PA then further strengthen the heat transfer capability of CPCM. SCPCM shows good thermal stability in the range of phase transition temperature higher than PA (49–85 °C). The simulation results show that PA and SEBS molecules exhibit good interfacial compatibility, hydrogen bonds are formed between the molecules where there is a strong interaction. Therefore, PA/SEBS show good thermal stability in the macro system. SCPCM exhibits excellent performance in heat dissipation. Under discharge conditions of 3C, the temperature difference in the SCPCM module is kept within 3 °C.

Large Enhancement in Thermal Conductivity of Solvent-Cast Expanded Graphite/Polyetherimide Composites.

We demonstrate in this work that expanded graphite (EG) can lead to a very large enhancement in thermal conductivity of polyetherimide−graphene and epoxy−graphene nanocomposites prepared via solvent casting technique. A k value of 6.6 Wm−1K−1 is achieved for 10 wt% composition sample, representing an enhancement of ~2770% over pristine polyetherimide (k~0.23 Wm−1K−1). This extraordinary enhancement in thermal conductivity is shown to be due to a network of continuous graphene sheets over long−length scales, resulting in low thermal contact resistance at bends/turns due to the graphene sheets being covalently bonded at such junctions. Solvent casting offers the advantage of preserving the porous structure of expanded graphite in the composite, resulting in the above highly thermally conductive interpenetrating network of graphene and polymer. Solvent casting also does not break down the expanded graphite particles due to minimal forces involved, allowing for efficient heat transfer over long−length scales, further enhancing overall composite thermal conductivity. Comparisons with a recently introduced effective medium model show a very high value of predicted particle–particle interfacial conductance, providing evidence for efficient interfacial thermal transport in expanded graphite composites. Field emission environmental scanning electron microscopy (FE−ESEM) is used to provide a detailed understanding of the interpenetrating graphene−polymer structure in the expanded graphite composite. These results open up novel avenues for achieving high thermal conductivity polymer composites.

Thermal energy storage composites with preformed expanded graphite matrix and paraffin wax for long-term cycling stability and tailored thermal properties

Harvesting solar energy, preventing hot spots in electronics, transport of temperature-sensitive materials, and capture and repurposing of thermal energy require a latent heat thermal energy storage (TES) system to store/discharge heat repeatedly. For the practical application of phase change material (PCM) composites within TES systems, reliable thermal performance throughout its operational lifetime is essential. Nevertheless, the reliability of thermal conductivity in multi-phase composites over relevant numbers (>103) of melt/freeze cycles has barely been studied, particularly for composites containing fillers for thermal conductivity enhancement. Here, we introduce a preform-type expanded graphite (EG)/paraffin wax composite possessing highly robust heat transfer and storage properties even after 10,000 melt/freeze cycles. To achieve such excellent reliability, comparative studies on the combined influence of fabrication process, particle size, EG vol%, binder amount, and compaction on both magnitude and robustness of thermal conductivity were undertaken. Our parametric study has yielded a trade-off between thermal conductivity and latent heat. Based on our modeling, 20 vol% EG approaches the case where all EG particles are well-connected thermally while 10 vol% EG is close to loosely connected fillers in the matrix. Thermal conductivity of our paraffin composites containing 20 vol% EG (25.1 W·m−1·K−1) is highest among other EG/paraffin composites without aligned EG in the literature. After 10,000 thermal cycling, negligible conductivity fading was observed for the 10 vol% EG composite, while reduction in latent heat remained within 10% for all 10, 14, 17 and 20 vol% EG samples. We anticipate this work provides insight on suitable recipe for desirable magnitude and robustness of thermal conductivity of EG/paraffin composites.

Thermal and vibrational analysis of flax fiber composite and effect of the addition of expandable graphite

Natural fiber composites are widely employed in various applications. Natural fiber offers outstanding mechanical qualities and a low weight-to-strength ratio compared to synthetic fiber. These materials cannot meet the job requirements in the automation, marine, and aircraft industries due to their extreme flammability. Various fire retardants can be employed to overcome this constraint. This research is focused on the qualities of flax fiber and how they alter when different quantities of expandable graphite are added. The thermal characteristics of the composite change after the inclusion of expandable graphite particles. The use of expandable graphite particles, which can resist greater temperatures, improves the thermal properties of composite materials. The thermal characteristics of flax fiber composite and expandable graphite flax fiber composites are compared; the expandable graphite flax fiber composite has more excellent thermal stability and flame resistance. Vibration testing was used to determine the dynamic properties of the sample. The logarithmic decrement technique derives damping parameters from the vibration response envelope curve. When compared to flax fiber composite, expandable graphite has better damping qualities. As a result, it can be concluded that adding expandable graphite particles to a composite material has a variety of effects on the composite's properties.

Mechanical characteristics of nanocomposite materials based on polytrifluorochloroethylene

In this work, elastic and strength properties of polymer composites with a polytrifluorochloroethylene matrix and expanded graphite (EG) filler have been evaluated using the microindentation method. The influence of the filler dispersion and concentration on the mechanical characteristics of the nanocomposite materials (NCM) has been studied. It has been established that the microhardness of the NCM decreases with increasing the filler concentration. An increase in the filler particles sizes of NCM with a filler concentration of 3 vol.% led to an increase of microhardness and Young's modulus. As for NCM with 10 vol.% of the filler, an increase in the EG particles size up to 180 μm showed a similar change in the mechanical characteristics. However, a further increase in the EGs average particle size caused a decrease in Young's modulus and the microhardness of the nanocomposites. The reason for that might be a different degree of the polymer structuring and the formation of different orientational ordering of the filler nanoparticles.

Effect of Expanded Graphite on Mechanical and Tribological Properties of Polyamide 6/Glass Fibre Composites

The quality of plastic gears, especially their durability, is becoming increasingly important due to advances in electric mobility. Therefore, new materials are being developed that must have better mechanical properties, high thermal conductivity for heat dissipation, and tribological properties. The composites of expanded graphite (EG) and glass fibre-reinforced polyamide 6 (PA6/GF) were prepared, and the effect of EG particle size (~5 μm (EG5) and ~1000 μm (EG1000)) on these properties was investigated. Composites with different contents (2-10 wt%) of EG in PA6/GF were prepared using a laboratory twin-screw extruder and then injection moulded in the form of rods and discs required for thermal, thermomechanical, and tribological tests. EG acted as a nucleating agent but hindered the crystallization rate at higher concentrations, which was more pronounced when EG5 was added. Dynamic mechanical analysis showed that the storage modulus increased with the addition of both types of EG. However, the addition of EG5 increased the storage modulus more than EG1000. The lowest coefficient of friction was obtained by the addition of 10 wt% EG5. The wear increased with the addition of both types of EG, only slightly with the addition of EG1000. The thermal conductivity of the composites with EG increased from 0.42 W/mK to 1 W/mK. The results show that the use of EG with smaller particle size is much more beneficial than with a larger one.

Study on thermal conductivities and mechanical properties of silicone/expanded graphite composites

In this study, series of expanded graphite (EG)-filled silicone composites were prepared by the bulk mixing and the solution methods to investigate the effect of thermal conductive EG particles and preparation methods on thermal conductivity of resulting silicone composites. With increasing EG contents and sizes, the thermal conductivity increased, and the solution mixing method showed higher thermal conductivity than the bulk mixing method. At 10 wt% of EG 140 μm-filled silicone composites, the solution mixing method showed the thermal conductivity of 0.789 W/m·K, which was about 147% over one prepared by the bulk mixing method and 538% increase over the pure silicone polymer. FE-SEM experiment was carried out to explore the dispersion and network formation of EG fillers in the silicone matrix. Tensile and dynamic mechanical analysis were also performed to investigate the mechanical reinforcement of the silicone composites. All the results suggested that the network structure of EG with larger size could improve mechanical reinforcement by increasing the modulus and optimize mechanical properties while improving the thermal conductivity of composites.

Effect of EG particle size on the thermal properties of NaNO3–NaCl/EG shaped composite phase change materials

The adsorption capacity of expanded graphite (EG) with three different particle sizes of 32 mesh, 50 mesh, and 80 mesh was studied by the water-soluble adsorption method. The self-made NaNO3–NaCl (95–5 wt%) was selected as the phase change heat storage material, and the three kinds of EG were used as additives. The 80 wt% NaNO3–NaCl/20 wt% EG shaped composite phase change materials (CPCM) were prepared and their properties were tested and analyzed. The research results showed that the smaller the particle size, the stronger the adsorption capacity of EG. However, the choice of EG should consider the particle size of the phase change material (PCM). The 50 mesh EG was more suitable as the adsorption carrier of NaNO3–NaCl. Compared with pure NaNO3–NaCl, NaNO3–NaCl/EG had a lower degree of supercooling, which improved the heat storage capacity of the material. As the particle size of EG decreased, the thermal conductivity increased slightly. The study analyzed the relationship between the EG adsorption capacity and its particle size, and prepared NaNO3–NaCl/EG heat storage material with high heat storage density and high thermal conductivity. It was helpful to promote the application of EG based composite heat storage materials and the development of heat storage technology.