Phase-change Media Research Articles

MXene quantum dots modified pitaya peel-based composite phase change material with excellent thermal properties for building energy efficiency applications

Bio-based materials have attracted much attention because their application in the construction field is conducive to energy saving and emission reduction. In this paper, a bio-based composite phase change material (CPCM) was prepared by utilizing pitaya peel as a bio-based material, MXene quantum dots (MQDs) as a modified material, and polyethylene glycol (PEG) as a phase change medium. MXene quantum dots dispersed in the pitaya peel-based porous carbon skeleton enhanced the three-dimensional thermal conductivity network of the porous carbon skeleton somewhat improved the thermal conductivity (0.676 W/mK) of the polyethylene glycol/MXene quantum dots-modified pitaya peel-based porous carbon foam (PPF) composite phase change material (PEG/PPF@M). It is worth noting that PEG/PPF@M has excellent thermal stability and its enthalpy is basically unchanged after 100 cycles, which proves the recyclable stability of PEG/PPF@M in practical applications. PEG/PPF@M has great potential for thermal management of buildings and electronic components. Overall, a novel multifunctional CPCM was prepared in this study using a simple process method, which can not only be applied in electronic products to improve the service life of electronic components, but also in the field of construction to realize energy saving and emission reduction, as well as the recycling and reuse of waste.

Diatom-based biomass composites phase change materials with high thermal conductivity for battery thermal management

Battery thermal management systems (BTMs) are a significant strategy for controlling the operating temperature of lithium-ion batteries (LIBs) used in electric vehicles (EVs). A promising approach for mitigating the risk of battery exceeding the highest operating temperature is the utilization of composite phase change materials (CPCMs) in BTMs, which have the potential to be applied in EVs. In this study, a vacuum impregnation process was employed to prepare the biomass-based CPCMs (PPE-0, PPE-10, PPE-30 and PPE-50), consisting of diatomite as a supporting matrix, expanded graphite (EG) as an additive, and polyethylene glycol (PEG) as the phase change media. The PPE-10 exhibits an enhancement of melting enthalpy (116.81 J/g) and crystalline enthalpy (118.44 J/g). Meanwhile, the thermal conductivity of PPE-10 is 1.203 W/m·K, which is higher than PEG and PPE-0 by 4.02 times and 2.18 times, respectively. Furthermore, the battery modules with prepared CPCMs were carried out the charge and discharge processes at 1C and 2C discharge rates. The results illustrate that the battery modules with PPE-10 show excellent thermal management capability, which maintains the temperature below 60 °C during a 2C discharge rate. Consequently, this study provides a novel insight into developing biomass-based CPCMs with high thermal conductivity to enhance the safety of battery modules in EVs.

MXene-modified lemon peel-based composite phase change material with excellent photo-thermal conversion efficiency, thermal storage capacity and thermal conductivity for thermal management of electronic components

The preparation of multifunctional composite phase change materials using green technology to achieve an efficient energy storage and conversion remains an issue of concern. In this paper, a lemon peel-based porous carbon (LPC) composite phase change material (CPCM) was prepared by using polyethylene glycol (PEG) 6000 as a phase change medium and MXene nanosheet-modified carbonized lemon peel as a support carrier. MXene nanosheets were bonded to a lemon peel-based porous carbon skeleton to construct an excellent continuous three-dimensional thermally conductive grid system. What makes it noteworthy is that the presence of MXene nanosheets substantially improves the thermal conductivity (0.66 W/mK) and photo-thermal conversion efficiency (θ = 96.4 %) of MXene-modified lemon peel-based porous carbon/polyethylene glycol composite phase change materials (PEG/LPC@M). It is noteworthy that PEG/LPC@M has remarkable thermal stability and still has high enthalpy after 100 cycles, which further proves the recyclability of PEG/LPC@M and PEG/LPC@M embodies great potential in the field of thermal management of electronic components. In conclusion, a novel multifunctional CPCM was prepared by a simple and green process method in this study, which provides a new idea for waste recycling and reuse, and also has a wide range of applications in thermal management of electronic devices.

Three-Dimensional Optothermal Manipulation of Light-Absorbing Particles in Phase-Change Gel Media.

Rational manipulation and assembly of discrete colloidal particles into architected superstructures have enabled several applications in materials science and nanotechnology. Optical manipulation techniques, typically operated in fluid media, facilitate the precise arrangement of colloidal particles into superstructures by using focused laser beams. However, as the optical energy is turned off, the inherent Brownian motion of the particles in fluid media impedes the retention and reconfiguration of such superstructures. Overcoming this fundamental limitation, we present on-demand, three-dimensional (3D) optical manipulation of colloidal particles in a phase-change solid medium made of surfactant bilayers. Unlike liquid crystal media, the lack of fluid flow within the bilayer media enables the assembly and retention of colloids for diverse spatial configurations. By utilizing the optically controlled temperature-dependent interactions between the particles and their surrounding media, we experimentally exhibit the holonomic microscale control of diverse particles for repeatable, reconfigurable, and controlled colloidal arrangements in 3D. Finally, we demonstrate tunable light-matter interactions between the particles and 2D materials by successfully manipulating and retaining these particles at fixed distances from the 2D material layers. Our experimental results demonstrate that the particles can be retained for over 120 days without any change in their relative positions or degradation in the bilayers. With the capability of arranging particles in 3D configurations with long-term stability, our platform pushes the frontiers of optical manipulation for distinct applications such as metamaterial fabrication, information storage, and security.

Research progress of thermoregulating textiles based on spinning of organic phase change fiber of energy storage

Thermal energy storage can contribute to the reduction of carbon emissions, motivating the applications in aerospace, construction, textiles and so on. Phase change materials have been investigated extensively in the field of high-performance intelligent thermoregulating fabrics for energy storage. Advances toward fibers or fabrics for thermo regulation are developed, but leakage of phase change medium is a concern when directly coated or filled with fibers or fabrics. Thus, different spinning methods have appeared to integrate phase change materials into copolymer fiber to prepare phase change fiber. The present review has been divided into three parts and first deals with spinning technologies such as wet spinning, melt spinning, electrostatic spinning, and centrifugal spinning with the thermal properties and mechanical properties of phase change fiber. Among them, the phase change medium loading in the phase change fiber with wet spinning is up to 70 wt.%, while the fiber strength is below 2.12 cN/dtex. In contrast, phase change fiber prepared by melt spinning achieves a breaking strength of up to 37.31 cN/dtex, but with an enthalpy of only 8.48 kJ/kg. Considering electrostatic spinning, not only enthalpies are satisfactory but the fiber diameters are mostly below 1000 nm, matching with the softness requirement for fabric. Moreover, centrifugal spinning enables efficient production of phase change fiber of large enthalpy by controlling spinning parameters such as rotational speed and spinning fluid concentration. The second part reports that the thermal management effects of different intelligent thermo regulating fabrics are evaluated by designed experiments or simulations to investigate further the more comfortable conditions of thermal comfort of humans. Simulation and experimental results show that the energy storage of smart fabrics extends the time duration of thermal comfort by more than 300 s. In the last part, multifunctional intelligent thermoregulating fabrics are systematically discussed, such as light and heat response, ultraviolet resistance, air permeability, and water resistance. Practical applications of phase change fibers and intelligent thermoregulating fabrics should be further studied and broadened in the future.

Radiative thermal coats for passive temperature management

Radiative thermal management has advantages in precision electronic instruments owing to zero-energy consumption and high integration convenience. The possibility to acquire high-performance thermal stability through engineering the surface emissivity of object has been investigated. Herein, developing a smart coat was reported that could passively maintain the temperature of objects (silicon chips) in a predefined thermal window to avoid overheating or overcooling in vacuum. The technique implements using a multilayer structure incorporating a 30 nm thick VO2 phase-change medium having a 300% modulation depth for emissivity under varying temperatures. In the experiment, a 1.78 μm thick smart coat could raise the temperature stability of a regular coat by ∼2.0 times. The potential of the work remains in thermal radiation for smart temperature management especially in space applications.

Combined passive enhancement techniques improve the thermal performance of latent heat storage system: A design anomaly?

Poor heat transfer rate due to low thermal conductivity of phase change material limits the wide application of latent heat storage (LHS) systems. Thermal performance enhancement techniques can be potential methods to address this major limitation of LHS systems. In this context, the present numerical study examines the individual and cumulative impact of two passive heat transfer enhancement techniques (the orientation of the domain and position of the heat transfer fluid (HTF) tube) on the thermal performance of the latent heat storage (LHS) system consisting of high-temperature (HT) phase change medium (PCM). The individual effect of orientation decreases the charging duration of θ = 0° (horizontal configuration) by 10.5 %, 15 %, and 19.04 % than θ = 30°, θ = 60° and θ = 90° (vertical configuration), respectively. However, the discharging duration remains unchanged for all inclinations (11.5–12 h). The individual effect of eccentricity decreases the charging duration of horizontal (θ = 0⁰, ey = −5 mm,-10 mm,-20 mm) system by 6.25 %,12.8 %, and 18.75 % than concentric horizontal (θ = 0°, ex = ey = 0) system. Moreover, the combined effect of orientation and eccentricity (θ = 0⁰,ey = −5 mm,-10 mm,-20 mm) reduces charging duration by 28.75 %, 33.33 %, and 38.1 % than vertical concentric domain (θ = 90°, ex = ey = 0), respectively. However, eccentricity in vertically upward and downward directions increases the discharging duration compared to the concentric domain. Hence, the combined effect results in a design anomaly for HT-LHS system. The charging and discharging performances are observed to be predominantly sensitive to the Rayleigh number than the Reynolds number.

Transient discharge performance of high-temperature latent storage system integrated with supercritical CO2 Brayton cycle: A combined analytical and numerical study

In this article, a generalized robust analytical model is developed to evaluate the discharge performance of a high-temperature latent heat storage (HT-LHS) system coupled with the supercritical CO2 (sCO2) recompression Brayton cycle. During discharging, the release of thermal energy from metallic phase change medium (PCM) based HT-LHS is the input to the sCO2 cycle. The thermal efficiency of sCO2 recompression cycle is observed to be significantly larger (> 50 %) than the conventional Rankine cycle at higher operating temperature (700–750 °C). The thermal efficiency increases with turbine input temperature for all split ratios and is maximized at a split ratio of 0.75. Turbine inlet pressure and air temperature are identified as the most and least sensitive parameters to affect the cycle efficiency. The average effectiveness of the LHS considering only conduction is compared with combined conduction and convection in PCM during discharging. The combined effect increases the average effectiveness of LHS maximum by 26.8 %. The analytical model is developed by eliminating two traditional assumptions considered so far in deriving analytical model. The derived dimensionless governing equations are solved using a Python routine to obtain the discharge performance (ε = 0.61,Q = 797.48 kW, ro = 138.61 mm) of LHS.

Study on Flow Resistance Characteristics of Cold Plate in Pump-driven Two-phase Cooling System

This paper summaries and analyzes the study on the two-phase flow pattern in cold plate in pump-driven two-phase cooling system. Based on the experimental system, the inlet and outlet flow resistance of the cold plate under different conditions is tested and analyzed. Through the experiment to get the cold plate in different heat flux, different inlet flow rate state of inlet and outlet pressure value, the relationship between the flow resistance and the flow rate, the flow resistance and heat flux of cold plate are analyzed and summarized. The experiment results show that the outlet pressure of cold plate is basically unchanged under different heat flux of cold plate, while the inlet pressure of the cold plate rises with the increase of the inlet flow rate of the phase change medium. The inlet pressure will accelerate after exceeding a certain critical flow, and the different heat flux has no effect on the flow resistance of the cold plate.

Phase-change materials based on amorphous equichalcogenides

Phase-change materials, demonstrating a rapid switching between two distinct states with a sharp contrast in electrical, optical or magnetic properties, are vital for modern photonic and electronic devices. To date, this effect is observed in chalcogenide compounds based on Se, Te or both, and most recently in stoichiometric Sb2S3 composition. Yet, to achieve best integrability into modern photonics and electronics, the mixed S/Se/Te phase change medium is needed, which would allow a wide tuning range for such important physical properties as vitreous phase stability, radiation and photo-sensitivity, optical gap, electrical and thermal conductivity, non-linear optical effects, as well as the possibility of structural modification at nanoscale. In this work, a thermally-induced high-to-low resistivity switching below 200 °C is demonstrated in Sb-rich equichalcogenides (containing S, Se and Te in equal proportions). The nanoscale mechanism is associated with interchange between tetrahedral and octahedral coordination of Ge and Sb atoms, substitution of Te in the nearest Ge environment by S or Se, and Sb–Ge/Sb bonds formation upon further annealing. The material can be integrated into chalcogenide-based multifunctional platforms, neuromorphic computational systems, photonic devices and sensors.

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

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

Novel industrial waste-based shape-stabilized composite phase change materials with high heat storage performance from calcium carbide furnace dust

Phase change materials with stable shape and superb thermal properties play a significant role in efficient utilization of solar energy. Herein, a novel industrial waste-based shape-stabilized phase change material (SSPCM) with a high paraffin load (61.32%) and environment-friendly was designed and prepared via a vacuum impregnation method, in which calcium carbide furnace dust (CCFD) was selected as the supporting materials for the first time. The acidified CCFD (HCCFD) and activated HCCFD (ACCFD) were obtained by hydrochloric acid pickling and potassium hydroxide activation, respectively. Scanning electron microscope (SEM) showed that calcium carbide furnace dust contains a certain amount of hollow spherical particles, which provided a well-maintained skeleton for the phase change medium. Differential scanning calorimetry (DSC) results indicated that the Paraffin/ACCFD with 57.0% effective impregnation of paraffin. Besides, the maximum melting and freezing latent heats were around 106.31 J/g and 104.53 J/g, respectively. Moreover, the obtained SSPCM exhibited excellent chemical compatibility and thermochemical stability. It is worth noting that the Paraffin/ACCFD showed optimal thermal management ability. The current work suggested that the SSPCM prepared from calcium carbide furnace dust industrial waste has expansive application potentials in thermal energy storage and solar energy conversion.

Graphene-pentaerythritol solid–solid phase change composites with high photothermal conversion and thermal conductivity

The use of phase change materials (PCMs) with high energy storage density is an ideal method to solve the problem of uneven and discontinuous of solar energy. At present, the common phase change media are mainly low-temperature solid–liquid phase change materials (SL-PCMs), which have shortcomings such as easy leakage, low thermal conductivity (TC), and low photothermal conversion performance. In response to these problems, a research idea of using pentaerythritol (PE) as a solid–solid phase change heat storage medium and gallic acid-modified graphene nanosheets (GNPs) as light absorbers and thermally conductive filler was proposed in this paper. The results showed that the composite phase change materials (CPCMs) containing 15 wt% GNPs had the highest photothermal conversion efficiency, reaching 93.86%, which was 247.76% higher than that of PE, and the latent heat of phase change was 190.88 J/g. Compared with PE (TC is 1.02 W/(m·K)), the TC of 15 wt% GNPs-CPCMs reached 3.86 W/(m·K), which increased by 278.43%. At the same time, their phase-change temperature remained at a medium–high temperature around 185 °C, and the UV–Vis spectra showed that the CPCMs also had high absorbance under visible light. This suggested that solid–solid composite phase change materials (SS-CPCMs) with high absorbance and TC provided a new approach for solar photothermal conversion and storage.

Numerical investigation of aqueous graphene nanofluid ice slurry passing through a horizontal circular pipe: Heat transfer and fluid flow characteristics

Ice slurry is an attractive phase-change cold storage medium that offers excellent thermal performance, thus rendering it a good prospect for applications in renewable energy storage, power peak-cutting, and valley filling. In this study, a computational fluid dynamic (CFD) numerical framework is employed based on the particle dynamics approach of an Euler-Euler two-fluid model coupling interphase transfer mechanisms. Thermal transport of a water-based graphene nanofluid ice slurry moving in the turbulent regime in a horizontal circular straight pipe is simulated and described. During the flow, the ice crystals tend to cluster on the top of the horizontal pipe, according to the findings, while uniformity of the crystal size distribution improves with an increase of velocity and the ice packing factor (IPF). Under the conditions of inlet IPF of 10% and heat flux q = 8000 (W m−2), the heat transfer coefficient on the heated section wall is increased by around 9% and 15%, respectively, as compared to pure water ice slurry and water. However, since the nanofluids have a higher viscosity than water, the pressure drop of nanofluid ice slurry is about 5% higher than that of pure water ice slurry in the same working environment.

Biomass porous potatoes/MXene encapsulated PEG-based PCMs with improved photo-to-thermal conversion capability

Encapsulated phase-change materials (PCMs) have been widely studied in the field of solar thermal energy storage due to the advantages of stable shape and repeatability. In this work, a series of potatoes phase-change materials (PPMs) were conceived and synthesized via a common vacuum impregnation method, with biomass porous potatoes (PP) as substrate, polyethylene glycol (PEG) as phase change medium and MXene nanosheets as functional filler. The experimental results show that the introduction of MXene nanosheets not only significantly improve the photo-to-thermal conversion efficiency, but also help to increase the adsorption rate of PEG in PCMs. The PEG percentage of potatoes phase-change material (PPM) increases from 60.9% (PPM-0) to 82.1% (PPM-12.5), melting/freezing enthalpy values are also increases from 94.08 J/g/100.46 J/g of PPM-2.5 to 135.57 J/g/139.88 J/g of PPM-12.5, and its enthalpy efficiency λ and relative enthalpy efficiency η also increase from 57.6%/91.5% to 77.7%/98.3%. The results show that the prepared PPMs can be effectively applied to solar photo-to-thermal energy storage.

Leak-free and shape-stabilized phase change composites with radial spherical SiO2 scaffolds for thermal management

A shape-stabilized phase change composite with high heat resistance was prepared by the strategy of adsorbing the phase change medium PEG by radial spherical SiO2 (RSSiO2) nanospheres.

Comparative study of cooling performance for portable cold storage box using phase change medium

The present study numerically investigates the cooling performance of portable cold storage boxes using phase change material (PCM) for safe and secure transportation of vaccines under a controlled temperature range of −55 °C to −40 °C at different ambient conditions. A suitable PCM (SP-50) is identified to comply with the temperature requirement of the cold storage box and a comparative study has been performed between a cuboid and cylindrical configuration having the same volume of the box and PCM. Temporal variation of temperature and liquid fraction during phase change of PCM are demonstrated with the help of CFD analysis. The inside temperature of the cylindrical configuration of the box is found to be 4.03% lower than the cuboid box after 17hrs of cooling duration for an ambient temperature of 45 °C. Cooling efficiency and cooling duration of the cylindrical configuration is 8.7% and 20.4% more than the cuboid one respectively at the ambient temperature of 30 °C. The relative dominance between convection and radiation heat transfer is evaluated at different surfaces for both configurations.

A Comparative Study of High-Temperature Latent Heat Storage Systems

High-temperature latent heat storage (LHS) systems using a high-temperature phase change medium (PCM) could be a potential solution for providing dispatchable energy from concentrated solar power (CSP) systems and for storing surplus energy from photovoltaic and wind power. In addition, ultra-high-temperature (>900 °C) latent heat storage (LHS) can provide significant energy storage density and can convert thermal energy to both heat and electric power efficiently. In this context, a 2D heat transfer analysis is performed to capture the thermo-fluidic behavior during melting and solidification of ultra-high-temperature silicon in rectangular domains for different aspect ratios (AR) and heat flux. Fixed domain effective heat capacity formulation has been deployed to numerically model the phase change process using the finite element method (FEM)-based COMSOL Multiphysics. The influence of orientation of geometry and heat flux magnitude on charging and discharge performance has been evaluated. The charging efficiency of the silicon domain is found to decrease with the increase in heat flux. The charging performance of the silicon domain is compared with high-temperature LHS domain containing state of the art salt-based PCM (NaNO3) for aspect ratio (AR) = 1. The charging rate of the NaNO3 domain is observed to be significantly higher compared to the silicon domain of AR = 1, despite having lower thermal diffusivity. However, energy storage density (J/kg) and energy storage rate (J/kgs) for the silicon domain are 1.83 and 2 times more than they are for the NaNO3 domain, respectively, after 3.5 h. An unconventional counterclockwise circular flow is observed in molten silicon, whereas a clockwise circular flow is observed in molten NaNO3 during charging. The present study establishes silicon as a potential PCM for designing an ultra-high-temperature LHS system.

High-temperature latent thermal storage system for solar power: Materials, concepts, and challenges

Limited reserves of fossil fuels, increased world energy demand and swelling of environment pollution drive a transition towards renewable energy resources which can deliver 3E objectives (Economic, environmental and energy security). However, the inherent intermittency necessitates efficient energy storage systems to harness the true potential of renewable resources. In this context, high-temperature latent heat storage (LHS) using phase change medium (PCM) can be a promising alternative to address the challenges of the variable renewable energy generation with respect to time and space. Currently, central receiver-based 3rd Gen concentrated solar thermal (CST) plant operating at high-temperatures (800-1000 °C) is the most attractive technology to convert solar energy to heat. Moreover, advanced power-generating cycles such as supercritical CO2 (sCO2) Brayton cycle operating at high-temperature can reduce the Levelized cost of Energy (LCoE) by achieving higher cycle efficiency. Hence, coupling a high-temperature LHS between the central receiver system and sCO2 cycle can have dual benefits: increase in dispatchability of energy and reduction in LCoE. Furthermore, high-temperature LHS can be devised to store high-grade energy such as spillage of energy from Photovoltaic (PV), wind power plant, and waste heat from energy-intensive industries (e.g. glass melting furnace). This article reports a holistic approach to review different components and design aspects of high-temperature LHS with techno-economic challenges to be overcome. A preliminary numerical study has been performed to predict the melting behavior of high-temperature silicon using COMSOL Multiphysics. Based on the review, two configurations of high-temperature LHS have been illustrated to produce continuous and cost-effective electricity. The first layout is high-temperature LHS coupled with 3rd generation (Gen) CST and the second one is a standalone high-temperature LHS device with Thermionic-photovoltaic (TIPV) diode.

Silicon as high-temperature phase change medium for latent heat storage: A thermo-hydraulic study

Latent heat storage (LHS) using high-temperature phase change medium (PCM) can provide cost-competitive solutions for dispatchable solar power and accumulate surplus Photo-voltaic (PV) and wind power. Moreover, at a sufficiently high temperature, the round trip efficiency of LHS system may approach that of electrochemical storage system. A conceptual LHS system utilizing high-temperature silicon as the phase change medium (PCM) is presented in the article. Silicon is chosen due to its high melting point (1414 °C), latent heat (1.8 × 106 J/kg), and thermal conductivity (25–50 W/mK). The thermo-hydraulic behavior during melting of silicon is modeled using a combined numerical methodology in COMSOL Multiphysics. The thermal performance of proposed system is compared against high-temperature salt-based system for different aspect ratios (AR). Results indicate that silicon systems are significantly superior to high-temperature salts under the same operating conditions. The anomalous behavior of silicon melting is established by demonstrating natural convection pattern in molten silicon. A generalized correlation is developed to predict the melting fraction as a function of Rayleigh number, Stefan number, and Fourier number for various domain sizes.