Glacier landslide cascading hazards pose threats to communities and infrastructure,affected by complex processes including the amplification of mass flow volume through erosion and entrainment,transformation of hazard...Glacier landslide cascading hazards pose threats to communities and infrastructure,affected by complex processes including the amplification of mass flow volume through erosion and entrainment,transformation of hazard types,ice-water phase change,and enhanced mobility of the mass flow.Scientifically simulating these physical phenomena proves challenging.This study introduces GMFA(glacier mass flow analysis),an integrated numerical model that advances the field by:(1)proposing depth-averaged fluctuation energy and internal energy equations,(2)incorporating the ice-water phase change and the entrainment-deposition process,and(3)capturing their effects on mass flow runout characteristics.The model employs the finite volume method to solve the multi-physics coupled governing equations,enabling efficient large-scale simulations.The model is verified through three numerical tests covering flow dynamics,temperature evolution,and thermo-hydro-mechanical runout processes.The model is applied to analyze a hazard chain that occurred on 10 September 2020 on the Tibetan Plateau.The multi-scenario simulation results indicate an entrained mass volume of(4.95±0.11)×10^(5)m^(3),and a ratio of entrained mass volume to source material volume of 0.44.The solid concentration decreases from 0.6-0.7 to 0.1-0.15 with increasing runout distance,indicating a transition from avalanche to debris flood.The internal energy rises by(3-4)×10^(3)kJ/m^(3),driving rapid ice melting from 0.1 to 0.2 to near-zero concentration.The model effectively quantifies volume amplification,ice-water phase changes,and multi-hazard transformations.This model pushes the geoscience frontier,extending computational capability from single-to multi-hazard simulations and providing a powerful tool for analyzing glacier cascading hazards.展开更多
In the context of the global energy low-carbon transition,phase change energy storage technology becomes a key technology to solve the problem of intermittent renewable energy.Oriented phase change composites(OCPCMs)r...In the context of the global energy low-carbon transition,phase change energy storage technology becomes a key technology to solve the problem of intermittent renewable energy.Oriented phase change composites(OCPCMs)receive widespread attention in practical energy storage applications due to their unique oriented thermally conductive structure,which achieves significant thermal conductivity enhancement in specific directions while retaining the high energy storage capacity of the phase change components.This review systematically summarizes the overall analysis of OCPCMs from synthesis and preparation to application scenarios in recent years.Herein,we introduce the analysis of the heat transfer mechanism of the materials and explore the advantages of the oriented structure in OCPCMs in the heat transfer behavior from a bionic perspective.We then focus on summarizing and generalizing the methods for preparing OCPCMs,giving suggestions for suitable methods according to different scenarios.Besides,we discuss the application of finite element simulation methods to the monitoring of the thermal management behavior of OCPCMs,and look into the potential future application areas of such materials.Finally,it is hoped that this review will provide guidance for the academic community in developing high-performance OCPCMs.展开更多
To address the challenge of balancing thermal management and thermal runaway mitigation,it is crucial to explore effective methods for enhancing the safety of lithium-ion battery systems.Herein,an innovative hydrated ...To address the challenge of balancing thermal management and thermal runaway mitigation,it is crucial to explore effective methods for enhancing the safety of lithium-ion battery systems.Herein,an innovative hydrated salt composite phase change material(HSCPCM)with dual phase transition temperature zones has been proposed.This HSCPCM,denoted as SDMA10,combines hydrophilic modified expanded graphite,an acrylic emulsion coating,and eutectic hydrated salts to achieve leakage prevention,enhanced thermal stability,cycling stability,and superior phase change behavior.Battery modules incorporating SDMA10 demonstrate significant thermal control capabilities.Specifically,the cylindrical battery modules with SDMA10 can maintain maximum operating temperatures below 55°C at 4 C discharge rate,while prismatic battery modules can keep maximum operating temperatures below 65°C at 2 C discharge rate.In extreme battery overheating conditions simulated using heating plates,SDMA10 effectively suppresses thermal propagation.Even when the central heating plate reaches 300°C,the maximum temperature at the module edge heating plates remains below 85°C.Further,compared to organic composite phase change materials(CPCMs),the battery module with SDMA10 can further reduce the peak thermal runaway temperature by 93°C and delay the thermal runaway trigger time by 689 s,thereby significantly decreasing heat diffusion.Therefore,the designed HSCPCM integrates excellent latent heat storage and thermochemical storage capabilities,providing high thermal energy storage density within the thermal management and thermal runaway threshold temperature range.This research will offer a promising pathway for improving the thermal safety performance of battery packs in electric vehicles and other energy storage systems.展开更多
Latent heat thermal energy storage(TES)effectively reduces the mismatch between energy supply and demand of renewable energy sources by the utilization of phase change materials(PCMs).However,the low thermal conductiv...Latent heat thermal energy storage(TES)effectively reduces the mismatch between energy supply and demand of renewable energy sources by the utilization of phase change materials(PCMs).However,the low thermal conductivity and poor shape stability are the main drawbacks in realizing the large-scale application of PCMs.Promisingly,developing composite PCM(CPCM)based on porous supporting mate-rial provides a desirable solution to obtain performance-enhanced PCMs with improved effective thermal conductivity and shape stability.Among all the porous matrixes as supports for PCM,three-dimensional carbon-based porous supporting material has attracted considerable attention ascribing to its high ther-mal conductivity,desirable loading capacity of PCMs,and excellent chemical compatibility with various PCMs.Therefore,this work systemically reviews the CPCMs with three-dimensional carbon-based porous supporting materials.First,a concise rule for the fabrication of CPCMs is illustrated in detail.Next,the experimental and computational research of carbon nanotube-based support,graphene-based support,graphite-based support and amorphous carbon-based support are reviewed.Then,the applications of the shape-stabilized CPCMs including thermal management and thermal conversion are illustrated.Last but not least,the challenges and prospects of the CPCMs are discussed.To conclude,introducing carbon-based porous materials can solve the liquid leakage issue and essentially improve the thermal conductivity of PCMs.However,there is still a long way to further develop a desirable CPCM with higher latent heat capacity,higher thermal conductivity,and more excellent shape stability.展开更多
High-temperature phase change materials(PCMs)have attracted significant attention in the field of thermal energy storage due to their ability to store and release large amounts of heat within a small temperature fluct...High-temperature phase change materials(PCMs)have attracted significant attention in the field of thermal energy storage due to their ability to store and release large amounts of heat within a small temperature fluctuation range.However,their practical application is limited due to problems such as leakage,corrosion,and volume changes at high temperatures.Recent research has shown that macroencapsulation technology holds promise in addressing these issues.This paper focuses on the macroencapsulation technology of high-temperature PCMs,starting with a review of the classification and development history of high-temperature macroencapsulatd PCMs.Four major encapsulation strategies,including electroplating method,solid/liquid filling method,sacrificial material method,and powder compaction into sphere method,are then summarized.The methods for effectively addressing issues such as corrosion,leakage,supercooling,and phase separation in PCMs are analyzed,along with approaches for improving the heat transfer performance,mechanical strength,and thermal cycling stability of macrocapsules.Subsequently,the structure and packing arrangement optimization of macrocapsules in thermal storage systems is discussed in detail.Finally,after comparing the performance of various encapsulation strategies and summarizing existing issues,the current technical challenges,improvement methods,and future development directions are proposed.More attention should be given to utilizing AI technology and reinforcement learning to reveal the multiphysics-coupled heat and mass transfer mechanisms in macrocapsule applications,as well as to optimize material selection and encapsulation parameters,thereby enhancing the overall efficiency of thermal storage systems.展开更多
The urgent demand for renewable energy solutions,propelled by the global energy crisis and environmental concerns,has spurred the creation of innovative materials for solar thermal storage.Photothermal phase change ma...The urgent demand for renewable energy solutions,propelled by the global energy crisis and environmental concerns,has spurred the creation of innovative materials for solar thermal storage.Photothermal phase change materials(PTPCMs)represent a novel type of composite phase change material(PCM)aimed at improving thermal storage efficiency by incorporating photothermal materials into traditional PCMs and encapsulating them within porous structures.Various porous encapsulation materials have been studied,including porous carbon,expanded graphite,and ceramics,but issues like brittleness hinder their practical use.To overcome these limitations,flexible PTPCMs using organic porous polymers—like foams,hydrogels,and porous wood—have emerged,offering high porosity and lightweight characteristics.This review examines recent advancements in the preparation of PTPCMs based on porous polymer supports through techniques like impregnation and in situ polymerization,assessing the impact of different porous polymer materials on PCM performance and clarifying the mechanisms of photothermal conversion and heat storage.Subsequently,the most recent advancements in the applications of porous polymer-based PTPCMs are systematically summarized,and future research challenges and possible solutions are discussed.This review aims to foster awareness about the potential of PTPCMs in promoting environmentally friendly energy practices and catalyzing further research in this promising field.展开更多
Solar-thermoelectric generators(STEGs)capable of harnessing solar energy for conversion into clean electricity are pivotal for advancing towards carbon neutrality.The integration of phase change materials(PCMs)with ST...Solar-thermoelectric generators(STEGs)capable of harnessing solar energy for conversion into clean electricity are pivotal for advancing towards carbon neutrality.The integration of phase change materials(PCMs)with STEGs facilitates power generation regardless of solar radiation flux due to their robust thermal management capacity.However,the inherent solar-thermal conversion efficiency limitation of PCMs hinders the production of high and sustained electrical output.Herein,a multidimensional engineering strategy is proposed to align two-dimensional(2D)molybdenum disulfide(MoS_(2))nanosheets vertically in situ on a dodecahedron composed of zero-dimensional(OD)Co nanoparticles and three-dimensional(3D)high graphitized carbon derived from ZIF-67,thus significantly boosting the solar-thermoelectric energy generation of polyethylene glycol(PEG).The resultant PEG-Co/C@MoS_(2)composite PCMs exhibit a high solar-thermal conversion efficiency of 92.89%,benefiting from the synergy of multiple components and unique structural arrangements.When coupled with thermoelectric devices,this powerful STEG yields a high and durable output voltage of 197.51 mV and a current of 52.47 mA under 100 mW cm^(−2),outperforming the majority of previously reported literature.This PCM-integrated solar-thermoelectric generator overcomes limitations associated with temporal and meteorological variations,enabling simultaneous high-density heat and electricity generation for energy conservation and environmental sustainability.展开更多
We adopted the solution impregnation route with aluminum dihydrogen phosphate solution as liquid medium for effective surface modification on graphite substrate.The mass ratio of graphite to Al(H_(2)PO_(4))_(3) change...We adopted the solution impregnation route with aluminum dihydrogen phosphate solution as liquid medium for effective surface modification on graphite substrate.The mass ratio of graphite to Al(H_(2)PO_(4))_(3) changed from 0.5:1 to 4:1,and the impregnation time changed from 1 to 7 h.The typical composite phase change thermal storage materials doped with the as-treated graphite were fabricated using form-stable technique.To investigate the oxidation and anti-oxidation behavior of the impregnated graphite at high temperatures,the samples were put into a muffle furnace for a cyclic heat test.Based on SEM,EDS,DSC techniques,analyses on the impregnated technique suggested an optimized processing conditions of a 3 h impregnation time with the ratio of graphite:Al(H_(2)PO_(4))_(3) as 1:3 for graphite impregnation treatment.Further investigations on high-temperature phase change heat storage materials doped by the treated graphite suggested excellent oxidation resistance and thermal cycling performance.展开更多
Oriented graphene aerogels have limited applica-tions because the flexibility of their graphene sheets and mi-crostructure give them a low skeleton strength,insufficient compression resilience,and poor flexibility.We ...Oriented graphene aerogels have limited applica-tions because the flexibility of their graphene sheets and mi-crostructure give them a low skeleton strength,insufficient compression resilience,and poor flexibility.We report the preparation of novel aerogel materials with a much better per-formance.Using the driving force of graphene oxide(GO)self-assembly andπ-πinteractions,carbon nanotubes(CNTs)were attached to the GO sheets,and an oriented composite carbon skeleton was constructed using“hydro-plastic foam-ing”.The introduction of CNTs significantly increased the strength of the skeleton and gave the aerogel an excellent re-versible compressibility.The innovative use of cold pressing greatly improved the thermal conductivity and flexibility of the aerogel,providing new ideas for the development of high-performance aerogels.Tests show that the obtained graphene composite aerogel has a reversible compressive strain of over 90%and can withstand 500 compression cycles along the direc-tion of pore accumulation.It can endure more than 10000 bending cycles perpendicular to the direction of composite carbon layer stacking,and its in-plane thermal conductivity reaches 64.5 W·m^(-1)·K^(-1).When filled with phase change materials,the high porosity of the carbon skeleton enables the material to have a high phase change filling rate,and its phase change enthalpy is greater than 150 J/g.Thanks to the exceptional flexibility of the carbon skeleton,the macrostructure of phase change materials can be bent as needed to adapt to thermal management scenarios and conform to device shapes.This significantly enhances practical application compatibility,providing flexible support for temperature control and thermal management across diverse device forms.展开更多
With the rapid advancement of 5G communication technology,increasingly stringent demands are placed on the performance and functionality of phase change switches.Given that RF and microwave signals exhibit characteris...With the rapid advancement of 5G communication technology,increasingly stringent demands are placed on the performance and functionality of phase change switches.Given that RF and microwave signals exhibit characteristics of high frequency,high speed,and high precision,it is imperative for phase change switches to possess fast,accurate,and reliable switching capabilities.Moreover,wafer-level compositional homogeneity and resistivity uniformity during semiconductor manufacturing are crucial for ensuring the yield and reliability of RF switches.By controlling magnetron sputter of GeTe through from four key parameters(pressure,power,Ar flow,and post-annealing)and incorporating elemental proportional compensation in the target,we achieved effective modulation over GeTe uniformity.Finally,we successfully demonstrated the process integration of GeTe phase-change RF switches on 6-inch scaled wafers.展开更多
Incorporating microencapsulated phase change materials (MPCM) into mortar enhances building thermal energy storage for energy savings but severely degrades compressive strength by replacing sand and creating pores. Th...Incorporating microencapsulated phase change materials (MPCM) into mortar enhances building thermal energy storage for energy savings but severely degrades compressive strength by replacing sand and creating pores. This study innovatively addresses this critical limitation by introducing nano-silicon (NS) as a modifier to fill pores and promote hydration in MPCM mortar. Twenty-five mixes with varying NS content from 0 to 4 weight percent and different MPCM contents were comprehensively tested for flowability, compressive strength, thermal conductivity, thermal energy storage via Differential Scanning Calorimetry, and microstructure via Scanning Electron Microscopy. Key quantitative results showed MPCM reduced mortar consistency while NS had minimal effect. Crucially, although MPCM decreased compressive strength, NS addition significantly counteracted this loss. Increasing NS content from 0 percent to 4 percent enhanced compressive strength by 12.53%, 14.21%, 25.49%, 21.70%, and 40.70%, respectively, across the tested MPCM levels. Thermal conductivity was primarily reduced by higher MPCM content leading to lower conductivity, with NS showing negligible and inconsistent influence. The phase change temperature of the modified mortar matched that of pure MPCM, although its relative latent heat slightly decreased. This work conclusively demonstrates the novel and effective use of nano-silicon, achieving up to a 40.7 percent strength recovery in MPCM mortar while preserving its essential phase change temperature and thermal conductivity reduction capability. This strategy presents a feasible pathway for developing high-performance, energy-efficient building composites.展开更多
Considering the three typical phase-change related rock mechanics phenomena during drilling and production in oil and gas reservoirs,which include phase change of solid alkane-related mixtures upon heating,sand liquef...Considering the three typical phase-change related rock mechanics phenomena during drilling and production in oil and gas reservoirs,which include phase change of solid alkane-related mixtures upon heating,sand liquefaction induced by sudden pressure release of the over-pressured sand body,and formation collapse due to gasification of pore fillings from pressure reduction,this study first systematically analyzes the progress of theoretical understanding,experimental methods,and mathematical representation,then discusses the engineering application scenarios corresponding to the three phenomena and reveals the mechanical principles and application effectiveness.Based on these research efforts,the study further discusses the significant challenges,potential developmental trends,and research approaches that require urgent exploration.The findings disclose that various phase-related rock mechanics phenomena require specific experimental and mathematical methods that can produce multi-field coupling mechanical mechanisms,which will eventually instruct the control on resource exploitation,evaluation on disaster level,and analysis of formation stability.To meet the development needs of the principle,future research efforts should focus on mining more phase-change related rock mechanics phenomena during oil and gas resources exploitation,developing novel experimental equipment,and using techniques of artificial intelligence and digital twins to implement real-time simulation and dynamic visualization of phase-change related rock mechanics.展开更多
Flexible phase change materials(PCMs)have become increasingly critical to address the demand for thermal management in electronic technologies and energy conversion.However,their application remains challenging becaus...Flexible phase change materials(PCMs)have become increasingly critical to address the demand for thermal management in electronic technologies and energy conversion.However,their application remains challenging because of their rigidity,liquid leakage,and insufficient thermal conductivity.Herein,flexible glutamic acid@natural rubber/paraffin wax(PW)/carbon nanotubes-graphene nanoplatelets(GNR/PW/CGNP)phase change composites with high thermal conductivity,excellent shape stability,and recyclability were reported.Zn^(2+)-based dynamic crosslinking was constructed through the reaction of zinc acetate and carboxyl groups on glutamic acid@natural rubber(GNR),which was used as a flexible matrix to physically blend with paraffin wax/carbon nanotubes/graphene nanoplatelets(PW/CGNP)to achieve uniform dispersion of PW/CGNP,continuous thermal conductivity networks,and good encapsulation of PW.The GNR/PW/CGNP composites showed excellent mechanical strength,flexibility,and recycling ability,and effective encapsulation prevented the outflow of melted PW during the phase transition.Also,the phase change enthalpy could attain 111.1 J/g with a higher thermal conductivity of 1.055 W/m K,428%higher than that of pure PW owing to the formation of efficient thermal conductive pathways,which exhibited outstanding thermal management performance and superior temperature control behavior in electronic devices.The developed flexible composite PCMs may open new possibilities for next-generation flexible thermal management electronics.展开更多
With the continuously increasing awareness of energy conservation and the intensifying impacts of global warming, Personal Thermal Management (PTM) technologies are increasingly recognized for their potential to ensur...With the continuously increasing awareness of energy conservation and the intensifying impacts of global warming, Personal Thermal Management (PTM) technologies are increasingly recognized for their potential to ensure human thermal comfort in extreme environments. Biomimetic structures have emerged as a novel source of inspiration for PTM applications. This review systematically summarizes the biomimetic structures, phase change materials, manufacturing methods, and the performance of multifunctional PTM wearables. Firstly, it analyzes the biomimetic structures with thermal regulation and encapsulated phase change material functionalities from different dimensions, highlighting their applications in PTM. Subsequently, it outlines the conventional manufacturing methods incorporating various biomimetic structures, offering strategies for the production of PTM wearables. The review also discusses the typical performance characteristics of multifunctional PTM wearables, addressing the current demands in thermal management. Finally, opportunities and challenges in PTM field are proposed, proposing new directions for future research.展开更多
Latent heat thermal energy storage(LHTES)is an attractive method for enhancing the functionality and availability of renew-able energy sources,and it is extensively used to support concentrated solar power technologie...Latent heat thermal energy storage(LHTES)is an attractive method for enhancing the functionality and availability of renew-able energy sources,and it is extensively used to support concentrated solar power technologies.The main feature of every LHTES sys-tem is a phase change material(PCM),i.e.,a substance used to absorb/release energy upon cyclic melting/solidification.This study in-vestigates the potential of ferro-alloys as high-performance PCM candidates,targeting energy storage capacities exceeding 1 MWh·m^(−3),and operational temperatures above 1000°C.A thermodynamic assessment of binary and ternary Fe-based systems,alloyed with Si,B,Cr,V,and Ti,was conducted to identify compositions with optimal phase transition characteristics and heat storage potential.The results highlight the significant potential of the Fe-Si-B system,where boron’s exceptionally high latent heat enhances energy storage capacity despite challenges posed by its high melting point and cost.The Fe-Si-Cr system revealed promising alloys,such as Fe-34Si-38Cr and Fe-34Si-43Cr,offering excellent energy storage density and favorable phase transition temperatures.In the Fe-Si-V system,vanadium additions produced alloys like Fe-36Si-14V and Fe-34Si-10V,which meet energy storage criteria,although the high melting points of some Si-V phases may restrict their practical applicability.The Fe-Si-Ti system showed standout compositions,including Fe-38Si-20Ti and Si-48Ti,achieving energy storage capacities of approximately 1.5 MWh·m^(−3).This study compares ferro-alloy PCMs against state-of-the-art metallic PCMs,highlighting the performance of certain ferro-alloys.展开更多
Rapid advances in thermal management technology and the increasing need for multi-energy conversion have placed stringent energy efficiency requirements on next-generation shape-stable composite phase change materials...Rapid advances in thermal management technology and the increasing need for multi-energy conversion have placed stringent energy efficiency requirements on next-generation shape-stable composite phase change materials(PCMs).Magnetically-responsive phase change thermal storage materials are considered an emerging concept for energy storage systems,enabling PCMs to perform unprecedented functions(such as green energy utilization,magnetic thermotherapy,drug release,etc.).The combination of multifunctional magnetic nanomaterials and PCMs is a milestone in the creation of advanced multifunctional composite PCMs.However,a timely and comprehensive review of composite PCMs based on magnetic nanoparticle modification is still missing.Herein,we furnish an exhaustive exposition elucidating the cutting-edge advancements in magnetically responsive composite PCMs.We delve deeply into the multifarious roles assumed by distinct nanoparticles within composite PCMs of varying dimensions,meticulously scrutinizing the intricate interplay between their architectures and thermophysical attributes.Moreover,we prognosticate future research trajectories,delineate alternative stratagems,and illuminate prospective avenues.This review is intended to stimulate broader academic interest in interdisciplinary fields and provide valuable insights into the development of next-generation magnetically-responsive composite PCMs.展开更多
Planar lightwave circuit(PLC)splitters have long been foundational components in passive optical communication networks,achieving commercial success since the 1990s.However,their inherent fixed splitting ratios impose...Planar lightwave circuit(PLC)splitters have long been foundational components in passive optical communication networks,achieving commercial success since the 1990s.However,their inherent fixed splitting ratios impose significant limitations on capacity expansion,often requiring physical replacement and causing service disruptions.Thermally tunable optical splitters address this challenge by enabling adjustable splitting ratios,but their operation is contingent upon a continuous power supply and complex driving systems.In this work,we present a novel,non-volatile tunable PLC platform based on Sb_(2)S_(3)phase-change materials.The proposed device,which incor-porates a Mach-Zehnder interferometer(MZI)optical switch structure,offers tunable splitting ratios via laser-direct writing or ohmic heating,providing flexible reconfiguration capabilities.Experimental results demonstrate non-volatile power splitting ranging from 50∶50 to 20∶80,with a modest increase of approximately 1 dB in additional loss.This work highlights the potential of the proposed platform for low-power,high-efficiency,and reconfigurable photonic networks.展开更多
Exploiting advanced nanocomposites isochronally integrating outstanding thermal conductivity(TC)and electromagnetic interference shielding effectiveness(EMI SE)can boost the cutting-edge application of phase change ma...Exploiting advanced nanocomposites isochronally integrating outstanding thermal conductivity(TC)and electromagnetic interference shielding effectiveness(EMI SE)can boost the cutting-edge application of phase change materials.Here,we report a tiramisu-like composite(GMP),where the typical“crust-and-cheese”hierarchical structure is replicated by an innovative two-step bidirectional freezing assembly(BFA)and compressive densification.Hierarchical-aligned graphene array(G-GA)with ultralow thermal resistance is fabricated through 1st BFA and graphitization.During the 2nd BFA,the MXene-CNF crosslinking network with hydrogen-bond actions is used for encapsulating polyethylene glycol(PEG)onto the microlayers of the G-GA skeleton.Remarkably,the microlaminated GMP4 achieves a recorded TC of 34.05 W m^(-1) K^(-1),unprecedented EMI SE of 87.4 dB,and preferable enthalpy density of 179.4 J cm^(-3),along with leakage-free function,and eminent thermal durability.Furthermore,the GMP-loaded equipment is demonstrated for efficient microelectronics cooling and sustainable solar energy utilization.This work opens new avenues for multiscale designing multifunctional macro-composites,broadening the application prospects in advanced electronics and solar energy utilization systems.展开更多
The recovery and utilization of ubiquitous low-grade heat are crucial for mitigating the fossil energy crisis.However,uncontrolled spontaneous heat dissipation limits its practical application.Inspired by skeletal mus...The recovery and utilization of ubiquitous low-grade heat are crucial for mitigating the fossil energy crisis.However,uncontrolled spontaneous heat dissipation limits its practical application.Inspired by skeletal muscle thermogenesis,we develop a compressible wood phase change gel with mechano-controlled heat release by infiltrating xylitol gel into wood aerogel.The xylitol gel can store recovered low-grade heat for at least 1 month by leveraging its inherent energy barrier.The hierarchically aligned lamellar structure of wood aerogel facilitates mechanical adaptation,hydrogen bond formation,and energy dissipation between the wood aerogel and the xylitol gel,increasing the compressive strength and toughness of wood phase change gel fivefold compared to xylitol gel.This enhancement effect enables repetitive contact-separation motions between the wood phase change gel and the substrate during radial compression,overcoming the energy barrier and releasing approximately 178.6 J g−1 of heat.As a proof-of-concept,the wood phase change gel serves as the hot side in a thermoelectric generator,providing about 2.13 W m^(−2) of clean electricity by the controlled utilization of recovered solar heat.This study presents a sustainable method to achieve off-grid electricity generation through the controlled utilization of recovered low-grade heat.展开更多
The development of efficient and clean heating technologies is crucial for reducing carbon emissions in regions with severe cold regions.This research designs a novel two-stage phase change heat storage coupled solar-...The development of efficient and clean heating technologies is crucial for reducing carbon emissions in regions with severe cold regions.This research designs a novel two-stage phase change heat storage coupled solar-air source heat pump heating system structure that is specifically designed for such regions.The two-stage heat storage device in this heating system expands the storage temperature range of solar heat.The utilization of the two-stage heat storage device not onlymakes up for the instability of the solar heating system,but can also directlymeet the building heating temperature,and can reduce the influence of low-temperature outdoor environments in severe cold regions on the heating performance of the air source heat pump by using solar energy.Therefore,the two-stage phase change heat storage coupled to the solar energy-air source heat pump heating system effectively improves the utilization rate of solar energy.A numerical model of the system components and their integration was developed using TRNSYS software in this study,and various performance aspects of the system were simulated and analyzed.The simulation results demonstrated that the two-stage heat storage device can effectively store solar energy,enabling its hierarchical utilization.The low-temperature solar energy stored by the two-stage phase change heat storage device enhances the coefficient of performance of the air source heat pump by 11.1%in severe cold conditions.Using the Hooke-Jeeves optimization method,the annual cost and carbon emissions are taken as optimization objectives,with the optimized solar heat supply accounting for 52.5%.This study offers valuable insights into operational strategies and site selection for engineering applications,providing a solid theoretical foundation for the widespread implementation of this system in severe cold regions.展开更多
基金supports from the National Natural Science Foundation of China(Grant No.U20A20112)the Research Grants Council of the Hong Kong SAR Government,China(Grant Nos.T22-606/23-R and 16206923).
文摘Glacier landslide cascading hazards pose threats to communities and infrastructure,affected by complex processes including the amplification of mass flow volume through erosion and entrainment,transformation of hazard types,ice-water phase change,and enhanced mobility of the mass flow.Scientifically simulating these physical phenomena proves challenging.This study introduces GMFA(glacier mass flow analysis),an integrated numerical model that advances the field by:(1)proposing depth-averaged fluctuation energy and internal energy equations,(2)incorporating the ice-water phase change and the entrainment-deposition process,and(3)capturing their effects on mass flow runout characteristics.The model employs the finite volume method to solve the multi-physics coupled governing equations,enabling efficient large-scale simulations.The model is verified through three numerical tests covering flow dynamics,temperature evolution,and thermo-hydro-mechanical runout processes.The model is applied to analyze a hazard chain that occurred on 10 September 2020 on the Tibetan Plateau.The multi-scenario simulation results indicate an entrained mass volume of(4.95±0.11)×10^(5)m^(3),and a ratio of entrained mass volume to source material volume of 0.44.The solid concentration decreases from 0.6-0.7 to 0.1-0.15 with increasing runout distance,indicating a transition from avalanche to debris flood.The internal energy rises by(3-4)×10^(3)kJ/m^(3),driving rapid ice melting from 0.1 to 0.2 to near-zero concentration.The model effectively quantifies volume amplification,ice-water phase changes,and multi-hazard transformations.This model pushes the geoscience frontier,extending computational capability from single-to multi-hazard simulations and providing a powerful tool for analyzing glacier cascading hazards.
基金financially supported by the Fundamental Research Funds for the Central Universities(No.FRF-KST-25-001)the Beijing Natural Science Foundation(No.L253029)。
文摘In the context of the global energy low-carbon transition,phase change energy storage technology becomes a key technology to solve the problem of intermittent renewable energy.Oriented phase change composites(OCPCMs)receive widespread attention in practical energy storage applications due to their unique oriented thermally conductive structure,which achieves significant thermal conductivity enhancement in specific directions while retaining the high energy storage capacity of the phase change components.This review systematically summarizes the overall analysis of OCPCMs from synthesis and preparation to application scenarios in recent years.Herein,we introduce the analysis of the heat transfer mechanism of the materials and explore the advantages of the oriented structure in OCPCMs in the heat transfer behavior from a bionic perspective.We then focus on summarizing and generalizing the methods for preparing OCPCMs,giving suggestions for suitable methods according to different scenarios.Besides,we discuss the application of finite element simulation methods to the monitoring of the thermal management behavior of OCPCMs,and look into the potential future application areas of such materials.Finally,it is hoped that this review will provide guidance for the academic community in developing high-performance OCPCMs.
基金financially supported by Natural Science Foundation of Guangdong province(2024A1515010228)CATARC Automotive Inspection Center Excellent Engineer Program(2023B0909050007).
文摘To address the challenge of balancing thermal management and thermal runaway mitigation,it is crucial to explore effective methods for enhancing the safety of lithium-ion battery systems.Herein,an innovative hydrated salt composite phase change material(HSCPCM)with dual phase transition temperature zones has been proposed.This HSCPCM,denoted as SDMA10,combines hydrophilic modified expanded graphite,an acrylic emulsion coating,and eutectic hydrated salts to achieve leakage prevention,enhanced thermal stability,cycling stability,and superior phase change behavior.Battery modules incorporating SDMA10 demonstrate significant thermal control capabilities.Specifically,the cylindrical battery modules with SDMA10 can maintain maximum operating temperatures below 55°C at 4 C discharge rate,while prismatic battery modules can keep maximum operating temperatures below 65°C at 2 C discharge rate.In extreme battery overheating conditions simulated using heating plates,SDMA10 effectively suppresses thermal propagation.Even when the central heating plate reaches 300°C,the maximum temperature at the module edge heating plates remains below 85°C.Further,compared to organic composite phase change materials(CPCMs),the battery module with SDMA10 can further reduce the peak thermal runaway temperature by 93°C and delay the thermal runaway trigger time by 689 s,thereby significantly decreasing heat diffusion.Therefore,the designed HSCPCM integrates excellent latent heat storage and thermochemical storage capabilities,providing high thermal energy storage density within the thermal management and thermal runaway threshold temperature range.This research will offer a promising pathway for improving the thermal safety performance of battery packs in electric vehicles and other energy storage systems.
基金supported by the National Natural Science Foundation of China(No.52127816),the National Key Research and Development Program of China(No.2020YFA0715000)the National Natural Science and Hong Kong Research Grant Council Joint Research Funding Project of China(No.5181101182)the NSFC/RGC Joint Research Scheme sponsored by the Research Grants Council of Hong Kong and the National Natural Science Foundation of China(No.N_PolyU513/18).
文摘Latent heat thermal energy storage(TES)effectively reduces the mismatch between energy supply and demand of renewable energy sources by the utilization of phase change materials(PCMs).However,the low thermal conductivity and poor shape stability are the main drawbacks in realizing the large-scale application of PCMs.Promisingly,developing composite PCM(CPCM)based on porous supporting mate-rial provides a desirable solution to obtain performance-enhanced PCMs with improved effective thermal conductivity and shape stability.Among all the porous matrixes as supports for PCM,three-dimensional carbon-based porous supporting material has attracted considerable attention ascribing to its high ther-mal conductivity,desirable loading capacity of PCMs,and excellent chemical compatibility with various PCMs.Therefore,this work systemically reviews the CPCMs with three-dimensional carbon-based porous supporting materials.First,a concise rule for the fabrication of CPCMs is illustrated in detail.Next,the experimental and computational research of carbon nanotube-based support,graphene-based support,graphite-based support and amorphous carbon-based support are reviewed.Then,the applications of the shape-stabilized CPCMs including thermal management and thermal conversion are illustrated.Last but not least,the challenges and prospects of the CPCMs are discussed.To conclude,introducing carbon-based porous materials can solve the liquid leakage issue and essentially improve the thermal conductivity of PCMs.However,there is still a long way to further develop a desirable CPCM with higher latent heat capacity,higher thermal conductivity,and more excellent shape stability.
基金supported by the National Natural Science Foundation of China(Grant No.51976092)。
文摘High-temperature phase change materials(PCMs)have attracted significant attention in the field of thermal energy storage due to their ability to store and release large amounts of heat within a small temperature fluctuation range.However,their practical application is limited due to problems such as leakage,corrosion,and volume changes at high temperatures.Recent research has shown that macroencapsulation technology holds promise in addressing these issues.This paper focuses on the macroencapsulation technology of high-temperature PCMs,starting with a review of the classification and development history of high-temperature macroencapsulatd PCMs.Four major encapsulation strategies,including electroplating method,solid/liquid filling method,sacrificial material method,and powder compaction into sphere method,are then summarized.The methods for effectively addressing issues such as corrosion,leakage,supercooling,and phase separation in PCMs are analyzed,along with approaches for improving the heat transfer performance,mechanical strength,and thermal cycling stability of macrocapsules.Subsequently,the structure and packing arrangement optimization of macrocapsules in thermal storage systems is discussed in detail.Finally,after comparing the performance of various encapsulation strategies and summarizing existing issues,the current technical challenges,improvement methods,and future development directions are proposed.More attention should be given to utilizing AI technology and reinforcement learning to reveal the multiphysics-coupled heat and mass transfer mechanisms in macrocapsule applications,as well as to optimize material selection and encapsulation parameters,thereby enhancing the overall efficiency of thermal storage systems.
基金supported by the National Natural Science Foundation of China(No.52103093,52103205)the Taishan Scholar Project of Shandong Province(No.tsqn202312187)+2 种基金the Natural Science Foundation of Shandong Province(ZR2024QE220)the Young Elite Scientists Sponsorship Program by CAST(No.2021QNRC001)the Jiangxi Provincial Natural Science Foundation(20232BAB214031,20242BAB25237).
文摘The urgent demand for renewable energy solutions,propelled by the global energy crisis and environmental concerns,has spurred the creation of innovative materials for solar thermal storage.Photothermal phase change materials(PTPCMs)represent a novel type of composite phase change material(PCM)aimed at improving thermal storage efficiency by incorporating photothermal materials into traditional PCMs and encapsulating them within porous structures.Various porous encapsulation materials have been studied,including porous carbon,expanded graphite,and ceramics,but issues like brittleness hinder their practical use.To overcome these limitations,flexible PTPCMs using organic porous polymers—like foams,hydrogels,and porous wood—have emerged,offering high porosity and lightweight characteristics.This review examines recent advancements in the preparation of PTPCMs based on porous polymer supports through techniques like impregnation and in situ polymerization,assessing the impact of different porous polymer materials on PCM performance and clarifying the mechanisms of photothermal conversion and heat storage.Subsequently,the most recent advancements in the applications of porous polymer-based PTPCMs are systematically summarized,and future research challenges and possible solutions are discussed.This review aims to foster awareness about the potential of PTPCMs in promoting environmentally friendly energy practices and catalyzing further research in this promising field.
基金supported by the Open Research Fund of Guangdong Advanced Carbon Materials Co.,Ltd (No. Kargen-2024B1707)
文摘Solar-thermoelectric generators(STEGs)capable of harnessing solar energy for conversion into clean electricity are pivotal for advancing towards carbon neutrality.The integration of phase change materials(PCMs)with STEGs facilitates power generation regardless of solar radiation flux due to their robust thermal management capacity.However,the inherent solar-thermal conversion efficiency limitation of PCMs hinders the production of high and sustained electrical output.Herein,a multidimensional engineering strategy is proposed to align two-dimensional(2D)molybdenum disulfide(MoS_(2))nanosheets vertically in situ on a dodecahedron composed of zero-dimensional(OD)Co nanoparticles and three-dimensional(3D)high graphitized carbon derived from ZIF-67,thus significantly boosting the solar-thermoelectric energy generation of polyethylene glycol(PEG).The resultant PEG-Co/C@MoS_(2)composite PCMs exhibit a high solar-thermal conversion efficiency of 92.89%,benefiting from the synergy of multiple components and unique structural arrangements.When coupled with thermoelectric devices,this powerful STEG yields a high and durable output voltage of 197.51 mV and a current of 52.47 mA under 100 mW cm^(−2),outperforming the majority of previously reported literature.This PCM-integrated solar-thermoelectric generator overcomes limitations associated with temporal and meteorological variations,enabling simultaneous high-density heat and electricity generation for energy conservation and environmental sustainability.
基金Funded by Scientific and Technological Innovation Project of Carbon Emission Peak and Carbon Neutrality of Jiangsu Province(No.BE2022028-4)。
文摘We adopted the solution impregnation route with aluminum dihydrogen phosphate solution as liquid medium for effective surface modification on graphite substrate.The mass ratio of graphite to Al(H_(2)PO_(4))_(3) changed from 0.5:1 to 4:1,and the impregnation time changed from 1 to 7 h.The typical composite phase change thermal storage materials doped with the as-treated graphite were fabricated using form-stable technique.To investigate the oxidation and anti-oxidation behavior of the impregnated graphite at high temperatures,the samples were put into a muffle furnace for a cyclic heat test.Based on SEM,EDS,DSC techniques,analyses on the impregnated technique suggested an optimized processing conditions of a 3 h impregnation time with the ratio of graphite:Al(H_(2)PO_(4))_(3) as 1:3 for graphite impregnation treatment.Further investigations on high-temperature phase change heat storage materials doped by the treated graphite suggested excellent oxidation resistance and thermal cycling performance.
文摘Oriented graphene aerogels have limited applica-tions because the flexibility of their graphene sheets and mi-crostructure give them a low skeleton strength,insufficient compression resilience,and poor flexibility.We report the preparation of novel aerogel materials with a much better per-formance.Using the driving force of graphene oxide(GO)self-assembly andπ-πinteractions,carbon nanotubes(CNTs)were attached to the GO sheets,and an oriented composite carbon skeleton was constructed using“hydro-plastic foam-ing”.The introduction of CNTs significantly increased the strength of the skeleton and gave the aerogel an excellent re-versible compressibility.The innovative use of cold pressing greatly improved the thermal conductivity and flexibility of the aerogel,providing new ideas for the development of high-performance aerogels.Tests show that the obtained graphene composite aerogel has a reversible compressive strain of over 90%and can withstand 500 compression cycles along the direc-tion of pore accumulation.It can endure more than 10000 bending cycles perpendicular to the direction of composite carbon layer stacking,and its in-plane thermal conductivity reaches 64.5 W·m^(-1)·K^(-1).When filled with phase change materials,the high porosity of the carbon skeleton enables the material to have a high phase change filling rate,and its phase change enthalpy is greater than 150 J/g.Thanks to the exceptional flexibility of the carbon skeleton,the macrostructure of phase change materials can be bent as needed to adapt to thermal management scenarios and conform to device shapes.This significantly enhances practical application compatibility,providing flexible support for temperature control and thermal management across diverse device forms.
基金supported by the National Natural Science Foundation of China(General Program,No.52473331).
文摘With the rapid advancement of 5G communication technology,increasingly stringent demands are placed on the performance and functionality of phase change switches.Given that RF and microwave signals exhibit characteristics of high frequency,high speed,and high precision,it is imperative for phase change switches to possess fast,accurate,and reliable switching capabilities.Moreover,wafer-level compositional homogeneity and resistivity uniformity during semiconductor manufacturing are crucial for ensuring the yield and reliability of RF switches.By controlling magnetron sputter of GeTe through from four key parameters(pressure,power,Ar flow,and post-annealing)and incorporating elemental proportional compensation in the target,we achieved effective modulation over GeTe uniformity.Finally,we successfully demonstrated the process integration of GeTe phase-change RF switches on 6-inch scaled wafers.
基金supported by the Fujian Provincial Department of Science and Technology Industrial University Industry.Education Cooperation Project(2022H6009)the Fujian Province Key Project of Science and Technology Innovation(2022G02025).
文摘Incorporating microencapsulated phase change materials (MPCM) into mortar enhances building thermal energy storage for energy savings but severely degrades compressive strength by replacing sand and creating pores. This study innovatively addresses this critical limitation by introducing nano-silicon (NS) as a modifier to fill pores and promote hydration in MPCM mortar. Twenty-five mixes with varying NS content from 0 to 4 weight percent and different MPCM contents were comprehensively tested for flowability, compressive strength, thermal conductivity, thermal energy storage via Differential Scanning Calorimetry, and microstructure via Scanning Electron Microscopy. Key quantitative results showed MPCM reduced mortar consistency while NS had minimal effect. Crucially, although MPCM decreased compressive strength, NS addition significantly counteracted this loss. Increasing NS content from 0 percent to 4 percent enhanced compressive strength by 12.53%, 14.21%, 25.49%, 21.70%, and 40.70%, respectively, across the tested MPCM levels. Thermal conductivity was primarily reduced by higher MPCM content leading to lower conductivity, with NS showing negligible and inconsistent influence. The phase change temperature of the modified mortar matched that of pure MPCM, although its relative latent heat slightly decreased. This work conclusively demonstrates the novel and effective use of nano-silicon, achieving up to a 40.7 percent strength recovery in MPCM mortar while preserving its essential phase change temperature and thermal conductivity reduction capability. This strategy presents a feasible pathway for developing high-performance, energy-efficient building composites.
基金Supported by the National Natural Science Foundation of China(NSFC)Major Project(51991362).
文摘Considering the three typical phase-change related rock mechanics phenomena during drilling and production in oil and gas reservoirs,which include phase change of solid alkane-related mixtures upon heating,sand liquefaction induced by sudden pressure release of the over-pressured sand body,and formation collapse due to gasification of pore fillings from pressure reduction,this study first systematically analyzes the progress of theoretical understanding,experimental methods,and mathematical representation,then discusses the engineering application scenarios corresponding to the three phenomena and reveals the mechanical principles and application effectiveness.Based on these research efforts,the study further discusses the significant challenges,potential developmental trends,and research approaches that require urgent exploration.The findings disclose that various phase-related rock mechanics phenomena require specific experimental and mathematical methods that can produce multi-field coupling mechanical mechanisms,which will eventually instruct the control on resource exploitation,evaluation on disaster level,and analysis of formation stability.To meet the development needs of the principle,future research efforts should focus on mining more phase-change related rock mechanics phenomena during oil and gas resources exploitation,developing novel experimental equipment,and using techniques of artificial intelligence and digital twins to implement real-time simulation and dynamic visualization of phase-change related rock mechanics.
基金financially supported by the China Postdoctoral Science Foundation(No.2024M751205)。
文摘Flexible phase change materials(PCMs)have become increasingly critical to address the demand for thermal management in electronic technologies and energy conversion.However,their application remains challenging because of their rigidity,liquid leakage,and insufficient thermal conductivity.Herein,flexible glutamic acid@natural rubber/paraffin wax(PW)/carbon nanotubes-graphene nanoplatelets(GNR/PW/CGNP)phase change composites with high thermal conductivity,excellent shape stability,and recyclability were reported.Zn^(2+)-based dynamic crosslinking was constructed through the reaction of zinc acetate and carboxyl groups on glutamic acid@natural rubber(GNR),which was used as a flexible matrix to physically blend with paraffin wax/carbon nanotubes/graphene nanoplatelets(PW/CGNP)to achieve uniform dispersion of PW/CGNP,continuous thermal conductivity networks,and good encapsulation of PW.The GNR/PW/CGNP composites showed excellent mechanical strength,flexibility,and recycling ability,and effective encapsulation prevented the outflow of melted PW during the phase transition.Also,the phase change enthalpy could attain 111.1 J/g with a higher thermal conductivity of 1.055 W/m K,428%higher than that of pure PW owing to the formation of efficient thermal conductive pathways,which exhibited outstanding thermal management performance and superior temperature control behavior in electronic devices.The developed flexible composite PCMs may open new possibilities for next-generation flexible thermal management electronics.
基金supported by Basic and Applied Basic Research Foundation of Guangdong Province(No.2024A1515010772)State Key Laboratory of Massive Personalized Customization System and Technology,No.H&C-MPC-2023-02-06(Q)+2 种基金“CUG scholar”Scientific Research Funds at China University of Geosciences,Wuhan(No.CUG2022185)Guangzhou Youth Top Talent ProgramChina College Student Innovation and Entrepreneurship Training Program(No.S202410491063).
文摘With the continuously increasing awareness of energy conservation and the intensifying impacts of global warming, Personal Thermal Management (PTM) technologies are increasingly recognized for their potential to ensure human thermal comfort in extreme environments. Biomimetic structures have emerged as a novel source of inspiration for PTM applications. This review systematically summarizes the biomimetic structures, phase change materials, manufacturing methods, and the performance of multifunctional PTM wearables. Firstly, it analyzes the biomimetic structures with thermal regulation and encapsulated phase change material functionalities from different dimensions, highlighting their applications in PTM. Subsequently, it outlines the conventional manufacturing methods incorporating various biomimetic structures, offering strategies for the production of PTM wearables. The review also discusses the typical performance characteristics of multifunctional PTM wearables, addressing the current demands in thermal management. Finally, opportunities and challenges in PTM field are proposed, proposing new directions for future research.
基金funding from Horizon Europe Research and Innovation Action programme under Grant Agreement No.101083827,funded by the European Union.
文摘Latent heat thermal energy storage(LHTES)is an attractive method for enhancing the functionality and availability of renew-able energy sources,and it is extensively used to support concentrated solar power technologies.The main feature of every LHTES sys-tem is a phase change material(PCM),i.e.,a substance used to absorb/release energy upon cyclic melting/solidification.This study in-vestigates the potential of ferro-alloys as high-performance PCM candidates,targeting energy storage capacities exceeding 1 MWh·m^(−3),and operational temperatures above 1000°C.A thermodynamic assessment of binary and ternary Fe-based systems,alloyed with Si,B,Cr,V,and Ti,was conducted to identify compositions with optimal phase transition characteristics and heat storage potential.The results highlight the significant potential of the Fe-Si-B system,where boron’s exceptionally high latent heat enhances energy storage capacity despite challenges posed by its high melting point and cost.The Fe-Si-Cr system revealed promising alloys,such as Fe-34Si-38Cr and Fe-34Si-43Cr,offering excellent energy storage density and favorable phase transition temperatures.In the Fe-Si-V system,vanadium additions produced alloys like Fe-36Si-14V and Fe-34Si-10V,which meet energy storage criteria,although the high melting points of some Si-V phases may restrict their practical applicability.The Fe-Si-Ti system showed standout compositions,including Fe-38Si-20Ti and Si-48Ti,achieving energy storage capacities of approximately 1.5 MWh·m^(−3).This study compares ferro-alloy PCMs against state-of-the-art metallic PCMs,highlighting the performance of certain ferro-alloys.
基金financially supported by the National Natural Science Foundation of China(No.51902025).
文摘Rapid advances in thermal management technology and the increasing need for multi-energy conversion have placed stringent energy efficiency requirements on next-generation shape-stable composite phase change materials(PCMs).Magnetically-responsive phase change thermal storage materials are considered an emerging concept for energy storage systems,enabling PCMs to perform unprecedented functions(such as green energy utilization,magnetic thermotherapy,drug release,etc.).The combination of multifunctional magnetic nanomaterials and PCMs is a milestone in the creation of advanced multifunctional composite PCMs.However,a timely and comprehensive review of composite PCMs based on magnetic nanoparticle modification is still missing.Herein,we furnish an exhaustive exposition elucidating the cutting-edge advancements in magnetically responsive composite PCMs.We delve deeply into the multifarious roles assumed by distinct nanoparticles within composite PCMs of varying dimensions,meticulously scrutinizing the intricate interplay between their architectures and thermophysical attributes.Moreover,we prognosticate future research trajectories,delineate alternative stratagems,and illuminate prospective avenues.This review is intended to stimulate broader academic interest in interdisciplinary fields and provide valuable insights into the development of next-generation magnetically-responsive composite PCMs.
基金sponsored by the National Key Research and Development Program of China(2020YFA0714504,2019YFA0709100)the program of the National Natural Science Foundation of China(U24A20309,62305043).
文摘Planar lightwave circuit(PLC)splitters have long been foundational components in passive optical communication networks,achieving commercial success since the 1990s.However,their inherent fixed splitting ratios impose significant limitations on capacity expansion,often requiring physical replacement and causing service disruptions.Thermally tunable optical splitters address this challenge by enabling adjustable splitting ratios,but their operation is contingent upon a continuous power supply and complex driving systems.In this work,we present a novel,non-volatile tunable PLC platform based on Sb_(2)S_(3)phase-change materials.The proposed device,which incor-porates a Mach-Zehnder interferometer(MZI)optical switch structure,offers tunable splitting ratios via laser-direct writing or ohmic heating,providing flexible reconfiguration capabilities.Experimental results demonstrate non-volatile power splitting ranging from 50∶50 to 20∶80,with a modest increase of approximately 1 dB in additional loss.This work highlights the potential of the proposed platform for low-power,high-efficiency,and reconfigurable photonic networks.
基金support from the National Natural Science Foundation of China(No.21878218)the Tianjin Research Innovation Project for Postgraduate Students(No.2023KJ262)+2 种基金the State Grid Corporation of China’s Research Program(No.5419-202019385A)the Fundamental Research Funds for the Central Universities(No.92320006)the Tianjin Key Science and Technology Program(No.18ZXSZSF00030)。
文摘Exploiting advanced nanocomposites isochronally integrating outstanding thermal conductivity(TC)and electromagnetic interference shielding effectiveness(EMI SE)can boost the cutting-edge application of phase change materials.Here,we report a tiramisu-like composite(GMP),where the typical“crust-and-cheese”hierarchical structure is replicated by an innovative two-step bidirectional freezing assembly(BFA)and compressive densification.Hierarchical-aligned graphene array(G-GA)with ultralow thermal resistance is fabricated through 1st BFA and graphitization.During the 2nd BFA,the MXene-CNF crosslinking network with hydrogen-bond actions is used for encapsulating polyethylene glycol(PEG)onto the microlayers of the G-GA skeleton.Remarkably,the microlaminated GMP4 achieves a recorded TC of 34.05 W m^(-1) K^(-1),unprecedented EMI SE of 87.4 dB,and preferable enthalpy density of 179.4 J cm^(-3),along with leakage-free function,and eminent thermal durability.Furthermore,the GMP-loaded equipment is demonstrated for efficient microelectronics cooling and sustainable solar energy utilization.This work opens new avenues for multiscale designing multifunctional macro-composites,broadening the application prospects in advanced electronics and solar energy utilization systems.
基金supported by the National Key R&D Program of China (2023YFD2201403)the National Natural Science Foundation of China (Grant Nos. 32171693, 32201482)+1 种基金the Heilongjiang Natural Science Foundation Outstanding Youth project (Grant No. YQ2022C002)College Students'Innovative Entrepreneurial Training Plan Program (202410225338)
文摘The recovery and utilization of ubiquitous low-grade heat are crucial for mitigating the fossil energy crisis.However,uncontrolled spontaneous heat dissipation limits its practical application.Inspired by skeletal muscle thermogenesis,we develop a compressible wood phase change gel with mechano-controlled heat release by infiltrating xylitol gel into wood aerogel.The xylitol gel can store recovered low-grade heat for at least 1 month by leveraging its inherent energy barrier.The hierarchically aligned lamellar structure of wood aerogel facilitates mechanical adaptation,hydrogen bond formation,and energy dissipation between the wood aerogel and the xylitol gel,increasing the compressive strength and toughness of wood phase change gel fivefold compared to xylitol gel.This enhancement effect enables repetitive contact-separation motions between the wood phase change gel and the substrate during radial compression,overcoming the energy barrier and releasing approximately 178.6 J g−1 of heat.As a proof-of-concept,the wood phase change gel serves as the hot side in a thermoelectric generator,providing about 2.13 W m^(−2) of clean electricity by the controlled utilization of recovered solar heat.This study presents a sustainable method to achieve off-grid electricity generation through the controlled utilization of recovered low-grade heat.
基金This work was supported by the project of the Research on Energy Consumption of Office Space in Colleges and Universities under the“Dual Carbon Target”(No.CJ202301006).
文摘The development of efficient and clean heating technologies is crucial for reducing carbon emissions in regions with severe cold regions.This research designs a novel two-stage phase change heat storage coupled solar-air source heat pump heating system structure that is specifically designed for such regions.The two-stage heat storage device in this heating system expands the storage temperature range of solar heat.The utilization of the two-stage heat storage device not onlymakes up for the instability of the solar heating system,but can also directlymeet the building heating temperature,and can reduce the influence of low-temperature outdoor environments in severe cold regions on the heating performance of the air source heat pump by using solar energy.Therefore,the two-stage phase change heat storage coupled to the solar energy-air source heat pump heating system effectively improves the utilization rate of solar energy.A numerical model of the system components and their integration was developed using TRNSYS software in this study,and various performance aspects of the system were simulated and analyzed.The simulation results demonstrated that the two-stage heat storage device can effectively store solar energy,enabling its hierarchical utilization.The low-temperature solar energy stored by the two-stage phase change heat storage device enhances the coefficient of performance of the air source heat pump by 11.1%in severe cold conditions.Using the Hooke-Jeeves optimization method,the annual cost and carbon emissions are taken as optimization objectives,with the optimized solar heat supply accounting for 52.5%.This study offers valuable insights into operational strategies and site selection for engineering applications,providing a solid theoretical foundation for the widespread implementation of this system in severe cold regions.
