Phase Change Material Research Articles

Effect of graphite powder on thermal behavior of phase change material

The effect of graphite powder on the thermal behavior of phase change material (PCM) was investigated experimentally. It is well known that the graphite is contributed to enhance the thermal response. However, the effect of graphite on the supercooling of the PCM is not clear when a highly heat conductive material is added. In this study, the specific heat of the PCM based on sugar alcohol such as D-mannitol and inositol was measured with an adiabatic scanning calorimeter. The enthalpy and entropy during the phase-change process were obtained by the measured specific heat of the PCM. Additionally, the exergy analysis was conducted to evaluate the thermal energy storage of PCM. As the experimental results, the specific heat of D-mannitol during the phase change process was higher than that of inositol. Moreover, it was found that the addition of graphite powder at the mass fraction of 9% improves the thermal behavior of D-mannitol with lower supercooling while maintaining latent heat. The suppression of supercooling by the addition of 9% graphite powder was 37.5%.

Comparative Study and Recommendations for Thermal Performance Enhancement of Energy Storage Materials: Mono, Binary and Ternary Nano-enhanced Organic Phase Change Materials

Comparative Study and Recommendations for Thermal Performance Enhancement of Energy Storage Materials: Mono, Binary and Ternary Nano-enhanced Organic Phase Change Materials

Research progress on efficient battery thermal management system (BTMs) for electric vehicles using composite phase change materials with liquid cooling and nanoadditives

Research progress on efficient battery thermal management system (BTMs) for electric vehicles using composite phase change materials with liquid cooling and nanoadditives

Comprehensive study on thermal properties and application of phase change materials in construction

Comprehensive study on thermal properties and application of phase change materials in construction

Preparation and characterization of high-enthalpy inorganic hydrated salt phase change materials based on sodium silicate precursor

Preparation and characterization of high-enthalpy inorganic hydrated salt phase change materials based on sodium silicate precursor

Numerical Analysis of the Thermal Performance of a Hybrid Heat Sink Comprised of Perforated Foam Fins Embedded Within a Phase Change Material

ABSTRACTThis study presented a numerical model to evaluate a novel design of a hybrid heat sink incorporating perforated foam fins (PFFs) instead of solid fins (SFs) within a phase change material (PCM). This innovation is designed to enhance thermal performance in electronic cooling applications. The base of the heat sink was subjected to constant heat fluxes of 2, 3, and 4 kW/m2. The effect of the perforation location (top, center, and bottom) within the foam fin and foam porosities (0.85, 0.90, and 0.95) were investigated. The results showed that the hybrid PFF design demonstrably improved thermal efficiency compared to the SF configuration. This innovative approach offered three benefits: a significant reduction in overall heat sink weight, an augmentation of the thermal conductivity of PCM, and the intermixed molten PCM between the fins passages through perforations. The PFF heat sink extended the operational time by 6%–8% for the range of heat fluxes at SPT of 70°C and led to a 24.5% increase in PCM volume, compared to the SF configuration. Complete melting of the PCM in the PFF heat sink is observed at 29 min for the highest heat flux of 4 kW/m2, while the melting rates are 25% and 62% for the applied heat flux of 2 and 3 kW/m2. Perforation location within the foam fin (top, center, and bottom) achieved equivalent heat transfer capabilities, enabling design flexibility for perforation location. The PFF with a porosity of 0.85 demonstrated superior thermal performance.

ICT for Smart and Energy-Efficient Buildings

The article examines the application of new technologies and ICT for the construction of intelligent and energy-efficient buildings. The state of the housing stock in Bulgaria is presented. The idea of using solar tiles both as a roof and as a photovoltaic source of electrical energy is substantiated. Other elements of the smart home management system are also described. The construction of a thermal energy storage system using phase change materials is given, as well as a thermometer for the blind, facilitating the life of visually impaired people at home.

A Periodic Horizontal Shell-And-Tube Structure as an Efficient Latent Heat Thermal Energy Storage Unit

Thermal energy storage systems utilising phase change materials offer significantly higher energy densities compared to traditional solutions, and are therefore attracting growing interest in both research and application fields. However, the further development of this technology requires effective methods to enhance thermal efficiency. We propose a horizontal periodic shell-and-tube structure as an efficient latent heat thermal energy storage unit. This research aims to analyse heat transfer not only between the tube containing the heat transfer fluid and the phase change material but also between adjacent shell-and-tube units. The results obtained for a single cell within the periodic structure are compared with those of reference single shell-and-tube units with insulated adiabatic and highly conductive shells. The enthalpy–porosity approach, combined with the Boussinesq approximation, is applied to address the heat transfer challenges encountered during melting and solidification. The periodic horizontal shell-and-tube structure proves to be an efficient latent heat thermal energy storage unit with short melting and solidification times. In contrast, the non-periodic case with neglected conduction in the shell increases the melting and solidification times by 213.8% and 21%, respectively. The shortest melting and solidification times were recorded for the case with a periodic horizontal shell-and-tube structure and shell aspect ratios of 0.44 and 1, respectively.

Simulation of Magnetic Field Effects on Heat and Mass Transfer in a Porous Spline Half‐Cylinder Using ANN and ISPH Approaches

ABSTRACTThis study utilizes Artificial Neural Networks (ANNs) and Incompressible Smoothed Particle Hydrodynamics (ISPH) simulations to explore the effects of magnetic fields on heat and mass transfer in a porous spline half‐cylinder filled with Nano‐Encapsulated Phase Change Material (NEPCM). Simulations were conducted over a range of physical parameters: buoyancy ratio () from −2 to 2, Darcy number () from 10−5 to 10−2, Hartmann number () from 0 to 50, Rayleigh number (Ra) from 103 to 106, and fusion temperature from 0.05 to 0.9. The results demonstrate that increasing the Ha reduces heat transfer efficiency by up to 15%, as the magnetic field stabilizes fluid flow and enhances conduction. Conversely, increasing the Ra improves heat transfer efficiency by approximately 25% due to enhanced convection and mixing. The buoyancy ratio significantly influences fluid flow, with higher values favoring concentration‐driven buoyancy, while lower values enhance temperature‐driven convection. The Da affects permeability, with higher values promoting convective heat transfer and dynamic flow, whereas lower values result in stable, conductive heat transfer. Fusion temperature impacts phase change behavior, affecting heat capacity and flow dynamics through latent heat absorption. These insights underscore the critical role of optimizing these parameters to enhance performance in applications such as thermal energy storage and industrial processes involving phase change materials.

Nonlinear chiroptical response in lithium niobate metasurface driven by quasi-bound states in the continuum

Quasi-bound states in the continuum (QBIC) can significantly localize the light field and enhance light–matter interactions at the nanoscale, providing a platform for high-Q chiral light response and promoting nonlinear effects of materials. In this work, we numerically study the chiral linear and nonlinear light responses of the QBIC lithium niobate (LN) metasurface and achieve chirality modulation. The designed metasurface consists of LN nanobar dimers, and the chiral QBIC mode is excited by breaking the in-plane and out-of-plane symmetries of the structure, with the circular dichroism (CD) value and Q-factor reaching 0.92 and 1.24×104, respectively. Then, we investigate the second harmonic generation (SHG) of this device. The conversion efficiency of SHG under right circularly polarized pumping reaches 7.3×10−3, which is more than three orders of magnitude higher than that under the left circularly polarized pumping. The corresponding CD value of SHG reaches 0.99. In addition, by introducing phase change materials, we study the active modulation of the chiroptical response. Our results provide a crucial route for high-quality chiral light sources.

Impacts of Double Rotating Cylinders on the Forced Convection of Nanoencapsulated Phase Change Material

ABSTRACTMany engineering and industrial applications rely on heat transfer (HT) as a basic and central process. Therefore, engineers and researchers place significant emphasis on optimizing HT rates. Here, we numerically attempt to maximize the heat transmission rate of mixed convection of nanoencapsulated phase change material in a square compartment. The compartment is differentially heated and incorporates two cold rotating cylinders. The Galerkin finite element approach is utilized for addressing the system governing equations. A range of various factors affecting the thermal activity in the compartment were considered. These factors include the speed of spinning cylinders (Re = 0–1000), the porousness of the compartment (Da = 10−5–10−2), the magnetic field intensity (Ha = 0–100), and the concentration of nanoadditives (ϕ = 0%–8%). The obtained numerical findings demonstrated that the thermal activity inside the compartment is positively correlated to the speed of the spinning cylinders, the concentration of nanoadditives, and the porousness of the compartment. In contrast, increasing the intensity of the magnetic field obstructs the heat transmission. It was noted that at the highest Re number, the average Nusselt number augmented by 257% and 13.6% when increasing Da and ϕ, respectively.

Point-of-Care Diagnostics Using Self-heating Elements from Smart Food Packaging: Moving Towards Instrument-Free Nucleic Acid-Based Detection.

Compromising between accuracy and rapidity is an important issue in analytics and diagnostics, often preventing timely and appropriate reactions to disease. This issue is particularly critical for infectious diseases, where reliable and rapid diagnosis is crucial for effective treatment and easier containment, thereby reducing economic and societal impacts. Diagnostic technologies are vital in disease modeling, tracking, treatment decision making, and epidemic containment. At the point-of-care level in modern healthcare, accurate diagnostics, especially those involving genetic-level analysis and nucleic acid amplification techniques, are still needed. However, implementing these techniques in remote or non-laboratory settings poses challenges because of the need for trained personnel and specialized equipment, as all nucleic acid-based diagnostic techniques, such as polymerase chain reaction and isothermal nucleic acid amplification, require temperature cycling or elevated and stabilized temperatures. However, in smart food packaging, there are approved and commercially available methods that use temperature regulation to enable autonomous heat generation without external sources, such as chemical heaters with phase change materials. These approaches could be applied in diagnostics, facilitating point-of-care, electricity-free molecular diagnostics, especially with nucleic acid-based detection methods such as isothermal nucleic acid amplification. In this review, we explore the potential interplay between self-heating elements, isothermal nucleic acid amplification techniques, and phase change materials. This paves the way for the development of truly portable, electricity-free, point-of-care diagnostic tools, particularly advantageous for on-site detection in resource-limited remote settings and for home use.

Design and Simulation of Flat Plate Collector With a Tube Rotation and Phase Change Materials Sn3N4‐LiNO3‐KNO3/Boron‐Arsenide for Enhanced Efficiency

ABSTRACTSolar thermal energy is crucial in our transition to renewable energy sources. Recent studies have focused on enhancing the efficiency of solar collectors by minimizing thermal energy loss during absorption. A promising approach involves an innovative design that integrates phase change materials (PCMs) and rotating tubes to capture thermal energy more effectively. Advanced nitride‐based salt hydrates, with boron‐arsenide additives, enhance thermal performance of the collector. In a flat plate collector using composite PCMs, radiative heat loss decreases from 250 to 210 W (a 6% reduction) with tube rotation, while convective heat loss drops from 225 to 195 W (a 4% decrease). The decomposition rate of the novel PCMs is low, measuring only 0.5% at a maximum temperature of 850°C, with a specific heat capacity of up to 4.50 W/m K. This unique blend, including the Sn₃N₄‐LiNO₃‐KNO₃/boron arsenide mixture, enhances thermal conductivity by 30%, significantly improving thermal absorption rates. The exergy efficiency achieved with the Nano‐enhanced phase change materials (NEPCM) and tube rotation reaches an impressive 90%. With tube rotation at 3 rad/min, the flat plate collector's efficiency improves by 22%, reaching an overall efficiency of 90% at a fluid flow rate of 25 kg/h. Simulations using Anaconda Jupyter Notebook and Python validate the effectiveness of both tube rotation and NEPCM in enhancing collector efficiency.

Controlling Temporally and Spatially Homogeneous Temperature Distribution of Paper Substrates by Biogenic Phase Change Hybrid Material Coatings

AbstractHere the performance of phase change material (PCM)‐coated paper made from unbleached kraft pulp is introduced. The applied PCM consists of a mixture of ethylene glycol distearate (EGDS), a well‐known PCM wax material, and a fully substituted cellulose stearoyl ester (CSE). Transfer of the PCM material onto/into paper is achieved by spray as well as blade coating of EGDS + CSE mixture. It is shown that the kind of coating method used does not interfere with observed PCM properties. The significantly higher melt viscosity of the EGDS + CSE blends ensures that the EGDS wax is not bleeding out of the paper, which avoids the use of further encapsulation processes. The PCM behavior, as observed by thermal load measurements, and the thermal buffering of the coated paper is a function of the applied mass of the PCM material applied. The thermal retention exhibited a quasi‐isothermal behavior at ≈65 °C with EGDS + CSE coatings. These effects can offset fluctuations in temperature, and the PCM papers can be employed to achieve a more uniform temperature setting. PCM‐modified papers are therefore interesting candidates for paper‐based packaging or for use in paper‐based sensors, where overheating can strongly affect reliability of results.

Optimization of Thermal Management for the Environmental Worthiness Design of Aviation Equipment Using Phase Change Materials

A phase change materials (PCM)-based heat sink is an effective way to cool intermittent high-power electronic devices in aerospace applications such as airborne electronics and aircraft external carry. Optimizing the heat sink is significant in designing a compact and efficient system. This paper proposes an optimization procedure for the PCM/expanded graphite (EG)-based heat sink to minimize the temperature of the heat source. The numerical model is built to estimate the thermal response, and a surrogate model is fitted using the Kriging model. An optimization algorithm is constructed to predict the optimum parameters of the heat sink, and the effects of heat sink volume, heat flux, and working time on the optimal parameters of the heat sink are investigated. This shows that the numerical results agree well with the experimental data, and the proposed optimization method effectively obtains the optimal EG mass fraction and the geometric dimensions of the PCM enclosure. The optimal EG mass fraction increases with the rise in heat sink volume and decreases with the increase in heat flux and working time. The optimal ratio of the height to the length of the heat sink is 0.43. This study provides practical guidance for the optimal design of a PCM/EG-based heat sink.

Three-Dimensional CFD Analysis of a Hot Water Storage Tank with Various Inlet/Outlet Configurations

This study presents a comprehensive 3D numerical analysis of thermal stratification, fluid dynamics, and heat transfer efficiency across six hot water storage tank configurations, identified as Tank-1 through Tank-6. The objective is to determine the most effective design for achieving uniform temperature distribution, stable stratification, and efficient heat retention in sensible heat storage systems, with potential for integration with phase change materials (PCMs). Using COMSOL Multiphysics 5.6, simulations were conducted to evaluate key performance indicators, including the Richardson number, capacity ratio, and exergy efficiency. Among the tanks, Tank-1 demonstrated the highest efficiency, with a capacity ratio of 84.6% and an exergy efficiency of 72.5%, while Tank-3, which achieved a capacity ratio of 70.2% and exergy efficiency of 50.5%, was identified as the most practical for real-world applications due to its balanced heat distribution and feasibility for PCM integration. Calculated dimensionless numbers (Reynolds number: 635, Prandtl number: 4.5, and Peclet number: 2858) indicated laminar flow and dominant convective heat transfer across all the configurations. These findings provide valuable insights into the design of efficient thermal storage systems, with Tank-3’s configuration offering a practical balance of thermal performance and operational feasibility. Future work will explore the inclusion of PCM containers within Tank-3, as well as applications for heat pump and solar water heaters, and high-temperature heat storage with various working fluids.

Substrate induced composition change during Ge2Sb2Te5 atomic layer deposition and study of initial reactions on SiO2 surface

Ge2Sb2Te5 (GST) is a well-known phase change material used in nonvolatile memory devices, photonics, and nonvolatile displays. This study investigates the impact of precursor sequence during atomic layer deposition (ALD) of GST from GeCl2.C4H8O2, SbCl3, and Te[(CH3)3Si]2 on Si/SiO2 substrates, focusing on growth per cycle, morphology, and composition along with initial precursor reactions on the substrate. We found that while thick layers approach stoichiometric Ge2Sb2Te5, a Ge-rich interfacial layer is initially formed, regardless of the binary ALD sequence used to start the deposition (GeTe vs Sb2Te3). Starting the ALD process with the GeTe-Sb2Te3 sequence results in a higher Ge content near the GST/SiO2 interface compared to the Sb2Te3-GeTe sequence. To understand these phenomena, we examine the initial precursor reactions on the SiO2 substrate by total reflection x-ray fluorescence spectrometry. The analysis reveals that SbCl3 exhibits lower reactivity with the SiO2 substrate than GeCl2.C4H8O2, and not all Ge adspecies react with the Te[(CH3)3Si]2 precursors. Additionally, the impact of the initial SiO2 surface on deposition extends over several ALD cycles, as the SiO2 surface only gradually gets covered by GST due to island growth. These processes contribute to the formation of a Ge-rich GST layer at the interface, irrespective of the precursor pulse sequence. These insights from the study may contribute to optimizing the initial deposition stages of GST and other ternary ALD processes to enable better composition control and enhanced device performance.

Theoretical Design of Smart Bionic Skins with Self-Adaptive Temperature Regulation.

Thermal management presents a significant challenge in electric design, particularly in densely packed electronic systems. This study proposes a theoretical model for radiative bionic skin that emulates human skin, enabling the self-adaptive modulation of the thermal exhaustion rate to maintain homeostasis for objects covered by the skin in fluctuating thermal environments. The proposed artificial skin consists of phase change material (VO2) nanoparticles embedded in a low-loss matrix situated on a metallic substrate with a minimal thickness of several micrometers. The findings from our theoretical analyses indicate that substantial alterations in thermal radiation power around the phase transition temperature of 340 K enable a silicone substrate to sustain a relatively stable temperature, with variations confined to ±6 K, despite external heat fluxes ranging from 150 to 450 W/m2. Furthermore, to improve the spectral resemblance to natural skin, a plasmonic surface composed of self-assembled silver nanocubes is incorporated, allowing for modifications to the visible light properties of the bionic skin while maintaining its infrared characteristics. This theoretical investigation offers a cost-effective and conformal approach to the design of ultra-compact, fully passive, and versatile thermal management solutions for robotic systems and related technologies.

Analysis of the Properties and Thermal Behavior of Low-Temperature Phase Change Materials (PCMs) That Can Be Applied in Heating and Ventilation Systems.

This article analyses the use of low-temperature PCMs in devices supplementing a room ventilation system to prevent the overcooling effect. In this study, the phase change is numerically simulated in an axisymmetric system consisting of two tubes. One is filled with RT11HC with an initial temperature of 0 °C, while air with an inlet temperature of 20 °C flows through the other, heating the PCM and causing it to melt. Calculations are performed using commercial software with the apparent heat method for a system of given dimensions. Spatial distributions of the system temperature and liquid volume fraction at different time moments (from 0 to 120 min) are determined. It is found that the results depended mainly on the method of determining the latent heat. For the beginning of the charging process (t < 40 min), the values of the liquid phase fraction determined by the H and S methods are similar, while the one determined by the G method is definitely higher (even three times at t = 10 min). In turn, the outlet air temperature determined by the S method is lower than that determined by the other methods. The size and shape of the mesh have no significant effect on the results.

Dual-Phase Singularity at a Single Incident Angle with Spectral Tunability in Tamm Cavities.

The phase singularity, a sudden phase change occurring at the reflection zero is widely explored using various nanophotonic systems such as metamaterials and thin film cavities. Typically, these systems exhibit a single reflection zero with a phase singularity at a specific incident angle, particularly at larger angles of incidence (>50 degrees). However, achieving multiple phase singularities at a single incident angle remains a formidable challenge. Here, the existence of a dual-phase singularity is experimentally demonstrated at a lower incident angle using a tunable Tamm plasmon polariton (TPP) cavity that consists of gold-coated ultralow-loss phase change material Sb2S3-based distributed Bragg reflector. It can excite narrowband TPP resonances from normal incidence to a wide angle of incidence for both s- and p-polarizations of light. Notably, this TPP cavity shows dual-phase singularity at lower angles of incidence since the excited TPP for s- and p-polarizations exhibits zero reflection at slightly different wavelengths for the same incident angle. A TPP cavity-based scalable hydrogen sensor is proposed and shows that the dual-phase singularity can further improve the sensitivity of singular phase-based sensing approaches. Moreover, spectrally tunable dual-phase singularity is experimentally demonstrated at a lower incident angle using a metal-free Tamm cavity.