Solid Phase Change Material Research Articles

Experimental investigation on charging and discharging performance of finned shell and tube device containing pentaerythritol for low and medium temperature thermal energy storage

This work concerns the investigation of the charging and discharging performance of a finned shell and tube device that utilized for low and medium temperature thermal energy storage application. An experimental rig is built for evaluation in which a so-called solid–solid phase change material of pentaerythritol is used as energy storage substance and air is employed as heat transfer fluid. The PE has tested to have a melting temperature range of 185-205℃ and a latent heat of 290 kJ/kg. The study first examines the effect of fin number on the device thermal performance by considering configurations with 4, 6, 8, and 10 fins. Then the impact of fin height is evaluated where four different fin heights of 9 mm, 14 mm, 19 mm and 24 mm is investigated, and finally the influence of heat transfer fluid working condition is explored. The results indicate that the PE could be ideal PCM utilized in shell-tube typed thermal energy storage device. The enhancement of fin number and fin heigh can largely improve both the charging and discharging performance of the device. For a given air inlet pressure of 0.1 MPa, the device having fin number of 10 and fin height of 19 mm could be identified as the optimal configuration for heat transfer, and at such working conditions, the device achieves a charging efficiency of 91.49 % and a discharging efficiency of 86.4 %.

Highly flexible GO-polyurethane solid-solid phase change composite materials for efficient photothermal conversion and thermal energy storage

Solid-solid phase change materials (SSPCMs) are considered one of the most promising candidates for thermal energy storage due to their efficient heat storage and discharge capabilities. However, achieving both stable...

Multifunctional Phase Change Films with High Mechanical Strength, Thermally Induced Switchable Adhesion, and Shape Recoverability for Infrared Stealth.

The application of organic solid-liquid phase change materials (PCMs) is limited for the leakage problem after phase change and high rigidity. In this work, a novel flexible solid-solid PCM (DXPCM) was synthesized using a block copolymerization process with polyethylene glycol (PEG) as the energy storage segment. The phase transition temperature (from 36.2 to 49.4 °C) and enthalpy (from 83.27 to 123.35 J/g) of DXPCM could be changed through adjusting the molecular weight of PEG. The introduction of hard chain segments endowed DXPCM with excellent flexibility, foldability, and mechanical properties at room temperature. The large number of internal hydrogen bonds and π-π stacking provided DXPCM with interesting thermally induced switchable adhesion and recyclability. The storage and release of elastic potential energy ensured that DXPCM could recover its original shape after being deformed by external forces. It is worth mentioning that DXPCM exhibits excellent infrared stealth capability as it can absorb and release latent heat for a long period of time. In conclusion, this work developed a novel solid-solid phase change film with high mechanical strength, thermally induced switchable adhesion, and shape recovery capability, which has great potential for application in infrared stealth.

Thermal and Mechanical Robust Solid‐Solid Phase Change Materials Enabled by Reactive Crosslinkable Poly(Ethylene Glycol)s via Facile Thiol‐Ene Photo‐Click Chemistry

AbstractSolid–solid phase change materials (SSPCMs) are among the most promising candidates for thermal energy storage and management. Excellent shape stability, high heat storage capacity, and satisfying mechanical properties are essential for the practical applications of SSPCMs, yet giving PCMs these characteristics at the same time remains an unmet challenge. Herein, the synthesis of PEG‐PVEG copolymers is reported with various vinyl content using a synergistic catalysis strategy, leading to novel cross‐linked PEG‐based SSPCMs via a thiol‐ene photo‐crosslinking reaction. These PCMs exhibit excellent shape stability and remarkable energy storage capabilities with latent heat up to 128.3 J g−1. The materials exhibit exceptional thermal stability and retain their energy storage capacity after 500 heating‐cooling cycles. Notably, the materials show superior mechanical strength and excellent toughness. Furthermore, the latent heat enthalpy can be further improved to 146.8 J g−1 without erosion of shape stability by the encapsulation of PEG into present SSPCM. The enhancement of both thermal and electrical conductivities is also demonstrated by the phase change composites (PCCs) incorporating multi‐walled carbon nanotubes (MWCNTs). Overall, this study presents a convenient and feasible strategy for developing SSPCMs with excellent shape stability, high latent heat and satisfying mechanical properties for thermal management.

Thermal performance enhancement with solidification effect of nickel foam and MXene nanoenhanced PCM composite based thermal energy storages

This paper presents a numerical investigation into the solidification behavior of phase change material (PCM) in duplex and triplex-tube latent heat thermal energy storage (LHTES) systems enhanced with nickel foam and MXene nanoparticles. The study aims to investigate how nickel foam integration enhances heat transfer during PCM solidification, aiming for faster, more uniform solidification, and to analyse energy and exergy efficiency for optimizing thermal energy storage systems. The study also assesses the impact of nickel foam on enhancing PCM thermal conductivity, improving solidification rates, and overall thermal management. Focusing on a nickel foam/PCM/MXene (5 % v/v.) composite, the study explores the effects of solidification characteristics, as well as the Stefan and Fourier numbers, in both duplex tube thermal energy storage (DuT-TES) and triplex tube thermal energy storage (TrT-TES) systems. It provides detailed insights into the thermal performance of these systems by evaluating key factors such as liquid fraction, solidification temperature profiles, exergy destruction, exergetic efficiency, system efficiency, and discharged energy.The findings reveal that systems incorporating nickel foam/PCM-MXene composites significantly outperformed those using nickel foam/PCM and pure PCM alone, achieving notably faster solidification. Specifically, the nickel foam/PCM composite demonstrated higher discharge exergy than pure cetyl alcohol PCM. The TrT-TES system with the nickel foam/PCM composite solidified 48.40% faster than the DuT-TES system. Additionally, the discharge energy of the TrT-TES system with nickel foam/PCM and nickel foam/PCM/MXene composites was 2.26 % and 3.65 % greater, respectively, than that of the DuT-TES system. At 90 s, the DuT-TES with nickel foam/PCM/MXene showed a 2.91 % improvement in system efficiency. Overall, the TrT-TES system using the nickel foam/PCM/MXene composite exhibited a 48.39 % faster solidification rate than the DuT-TES system. Thus, this study highlights the superior potential of the TrT-TES system with nickel foam/PCM/MXene composite for enhancing latent heat thermal energy storage, outperforming the DuT-TES system in terms of solidification speed, discharge energy, and efficiency.

High-performance and stress-controllable solid-solid phase change material for long-term thermal energy storage

Phase change materials (PCMs) show substantial promise in regulating the supply and demand of renewable energy and in recovering and utilizing waste heat. However, existing PCMs face challenges with spontaneous thermal energy dissipation and lack the ability of long-term heat storage and controlled release of thermal energy. In this study, we successfully predicted a class of Ni-Ti-Zr-Cu PCMs with high performance by using machine learning method, which can effectively recover low-grade waste heat, and has the characteristics of long-term thermal energy storage and stress-driven controlled thermal energy release. The experimental results show that the inverse martensitic transformation entropy is as high as 51.8 J kg−1 K−1. Under the uniaxial stress, martensitic transformation can be induced and adiabatic temperature change of 20K, resulting in an isothermal entropy change greater than 44.7 J kg−1 K−1. In addition, it has a high thermal conductivity of 12.68 Wm-1 K−1 and a figure of merit (FOM) greater than 1300 × 106 (J2 K−1 s−1 m−4), an order of magnitude improvement over conventional PCMs. This work provides a new idea for designing long-term storage, long distance transmission and controlled release of PCMs.

Optimization of antenna-shaped fins configuration for enhanced solidification in triplex thermal energy storage systems with radiative heat transfer

The objective of this study is to enhance the rate of solidification of Phase Change Materials (PCMs) in Latent Thermal Energy Storage Systems (LTESSs) by incorporating hybrid nanoparticles (MoS2-Fe3O4) and utilizing a unique optimized antenna-shaped fin configuration in a triplex-tube energy storage device. The problem was solved by applying the Finite Element Method (FEM), considering some numerical analysis. For studying the effects of a variety of angles and dimensions of antenna-shaped fins with a radiation parameter during the process of solidification, a computational model validated by historical experimental data is developed. This paper will present an analysis of the effect of different angles and dimensions of antenna-shaped fins in conjunction with the radiation parameter during the solidification process. Results show that the full solidification time (FTS) decreases by 51 % when Rd = 1 compared to zero radiation, indicating a significant improvement in the efficiency of the solidification process. Furthermore, at 4000 s, the average temperatures for Rd = 0 and Rd = 1 differ, showing a noticeable drop of 4.51°. Furthermore, using Taguchi and Response Surface Methodology (RSM), the optimal settings were determined to minimize the full solidification time in the triplex-tube LHESS. Interestingly, a highly accurate and precise correlation for FST was established.

Investigation on the heat transfer characteristics of thermal control system based on phase change material coupled with three-dimensional arrayed pulsating heat pipe

The rapid development of electronic devices necessitates reliable thermal control systems for efficient thermal management. The combination of pulsating heat pipes (PHPs) with phase change materials (PCMs) facilitates uniform and efficient thermal regulation. This study presents a novel coupled thermal control module that integrates a three-dimensional arrayed pulsating heat pipe (3D-APHP) with a dual-plane and arrayed structure and solid-solid PCM composites. The heat transfer characteristics of the 3D-APHP, the phase change characteristics of the PCM composites, and the interaction between the 3D-APHP and PCM composites under different heating powers and filling rates were experimentally investigated. The results show that the latent heat absorption properties of the PCM composites significantly reduce the temperature fluctuation range and pulsation amplitude of the 3D-APHP, enhancing the temperature uniformity and lowering the overall temperature of the 3D-APHP by approximately 3–10 °C. The efficient thermal conductivity mechanism of the 3D-APHP ensure that the axial temperature difference of the PCM composites is controlled within 10 °C and the radial temperature difference is controlled within 1.5 °C, effectively promoting uniform heat distribution and enhancing the overall temperature rise rate. Additionally, in passive operating mode, the overall temperature difference of the 3D-APHP is smaller and the heat transfer stability is enhanced; in passive/active coupling operating mode, the average temperature of the evaporation section of the 3D-APHP decreases and the thermal response speed increases. The working characteristics of these two modes can be applied to different scenarios, highlighting the innovative integration of PHPs and PCMs in advanced thermal management solutions.

A novel photocurable polymeric solid–solid phase change material for intelligent temperature regulators

The advancement of solid–solid phase change materials (SSPCMs) with crystalline segments embedded onto crosslinked polymer backbones offers a promising solution to the leakage problems associated with traditional phase change materials. Despite its potential, this technology faces challenges, including energy-intensive synthesis processes of SSPCMs and difficulties in custom designing materials for confined spaces. Herein, we introduce a novel strategy for the rapid preparation of polyurethane acrylate-based SSPCMs via UV-initiated polymerization. By leveraging crystalline segments from polyethylene glycol, the resulting SSPCM exhibits an impressive enthalpy of 110.4 J⋅g−1, enabling seamless transitions from rigid to soft states during solid–solid phase changes. When applied in portable electronic devices, this SSPCM can be synthesized in-situ to meet various size requirements, demonstrating exceptional temperature regulation performance based on latent thermal energy storage mechanisms. Furthermore, by integrating thin layers of carbon nanotubes (CNTs) onto the rough surfaces of SSPCM films and employing a face-to-face configuration to convert temperature-sensitive mechanical changes into electric resistance variations, we have engineered high-temperature alarms for SSPCM-based temperature regulators. The advantages of this preparation strategy, combined with the thermal regulation capabilities and innovative temperature alarm design, underscore the significant potential for intelligent and adaptive applications of SSPCMs in advanced technological landscapes.

Integrating MXene Film With Recyclable Polyethylene Glycol-co-Polyphosphazene Copolymer as Solid-Solid Phase Change Material for Versatile Applications.

Phase-change materials (PCMs) stand a pivotal advancement in thermal energy storage and management due to their reversible phase transitions to store and release an abundance of heat energy. However, conventional solid-liquid PCMs suffer from fluidity and leakage in their molten state, limiting their applications at advanced levels. Herein, a novel Zn2+-crosslinked polyethylene glycol-co-polyphosphazene copolymer (PCEPN-Zn) as a solid-solid PCM through dynamic metal-ligand coordination is first designed and synthesized. The as-synthesized PCEPN-Zn is further integrated with an MXene film to construct a double-layered phase-change composite through layer-by layer adhesion. Owing to the introduction of MXene film with low emissivity, good light absorptivity, and nonflammability, the resultant phase-change composite not only presents a high latent-heat capacity, good thermal stability, high thermal reliability, and excellent shape stability, but also exhibits a superior self-healing ability, good recyclability, high adhesivity, and good flame-retardant performance. It can be easily adhered to on most objects for various application scenarios. With a combination of the excellent functions derived from PCEPN-Zn and MXene film, the developed phase-change composite exhibits broad prospects for versatile applications in the thermal management of CPUs and Li-ion batteries, thermal infrared stealth of high-temperature objects, heat therapy in the clinic, and fire-safety for various scenarios.

Flexibility, malleability, and high mechanical strength phase change composite films for solar-thermal and electro-thermal energy storage

Phase change materials (PCMs) are widely used in a range of energy storage applications due to high latent heat absorption and release capacities during phase change processes. There is still a lot to be done to resolve the inherent leakage, stiffness problems, and poor solar-thermal and electrical-thermal conversion capacities of PCMs to functionalize them. Here, a novel solid-solid phase change material (IGPCM) is created using block copolymerization. The IGPCM has a tunable enthalpy (from 58.16 to 99.60 J g−1) by adjusting the molecular weight of the PEG. The obtained IGPCM10K has high toughness (479.1 MJ/m3), excellent bending and malleability. Since IGPCM10K suffers from poor thermal conductivity, photo responsiveness, and electro-thermal conversion, carbon nanotubes (CNT) can be added to our IGPCM10K in a simple way to improve these issues. The thermal conductivity of IGPCM10K-CNT-3 is improved by 55.6 % compared to IGPCM10K. The photothermal conversion efficiency is 84.9 % at 300 mW/cm2. The electrothermal conversion efficiency is 82.3 % at 12 A. The prepared flexible PCM composites have super toughness, high enthalpy, excellent thermal conductivity, and photo-thermal and electro-thermal conversion capabilities, which will show great potential in future applications.

Experimental study on an improved direct-contact thermal energy storage container

Direct-contact thermal energy storage (TES) systems characterized by high heat density and rapid heat transfer rates have been exploited for the collection of industrial waste or surplus heat for subsequent utilization. In order to address blockage issue at the initial stage of charging process, an improved direct-contact TES container was developed by incorporating a double-pipe structure at both the inlet and outlet. Within the container, a U-shaped tube serving as the inner tube was concentrically positioned from the inlet to the outlet. Erythritol was selected as the phase change material (PCM), while heat transfer oil (HTO) functioned as the heat transfer medium during experimentation. During the charging process, hot HTO initially flowed through the U-shaped tube, establishing an indirect contact with the PCM. The high thermal conductivity of the U-shaped tube wall expedited the formation of a flow channel within the solid PCM. The duration of forming flow channel was 6 to 13 min. In the discharging phase, the liquid PCM was segregated into convection and conduction zones. The indirect-contact TES experiments were also conducted in the same container. Comparison between indirect-contact and direct-contact TES were analysed from the aspects of phase change behavior, charging and discharging time with the identical container structure and theoretical heat capacity. Results indicated that the direct-contact TES container exhibited superior heat storage and release rates, with the direct-contact discharging time being approximately a quarter of the indirect-contact duration. The phase change behavior of the PCM was notably influenced by the movement of HTO within the direct-contact storage container.

Discharging Performance Analysis of MXene Nano‐Enhanced Phase Change Material for Double and Triplex Tube Thermal Energy Storage

ABSTRACTThe present study numerically investigates the energy and exergy analysis of solidification of phase change materials within a double tube and triple tube latent heat storage unit using ANSYS Fluent. Double tube and triple tube thermal energy storage system's thermal characteristics are examined using MXene nano‐enhanced phase change material to determine system efficiency, discharged energy, heat transfer rate, exergy destruction, entropy generation number, exergetic efficiency, liquid fraction, solidification temperature contours. The result revealed that the double tube thermal energy storage with pure cetyl alcohol PCM has 14.76% lower discharge exergy than MXene‐based nano‐enhanced phase change material in pure solidification. In a triple tube thermal energy storage system, the solidification time for MXene‐based nano‐enhanced phase change material is impressively reduced by 54.76% compared to a double tube system using pure phase change material. At a Fourier number of 0.00672, MXene nano‐enhanced phase change material exhibits an 11.69% higher Stefan number (St) than cetyl alcohol phase change material in a double tube thermal energy storage system. At 2400 s, pure phase change material and MXene nano‐enhanced phase change material generated 3.14% and 4.88% less entropy than pure cetyl alcohol in the triple tube thermal energy storage system. During the pure solidification process in a double tube thermal energy storage system, pure cetyl alcohol experiences 7.60% higher exergy destruction compared to MXene nano‐enhanced phase change material at a solidification time of 2400 s. In a triple tube thermal energy storage system, the discharging temperature for pure cetyl alcohol phase change material is 2.92% lower than that in a double tube system. Double tube thermal energy storage with pure cetyl alcohol discharged more efficiently over 2400 s. The triple tube thermal energy storage system solidified cetyl alcohol PCM 20.83% faster than pure phase change material due to MXene nanoparticles' better thermophysical properties. Thus, MXene‐based nano‐enhanced cetyl alcohol phase change material solidifies faster per volume in a triple tube thermal energy storage latent heat system.

Enhancing building energy efficiency: Innovations in glazing systems utilizing solid-solid phase change materials

This study investigates the energy efficiency of a double-glazing window (DGW) integrating a solid–solid phase change material (SSPCM) with limited thickness, applied to the inner glass pane within the air gap. Numerical model, validated against experimental data, is developed using a finite volume method in ANSYS Fluent. In this model, the Discrete Ordinates (DO) model is applied to simulate radiation, while the enthalpy-porosity approach is used to capture the solidification and melting processes in the phase change material. With this model, the energy performance of the system is analyzed under various transient temperature values (10 to 30 °C) and ranges (1 to 5 °C) during the coldest and hottest days of the year, as well as during cloudy and sunny days in Montreal (Dfb), Vancouver (Cfb), and Miami (Aw). According to the obtained results in Montreal, the DGW-SSPCM system consistently saves energy under summer sunny conditions, with optimal performance when the SSPCM remains transparent. However, it incurs energy losses in cloudy days, where the energy lost is 2.3 times greater than the energy saved in sunny days. In Vancouver, the system shows consistent energy savings, particularly at Tc = 30 °C, with average savings of 20.5 kJ (23 %) under summer sunny conditions. The system is most beneficial in Vancouver, where winter energy savings in cloudy days (50.6 kJ) are 7.1 times greater than the losses in sunny days (7.1 kJ). In Miami, the system results in energy losses by 60 % and 5 % (at Tc = 30 °C) under both summer sunny and cloudy conditions, respectively, indicating unsuitability for its climate. During winter sunny conditions, all three cities experience energy losses, with Vancouver showing the lowest of 7.1 kJ (3 %) and Montreal the highest of 64.4 kJ (19 %) at Tc = 30 °C. In winter cloudy conditions, the system saves energy in all cities, with the highest savings in Miami of 54.5 kJ (26 %) at Tc = 30 °C. Overall, the SSPCM-DGW system has proven to be beneficial in Vancouver across various conditions in terms of energy and visual performance. These findings highlight the necessity of considering localized climate factors when designing and implementing energy-efficient glazing systems. Finally, the SSPCM-DGW system has provided complete visual clarity during office hours, making it more suitable for commercial buildings.

Two‐Dimensional Solidification Simulation of PCM Molten Salt as a Thermal Energy Storage for Stirling Engine

ABSTRACTThermal energy storage technologies have been widely used to mitigate intermittency from renewable energy sources such as solar energy. Phase change material (PCM) is a material that can be used as a heat storage medium and is available in a wide range of operating temperatures. Molten salt is one of the PCMs that has the advantage of a very high operating temperature. The PCM solidification simulation based on HitecXL molten salt using COMSOL Multiphysics software was carried out with variations in heat absorption of 1–5 kW/m2, assuming constant heat absorption. The results showed that the PCM solidification process started from the surface of the Stirling engine heat exchanger pipe. The part of the PCM that is solidified falls due to gravity, causing a phenomenon similar to a droplet. The flow that occurred was natural, driven by the buoyancy force resulting from density changes due to temperature gradients in the solidification process. The time required for the PCM to completely solidify was closely related to the amount of heat absorption; the greater the heat absorption from the pipe, the faster the PCM is fully solidified.

Experimental study on thermocline behavior and management in phase change material-enhanced thermal energy storage: Implications for charging and discharging cycles

The increasing costs of designing and constructing a thermal energy storage (TES) tank have led many researchers to seriously consider the factors affecting thermocline deterioration inside the tank during charging and discharging cycles. It is crucial to regulate the thermocline, which is the boundary between the hot and cold heat transfer fluid (HTF) zones, to minimize its expansion and optimize the operating efficiency of the storage tanks. The study focuses on various experimental aspects of the hot water storage tank (HWST). It also shows the effect of phase change material (PCM) on the thermocline, the total energy storage capacity, and the actual energy extracted from the tank model during the charging and discharging processes. The HWST with a TES tank model was constructed for experimental purposes. The TES tank model used a solid phase change material of 54 kg (15 %) of cylindrical paraffin wax, specifically of the RT42 classification. Additionally, 18 aluminum cylinders were employed to increase the surface area of the phase change material, accelerate the charging and discharging processes, and improve the utilization factors. The incorporation of paraffin wax into the water-PCM storage tank improved the thermocline layer during the discharging process, reducing its thickness by 50 %, 50 %, and 34 % after 30 min at extracted water temperatures of 48 °C, 53 °C, and 56 °C, respectively, with a mass flow rate of 0.13 kg/s. The maximum utilization factors reached 72.2 % with total energy storage increasing by 30.5 % and extracted energy by 68.8 % during charging and discharging cycles, respectively.

Photo-thermal effects initiate multi-level energy conversion in “solid-solid” phase-changing fibers

The current textiles primarily employ passive heat barriers to minimize heat loss and achieve effective thermal insulation for human beings. Accordingly, intelligent fibers with energy storage and temperature control capabilities have garnered significant attention due to their potential to revolutionize textile technology. The study integrates the photo-thermal effect and phase change energy storage materials onto a fiber, thereby fabricating a fully intelligent energy storage fiber. This innovation enables the multi-level conversion of sunlight: “Optical energy - Thermal energy - Phase transition energy - Thermal energy”. The intelligent fiber efficiently converts solar energy into heat energy through the photo-thermal coupling of CuNPs, subsequently inducing a spatial conformational change in the solid-solid phase change material within the fiber for effective heat storage. The hybrid fiber possesses enhanced mechanical properties but also exhibits a significantly high phase transition enthalpy value of 49.75 J g−1 and a phase transition temperature suitable for human body temperature (20.19–30.21 °C), especially the fiber is more durable. The photo-thermal conversion test vividly demonstrates the systematic transformation of four distinct forms of energy within the composite fiber. This approach holds significant potential for advancing the field of smart fiber technology.

Experimental and numerical investigation on the performance of binary solid-solid phase change materials with integrated heat pipe and aluminium foam based heat sink for thermal management of electronic systems

Phase change material (PCM) is widely utilised in thermal management systems (TMS), however its low thermal conductivity inhibits performance. Heat pipe and porous materials are incorporated into PCM due to their high thermal conductivities to form a hybrid system that substantially enhances PCM's heat transfer capability. This study investigates experimentally and numerically, the cooling performance of heat sink by integrating aluminium foam and heat pipe (HP) with binary Neopentyl glycol (NPG)/Trihydroxy methyl-aminomethane (TAM) solid-solid phase change material (SS_PCM) obtained at 90/10 wt% (N9T1), 70/30 wt% (N7T3) and 50/50 wt% (N5T5). Compared to pure NPG thermal conductivity, N9T1, N7T3, and N5T5 samples demonstrated relative enhancement ratios of 0.017, 2.46, and 2.84. Different heat sink configurations are examined at three constant power levels 15, 17 and 19 W for the same charging period of 10000 s to determine the optimal cooling arrangement. During the charging period, hybrid cooling (PCM-Foam-HP) system with fan in contrast to an empty sink achieved the highest temperature reduction of 58.31 %, 58.99 % and 59.89 % at power levels of 15, 17 and 19 W, respectively. N9T1, N7T3 and N5T5 combinations lowered temperature by 4.6 %, 5.9 % and 10.8 %, respectively, when compared to NPG. Furthermore, all configurations performed better at lower heat generation rates by extending the safe operational period (SOP).The investigation concluded that N5T5 SS_PCM-aided heat sinks with integrated aluminium foam and heat pipe with fan reduced temperatures the most and performed best in all aspects. Finally, the experimental results for TMS were numerically validated using COMSOL software.

Colossal Barocaloric Effect in Encapsulated Solid‐Liquid Phase Change Materials

AbstractBarocaloric cooling as an emerging cooling technology offers an eco‐friendly alternative to traditional vapor compression refrigeration. Research on barocaloric materials primarily concentrates on solid–solid phase change materials (PCMs), among which plastic crystals exhibit colossal barocaloric effect. Solid‐liquid PCMs such as paraffin also exhibit giant barocaloric effect, however, their potential is often overshadowed by leakage issues. In this work, a strategy is demonstrated by encapsulating solid‐liquid PCMs into porous carbon matrixes to generate a large family of colossal barocaloric materials. In practice, by orthogonally combining paraffins with encapsulation matrixes like graphene foam, carbon nanotube foam, and carbon foam, it can be obtained composites that work without leakage issues. The significant advantage is their colossal barocaloric effect with the highest entropy value up to 570 J K−1 kg−1 in paraffin‐20@graphene foam. Moreover, the composites possess thermal conductivity up to 89.9 W m−1 K−1 in paraffin‐20@carbon foam, and tunable working temperature in the range of 270—330 K. Most importantly, this strategy, demonstrated with 5 solid‐liquid PCMs and 3 encapsulation matrixes in this work, is just the beginning. Further exploration with more materials can develop a huge family of encapsulated solid‐liquid PCMs with colossal barocaloric performance for modern cooling technology.

Titanium dioxide/graphene oxide synergetic reinforced composite phase change materials with excellent thermal energy storage and photo-thermal performances

The development of advanced composite solid-solid phase change materials (SSPCMs) is urgent to explore for improving solar energy harvesting and storage. Herein, novel composite SSPCMs with synergetic cross-linking structure were fabricated through polymerization using GO and TiO2 constructed on the polyurethane framework skeleton. GO and TiO2 synergetic enhanced polymer framework played a role as skeletal structure to encapsulate PEG in the molecular chains, and provided as highly thermal conductive pathways for the composite SSPCMs. TiO2 nanoparticles performed as extended surface on the skeletal structure for further improvement in thermal conductivity. The composite SSPCMs exhibited a remarkably improved thermal conductivity as high as 0.7 W/(m‧K) and fast thermal response rate. The good light adsorption property of TiO2 enhanced the light absorbance efficiency of the composite SSPCMs by 94.4%. And the photo-thermal conversion efficiency of the composite SSPCMs highly reached 93.5%. Meanwhile, the composite SSPCMs exhibited excellent anti-leakage performance and shape stability under high temperature. Consequently, the as-prepared composite SSPCMs possessed a potential for applications in thermal energy storage and solar energy utilization systems.