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For the numerical simulation of a heat storage based on phase change materials (PCMs) an enhanced model is presented, considering the physical effects of convection flow in the liquid phase as well as the volume change during phase change. A modified heat capacity is used to realize the phase change. The phase change material is initially defined as a liquid with temperature-dependent material properties. A volume force is added to the Navier-Stokes equations to allow a circulating flow field in the liquid phase and prevent flow motion in the solid phase. The volume change is implemented with the Arbitrary Lagrangian-Eulerian method. A laboratory phase change experiment was performed using the PCM RT42 with a melting temperature of 42 °C. The laboratory experiment was calculated numerically using the enhanced model to evaluate the numerical model and to investigate the influence of the simulation parameters on the thermal behavior of the PCM. The thermal conductivity is determined as the main influencing parameter. A good agreement of the simulated melting front throughout a major part of the laboratory experiment has been shown. COMSOL Multiphysics provides a default model for phase change, which neglects convection flow and volume change. Compared to the default model, the enhanced model achieves more accurate results but requires more computational cost for complex latent heat storage systems. Using the default model without convection can be reasonable, considering that the heat storage design is either over-dimensioned or a suitable correction factor must be applied.

Optimization techniques, particularly meta-heuristic algorithms, are highly effective in optimizing and enhancing efficiency across diverse models and systems, renowned for their ability to attain optimal or near-optimal solutions within a reasonable timeframe. In this work, the Puma Optimizer (PO) is proposed as a new optimization algorithm inspired from the intelligence and life of Pumas in. In this algorithm, unique and powerful mechanisms have been proposed in each phase of exploration and exploitation, which has increased the algorithm’s performance against all kinds of optimization problems. In addition, a new type of intelligent mechanism, which is a type of hyper-heuristic for phase change, is presented. Using this mechanism, the PO algorithm can perform a phase change operation during the optimization operation and balance both phases. Each phase is automatically adjusted to the nature of the problem. To evaluate the proposed algorithm, 23 standard functions and CEC2019 functions were used and compared with different types of optimization algorithms. Moreover, using the statistical test T-test and the execution time to solve the problem have been discussed. Finally, it has been tested using four machine learning and data mining problems, and the results obtained from all the analysis signifies the excellent performance of this algorithm against all kinds of problems compared to other optimizers. This algorithm has performed better than the compared algorithms in 27 benchmarks out of 33 benchmarks and has obtained better results in solving the clustering problem in 7 data sets out of 10 data sets. Furthermore, the results obtained in the problems of community detection and feature selection and MLP were superior. The source codes of the PO algorithm are publicly available at https://www.mathworks.com/matlabcentral/fileexchange/157231-puma-optimizer-po .

Phase change energy storage (PCES) materials have attracted considerable interest because of their capacity to store and release thermal energy by undergoing phase changes. This paper offers a thorough examination of the latest developments in PCES materials (PCESMs) and their wide‐ranging applications in several industries. The text focuses primarily on the most recent advances in the design and creation of PCESMs. It emphasizes the investigation of new phase change materials (PCMs) that possess specific features, such as high latent heat, thermal conductivity, and cycling stability. The study investigates advanced methods such as nano structuring, hybridization, and encapsulation to improve the efficiency and dependability of PCESMs. PCESMs are employed in the construction industry for passive solar heating, thermal regulation, and energy‐efficient building designs. They facilitate effective thermal dissipation in electronics, hence, improving the efficiency and durability of electronic devices. Moreover, PCESMs are essential in enabling the incorporation of intermittent energy sources like solar and wind power into the grid, hence, supporting renewable energy storage. Furthermore, the research examines upcoming patterns and potential outcomes in the domain of PCESMs, including the progress of versatile PCES composites, integration with intelligent materials, and breakthroughs in thermal energy conversion technologies. These advancements have enormous promise to tackle worldwide energy concerns, decrease greenhouse gas emissions, and promote sustainable development. Recent advancements in PCESMs have opened up opportunities for their extensive use in many industries, providing inventive solutions for effective energy storage, thermal regulation, and ecological sustainability. Ongoing research and technological breakthroughs in this field are anticipated to propel further advancements and facilitate the achievement of a more environmentally friendly and energy‐efficient future.

HighlightsA core–sheath structured phase change nanocomposite (PCN) with aligned and overlapping interconnected BNNS networks were successfully fabricated.The PCN has an ultrahigh in-plane thermal conductivity (28.3 W m−1 K−1), excellent flexibility and high phase change enthalpy (101 J g−1).The PCN exhibits intensively potential applications in the thermal management of 5G base stations and thermoelectric generators.Thermal management has become a crucial problem for high-power-density equipment and devices. Phase change materials (PCMs) have great prospects in thermal management applications because of their large capacity of heat storage and isothermal behavior during phase transition. However, low intrinsic thermal conductivity, ease of leakage, and lack of flexibility severely limit their applications. Solving one of these problems often comes at the expense of other performance of the PCMs. In this work, we report core–sheath structured phase change nanocomposites (PCNs) with an aligned and interconnected boron nitride nanosheet network by combining coaxial electrospinning, electrostatic spraying, and hot-pressing. The advanced PCN films exhibit an ultrahigh thermal conductivity of 28.3 W m−1 K−1 at a low BNNS loading (i.e., 32 wt%), which thereby endows the PCNs with high enthalpy (> 101 J g−1), outstanding ductility (> 40%) and improved fire retardancy. Therefore, our core–sheath strategies successfully balance the trade-off between thermal conductivity, flexibility, and phase change enthalpy of PCMs. Further, the PCNs provide powerful cooling solutions on 5G base station chips and thermoelectric generators, displaying promising thermal management applications on high-power-density equipment and thermoelectric conversion devices.

Phase change memory (PCM) is an emerging technology that combines the unique properties of phase change materials with the potential for novel memory devices, which can help lead to new computer architectures. Phase change materials store information in their amorphous and crystalline phases, which can be reversibly switched by the application of an external voltage. This article describes the advantages and challenges of PCM. The physical properties of phase change materials that enable data storage are described, and our current knowledge of the phase change processes is summarized. Various designs of PCM devices with their respective advantages and integration challenges are presented. The scaling limits of PCM are addressed, and its performance is compared to competing existing and emerging memory technologies. Finally, potential new applications of phase change devices such as neuromorphic computing and phase change logic are outlined.

While polymorphism is prevalent in crystalline solids, polyamorphism draws increasing interest in various types of amorphous solids. Recent studies suggested that supercooling of liquid phase-change materials (PCMs) induces Peierls-like distortions in their local structures, underlying their liquid-liquid transitions before vitrification. However, the mechanism of how the vitrified phases undergo a possible polyamorphic transition remains elusive. Here, using high-energy synchrotron X-rays, we can access the precise pair distribution functions under high pressure and provide clear evidence that pressure can reverse the Peierls-like distortions, eliciting a polyamorphic transition in GeTe and GeSe. Combined with simulations based on machine-learned-neural-network potential, our structural analysis reveals a high-pressure state characterized by diminished Peierls-like distortion, greater coherence length, reduced compressibility, and a narrowing bandgap. Our finding underscores the crucial role of Peierls-like distortions in amorphous octahedral systems including PCMs. These distortions can be controlled through pressure and composition, offering potentials for designing properties in PCM-based devices. The subtle distortion in atomic structure underlies the drastic changes in the properties of amorphous phase-change materials. Here authors show that that pressure can reverse the Peierls-like distortions introduced by temperature, eliciting a polyamorphic transition in GeTe and GeSe.

Phase change cold storage materials are functional materials that rely on the latent heat of phase change to absorb and store cold energy. They have significant advantages in slight temperature differences, cold storage, and heat exchange. Based on the research status of phase change cold storage materials and their application in air conditioning systems in recent years, this paper provides an overview of the materials and their enhanced research progress. It summarizes the types of phase change cold storage air conditioning systems, optimization schemes, and system applications. This paper also identifies the current issues in phase change cold storage air conditioning and discusses the development trends in cold storage materials and air conditioning systems. It anticipates that future advancements will focus on composite phase change cold storage materials and low-energy consumption intelligent phase change cold storage air conditioning systems in steam compression using spherical capsules and concave–convex plate PCM.

The layered crystal structure of Cr2Ge2Te6 shows ferromagnetic ordering at the two‐dimensional limit, which holds promise for spintronic applications. However, external voltage pulses can trigger amorphization of the material in nanoscale electronic devices, and it is unclear whether the loss of structural ordering leads to a change in magnetic properties. Here, it is demonstrated that Cr2Ge2Te6 preserves the spin‐polarized nature in the amorphous phase, but undergoes a magnetic transition to a spin glass state below 20 K. Quantum‐mechanical computations reveal the microscopic origin of this transition in spin configuration: it is due to strong distortions of the CrTeCr bonds, connecting chromium‐centered octahedra, and to the overall increase in disorder upon amorphization. The tunable magnetic properties of Cr2Ge2Te6 can be exploited for multifunctional, magnetic phase‐change devices that switch between crystalline and amorphous states. This work demonstrates that Cr2Ge2Te6 preserves the spin‐polarized nature in the amorphous phase, but undergoes a magnetic transition to a spin glass state below 20 Kelvin. Ab initio simulations indicate that the presence of angular disorder and bonding distortions weakens the magnetic order in amorphous Cr2Ge2Te6, leading to the coexistence of ferromagnetic and antiferromagnetic couplings.

Nanophotonics has garnered intensive attention due to its unique capabilities in molding the flow of light in the subwavelength regime. Metasurfaces (MSs) and photonic integrated circuits (PICs) enable the realization of mass-producible, cost-effective, and efficient flat optical components for imaging, sensing, and communications. In order to enable nanophotonics with multipurpose functionalities, chalcogenide phase-change materials (PCMs) have been introduced as a promising platform for tunable and reconfigurable nanophotonic frameworks. Integration of non-volatile chalcogenide PCMs with unique properties such as drastic optical contrasts, fast switching speeds, and long-term stability grants substantial reconfiguration to the more conventional static nanophotonic platforms. In this review, we discuss state-of-the-art developments as well as emerging trends in tunable MSs and PICs using chalcogenide PCMs. We outline the unique material properties, structural transformation, and thermo-optic effects of well-established classes of chalcogenide PCMs. The emerging deep learning-based approaches for the optimization of reconfigurable MSs and the analysis of light-matter interactions are also discussed. The review is concluded by discussing existing challenges in the realization of adjustable nanophotonics and a perspective on the possible developments in this promising area.

The construction industry is responsible for consuming large amounts of energy. The development of new materials with the purpose of increasing the thermal efficiency of buildings is, therefore, becoming, imperative. Thus, during the last decades, integration of Phase Change Materials (PCMs) into buildings has gained interest. Such materials can reduce the temperature variations, leading to an improvement in human comfort and decreasing at the same time the energy consumption of buildings, due to their capability to absorb and release energy from/in the environment. In the present paper, recent experimental studies dealing with mortars or concrete-containing PCMs, used as passive building systems, have been examined. This review is mainly aimed at providing information on the currently investigated materials and the employed methodologies for their manufacture, as well as at summarizing the results achieved so far on this subject.