Search Results (500)

With the continuous growth in global energy consumption and the increase in the proportion of energy use attributed to buildings, the development of highly efficient and energy-saving building materials has become necessary for reducing energy demands and greenhouse gas emissions. Phase change materials (PCMs) exhibit great potential for enhancing the thermal inertia of buildings owing to their ability to efficiently absorb and release latent heat during phase transitions. In this study n-hexadecane@ polymethyl methacrylate (16-MMWS-K) microcapsules (where “@” denotes the core-shell encapsulation structure) with a crosslinked structure were successfully prepared via emulsion polymerization, using n-hexadecane as the core material and polymethyl methacrylate as the shell. The prepared microcapsules were incorporated into a cement matrix to fabricate a phase-change energy-storage composite material. The morphology, structure, and thermal properties of the microcapsules, as well as their effects on the thermal and mechanical performance of the cement composites, were systematically investigated. The prepared 16-MMWS-K microcapsules exhibited a well-defined core–shell structure, excellent thermal stability, and a suitable phase-change temperature. Increasing the microcapsule content significantly enhanced the thermal energy storage capacity of the cement composites, reduced thermal conductivity, improved hydrophobicity, and demonstrated effective temperature regulation in building simulation experiments. This study provides both theoretical insight and experimental evidence supporting the practical application of 16-MMWS-K microcapsules in cement composites.The 28-day compressive strength (51.7 MPa) remains acceptable despite higher porosity and slight strength reduction. Full article

Decarbonizing heavy-duty logistics requires powertrains that integrate novel topology design, degradation-aware optimization, and robust dynamic performance under real-world operational loads. While solid oxide fuel cells offer high efficiency, their application in transportation is hindered by thermal fatigue. This study proposes a novel hybrid powertrain topology integrating a metal-supported solid oxide fuel cell (SOFC), a micro gas turbine (MGT), and an aluminum–silicon phase change material (PCM) thermal buffer. A high-fidelity dynamic model is developed and coupled with a multi-objective optimization framework to size the PCM buffer and battery pack, balancing capital expenditure and system lifetime. Furthermore, a degradation-aware energy management strategy based on a thermal state-of-charge metric is introduced. Simulations over a 10 h dynamic drive cycle indicate that the optimal configuration (120 kg PCM, 80 kWh battery) extends the SOFC’s simulated remaining useful life to 38,400 h, a 2.5-fold improvement over unbuffered systems. Concurrently, the proposed energy management strategy reduces the MGT mechanical wear index by 98% compared to conventional load-following strategies. The system demonstrates robust performance across ambient temperatures from −20 °C to +45 °C and achieves a 22% reduction in projected capital expenditure compared to standard proton exchange membrane fuel cell powertrains. This topology offers a highly durable and economically viable pathway for next-generation zero-emission heavy-duty vehicles. This work addresses a critical gap in the literature: the lack of integrated thermal buffering and degradation-aware control strategies for high-temperature fuel cell systems in dynamic vehicular applications. By coupling a physical latent heat buffer with a novel Thermal-SOC-proportional Energy Management Strategy, the proposed architecture directly targets the primary degradation mechanisms that have historically impeded SOFC commercialization in heavy-duty transport. Full article

The low thermal conductivity of phase-change materials (PCMs) remains a primary barrier to rapid charging in shell-and-tube latent heat thermal energy storage (LHTES). This work proposes a hierarchical multi-branch Y-shaped fin network with extended conductive pathways and evaluates its performance through a two-stage numerical framework, including two-dimensional (2D) geometric screening of fin topology and arrangement followed by three-dimensional (3D) simulations under practical operating conditions. The enthalpy-porosity method and the Boussinesq approximation are used to resolve transient melting and buoyancy-driven convection in RT35 paraffin. In the 2D comparison, the optimized multi-branch topology improves temperature uniformity and advances the melting front more effectively than finless and straight-fin structures, reducing complete melting time by 68.6% and 41.4%, respectively. Rotational arrangement further affects the coupling between conductive paths and natural-convection cells; the best arrangement shortens melting time by 29.8% relative to alternative layouts. In the 3D model, increasing inlet velocity from 0.06 to 0.16 m/s reduces melting time by 44.3% but produces limited gains in stored energy, indicating diminishing returns at high flow rate. Increasing inlet temperature from 333 to 363 K is more influential, reducing melting time by 47.9%, increasing stored energy by 10.6%, and raising average heat-flux density from 500.10 to 1062.16 W/m². The results demonstrate that the hierarchical branched fin network accelerates thermal charging by redistributing and extending conductive pathways, while inlet temperature governs both melting kinetics and final storage capacity. Full article

Passive thermal energy storage materials are effective for reducing cooling demand in hot climates. Paraffin-based phase change materials (PCMs) provide high latent heat storage but suffer from low thermal conductivity. This study investigates dolomite-enhanced paraffin PCM composites using locally sourced UAE minerals. Composites containing 5.7 wt.% and 11.4 wt.% dolomite were prepared and evaluated using controlled heating and cooling experiments with thermocouple monitoring. Results showed melting plateaus of approximately 55–60 °C for the baseline PCM, 59–64 °C for the 5.7 wt.% dolomite composite, and 56–60 °C for the 11.4 wt.% dolomite composite, while all samples exhibited stable solidification near 55–56 °C. Dolomite addition did not significantly alter phase transition temperature but slightly increased melting duration due to higher thermal mass, while maintaining stable thermal energy storage performance. Full article

Offshore wind turbine blades in cold marine environments are exposed to low-temperature, high-humidity, and saline-droplet conditions, under which the melting behavior, interfacial sliding, and de-icing energy demand of saline ice differ from those of freshwater ice. Existing studies on combined phase-change coating–electrothermal de-icing have mainly focused on freshwater icing. Here, a glass-fiber-reinforced polymer (GFRP) NACA0018 airfoil was tested in a recirculating low-temperature icing wind tunnel to evaluate an n-tetradecane phase-change microcapsule/polyurethane (PCMS-PUR) coating combined with electrothermal heating at a salinity of 3%. Operating parameters, including heat flux density (8, 10, and 12 kW/m²), ambient temperature (−5, −10, and −15 °C), and incoming wind speed (3, 6, and 9 m/s), were systematically varied under a constant water flow rate (60 mL/min) and spray pressure (0.3 MPa) to characterize the evolution of ice morphology, temperature response, and de-icing energy consumption. During electrothermal de-icing, saline ice was more prone to interfacial softening and lubricating meltwater-layer formation, resulting in a dominant whole-block sliding detachment mode rather than gradual local melting. The PCMS-PUR coating further promoted interfacial melting and advanced ice destabilization through latent-heat release and thermal buffering. When the heat flux density increased from 8 to 12 kW/m², the de-icing energy consumption of the uncoated and coated blades decreased by 45.08% and 42.53%, respectively. The maximum energy-saving efficiency of the combined system reached 16.27% at 9 m/s. These findings clarify the de-icing behavior and energy-saving potential of combined phase-change coating–electrothermal systems under saline icing and provide guidance for the design of low-energy de-icing systems for offshore wind turbine blades. Full article

Thermal regulation of lithium-ion (Li-ion) battery modules is a critical constraint for electric vehicle (EV) safety and durability, particularly during high-C-rate operation. Phase change materials (PCMs) have emerged as promising passive solutions due to their latent heat storage capability; however, current literature is heavily biased toward organic paraffin-based systems and lacks structured benchmarking across PCM categories and integration architectures. This review provides a systematic comparative assessment of PCM-based battery thermal management systems (BTMSs) comprising organic, inorganic, and eutectic materials under EV-relevant discharge conditions. The review is structured according to the conventional classification of PCMs; however, the available literature is predominantly focused on organic materials, particularly paraffin-based PCMs, leading to greater depth of analysis for this category. Thermophysical properties are analyzed in conjunction with discharge rate, module configuration, and hybrid cooling strategies. The results indicate that peak temperature mitigation is weakly correlated with latent heat magnitude when thermal conductivity remains below critical values. Conductivity-enhanced composites incorporating expanded graphite or metal foams significantly improve heat diffusion, reducing hotspot intensity and inter-cell temperature gradients under medium-to-high C-rates. Pure passive PCM systems exhibit thermodynamic limitations during sustained high-power operation due to saturation effects, underscoring the need for hybrid architectures for continuous heat rejection. This work establishes a structured benchmarking framework and demonstrates that effective thermal conductivity, integration strategy, and discharge-dependent design dominate BTMS performance over latent heat alone. The findings also reveal that inorganic and eutectic PCM-based BTMSs remain comparatively less explored in the literature, particularly at the battery module level and under realistic electric vehicle operating conditions, highlighting opportunities for future research. Full article

This study numerically investigates the thermo-energetic behaviour of partitioned cavity walls integrating hypothetical phase change material (PCM) arrangements with single and staggered transition temperatures under cyclic thermal excitation representative of building-envelope operating conditions. The investigated configurations included single-PCM cases with transition temperatures of $20 °\mathrm{C}$, $22 °\mathrm{C}$, and $24 °\mathrm{C}$, as well as two staggered multi-PCM arrangements, namely $(20,22,24 °\mathrm{C})$ and $(24,22,20 °\mathrm{C})$. A two-dimensional transient numerical model based on the enthalpy–porosity approach was developed and validated against previously published numerical and experimental studies available in the literature. Several thermo-energetic indicators were introduced, including temperature amplitude reduction, damping factor, heat-flux attenuation, thermal time lag, cumulative transmitted thermal energy, and liquid-fraction evolution. A normalized multi-objective thermo-energetic assessment was additionally performed to identify the most balanced PCM arrangement. The results demonstrated that the $20 °\mathrm{C}$ PCM provided the strongest indoor-side thermal attenuation, reducing the temperature amplitude and heat-flux amplitude at facet $x8$ by $66.34\%$ and $62.20\%$, respectively, while increasing the thermal time lag to approximately $7.41\mathrm{h}$. The liquid-fraction analysis further revealed that latent heat activation remained strongly localized and spatially selective within the partitioned cavity structure. The staggered multi-PCM arrangements generated broader and spatially redistributed latent heat activation patterns, promoting more progressive thermal regulation over time. In particular, the $(20,22,24 °\mathrm{C})$ arrangement produced the highest partial latent activation, with a maximum liquid fraction approaching $0.1596$, corresponding to the highest latent activation ratio observed in the present study (≈15.96%), whereas the reversed arrangement $(24,22,20 °\mathrm{C})$ provided enhanced indoor-side stabilization associated with delayed and spatially redistributed latent heat activation. The combined thermo-energetic assessment further revealed important trade-offs between peak thermal damping, delayed thermal response, and distributed latent heat activation. Overall, the obtained findings demonstrate that both PCM transition temperature and spatial ordering strongly influence the transient thermal behaviour of partitioned cavity walls and should therefore be carefully considered in the design of adaptive PCM-integrated building envelopes. Full article

To address heat accumulation, localized hot spots, and non-uniform temperature distribution in large-capacity lithium iron phosphate energy storage battery modules under high ambient temperature and high-rate charge/discharge conditions, this study proposes a fin-enhanced phase change material (PCM)-air hybrid thermal management structure for a 100 Ah prismatic lithium iron phosphate battery and a 2P18S energy storage battery module. First, the battery thermal model is validated using single-cell experimental data reported in the literature. Subsequently, a three-dimensional transient fluid–solid coupled heat transfer model is established by considering transient battery heat generation, PCM solid–liquid phase change, air-side flow and heat transfer, and temperature-dependent thermophysical properties. User-defined functions are employed to implement the transient heat source and temperature-dependent material properties. Under identical boundary conditions, the thermal management performances of three configurations, namely Fin-Air, PCM-Air, and Fin-PCM-Air, are compared. The effects of ambient temperature (20 °C, 25 °C, and 30 °C) and inlet air velocity (1 m/s, 2 m/s, and 3 m/s) on the maximum module temperature, temperature uniformity, PCM liquid fraction evolution, and flow field distribution are quantitatively analyzed. The results show that, compared with the Fin–Air system without PCM and the PCM-Air system without fins, the Fin-PCM-Air configuration reduces the maximum module temperature by 1.57% and 0.25%, respectively, at an ambient temperature of 30 °C and an inlet air velocity of 3 m/s. After four charge–discharge cycles, the peak maximum temperature of the module is approximately 38.56 °C, and the peak maximum temperature difference remains below 3.6 K, indicating good temperature uniformity and latent heat buffering capability. In addition, the air velocity trade-off analysis indicates that increasing the inlet air velocity can improve cooling performance but also increases the air-channel pressure drop and fan power consumption. Therefore, the Fin-PCM-Air structure is more suitable for high-thermal-load conditions, and its practical application should comprehensively consider cooling benefits, additional mass, manufacturing cost, and long-term reliability. This study provides a reference for the design and engineering application of hybrid thermal management structures for large-capacity energy storage battery modules. Full article

Power batteries used in electric-powered vessels, new-energy tractors or construction machinery typically require prolonged, continuous operation at high power levels, which can lead to significant heat buildup and pose serious threats to battery safety, cycle life, and operational stability. Traditional air-cooled and liquid-cooled systems struggle to meet the requirements for efficient heat dissipation under heavy loads. Phase change materials (PCMs) are ideal for passive battery thermal management due to their high latent heat but are severely limited by low thermal conductivity and liquid leakage. In this study, nitrogen-doped carbon nanotubes@SiO₂ (PNT@SiO₂) were synthesized and further fabricated into oriented porous aerogels by directional freeze-drying using cellulose-based materials as the skeleton. Polyethylene glycol-8000 (PEG-8000) was loaded via vacuum impregnation to obtain the PSAP composite PCM. The optimized composite exhibits a thermal conductivity of 0.93 W/m·K, 3.2 times that of pure PEG, with 96% PEG loading and a phase change enthalpy of 158 J/g. Battery thermal management tests demonstrate its excellent temperature control and heat suppression performance. This study provides a high-performance and feasible thermal management solution for power batteries used in relevant fields. Full article

Phase change materials (PCMs) are increasingly incorporated into façades and wall systems to enhance passive thermal regulation; however, their fire safety remains poorly understood. While PCMs effectively reduce cooling loads, limited data exist on their behaviour under real fire exposure. In this study, the thermal response of PCM-integrated concrete panels was investigated through two-dimensional finite element modelling using an apparent heat-capacity formulation that accounts for phase change, latent-heat absorption, and encapsulation softening. Simulations were performed under the ISO 834 standard fire curve and constant furnace exposures between 200 °C and 800 °C for 60 min to evaluate insulation performance and encapsulation stability. Results show that PCM melting at approximately 31 °C provides a 20–25 min delay in rear-face temperature rise under moderate fire exposure (≤400 °C), maintaining the rear-face temperature increase below 180 °C for one hour. Beyond 500 °C, the acrylonitrile butadiene styrene (ABS) encapsulation softens near 95 °C, suppressing latent-heat storage and leading to rear-face temperatures between 260 °C and 360 °C. Comparative analyses indicate that organic PCMs lose effectiveness rapidly unless protected by at least a 25 mm concrete cover, whereas inorganic PCMs exhibit superior stability owing to their non-combustibility and endothermic dehydration behaviour. The results identify performance trends, thermal limitations, and design considerations for the investigated PCM–ABS–concrete assembly under the studied fire exposure conditions. The validated experimental–numerical framework provides insight into the thermal response of PCM-integrated concrete assemblies and supports future development of fire-resilient building-envelope components. Full article

Phase change materials (PCMs) have been widely investigated for latent thermal energy storage in building envelopes; however, conventional single-melting-point PCMs often exhibit limited adaptability under dynamically varying thermal conditions. This study investigates the thermodynamic feasibility of hybrid-melting-point PCMs to improve transient thermal regulation in multilayer building wall systems. A transient numerical model was developed to evaluate wall assemblies incorporating single and hybrid PCM configurations under structured dynamic thermal loading conditions representing mild, hot, and cold regimes. To isolate the influence of melting-point distribution, hybrid systems containing multiple phase-transition temperatures were compared against conventional single-transition PCM systems with identical total latent heat capacities. The results demonstrate that distributing melting thresholds broadens the effective activation temperature range and enhances attenuation of indoor temperature fluctuations under varying thermal loads. Compared with the conventional single-melting-point system, the proposed hybrid configuration reduced peak indoor temperature by up to 18.5% and increased the minimum indoor temperature by up to 51.9%. Additional material-level simulations revealed that staged phase transitions promote sequential latent heat activation and prolong thermal buffering behavior. The findings suggest that hybrid-melting-point PCMs can improve the transient thermal adaptability of PCM-integrated building envelopes without increasing total latent heat storage capacity. The present study is intended as an exploratory thermodynamic feasibility assessment rather than a climate-specific annual building-energy prediction framework. Full article

The rapid development of cold chain logistics has generated a strong demand for high-performance phase change materials (PCMs). In this study, a composite PCM (CPCM) applicable to 5 °C cold chain logistics, integrated with PVA/CMC-Na hydrogel to maintain form stability, is developed. N-Tetradecane and water are employed as the primary cold storage media in the composite. Span 80, Tween 80 and borax are introduced into the composite as homogenizing agents and supercooling depressant, respectively. The main preparation steps of the CPCM include aqueous phase preparation, emulsifier compounding, oil-phase preparation, blending, homogenization, and molding, in sequence. Experimental results demonstrate that the CPCM exhibits a phase transition temperature of 0–5 °C, a latent heat of 236.2 J/g, a supercooling degree of no more than 0.5 °C, and a volume expansion ratio of 3%. Therefore, the CPCM is able to satisfy the cold storage demand for cold chain transportation with a target temperature of approximately 5 °C, and can serve as a superior-performance alternative to the PCMs currently used for similar applications in the market. Full article

As the power density of office computing clusters rises to 200–250 W per chip, the substantial heat generated during operation not only impairs chip performance and shortens lifespan but also compels heating, ventilation, and air conditioning (HVAC) systems to operate at high loads. This increases energy consumption by 30–40% and causes indoor temperature fluctuations that reduce office workers’ comfort. Targeting centralized thermal management for such clusters, this study proposes a hybrid cooling strategy integrating outdoor natural cold air (as a continuous heat sink) with phase change materials (PCMs, for transient heat peak absorption). Six adjustable heating plates (power range: 50–250 W per unit, simulating 7 nm office chips) mimicked heat dissipation in a six-chip cluster. Latent heat storage (LHS) units served as passive cooling, with fan coils as auxiliary for natural/forced convection. By using PCMs (melting point: 48 °C) to absorb transient peaks and coils to utilize outdoor cold air, the system maintained circulating water at approximately 60 °C (steady-state equilibrium temperature under full-load conditions) and kept chip temperatures below 80 °C (industrial safety threshold). The hybrid system reduced combined pump and fan power to 125 W, achieving 75% energy savings compared to the HVAC system (500 W) and 40% savings compared to using only natural cold air (210 W pump and fan power). Positive pressure in the outdoor unit (increasing coil air velocity by 1.2 m/s relative to natural convection) further improved heat dissipation efficiency by 15%. Finally, this study quantifies the influence of PCM thermal conductivity and filling mass on the system’s temperature control performance through numerical simulations, providing direct evidence for parameter design of LHS units. Full article

Buildings account for a substantial proportion of global energy consumption and greenhouse-gas emissions, largely due to the widespread use of conventional heating, ventilation, and air-conditioning (HVAC) systems. Hybrid systems that integrate passive and active technologies have emerged as a promising strategy for reducing energy demand while maintaining adequate indoor environmental conditions. This study evaluates the thermal and airflow performance of a hybrid air-conditioning system (HACS) that combines transparent thermal insulation (TTI) filled with R-410A refrigerant and a pig-fat-based organic phase-change material (PCM). Experimental measurements of heat flux, temperature, airflow velocity, and CO₂ concentration were conducted in a controlled prototype system. In parallel, computational simulations were performed using computational fluid dynamics (CFD) and multizone airflow modeling. The hybrid system incorporates a TTI container acting as a solar absorber and a galvanized-steel PCM container filled with 10 kg of pig fat used as latent heat storage. Heat-flux measurements were obtained using an HFS-5 sensor connected to a data acquisition system, while airflow velocity and temperature were monitored with analog data loggers. Indoor CO₂ concentrations were recorded using a dedicated CO₂ meter and simulated using CONTAMW software version 3.4.0.8. The experimental results show that the TTI and PCM containers reached average heat-flux values of 77.04 W/m² and 55.31 W/m², respectively. Airflow within the system is induced by buoyancy forces arising from temperature gradients generated by heat transfer processes at the surfaces of the TTI and PCM, resulting in a mixed air stream with an average temperature of 37.54 °C during winter operation. Recorded CO₂ concentrations remained between 290 and 413 ppm, indicating high indoor air quality levels. The overall experimental campaign spanned 6 years and 3 months. CFD simulations confirmed the airflow patterns and heat-transfer behavior observed experimentally. The findings demonstrate that hybrid air-conditioning systems combining refrigerant-filled transparent insulation with bio-based phase-change materials can effectively enhance passive thermal performance while maintaining acceptable indoor air quality. The integration of photovoltaic-powered ventilation systems could further the operational autonomy and overall energy efficiency of such hybrid systems. Full article

To mitigate the spatiotemporal mismatch between renewable energy supply and building heating demand, this study proposes a novel non-pressurized shell-and-tube latent heat storage (NP-LHS) device coupled with an air-source heat pump (ASHP) system. To overcome the inherent low thermal conductivity of organic phase change materials (PCMs), the thermal performances of plain, corrugated, and finned tubes were systematically compared using both computational fluid dynamics (CFD) simulations and full-scale experiments. Numerical results indicate that the optimal tube spacing ratio ranges from 1.0 to 1.5. Among the evaluated geometries, the finned tube configuration exhibited superior comprehensive performance. It achieved an exceptionally high PCM volume fraction of 92.5% and dramatically reduced the complete melting time to 180 min—significantly faster than both corrugated (280 min) and bare tubes—while attaining a higher terminal temperature. Full-cycle dynamic experiments further demonstrated that integrating the finned tube NP-LHS into the ASHP system yielded a peak-shaving power reduction rate of 98.0%, effectively maintaining indoor thermal comfort. These findings conclude that expanding the conductive surface area via fins is practically more effective than inducing fluid turbulence for low-conductivity PCMs in non-pressurized storage applications. Full article