Form-stable Phase Change Materials Research Articles

Porous diamond Co-MOF and polyethylene glycol composites as form-stable phase change materials for thermal energy storage

Porous diamond Co-MOF and polyethylene glycol composites as form-stable phase change materials for thermal energy storage

Carboxymethyl Cellulose Enhanced Polymeric Form Stable Phase Change Materials with Reversible Transparency for Energy Storage

Carboxymethyl Cellulose Enhanced Polymeric Form Stable Phase Change Materials with Reversible Transparency for Energy Storage

Lauric acid based form-stable phase change material for effective electronic thermal management and energy storage application

Poor thermal management in electronic systems can lead to higher junction temperatures, accelerating failure mechanisms and reducing component lifespan. Integrating efficient thermal management techniques, such as heat sinks, is essential for ensuring durability and efficiency of electronic equipment. Heat sinks have limited capacity, but integrating phase change materials (PCMs) enhances cooling performance by harnessing latent heat storage. However, leakage and low thermal conductivity limit PCM's effectiveness. The current study developed highly conductive leakage-proof PCMs based composites using an ultrasonic and vacuum impregnation method with lauric acid as base, hexagonal boron nitride and expanded graphite as additives. The results demonstrate persistence of chemical integrity, as proven by FTIR analysis, and complete encapsulation of PCMs inside the expanded graphite structures. The form-stable composite PCMs exhibit a 450% increase in thermal conductivity and 77% photo-transmittance decrease compared to base PCMs. Despite a trade-off of a 11.5% reduction in latent heat, the composite demonstrates thermal stability up to 220 °C. Further, excellent chemical and thermal reliability is maintained even after 500 cycles. Furthermore, in thermal management for heat sink, the form stable composite efficiently dispersed heat, resulting in a 16 °C decrease in peak temperature compared to the heat sink without the composite.

Analysis of Freeze-Thaw Damage of Cement Mortars Doped with Polyethylene Glycol-Based Form Stable Phase Change Materials.

The development of construction materials with the integration of phase change materials (PCMs) has been a topic of wide interest in the scientific community, especially in recent years, due to its positive impact on temperature regulation inside buildings. However, little is known about the behavior of materials doped with PCMs when exposed to accidental or severe environments. Currently, a large area of the planet experiences seasonal freeze-thaw effects, which impact the durability and performance of construction materials. Accordingly, the main objective of this study was to evaluate the damage caused by cyclic freeze-thaw actions on the behavior of a cement mortar, including a PEG-based form-stable PCM. An experimental methodology was developed based on the physical and mechanical characterization of mortars under normal operating conditions and after being subjected to freeze-thaw cycles. The results indicated that, under normal exposure conditions, the incorporation of aggregate functionalized with PCM led to a decrease in the mortar's water absorption capacity, compressive strength, and adhesion. However, its applicability has not been compromised. Exposure to freeze-thaw cycles caused a loss of mass in the specimens and a decrease in the compressive strength and adhesion capability of the mortar.

Confined Crystallization Polyether-Based Flexible Phase Change Film for Thermal Management.

Phase change materials (PCMs) possess the potential to regulate temperature by utilizing their thermal properties to absorb and release heat. Nevertheless, the application of PCMs in thermal management is constrained by issues such as liquid leakage and limited flexibility. In this study, we propose a novel approach to address these challenges by incorporating a pore structure within nanofibers to confine the crystallization of phase change molecules, thereby enhancing the flexibility of the composite material. Additionally, inspired by the adaptive mechanisms observed in plants, we have developed a form stable PCM based on polyether, which effectively mitigates the issue of liquid leakage at higher temperatures. Despite being a solid-liquid PCM at its core, this material exhibits molecular-scale flow and macroscopic shape stability as a result of intermolecular forces. The composite film material possesses remarkable flexibility, efficient thermal management capabilities, adjustable phase transition temperature, and the ability to undergo repeated processing and utilization. Consequently, it holds promising potential for applications in personal thermal energy management.

Study on phase change materials integration in concrete: Form-stable PCM and direct addition

As the economy continues to develop, building energy consumption rises, necessitating sustainable solutions. Concrete, a pivotal building material, assumes a vital role in this context. To address the challenge of escalating energy consumption and environmental impact, this study studied the integration of phase change materials (PCMs) into concrete by two methods. Recycled aggregates serve as form-stable mediums for PCM absorption, while direct addition methods incorporate 7.5 % and 15 % free liquid PCM by volume of river sand. Six concrete mixtures underwent comprehensive evaluation encompassing workability, density, water absorption by immersion, compressive strength, flexural strength, chloride ion penetration, freeze-thaw cycling tests, and carbonation. The results reveal a decrease in concrete density and mechanical properties with increasing PCM content. Nevertheless, notable enhancements in chloride ion penetration resistance, reaching up to 18.5 % with free PCM incorporation, and zero carbonation depth were observed. These results underscore the potential of PCM-concrete composites in harmonizing energy efficiency and structural integrity, offering a sustainable alternative to fossil fuel-based air conditioning systems and with great potential from the point of view of the durability of the structures.

Evaluation of carbonized cotton stalk for development of novel form stable composite phase change materials for solar thermal energy storage

Generating energy from the renewable sources is a pathway to attain sustainable energy systems. Utilizing bio-char produced from pyrolysis process as porous material would not only add great value to the waste discards, but also contributes towards enhancing the thermal properties. This work is focussed on the development of form stable phase change material (FSPCM) through a facile impregnation method by introducing cotton stalk biochar (CSB) as porous matrix along with polyethylene glycol having molar mass 10000 g/mol (PEG10000) as PCM. Cotton stalk is an agriculture waste material and biochar was produced by intermediate pyrolysis method at 550 °C. Thermal, chemical and surface characterization tests were executed on seepage free FSPCM (BCPCM4) as it showed no leakage at 60 °C. XRD, FTIR, FESEM, TGA, DSC, Raman spectroscopy and BET analysis were carried out to characterize thermal, chemical and surface properties of BCPCM4. The microporous structure of CSB was able to accommodate 80 wt% of PEG10000. Surface characterization tests demonstrated that adequate amount of PEG10000 was absorbed into the pores of CSB and the crystal structure of PEG10000 was not modified. The results of TGA illustrated that BCPCM4 was thermally stable. Additionally, cotton stalk derived FSPCM displayed high heat transfer rate which indicates an increase in thermal conductivity. To substantiate thermal reliability, 500 thermal cycles were run on BCPCM4 and about 1 % variation in latent heat has been noticed with meagre change in chemical properties. Therefore, biochar derived FSPCMs would serve as promising materials to accommodate solar thermal energy.

Synthesis of Form-stable Phase Change Materials for Application in Lunch Box to Keep the Food Warm

Introduction: The invention of a lunch box with phase-change materials incorporated to keep food warm throughout work hours is the subject of this paper. Since harmful chemicals render the food unfit for consumption when they come into contact with it, the choice of phase change material is essential. Method: Adopting a healthy lifestyle now includes carrying electronic lunch boxes and ordering takeaways. Nevertheless, utilizing the electric lunch box at work is a bother. Therefore, this study discusses a prototype of a lunch box that has been created and can keep food warm after it has been packed at home for 4-5 hours. The method of preparing the PCM FS65 is discussed and its stability over thermal cycling is analyzed. objective: To synthesize phase change material composite which does not go into liquid state in melting cycle. To understand the thermal stability of the phase change material composite To prove the efficacy of the composite in lunch box for keeping the food warm Result: The thermal resistance of the insulating materials and the quantity of PCM are the two design considerations for the lunch box that have been covered in this study. To explore these, a warm food criterion at a temperature of 45°C has been used. Conclusion: This research article has discussed the ideal PCM weight required for a 5-hour retention time as well as the ideal insulating material to make the least bulky lunch box design.

The preparation and selection process for a new form stable phase change material (FSPCM) intended for use as thermal storage in applications at intermediate temperatures

There is a greater focus on solar energy since the food processing business requires a lot of thermal energy to remove moisture from agricultural products. This study thoroughly explains how to choose Phase Change Materials (PCMs) within a specific temperature range. The best PCM is selected from the Multiple Criteria Decision Making (MCDM) procedures based on a few characteristics. Based on the results of the MCDM method, the eutectic of paraffin and palmitic acid is chosen. PCM is bound, and FSPCM is formed using clay. The method of preparation of Clay-based FSPCM is described in detail. The amount of clay materials and different clay percentage combinations are chosen from the leakage experiment. Kaolin has the least amount of leakage out of all the clay materials tested. Kaolin-based FSPCM Exhibits improvement in thermal conductivity compared to Pure PCM.

Physical-Entanglements-Supported Polymeric Form Stable Phase Change Materials with Ultrahigh Melting Enthalpy.

With the rapid development of new energy and the upgrading of electronic devices, structurally stable phase change materials (PCMs) have attracted widespread attentions from both academia and industries. Traditional cross-linking, composites, or microencapsulation methods for preparation of form stable PCMs usually sacrifice part of the phase change enthalpy and recyclability. Based on the basic polymer viscoelasticity and crystallization theories, here, a kind of novel recyclable polymeric PCM is developed by simple solution mixing ultrahigh molecular weight of polyethylene oxide (UHMWPEO) with its chemical identical oligomer polyethylene glycol (PEG). Rheological and leakage-proof experiments confirm that, even containing 90% of phase change fraction PEG oligomers, long-term of structure stability of PCMs can be achieved when the molecular weight of UHMWPEO is higher than 7000kg mol-1 due to their ultralong terminal relaxation time and large number of entanglements per chain. Furthermore, because of the reduced overall entanglement concentration, phase change enthalpy of PCMs can be greatly promoted, even reaching to ≈185 J g-1, which is larger than any PEG-based form stable PCMs in literatures. This work provides a new strategy and mechanism for designing physical-entanglements-supported form stable PCMs with ultrahigh phase change enthalpies.

Performance analysis of solar thermal storage systems with packed bed utilizing form-stable phase change materials and heat pump integration

Solar energy, a pivotal renewable resource, faces operational challenges due to its intermittent and unstable power output. Thermal energy storage systems emerge as a promising solution, with phase change materials (PCMs) packed beds attracting attention for their compactness and stable temperature transitions. This paper details a laboratory-scale solar thermal storage PCM packed bed integrated with a heat pump, utilizing a novel form-stable PCM. A numerical model was established to assess the thermal storage characteristics and heat extraction performance of the solar PCM packed bed coupled with a heat pump. Simulation results show that increasing solar irradiance significantly reduces storage duration, achieving full thermal storage in 3.4 h at 900 W/m2 irradiance. Optimal starting times were identified as 9:00 a.m. or 11:00 a.m., with later starts resulting in incomplete storage due to the PCM not reaching its phase change temperature. Additionally, packed bed parameters influenced storage conditions; increasing the paraffin content in the PCM extended the phase change duration, while graphene nanoparticles slightly reduced it. Lower porosity (0.49) beds, with higher PCM content, reached 70 °C quicker than higher porosity (0.61) beds due to higher pressure drops promoting more uniform flow and temperature distribution. During heat extraction, coupling the heat pump at 2 liters/min achieved temperatures below 45 °C in 4.1 h, while at 6 liters/min, the time reduced to 1.6 h, demonstrating adaptability to different extraction rates. These findings provide insight into the thermal performance of solar PCM packed beds coupled with heat pumps, contributing to efficient and stable thermal utilization of solar energy.

Epoxy resin/ aluminium hydroxide/expanded graphite synergistic effects on advancing flame retardancy, mechanical structure and thermal management of octadecanoic acid and octadecanol-based eutectic phase change materials

In the present research, a novel approach wherein a flame-retardant composite phase change material (PCMs) is devised by incorporating eutectic PCMs, epoxy resin (ER), aluminium hydroxide (ATH), and expanded graphite (EG). This innovative formulation capitalizes on the synergistic interaction between ER and ATH, alongside the porous structure of EG, resulting in a triple-layer encapsulation of the eutectic PCMs. The outcome of this formulation is marked by remarkable thermal stability, even under extreme conditions such as exposure to temperatures as high as 800 °C. Notably, one of the representative samples, denoted as S5, showcases impressive attributes with a thermal conductivity of 1.335 W∙m-1K−1 and a substantial phase change latent heat of 150.4 J∙g−1. It was observed an increase in latent heat up to 181.3 J∙g−1 after 100 heating–cooling cycles of composite PCMs. This indicates the good thermal reliability of the form-stable composite PCMs synthesized. Moreover, the composite PCMs exhibit outstanding mechanical properties, especially S5 which showed a 14.69 % and 400.12 % increase in compression strength and compression modulus compared with pure eutectic PCM (S0), respectively. Besides, the ternary composition of ER, ATH, and EG enhances the flame retardancy of the composite PCMs, yielding a substantial reduction of 67.33 % in peak heat release rate and 50.38 % in total heat release. This collaborative effect also establishes a robust defense mechanism against the rapid propagation of flames, as exemplified by the attainment of a V-0 rating in the UL-94 test. As a result, the flame-retardant ER/ATH/EG ternary-based form-stable composite PCM presents itself as a promising candidate for ensuring both safety and efficiency in thermal management applications.

Preparation and characterization of eicosane-paraffin/expanded graphite/polyurethane as form-stable composite phase change materials with wide phase change temperature range

Phase change materials (PCMs) with wide phase change temperature range, high latent heat, good thermal conductivity, and shape stability are essential for applications such as solar energy conservation and thermal management of electronic devices. Form-stable composite PCMs (FSCPCMs) with a broad phase change temperature range of 18–65 °C were successfully developed by using a mixture of eicosane and paraffin mixture along with cross-linking polyurethane as PCM, expanded graphite as thermally conductive filler and supporting material. The prepared FSCPCMs demonstrated excellent thermal stability and thermal conductivity with a latent heat up to 142.5 J/g. In conclusion, the synthesized FSCPCMs exhibit promising potential for practical applications in thermal energy storage.

Novel PVA-based foams for cold chain logistics with high efficiency

The rapid advancement of fresh e-commerce has driven the growth of the cold chain logistics, which spurs a significant demand for the upgrading of the phase change material (PCM) ensuring the transported items maintain at the required low temperature. This paper reported a novel form-stable phase change material poly (vinyl alcohol) (PVA) -based foams (FPCMPFs) with high efficiency fabricated by combining thermal foaming of PVA and in-situ polymerization of polyacrylic acid (PAA). The constructed double network structure improved the water storage to as high as 85.81 wt%, and enhanced the mechanical strength to maintain the shape stability even under 60 % compressive strain, which endowed FPCMPFs with good cold storage performance with high latent heat of 309.6 J/g, and prevented the water leakage in use. 65 g FPCMPFs located in a 7.0 × 7.0 × 10.5 cm box extended the storage time of the precooled grapes at -1-0 °C keeping at 5 °C from 28.7 min to 229.1 min, demonstrating the significant prospects for application in the cold chain logistics.

Form-stable Na2CO3-NaCl/mullite phase change composite with SiC enhanced thermal conductivity for high temperature thermal storage

High-temperature energy storage technologies are gaining prominence to meet the needs of concentrating solar power plants and industrial waste heat recovery. In this study a series of form-stable phase change materials are prepared by a simple and efficient cold compression sintering method. In this method, Na2CO3-NaCl will be mixed with mullite ceramic powder; simultaneously, SiC nanoparticles are introduced to improve the thermal conductivity of the material. The leakage, microstructure, chemical compatibility and thermal physical properties of the prepared composites are systematically analyzed using Fourier-transform infrared spectroscopy, X-ray powder diffraction, Scanning electron microscope, Differential Scanning Calorimetry and Thermogravimetric. The results of the study show that good chemical compatibility of the components in the composites, and the latent heat of melting of the encapsulated composites as well as the sample with added SiC are 266.97 J/g and 217.63 J/g, respectively, while the latent heat of crystallization is 197.37 J/g and 151.13 J/g, respectively. Compared to the thermal conductivity of PCMs (0.41 W/(m·K)), the thermal conductivity of the sample with 20 % SiC added is 1.83 W/(m·K), an increase of 8.7 times. Thermal cycling and reliability tests show that even after 300 cycles, good chemical compatibility is maintained between the components in composites, and the phase change properties and quality remain stable. In addition, the thermal storage cost of FSPCM-M40-S20 is 1.90 $/MJ. Therefore, we believe that the prepared Na2CO3-NaCl/mullite/SiC FSPCM has promising applications in high-temperature thermal energy storage, especially in solar power generation and industrial waste heat recovery.

Biodegradable polylactic acid/polyethylene glycol blends as form-stable phase change materials for thermal energy storage and management

Polyethylene glycol (PEG) is a commonly used phase change material for thermal energy storage. It can store amounts of heat in the process of phase transition, whereas the solid-to-liquid transition requires it to be form-stabilized before application. In this study, a phase change composite with form-stability and processibility is prepared by simply blending PLA with PEG at 180 °C, reaching a maximum PEG loading of 90 wt%. The preparation is easy, cheap, environmental-benign, and scalable. Besides, the obtained PLA/PEG (PLEG) composites are feasible for regulating the thermal behaviors of batteries operated at high rates, providing a low-cost and simple approach to improving the cyclability of fast-charging batteries.

High thermal conductivity and high energy density compatible latent heat thermal energy storage enabled by porous Al2O3@Graphite ceramics composites

Phase change material (PCM) is an ideal heat storage material with huge latent heat and nearly constant phase change temperature, but there are serious problems in application such as leakage and low thermal conductivity. Porous ceramic is widely used in PCM packaging because of its advantages of controllable porosity and high thermal conductivity. Porous Al2O3 ceramics were prepared by foaming injection coagulation method. In order to improve the thermal conductivity of porous ceramic matrix, Porous Al2O3@Graphite Ceramics (PAGC) were prepared by sucrose decomposition. Form-Stable Phase Change Materials (FSPCMs) were prepared by adsorption of Lauric Acid/Myristic Acid (LA/MA) in PAGC by vacuum impregnation method. SEM showed that the prepared PAGC had a three-dimensional interpenetrating structure and high porosity. TEM and XPS showed that alumina skeleton were uniformly coated with graphite. After PAGC impregnated by LA/MA, the maximum PCM storage reached 62.11 wt %. The maximum latent heat of FSPCMs reaches 83.33 J/g. Thermogravimetric analysis, thermal cycling test and Fourier transform infrared spectroscopy show that the prepared FSPCMs has good thermal stability, thermal reliability, chemical stability and compressive strength. More importantly, the thermal conductivity of the prepared FSPCMs is greatly improved, reaching up to 3.73 W/mK. It is 20.72 times the original PCM, mainly due to the synergistic effect of the Al2O3 skeleton and the graphite coating to build a continuous highway for heat transfer. This study provides a practical means to greatly improve the thermal conductivity of FSPCMs, which will promote the practical application of FSPCMs.

Photo-curable bio-based comb/bottle brush epoxy resin/beeswax/copper foam phase change materials with high enthalpy value, high conductivity, and multifunctional properties

At present, the demand for green energy has reached a new height in history, and thermal energy storage technology has been widely used to reduce energy consumption. It is still a challenge to develop bio-based polymeric form-stable phase change materials (FSPCMs) with high enthalpy value and thermal conductivity (TC), short curing time, and multifunctional properties. This work not only exploited a series of adjustable and photo-curable comb/bottle brush bio-based epoxy resin/beeswax (bw) FSPCMs with the above superiorities, but also revealed the effects of cross-linking density on the energy storage capacity and encapsulation rate of the FSPCMs. As a result, the optimal system can encapsulate the maximum amount of bw (60 wt%) and obtain the highest enthalpy value (142.1 J/g) with only 0.5% enthalpy loss. Through further introducing the optimal curing system into the copper (Cu) foam, the electromagnetic interference shielding property, TC, tensile strength, and photo-thermal conversion efficiency of the final composite (modified by Cu of 95% porosity) can reach 110 dB, 2.387 W m−1K−1, 2.81 MPa, and 80%, respectively, and the enthalpy value (84.2 J/g) is still satisfactory. This study can provide theoretical guidance for the structural design of reliable fast photo-curable bio-based polymeric FSPCMs with excellent phase change performances and multifunctional properties.

Development of novel form-stable PCM-biochar composites and detailed characterization of their morphological, chemical and thermal properties

Storing heat with phase change materials has the potential for several modern-day applications such as building thermal regulation, isothermal solar drying, electronic cooling, etc. However, to suitably incorporate latent heat energy storage systems, the challenges of leakage and low thermal conductivity of these materials need to be addressed. In this direction, biochar derived from abundantly available biomass feedstocks has been explored to develop form-stable, environmentally compatible energy storage materials. Biochar has been derived from wheat straw and softwood and has been analysed for their surface structure and utilised in the preparation of form-stable phase change material. The biochar derived from softwood was found to have a superior porous structure with a surface area of 441 m2/g compared to wheat straw. Biochar and phase change material Rubitherm 28 (RT28) were blended at various wt% and tested for leakage. The composite with 50 wt% of softwood biochar and RT28 had the lowest leakage rate. The developed green phase change-bio composite with minimum leakage has been thoroughly evaluated for its chemical and thermal properties. The latent heat of fusion has been found to be 228.6 J/g, 132.3 J/g and 51.6 J/g, for the RT28, softwood biochar composite, and wheat straw biochar composite respectively. Thermal conductivity was also higher for the composites than that of RT28. The thermal cycling reliability is suitable for thermal storage applications as there is a minimal alteration in the thermal properties observed after 200 cycles. The melting enthalpy of the new and aged composites after 200 cycles has been found to be 136.6 J/g and 132.42 J/g, respectively. The composite with minimal leakage and high thermal conductivity can potentially revolutionise the area of low temperature latent heat storage. The properties of the form-stable phase change-bio composite synthesised in this work make it suitable for application in the field of thermal management of photovoltaic modules, electronic devices, and buildings.

Selection of PEG-Matrix Combinations to Achieve High Performance Form-Stable Phase Change Materials for Building Applications

The construction sector’s pursuit of sustainability, driven by growing concerns about climate change and resource depletion, requires innovative solutions to reduce the energy consumption necessary to ensure thermal comfort in buildings. The introduction of phase change materials (PCMs) in construction elements represents an effective solution to these problems. PCMs are, in fact, able to regulate internal temperature by storing and releasing thermal energy during their phase transitions. In particular, polyethylene glycol (PEG)-based organic PCMs offer high heat storage capacity, compatibility with building materials, and minimal environmental impact. They are often used in building applications incorporated in an inert matrix, using the “form-stable method”. This article critically examines various matrices proposed in the existing literature to realize PEG-based PCMs, with the aim of analyzing their influence on the final characteristics of any PCM. In addition, an attempt to correlate the quantity of PEG with the heat stored and released by the PCM is presented, using a linear regression model applied to groups of matrices of the same chemical nature. The results of these analyses would, in fact, provide useful indications for an optimal choice of the PEG/matrix system capable of responding to specific application needs, particularly in the building sector.