Search Results (1,371)

The article presents a novel, energy-efficient composite of clinoptilolite and an organic phase change material (PCM), exhibiting a greater heat storage capacity than would be expected based solely on the PCM content within the composite. The study included a structural and textural analysis of clinoptilolite powder as a fine-grained material, with particular emphasis on its properties and compatibility with paraffin-based phase change materials. The second stage of the research involved determining changes in the enthalpy of melting and solidification of the composites, as well as evaluating their ability to retain the liquid phase and confirming the absence of chemical reactions between individual composite components. The obtained results demonstrated an increase in the enthalpy of the composite by approximately 14% and 44% relative to the expected values for PCM contents of 50% and 40%, respectively. Furthermore, the approximate content of paraffin-based PCM in the clinoptilolite composite at which no leakage occurs during the melting process was determined. This work represents a new approach to the integration of porous materials and phase change materials, enabling the formation of energetically favorable structures that significantly enhance the effective thermal storage capacity of PCM-based composites. Full article

Paraffins are attractive as phase-change materials (PCMs) due to their high latent heat capacity and adjustable phase transition temperatures. However, the individual high-purity paraffins, especially the long-chain ones, are labor-intensive and costly to produce and capable of storing and releasing latent heat only within a limited temperature range. Herein, we demonstrate the feasibility of a high-purity paraffin wax fraction (C13–C49) obtained via the Fischer–Tropsch (FT) process as a versatile latent heat storage additive within a wide range of phase transition temperatures (8.1–98.2 °C). To avoid the leakage, the FT wax was encapsulated via nanoemulsion interfacial polymerization of melamine formaldehyde (MF) shells with various core-to-monomer and melamine/formaldehyde ratios. Differential scanning calorimetry revealed that the latent heat storage capacity of the FT/MF capsules was 104.5–163.4 J/g depending on the FT loading efficiency, with the heat storage and release range of −0.7–100.2 °C and −9.8–85.8 °C, respectively. The capsules were tested as a thermoregulating additive to commercially available gypsum plaster. Unlike employment of the additives based on individual paraffins, the addition of FT/MF capsules led to a smooth reduction in heating/cooling rates of plaster layers in an extended temperature range. This makes FT/MF capsules a promising and versatile additive for a diversity of thermal energy storage applications. Full article

Engineering systems increasingly demand multifunctional and energy-efficient integration within constrained volume and energy budgets. One promising solution is the monolithic integration of components and functions to minimize occupied volume and simplify control interfaces. Paraffin-based phase change material (PCM) actuators provide high mechanical work density and can be coupled with thermoelectric generators (TEGs) for multifunctional operation. However, their dynamic response is typically constrained by the intrinsically low thermal conductivity of PCM materials. This work introduces a quasi-monolithic fabrication method for a fully integrated TEG-PCM system combining standard four-layer printed circuit board (PCB) technology and CNC milling. By constructing the system as a quasi-monolithic block, thermal interface materials are considerably reduced, thereby diminishing parasitic thermal resistance and promoting faster heat transport from the TEG to the PCM cavity. The system is fabricated using CNC milling with high depth resolution enabled by an electrical sensing-via structure. Experimental validation shows a 76% improvement in displacement rate (15.03 µm/s) at half the input power (1 W) compared to a conventional hybrid-assembled TEG-PCM actuator system consisting of a commercial TEG and an aluminum PCM container. The exploitation of the PCM as a thermal flux modulator for energy harvesting has been preliminarily investigated; considering the measured 5 K temperature difference sustained during a simulated short “day–night” cycle, an estimated open-circuit voltage of ∼13.5 mV is expected to be retrieved under load-match conditions. The actuator is compatible with PCB-based power management and thermal routing, enabling scalable incorporation into compact microsystems and multifunctional MEMS devices. Full article

Mobile thermal energy storage (M-TES) demonstrates significant commercialization potential in industrial waste heat recovery, distributed heating, and clean heating applications, which is primarily based on three technical pathways: sensible heat storage, latent heat storage using phase change materials (PCMs), and thermochemical heat storage. The updated status of M-TES, mainly on PCMs and thermochemical ones, and the challenges facing application were reviewed, and potential development trends were discussed in the present study. Sensible heat storage is relatively mature and cost-effective; however, it suffers from low energy density and comparatively high heat loss during storage and transport. Latent heat storage utilizes the phase transition enthalpy of PCMs to store thermal energy, offering higher energy density and near-isothermal heat release, making it a focal point of current academic and industrial research. Nevertheless, latent heat storage still faces technical bottlenecks, including low thermal conductivity, phase separation, and supercooling of PCMs. Thermochemical heat storage relies on reversible chemical reactions to convert and store thermal energy as chemical energy, theoretically achieving the highest energy density and minimal heat loss. However, due to its technical complexity and high system cost, thermochemical storage remains largely in the early stages of research and demonstration. Overall, as a bridge between heat supply and demand, the development trend emphasizes the design of high-performance composite PCMs, enhanced system integration, and intelligent operational management. However, its large-scale deployment is still constrained by challenges related to energy density, heat transfer enhancement, long-term material stability, and techno-economic feasibility. Full article

With the accelerated transformation of green shipping and the advancement of ship electrification, lithium-ion batteries have become the core solution for ship propulsion due to their advantages of high energy density and zero emission. Efficient thermal management serves as a key technical support to ensure the safe and stable operation of batteries, extend their service life, and mitigate the risk of thermal runaway. Lithium-ion batteries accumulate heat during discharge, and pure phase change material (PCM) cooling systems are limited by low thermal conductivity, leading to excessive battery temperature rise and poor temperature uniformity. To address this problem, RT42 (a paraffin-based PCM with a melting temperature range of 311.15–316.15 K) was selected as the PCM in this study. The battery thermal management system (BTMS) coupling RT42 with a three-dimensional fin network structure was designed. Numerical simulations were conducted via ANSYS Fluent, and the enthalpy-porosity method was adopted to simulate the PCM phase change process. The effects of fin distribution, spacing and layer number on BTMS performance were systematically investigated and compared. Results show that the heat transfer process in the PCM can be significantly improved due to the three-dimensional fin network, and the battery maximum temperature can be reduced by 7.53 K compared with the pure PCM system. This study provides theoretical support for the design and optimization of high-efficiency BTMS. Full article

Phase change material (PCM)-based latent heat storage (LHS) systems help address the mismatch between renewable energy supply and thermal demand. However, their practical implementation is constrained by the strongly nonlinear and multiphysics nature of phase change, which makes high-fidelity simulations and real-time applications computationally expensive. This review examines mathematical reduced-order modeling (ROM) as an effective strategy to overcome this limitation by combining physics-based simplifications, projection methods, interpolation techniques, and data-driven models for PCM-based LHS systems. While physical simplifications (such as dimensional reduction and effective property approximations) represent an important first layer of model reduction, the primary focus of this work is on the mathematical ROM methodologies that operate on the governing equations after such physical simplifications have been applied. The review covers approaches including two-temperature non-equilibrium and analytical thermal-resistance models, Proper Orthogonal Decomposition (POD), CFD-derived look-up tables, kriging and ε-NTU grey/black-box metamodels, and machine-learning methods such as artificial neural networks and gradient-boosted regressors trained from CFD data. These ROM techniques have been applied to packed beds, PCM-integrated heat exchangers, finned enclosures, triplex-tube systems, and solar thermal components, achieving speed-ups from tens to over 80,000 times faster than full CFD simulations while maintaining prediction errors typically below 5% or within sub-Kelvin temperature deviations. A critical comparative analysis exposes the fundamental trade-off between interpretability, data dependence, and computational efficiency, leading to a practical decision-making framework that guides method selection for specific applications such as design optimization, real-time control, and system-level simulation. Remaining challenges—including accurate representation of phase change nonlinearity, moving phase boundaries, multi-timescale dynamics, generalization across geometries, experimental validation, and integration into industrial workflows—motivate a structured roadmap for future hybrid physics–machine learning developments, standardized validation protocols, and pathways toward industrial deployment. Full article

This study addresses a critical methodological gap in evaluating building envelope performance in hot, arid climates, the overreliance on annual energy indicators, which fail to capture transient thermal behavior during peak-load periods. In such environments, instantaneous heat gains, their intensity, and temporal distribution are decisive factors for cooling demand, occupant comfort, and grid stability. To overcome this limitation, a dynamic evaluation framework—the Thermal Adaptation Rating (TAC) system—is proposed. TAC integrates three interrelated indices—peak temperature reduction (ΔT_peak), relative peak cooling load reduction (ΔP_peak, %), and peak thermal delay (Δt_delay), representing thermal damping, load intensity mitigation, and temporal redistribution, respectively. A typical residential building in Karbala was modeled in DesignBuilder using the EnergyPlus engine, with inputs documented and calibration performed against real consumption data following ASHRAE standards (MBE and CV(RMSE)) to ensure reliability. The study examined advanced envelope systems, including thermochromic glass (TG), phase-change materials (PCMs), aerogel materials (AMs), and hybrid combinations. Results revealed that while AM achieved the greatest annual energy savings, its impact on instantaneous cooling load was limited. PCM, by contrast, effectively mitigated and delayed peak loads, enhancing thermal comfort (PMV/PPD). Hybrid systems, particularly TG-PCM, delivered the most balanced performance, simultaneously reducing peak cooling load and shifting its occurrence to reshape the cooling demand curve during critical periods. These findings demonstrate that annual indices alone are insufficient for evaluating envelope performance in extreme climates. Peak-condition analysis, expressed in terms of instantaneous cooling load, as operationalized through TAC, provides a more accurate representation of thermal behavior and offers a practical tool to guide envelope design decisions in hot, dry regions. Full article

Thermal management is critical for maintaining the safety and performance of lithium-ion batteries. Phase change materials (PCMs) have been widely studied as passive cooling media due to their high latent heat capacity, but major technical challenges remain due to their relatively low thermal conductivity and nanoparticle sedimentation in composite systems. In this work, a composite phase change material (PCM) consisting of paraffin wax, a microencapsulated phase change material (MicroPCM 28D), and nano carbon black is developed to enhance thermal stability and suppress particle sedimentation through increased viscosity of the PCM matrix. Five capsule geometries fabricated by fused filament fabrication (FFF) 3D printing are experimentally investigated under airflow velocities ranging from 0 to 10 m s⁻¹. Wind tunnel experiments with infrared thermography are used to evaluate the thermal response of the PCM capsules. The results show that airflow velocity and capsule geometry strongly influence heat dissipation behavior. Compared with conventional wax composites, the MicroPCM 28D composite capsules reduce peak temperature by approximately 2–4 °C under airflow velocities of 0–10 m/s. These findings provide insights into geometry-regulated convection and stable composite PCM design for lithium-ion battery thermal management systems. Full article

Freeze–thaw damage significantly reduces the performance and durability of airport pavements in cold regions. Traditional assessment methods, such as the F300 freeze–thaw test, are time-consuming and hinder rapid optimisation of mix design. In addition, previous studies have mostly relied on long-term laboratory testing and have evaluated phase-change concrete (PCC) independently, without considering synergistic effects. These approaches lack fast, synergy-aware predictive capability and interpretable tools for mix proportion design, resulting in a gap between laboratory research and practical engineering applications. To address this issue, this study proposes an intelligent and explainable framework for predicting freeze–thaw damage and guiding mix design of steel fibre-reinforced phase-change concrete (SF–PCC). A boundary-controlled experimental programme was first conducted, varying steel fibre (SF) content from 0 to 1.2% and phase-change material (PCM) content from 0 to 12% under fixed mixture conditions. The freeze–thaw test results were recorded sequentially and used to construct a supervised learning dataset. Then, an XGBoost model was developed to predict two key durability indicators: relative dynamic modulus of elasticity (RDEM) and mass loss. SHAP (SHapley Additive exPlanations) analysis was further applied to quantify feature importance and interaction effects. The model achieved high predictive accuracy (R² = 0.9938 for mass loss and R² = 0.9935 for RDEM) under controlled experimental conditions. After 300 freeze–thaw cycles, the reference mix exhibited an RDEM of 61.2%, while optimised configurations showed improved performance. The economical design (9% PCM + 0.9% SF) achieved an RDEM of 66.8%, and the high-performance design (12% PCM + 1.2% SF) reached 72.6%. These results demonstrate that the proposed framework can effectively enhance durability and support rapid preliminary decision-making. The framework significantly accelerates freeze–thaw performance evaluation by enabling near-instant prediction and serves as an efficient supplementary tool for mix design optimisation alongside conventional laboratory testing. It also provides interpretable, data-driven insights for the design of freeze–thaw-resistant airport pavement concrete in cold regions. Full article

Phase change thermal storage fibers with high latent heat have attracted significant attention in thermal management and heat storage. Through fiber encapsulation, shape-stable phase change materials can be prepared, thereby expanding their applications. In this study, electro-blown spinning was utilized to prepare phase change materials (PCM) using erythritol, with polyethylene oxide (PEO) as the carrier material. Coaxial thermal storage fibers encapsulating the phase change materials were prepared using polyvinyl alcohol (PVA) and polyvinylpyrrolidone (PVP). The results indicate that the composite fibers have a smooth surface, uniform and smooth morphology, a maximum latent heat of 223.01 J/g, as well as excellent thermal stability. The coaxial fibers exhibit a distinct core–shell structure, with the coaxial fibers encapsulated with PVA as the shell material, demonstrating a high latent heat of 118.62 J/g, a residual rate of 93.81% after heating, and excellent thermal performance. The encapsulation efficiency is 53%, effectively addressing the issue of erythritol leakage. The research results provide valuable guidance for the efficient preparation of erythritol coaxial thermal storage fibers. Full article

Phase change materials (PCMs) offer potential for passive thermal regulation in building envelopes through latent heat storage; however, their effectiveness remains strongly climate-dependent, and configurations optimized for one region often underperform in others. Existing evaluation approaches rely largely on location-specific simulations or surrogate models with limited climate transferability. This study develops a physics-informed, climate-aware machine-learning framework to assess PCM-integrated wall assemblies across diverse climates. A structured dataset of 720 EnergyPlus simulations was generated across nine PCM materials, ten ASHRAE climate zones, two placement configurations, and four thickness levels using automated model generation and batch simulation through Eppy-based workflows. Ensemble-based models (XGBoost, LightGBM, CatBoost, Random Forest) were trained under climate-grouped validation to predict total annual energy consumption, peak cooling demand, and peak heating demand. The models achieved high predictive accuracy for total annual energy use (R² ≈ 0.98–0.99) and peak cooling demand (R² ≈ 0.93–0.96), outperforming statistical, climate-only, and PCM-agnostic baselines. In contrast, peak heating demand showed low predictability (R² ≤ 0.26), indicating limited sensitivity to PCM parameters under the studied configuration. These results demonstrate that climate-aware validation enables defensible cross-climate PCM assessment, supporting energy demand reduction and sustainable envelope design decisions aligned with global building decarbonization goals. Full article

Metastructures, waveguides composed of multiple unit cells (meta-atoms), have gained significant attention for controlling wave propagation in engineering applications, especially in the context of elastic and acoustic waves. However, existing metastructures often lack sufficient tunable functionality to dynamically control both elastic vibration and acoustic wave transmission using a single external parameter. This study introduces a phase-change material (PCM)-embedded meta-atom, where a core mass is connected to an outer shell by Archimedean spiral bridges. The solid–liquid phase transition of PCM induces a notable change in the effective shear modulus, enabling dynamic wave control. The mechanism for bandgap formation transitions from Bragg scattering in the solid PCM state to local resonance in the liquid state. Core rotation, driven by the phase transition, is key to generating flat bands and low-frequency locally resonant bandgaps at high temperatures. Temperature-dependent, mode-selective transmission behavior is observed, with transverse vibrations and acoustic waves exhibiting opposite blocking and transmission characteristics at the same frequency. This design provides a promising approach for decoupling sound and vibration management, using temperature control driven by the PCM phase transition. The work contributes to multifunctional metastructures with applications in adaptive noise control, structural health monitoring, and tunable vibration isolation systems. Full article

Cold thermal energy storage (CTES) has emerged as a critical clean-energy technology for enhancing postharvest management in rural agricultural supply chains, where losses often exceed 20–40% due to inadequate cooling infrastructure and unreliable electricity. This review synthesizes the recent literature on CTES systems, including ice-, chilled-water-, and phase-change material (PCM)-based storage, with a focus on smart-farm integration, IoT-based monitoring, predictive control, and solar photovoltaic (PV) energy coupling. Trends in village-level cold rooms, micro-dairy milk cooling, and fruit–vegetable storage are critically examined, highlighting efficiency, resilience, and scalability relative to battery-dominant and conventional refrigeration systems. Current research gaps are identified in multi-scale modeling, PCM stability, state-of-charge estimation, techno-economic optimization, and AI-based operational strategies. Addressing these gaps is essential to realizing sustainable, low-carbon, and energy-efficient rural cold chains. Full article

To overcome the low thermal conductivity and flow channel clogging inherent in traditional phase change materials (PCMs) for immersion cooling, this study develops a novel oil-based phase change emulsion (PCE) integrating high thermal transport with adaptive rheological behavior. A liquid thermal conductivity enhancer was synthesized by modifying epoxidized soybean oil with LiTFSI and blending it with a synthetic ester to form a dielectric base fluid. A mid-to-low-temperature PCM (Span65) was then incorporated via surfactant-free ultrasonic emulsification. The resulting PCE exhibits a tunable phase-change window (25~40 °C) driven by interfacial confinement effects and a multiscale lamellar network. It achieves significantly enhanced thermal conductivity (15% increase over base oil) while maintaining excellent electrical insulation (<10⁻⁹ S/cm). Rheologically, the emulsion transitions from shear-thinning in the solid state to near-Newtonian in the liquid state, optimizing both suspension stability and pumping efficiency. This work establishes a strategy for designing high-performance, safe, and energy-efficient dielectric coolants, offering a robust solution for next-generation electronic and battery thermal management systems. Full article

This study integrates phase change material (PCM) with semi-transparent photovoltaic (PV) glazing to develop a composite window providing thermal buffering and PV temperature regulation in summer. A PCM-PV double glazing window (PCM-PV-DGW) using paraffin PCM and CdTe semi-transparent PV glass was fabricated and evaluated through outdoor hot-box experiments and transient modeling in Qingdao, China. Four window types—DGW, PCM-DGW, PV-DGW, and PCM-PV-DGW—were tested under identical boundary conditions. The coupled system showed improved photothermal performance, achieving a daily average Solar Heat Gain Coefficient (SHGC) of 0.105, compared with 0.180 for PV-DGW without PCM filling, together with a temperature attenuation factor of 0.904 and a 35 min peak temperature delay. A two-dimensional transient heat transfer model incorporating radiative transfer through semi-transparent layers and an enthalpy-based phase change method was established and validated against measured inner-surface temperatures, showing good agreement (RMSE 1.54–1.80 °C). Parametric and sensitivity analyses indicate that PCM phase transition temperature is the dominant parameter (suggested 28–32 °C), while ~12 mm PCM thickness and 50% PV coverage offer a practical balance for the Qingdao summer scenario. The results provide preliminary guidance for PCM–PV window design under the investigated summer conditions. Full article