Disodium Hydrogen Phosphate Dodecahydrate Research Articles

Composite Shell Microcapsules With Room Temperature Phase‐Change Properties and High Thermal Storage Density

AbstractInorganic hydrated salts, noted for their high thermal storage density, excellent thermal conductivity, and non‐toxicity, are suitable candidate material for thermal management, particularly in enhancing human living environments when their phase transition points are near room temperature. Herein, we present an efficient and environmentally friendly microencapsulation method for inorganic hydrated salt through organic phase separation method. Eutectic hydrated salt (EHS) consisted of sodium carbonate decahydrate (SCD) and disodium hydrogen phosphate dodecahydrate (DHPD) was prepared as the core material while the mixture of ethyl cellulose (EC) and acrylonitrile‐butadiene‐styrene (ABS) as composite shell materials. Various characterization techniques were used to evaluate the micromorphology, chemical structure, thermal properties and thermal stability of the microcapsules. The resulting microcapsules exhibited a phase change temperature of 22.6 °C with a remarkable enthalpy of 131.4 J/g. Particularly, the enthalpy remained at 117.7 J/g even after 50 thermal cycles, indicating stable cycling thermal reliability. Furthermore, it was confirmed that the EHS was effectively encapsulated within the composite shell, and the microcapsules had a quasi‐spherical shape and core‐shell structure. More importantly, this method of microencapsulation could potentially be extended to other liquid hydrated salts at room temperature, offering a versatile approach for future applications.

Enhanced Thermal Conductivity and Stability of Hydrated Salt Phase Change Microcapsules With GO/SiO2 Hybrid Shell for Battery Thermal Management

AbstractHerein, the synthesis of a novel microencapsulated phase change material via a sol–gel method is presented, featuring disodium hydrogen phosphate dodecahydrate as the core and a SiO2/graphene oxide composite as the shell. The morphology and core–shell microstructure of the synthesized microcapsules are characterized using scanning electron microscopy. The phase change performance and thermal stability are evaluated by differential scanning calorimetry and a high/low temperature test chamber, respectively. Energy dispersive X‐ray spectroscopy and Fourier transform infrared spectroscopy are employed to determine the chemical composition of the microcapsules. The findings reveal that the MEPCM exhibited a high melting enthalpy of 174.3 J g−1. The degree of supercooling is reduced by 2.1 °C, and after 600 thermal cycles, the phase change enthalpy of the microcapsules showed a minor decrease of ≈6.0%. Notably, the thermal conductivity of the microcapsules is significantly enhanced, increasing by up to 51.8%. When integrated into the thermal management systems of lithium‐ion batteries, the MEPCM effectively maintained the battery temperature below 46 °C under a 3 C charging rate. In summary, these results suggest that the hydrated salt microcapsule with its hybrid silica and graphene oxide shell is a promising material for the thermal management of lithium‐ion batteries.

Experimental study on supercooling performance optimization of sodium acetate trihydrate phase change energy storage materials

In response to the pressing demands for sustainable energy, the development of efficient energy storage materials and technologies has emerged as a focal point in contemporary research. Sodium acetate trihydrate (CH3COONa·3H2O, SAT), recognized for its potential as a mid-to-low temperature phase change material (PCM) in energy storage systems, encounters significant limitations due to its substantial supercooling effect and inferior thermal conductivity. Traditional approaches to enhance SAT's thermal performance often involve costly additives, which hinder their adoption on an industrial scale. This study introduces SAT as a base compound, and through a fusion blending method, binary eutectic hydrate salt composites (CPCMs) are synthesized with either sodium sulfate decahydrate (Na2SO4·10H2O, SSD) or disodium hydrogen phosphate dodecahydrate (Na2HPO4·12H2O, DHPD) in varying ratios. The results demonstrate that the prepared eutectic hydrates effectively reduce the supercooling degree of pure SAT from above 35 °C to below 10 °C, with the SAT/SSD-5/5 composition exhibiting the lowest supercooling at 3.17 °C. Notably, these eutectic blends possess appreciable latent heat capacities, with SAT/SSD-9/1 delivering 196.18 J/g, and exhibit improved thermal conductivity, as seen in SAT/SSD-3/7 with a coefficient of 0.8925 W/(m·K). Furthermore, the SAT-based eutectic hydrates are devoid of expensive additives, facile to manufacture, and applicable over a broad temperature range (20–60 °C), making them highly suitable for large-scale commercial applications.

Thermal Properties of Disodium Hydrogen Phosphate Dodecahydrate–Coated Metal Foam/Sodium Acetate Trihydrate Composite as Phase Change Material

Abstract Salt hydrates, like the sodium acetate trihydrate (SAT), possess a remarkable ability to store copious amounts of thermal energy, thanks to their ingenious utilization of a high latent heat of fusion. This unique property makes them a compelling choice for various energy storage applications. In this study, aluminum and copper foams with pore sizes of 40, 80, and 110 pores per inch (PPI) coated with disodium hydrogen phosphate dodecahydrate were prepared, and their effects on the SAT solidification temperature, latent heat of fusion, and thermal conductivity were investigated. The samples' thermal conductivity was measured using the guarded heat flow method. Thermal properties, including latent heat of fusion and supercooling were measured using the T-History method. The results showed that the metal foam matrix is an effective method of enhancing the thermal conductivity of SAT while occupying a small volume of the composite. The copper foam with a PPI of 80 was able to increase the effective thermal conductivity to 2.62 W/(m⋅K), an increase of 388.15% compared to pure SAT while occupying approximately 6.5% of the composite volume. The T-History results showed a solidification temperature of 57.52 °C along with a super cooling of 3.28 °C for the same sample set. Furthermore, it was also found that copper samples significantly outperformed the aluminum ones, despite the higher porosity.

Double-network aerogel-based eutectic composite phase change materials for efficient solar energy storage and building thermal management

Phase change materials (PCMs) have shown great promise in solar energy storage and thermal management of buildings. Nevertheless, the solid-liquid PCMs currently used in these applications face multiple challenges that need to be addressed, such as inadequate solar absorption capacity, leakage issues, and low phase change enthalpy. In this research, urea and sodium acetate trihydrate (SAT) were employed as the main PCMs, while disodium hydrogen phosphate dodecahydrate (DHPD) served as the nucleating agent. Additionally, we used polyvinyl alcohol/silica (PVA/SiO2) aerogel as a porous support structure. Carbon nanotubes (CNTs) were also introduced as photothermal conversion materials to fabricate a photothermal conversion-type double-network aerogel-based eutectic composite PCM (ECPCM). The prepared ECPCM exhibited excellent shape stability, high mechanical strength, and outstanding photothermal conversion performance. Moreover, the ECPCM demonstrated good flame retardancy, low supercooling, and the absence of phase separation issues. Furthermore, the ECPCM demonstrated efficient solar energy storage capacity and outstanding performance in building thermal management. This study offers a new perspective on the advancement of ECPCMs in solar energy storage and thermal management of buildings.

Disodium hydrogen phosphate dodecahydrate/fumed silica composites with high latent heat and suitable phase change temperature for use in building roof

Introducing phase change materials (PCM) with suitable phase change temperature and large latent heat into the application of building roofs is conducive to building energy efficiency, which can reduce indoor temperature fluctuation and improve thermal comfort. In this paper, the optimized disodium hydrogen phosphate dodecahydrate (DHPD) was combined with fumed silica (FS) to prepare a new type of DHPD/FS composites, with a phase change temperature of 41.5 °C, a latent heat of change of 103.46 J/g, and an optimal content of 22.5 % of FS. The leakage experiments proved that there was no leakage of the PCM at this ratio, and after 200 cycles of thermal cycling, the phase change temperature of DHPD/FS composites basically remains unchanged, with good thermal reliability, but the addition of FS will make the material decrease in thermal conductivity, and the thermal conductivity is reduced to 0.19 W·m−1·K−1. Furthermore, the study investigated the application of the encapsulated DHPD/FS composites as a phase change board on the roof. The results indicated that the inclusion of the phase change board improved indoor thermal comfort and demonstrated good thermal performance. When the phase change board was positioned in the top layer, the enhancement of thermal comfort was most optimal.

Experimental and analytical studies on latent heat of hydrated salt/modified EG-based form-stable composite PCMs for energy storage application

Expanded graphite (EG) is often used to encase phase change materials (PCMs) and improve their thermal performance. However, EG's effectiveness when used with disodium hydrogen phosphate dodecahydrate (DHPD) as a hydrated salt is diminished, due to its hydrophobic property. This study proposes modifying the hydrophobic surface of EG with highly hydrophilic nanoparticles, such as SiO2 and TiO2, to address this shortcoming and boost its hydrophilicity. Herein, the nanoparticles were synthesized by the sol-gel technique and mixed with EG to construct a modified EG (MEG). The microstructure, morphology, and adsorption ability of MEG were analyzed. Additionally, the thermal properties, as well as the thermal stability of form-stable composite PCMs, were investigated. The results revealed that by varying the mass ratio of SiO2@TiO2 in MEG, the supercooling degree of the form-stable composite PCMs decreased by 77.36%–78.49%. With 9% SiO2@TiO2 in MEG, the water contact angle of MEG was optimal, and the form-stable composite PCMs prepared (DSMEG3) exhibited a phase change temperature and latent heat of 32.88 °C and 142.13 J/g, respectively. This experimental latent heat was slightly lower than the calculated latent heat by 0.12 J/g. Meanwhile, the supercooling degree decreased to 3.01 °C, and the thermal conductivity increased to 1.23 W/(m ∙ K), which was 1.73 times than that of DHPD. Moreover, DSMEG3 also showed good shape stability, preventing leakage. Therefore, the form-stable composite PCMs, as prepared, are a great potential candidate for the energy storage applications.

Modified sodium acetate trihydrate/expanded perlite composite phase change material encapsulated by epoxy resin for radiant floor heating

In this study, sodium acetate trihydrate was modified with urea, ethylene glycol, and disodium hydrogen phosphate dodecahydrate. The modified phase change material was impregnated into expanded perlite to obtain a composite phase change material, which was encapsulated with epoxy resin as the coating to obtain a coated composite phase change material with a phase change temperature of 46.4 °C, a latent heat of phase change of 132.7 J/g, and a low supercooling temperature of 0.6 °C. Leak tests and thermal cycle stability showed that the coating could effectively slow down the escape rate of the liquid phase and solve the macroscopic leakage problem. Moreover, the decrease in latent heat was only 1.8 % after 100 cycles, demonstrating excellent thermal cycle stability. The morphology and elemental distribution of the modified phase change materials and coatings were studied. In addition, laboratory insulation simulation tests were conducted, and the coated composite phase change material panels showed a significant delay in temperature reduction, while the insulation box showed longer lasting thermal performance. The excellent properties of the material find their application in radiant floor heating systems and play a key role in the expansion of coated phase change materials.

Optimization of super water-retention phase change gels for cold energy storage in cold chain transportation

A eutectic hydrated salt (EHS) formed by disodium hydrogen phosphate dodecahydrate (DHPD) and sodium carbonate decahydrate (SCD) was used as the cold energy storage functional medium, and then the nucleating agent sodium pyrophosphate decahydrate (SPD), the phase change temperature regulators ammonium sulfate (N) and potassium sulfate (K) were added to prepare a sample DSSNK5, and by adding superabsorbent polymer (SAP), a phase change gel DSSNK5-SAP was finally obtained. The results show that the phase change temperature of DSSNK5-SAP is 7.71 °C, and its latent heat value is 122.1 J g−1, which remains unchanged after 50 cycles. Compared with pure DHPD, the supercooling degree of DSSNK5-SAP is reduced to 3 °C, and the thermal conductivity is 1.5 times that of DHPD. In addition, the crystal structure and chemical compatibility of DSSNK5-SAP were analyzed, and the regulation mechanism of auxiliaries and SAP on the phase change behavior of EHS was described. The cold energy storage/release and transient response performance of DSSNK5-SAP were tested, and the application experiment of fruit preservation was also carried out. As a result, DSSNK5-SAP can make the fruit have a good fresh-keeping effect, which proves its considerable application potential in cold chain transportation. It reduces the cost of cold chain transportation from the root and contributes to the stable development of the city and society.

Preparation and characterization of modified activated carbon-based shape stabilized eutectic phase change materials for gypsum composites application

Modified SAT-urea eutectic salts (EPCM) as the phase-change materials were prepared using modifiers such as disodium hydrogen phosphate dodecahydrate (DHPD) and carboxymethyl cellulose (CMC). The support material, hydrophilic modified activated carbon (MAC), was prepared using OP-10 as a hydrophilic modifier. The vacuum impregnation method was used to fabricate the MAC-based shape-stabilized eutectic phase-change materials (SSEPCM). The gypsum-based building materials with thermal storage capacity were obtained by compositing surface-treated SSEPCM and gypsum. The surface contact angle, surface functional group, phase transition temperature, latent heat, phase composition, and microstructure of the SSEPCM were examined using the static contact angle meter, Fourier infrared spectrometer, in-situ infrared spectrometer, differential scanning calorimeter, X-ray diffractometer, and scanning electron microscope. The adsorption capacity of MAC increased first and then decreased with the increase of OP-10 content in the modified solution. When the OP-10 content was 0.3 wt%, the contact angle between the surface of MAC and water reduced to 0°, and the mass fraction of EPCM relative to MAC was 93.1 wt%. The results showed that the OP-10 had a good hydrophilic modification effect on the granular activated carbon. The X-ray diffractometer and differential scanning calorimeter results of SSEPCM indicated that there was no chemical reaction between EPCM and MAC, the phase transition temperature was 32.11 °C, and the latent heat was 103 J/g. The latent heat loss rate of SSEPCM was 5.8 % after 100 thermal cycles, and the number of –OH did not decrease during the heating process of SSEPCM, which showed that SSEPCM had good thermal stability. The flexural and compressive strength values of the SSEPCM/gypsum composites were 2.50 MPa and 7.36 MPa, respectively, when 45 wt% SSEPCM was incorporated into the gypsum matrix, which was sufficient for practical applications. The introduction of SSEPCM could slowly reduce the thermal conductivity and significantly improved the thermal inertia of the composites.

Optimization of low-temperature preheating strategy for Li-ion batteries with supercooling phase change materials using response surface method

The supercooling phase change materials (SPCMs) for preheating lithium-ion batteries (LIBs) in cold environments have demonstrated efficacy and improved the discharge performance in practical applications. However, the bulky and heavy SPCM blocks and the uneven temperature distribution deteriorate the discharge performance of LIBs. In this paper, an optimization study based on the response surface method (RSM) is carried out on the low-temperature preheating strategy of LIBs using SPCMs to obtain a lightweight design with satisfactory performance. The three key factors of PCM thickness, gap, and PCM type are optimized based on six responses. The optimization goals are to minimize the preheating time, the maximum and average battery pack temperature, and the temperature difference between cells, as well as to maximize the volume and mass energy densities. The PCMs with different melting points and heat of fusion, including the sodium acetate trihydrate (SAT), the sodium thiosulfate pentahydrate (STP), and the disodium hydrogen phosphate dodecahydrate (DHPD), are evaluated to preheat a 3S3P 18650 battery pack from 5 °C to 20 °C. The simulation results show that the increase of the PCM thickness will decrease the preheating time and the temperature difference, but increase cell temperature and mass-energy density. The decrease of the gap can reduce the temperature difference and increase the volume energy density. Optimization case studies show that the thin PCM thickness, small gap, and DHPD demonstrate high energy density and safe thermal performance, such as case 10 (PCM thickness = 3.05 mm, Gap = 1.0 mm, PCM type = DHPD).

The Potential Environmental and Social Influence of the Inorganic Salt Hydrates Used as a Phase Change Material for Thermal Energy Storage in Solar Installations.

The aim of this article is to assess the potential impact of inorganic salt hydrates used as PCM material in solar installations on the environment and human health and to assess the society's approach to this technology. The properties of salt are discussed in two ways: first, by analyzing the environmental and health problems caused by chemical hazards on the basis of the available material safety data sheets. Secondly, by analyzing the potential disadvantages of salt hydrates in terms of environmental hazards based on the results of experimental studies available in the literature. Then, using questionnaires, the public approach to solar installations with a built-in converter containing salt hydrates is assessed. Disodium hydrogen phosphate dodecahydrate turned out to be the most prospective salt in terms of environmental, thermophysical, and economic properties for use in solar installations. Understanding the attitudes of the local community toward technologies using inorganic salt hydrates will enable appropriate action to be taken in the future to promote their development. Surveys have shown great public concern about their impact on the environment and human health. In this regard, it is necessary to implement information and promotion activities.

Preparation, thermal storage properties and application of sodium acetate trihydrate/expanded graphite composite phase change materials.

The development of energy storage technology is beneficial for the efficient use of energy and sustainable development. As an effectual approach for storing and transporting thermal energy, latent heat storage using phase change materials (PCMs) has attracted tremendous attention. However, low thermal conductivity, poor stability, and leakages are considerable challenges to the widespread application of solid-liquid PCMs. Composite phase change materials (CPCMs) were prepared by combining expanded graphite (EG) and sodium acetate trihydrate (CH3COONa·3H2O, SAT). EG as a supporting material plays a crucial part in both enhancing the thermal conductivity and preventing the melted PCMs from leakage. The chemical structure, micromorphology, thermal stability, thermal conductivity, phase change behavior and heat storage performance of SAT/EG CPCMs have been extensively investigated by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermal conductivity analysis, differential scanning calorimetry (DSC), and cycling stability measurement. The results of SEM indicate that EG with a loose and porous layered structure has a good molding effect and can adsorb SAT well. XRD and FTIR results show that only a simple physical combination between EG and SAT exists, and no new substances have been produced. Compared with pure SAT, thermal conductivity and supercooling tests show that the supercooling degree of the CPCMs was decreased and the thermal conductivity was increased by 205.1%. In addition, the addition of 2 wt% of disodium hydrogen phosphate dodecahydrate (Na2HPO4·12H2O, DHPD) as a nucleating agent and 0.5 wt% of gelatin as a thickening agent to SAT could reduce the supercooling degree and inhibit the phase separation well. Based on SAT/EG-8% CPCMs, an oven with phase change energy storage was designed and the heat storage/release performance of the oven was investigated under different operating conditions.

Study on sodium acetate trihydrate-expand graphite-carbon nanotubes composite phase change materials with enhanced thermal conductivity for waste heat recovery

Developing phase change materials (PCMs) with excellent thermal properties and low cost is of great significance for accelerating the applications of the latent heat storage technology in waste heat recovery. In this work, a novel composite PCM based on sodium acetate trihydrate (SAT), expanded graphite (EG) and carbon nanotubes (CNTs) was prepared and optimized for efficient heat storage and release effect. To confirm the phase change effect of composite PCM was acted above 50 °C, urea was introduced to improve the melt uniformity of SAT and its proportion was optimized in the range of 0–10 wt% based on the DSC results. The nucleating promotion of disodium hydrogen phosphate dodecahydrate (DHPD) on the SAT-Urea mixture crystals was characterized by a metallographic microscope. EG was used as the porous carrier to eliminate the liquid mobility of melted PCM. CNTs were introduced to further enhance the thermal conductivity of the composite PCM. It is shown that 4 wt% urea can effectively inhibit the phase segregation of SAT and keep the phase change temperature of mixture above 55 °C. The melting enthalpy of SAT-Urea mixture is as high as 250.5 kJ/kg. It is observed from the microscope images that 4 wt% DHPD can promote the rapid formation of small crystals of SAT-Urea mixture, thereby providing more nuclei and accelerating the crystal growth rate. And the supercooling degree can be reduced to 0.6 °C. The porous network provided by EG and the addition of CNTs can significantly enhance the thermal conductivity of SAT-Urea mixture. As a result, the SAT-Urea/EG/CNTs composite PCM exhibits a high enthalpy of 180.1 kJ/kg, a high thermal conductivity of 6.904 W/(m·K), and excellent thermal reliability after 300 cycles of melt-solidification experiments.

Theoretical prediction and experimental investigation on nanoencapsulated phase change material with improved thermal energy storage performance

Nanoencapsulated phase change material (NanoEPCM) has the advantage of small size, large specific surface, good thermal reliability, and has broad application prospects in the field of thermal energy storage. However, most of the existing process conditions are relatively complicated, and it is difficult to prepare NanoEPCM with good microscopic morphology and excellent thermal properties. In this paper, a series of NanoEPCM with silicon dioxide (SiO 2 ) as the shell material and disodium hydrogen phosphate dodecahydrate (DHPD) as the core material are synthesized successfully by a facile sol-gel method. Firstly, the influence of the component ratio on the microscopic morphology of the NanoEPCM is predicted through a series of dissipative particle dynamics (DPD) mesoscopic simulation methods, as a result, the experimental parameters are determined initially. Furthermore, NanoEPCM possessed excellent properties is synthesized and characterized completely. The results show that all the NanoEPCM synthesized have relatively obvious spherical shape, which verifies the accuracy of the simulation results. In addition, the melting enthalpy and the encapsulation ratio of the obtained NanoEPCM achieves as high as 165.6 J/g and 70.1%, respectively, the maximum charging-discharging efficiency is 90.3%, and the supercooling is suppressed to 1.0 °C. The excellent microscopic morphology and thermal properties of NanoEPCM benefit from the reasonable component ratio and appropriate reaction conditions. Therefore, the NanoEPCM with excellent thermal properties is of great importance in the prospective thermal energy storage application. • DPD mesoscopic simulation method was employed to confirm the component ratios of the NanoEPCM. • A series of DHPD/SiO 2 NanoEPCM were synthesized successfully by a facile sol-gel method. • The obtained NanoEPCM had excellent microscopic spherical shape. • The supercooling of NanoEPCM was suppressed obviously.

Study on Performance Improvement of Sodium Acetate Trihydrate in Thermal Energy Storage System by Disturbance

Phase change materials (PCM) have been widely used in Thermal Energy Storage (TES) Systems. Considering the energy efficiency and the use of domestic hot water, the melting temperature range of phase change materials is considered to be optimal in the range of 50–60 °C. The most commonly used is sodium acetate trihydrate-based phase change material, which has the advantages of high latent heat and low price, but its high supercooling, low thermal conductivity, and phase separation affect its application. Therefore, this paper used sodium acetate trihydrate, disodium hydrogen phosphate dodecahydrate (DSP), and expanded graphite (EG) as raw materials to prepare composite phase change materials (CPCM) and used physical disturbance to further improve their properties. Firstly, their thermophysical properties were investigated by the step cooling curve method, differential scanning calorimetry (DSC), and x-ray diffraction (XRD). Secondly, in order to further evaluate the effect of physical disturbance on CPCM crystallization, further experimental studies were carried out by adjusting the rotor mass and rotational speed. The experimental results showed that when 1.5 wt.% DSP, 1.5 wt.% EG and physical perturbation work together, the CPCM phase transition temperature is 56.7 °C, and the latent heat is as high as 258.98 kJ/kg. At this time, its thermal conductivity increased from 0.62 w/m·k to 1.1625 w/m·k, and its subcooling degree decreased from above 20 °C to less than 0.5 °C, and no phase separation occurred. The greater the disturbance momentum (the greater the rotor mass or the greater the rotational speed), the shorter the induction time, which is more conducive to the crystallization of CPCM. The results obtained in this paper are instructive for the preparation of efficient new CPCMs.

Experimental investigation of aluminum nitride/carbon fiber‐modified composite phase change materials for battery thermal management

The phase change material is currently being regarded as an effective cooling media to be applied in the thermal management of lithium batteries-powered vehicles, in which the inorganic hydrate phase change material is desirable and widely investigated due to the high thermal conductivity, latent heat value, and low cost. However, when applied to thermal energy storage applications, supercooling and phase separation are problematic. To effectively circumvent this issue, this work considers utilizing the disodium hydrogen phosphate dodecahydrate as the matrix of the composite phase change material, as the phase transition temperature is suitable for the battery's operating temperature range. Meanwhile, the nucleating agent sodium metasilicate nonahydrate with similar lattice parameters and the thickener carboxymethyl cellulose are used to suppress the supercooling and eliminate the phase separation, respectively. Effects of nucleating agent, surface modified aluminum nitride, and short-cut carbon fiber on the supercooling degree, and thermal conductivity and curing performance in the phase change material are evaluated and discussed in detail to determine the optimal preparation scheme for Na2HPO4·12H2O/modified AlN/CF inorganic composite phase change materials. Experimental results show that the addition of 4 wt% Na2SiO3·9H2O, 4 wt% CMC, 12 wt% modified AlN, and 6 wt% CF reduces the supercooling degree of the composite phase change material to 1.9°C and increases the thermal conductivity to 1.86 W/(m·K). The composite phase change material is found to have a suitable phase change temperature (35°C), high latent heat (249 J/g), excellent shaping effect, and electrical safety performance. In addition, the composite phase change material battery module can effectively control the battery's temperature, with the maximum temperature reduced by 40.9°C at 3C discharge rate and 30°C ambient temperature compared with the natural cooling battery module. The maximum temperature difference of the composite phase change material battery module is shown to be reduced to the minimum value of 0.9°C. Highlights A novel disodium hydrogen phosphate dodecahydrate—modified aluminum nitride—carbon fiber composite phase change material is designed and prepared for battery thermal management systems. The antiwater modification scheme of AlN is proposed and assessed. The effects of AlN before and after modification on the thermal properties of CPCM are compared. The joint use of nucleating agent sodium metasilicate nonahydrate and thermal conductive filler AlN contributes to significantly inhibiting the supercooling of hydrate salt. The addition of CF can effectively increase the thermal conductivity of CPCM and prevent its leakage. CPCM has suitable phase change temperature, high thermal conductivity and latent heat value, excellent electrical safety, and stable curing performance. The battery test bench is constructed and the discharge test of the CPCM battery module is carried out. The results show that the CPCM battery module has excellent cooling performance and temperature uniformity.

Preparation and characterization of a solar-driven sodium acetate trihydrate composite phase change material with Ti4O7 particles

Thermal energy storage using phase change materials has received much attention as it can effectively relieve the contradiction of renewable energy between supply and demand. The novel bifunctional sodium acetate trihydrate (SAT) composite phase change materials with photo-thermal conversion and heat storage properties were developed to promote the thermal utilization of solar energy. The Ti 4 O 7 particles were selected as photo-thermal conversion media with full spectral absorption of sunlight and efficient photo-thermal conversion performance. 5 wt% disodium hydrogen phosphate dodecahydrate (DSP) and 3 wt% carboxymethyl cellulose were used to decrease supercooling and restrain phase separation of SAT, respectively. The as-prepared SAT composites with different content of Ti 4 O 7 possess a low supercooling degree of 0.9–1.5 °C and high latent heat of 228.6–257.7 kJ kg -1 . Ti 4 O 7 has a stable absorption capacity covering the full solar spectrum (200–2500 nm) and the absorption capacity of SAT and DSP in the infrared light even more than Ti 4 O 7 at 1900 nm–2500 nm. The SAT composite sample with 10 wt% Ti 4 O 7 has the best total solar absorption capacity of 93.33% more than Ti 4 O 7 of 92.76% because SAT and DSP have outstanding absorption capacity in the long-wave infrared wavelength. The photo-thermal storage efficiency of all SAT composite photo-thermal conversion phase change materials exceeds 50%, of which the composite with 10 wt% Ti 4 O 7 has the optimal photo-thermal conversion storage efficiency of 76.63%. The composite photo-thermal storage phase change materials have potential applications in solar energy systems. • The SAT-based composites have optical absorption and thermal storage properties. • The absorption capacity of the composite phase change materials is 93.33%. • The optical photo-thermal conversion and storage efficiency is 76.63%. • Ti 4 O 7 was a vital component in facilitating solar to heat for phase change materials.

Preparation, thermal properties and charging/discharging characteristics of sodium acetate/stearic acid/octadecyl alcohol composite as phase change materials

In order to improve the thermal conductivity of organic phase change materials and overcome the shortcomings of large supercooling degree and phase separation of inorganic phase change materials, the composites of sodium acetate, stearic acid and octadecyl alcohol as phase change materials were prepared by melt blending method, where disodium hydrogen phosphate dodecahydrate was used as nucleating agent and carboxymethyl cellulose as thickener in this work. XRD, DSC and T-history techniques were used to analyze the composite phase change materials. Sodium acetate, stearic acid and octadecyl alcohol are physically blended in the ternary composite phase change materials. Sodium acetate improves the thermal conductivity and latent heat of the eutectic mixtures of stearic acid and octadecyl alcohol, where the thermal conductivity and latent heat of the eutectic mixtures of stearic acid and octadecyl alcohol is increased by 384 % and 28%, respectively. Heat conduction and natural convection act together, but natural convection plays an important role in the melting process. While heat conduction plays an important part in the discharging process. Due to natural convection, the charging time of the composite phase change materials is less than the discharging time.

Preparation and Thermal Performance Analysis of New Composite Phase Change Materials of Sodium Acetate Trihydrate and Different Additives.

AbstractA thickener that could address the phase separation problems of sodium acetate trihydrate (SAT) was determined by the gravity sedimentation method. Additionally, a hydrated salt nucleating agent to effectively reduce the supercooling of SAT was sought using the step‐cooling method. Combining these findings, a new SAT composite phase change material (SAT CPCM) was prepared. Additionally, a sample containing expanded graphite (EG) was prepared by melt blending to enhance the thermal conductivity. Our results show that a sample prepared with 1.5 % xanthan gum and 2 % sodium pyrophosphate decahydrate as a hydrated salt nucleating agent basically eliminates supercooling, its thermostability better than that of the composite phase change material using disodium hydrogen phosphate dodecahydrate. A sample with 6 % EG stays molten without leakage at a higher temperature and in the cooling test, the material‘s supercooling degree was only 1.1 °C. After 200 cooling‐heating cycles, the thermal stability was good, with high latent heats of 230.52 kJ/kg and thermal conductivities of 1.789 W(m ⋅ K) −1. This composite phase change material has great application potential in the field of low‐temperature heat storage.