With increasing strict regulation on single-use plastics,lactic acid(LA)and alkyl lactates,as essential monomers for bio-degradable polylactic acid(PLA)plastic products,have gained worldwide attention in both academia...With increasing strict regulation on single-use plastics,lactic acid(LA)and alkyl lactates,as essential monomers for bio-degradable polylactic acid(PLA)plastic products,have gained worldwide attention in both academia and industry.While LA is still dominantly produced through fermentation processes from start,chemical synthesis from cellulosic biomass remains a grand challenge,owing to poor selectivity in activating CAH and CAC bonds in sugar molecules.To our best knowledge,recent publications have been focused on hydrothermal conversion of glucose to LA,while this review summarizes the highlights on direct thermal conversion of fructose as starting material to LA and derivatives.In particular,the synergies of metal/metal cations and acid/base catalysts will be critically revised on retro-aldol and dehydration reactions.This work will provide insights into rational design of active and selective catalysts for the production of carboxylic acids from biomass feedstocks.展开更多
As a controllable power generation method requiring no energy storage,Ocean Thermal Energy Conversion(OTEC)technology demonstrates characteristics of abundant reserves,low pollution,and round-the-clock stable operatio...As a controllable power generation method requiring no energy storage,Ocean Thermal Energy Conversion(OTEC)technology demonstrates characteristics of abundant reserves,low pollution,and round-the-clock stable operation.The free-standing cold-water pipe(CWP)in the system withstands various complex loads during operation,posing potential failure risks.To reveal the deformation and stress mechanisms of OTEC CWPs,this study first analyzes wave particle velocity and acceleration to determine wave loads at different water depths.Based on the Euler-Bernoulli beam model,a quasi-static load calculation model for OTEC CWPs was established.The governing equations were discretized using the finite difference method,and matrix equations were solved to analyze bending deformation,bending moments,and surface stresses at discrete points along the pipe.Results indicate that water depths within 50 m represent a critical zone where wave particle velocity,acceleration,and wave loads exhibit significant variations in harmonic patterns,while beyond 50 m depth wave loads decrease linearly.Ocean currents and surface wind-driven currents substantially influence the CWP’s lateral displacement.Considering the effect of clump weights,the maximum lateral displacement occurs at 600–800 m below sea level.Utilizing large-wall-thickness high-strength pipes at the top section significantly enhances the structural safety of the CWP system.展开更多
One of the solutions to the global warming risk and other climate issues is to concentrate on research and development of utilizing biomass as a fossil fuel alternative.The current estimate of cotton residue waste in ...One of the solutions to the global warming risk and other climate issues is to concentrate on research and development of utilizing biomass as a fossil fuel alternative.The current estimate of cotton residue waste in the world is about 50 million tons.This massive volume of biomass waste should be turned into clean energy to avert burning the stalks in open fields after cotton harvesting.Therefore,harmful emissions such as CO_(2) will be reduced.This study aims to investigate the published literature to comprehend the bioenergy production from the thermal treatment of cotton stalks,including combustion,pyrolysis,carbonization,torrefaction,liquefaction,and gasification.Furthermore,the future outlook,utilization,and prospective challenges of agricultural biomass for biofuel production are discussed.According to the literature,biochar and bio-oil derived from cotton stalks have high heating values of about 27.5 and 37.2 MJ·kg~(–1),respectively.These values are double those of cotton stalk raw materials,which make it a good candidate for bioenergy production.This article offers valuable insight into cotton stalk utilization via thermochemical treatment and provides a solid reference for researchers,policymakers,and other stakeholders in this field.展开更多
The influence of electron thermal conductivity on the laser x-ray conversion in the coupling of 3w. laser with Au plane target has been investigated by using a non-LTE radiation hydrodynamic code. The non-local electr...The influence of electron thermal conductivity on the laser x-ray conversion in the coupling of 3w. laser with Au plane target has been investigated by using a non-LTE radiation hydrodynamic code. The non-local electron thermal conductivity is introduced and compared with the other two kinds of the flux-limited Spitzer-Harm description. The results show that the non-local thermal conductivity causes the increase of the laser x-ray conversion efficiency and important changes of the plasma state and coupling feature.展开更多
Phase change materials(PCMs)offer a promising solution to address the challenges posed by intermittency and fluctuations in solar thermal utilization.However,for organic solid-liquid PCMs,issues such as leakage,low th...Phase change materials(PCMs)offer a promising solution to address the challenges posed by intermittency and fluctuations in solar thermal utilization.However,for organic solid-liquid PCMs,issues such as leakage,low thermal conductivity,lack of efficient solar-thermal media,and flamma-bility have constrained their broad applications.Herein,we present an innova-tive class of versatile composite phase change materials(CPCMs)developed through a facile and environmentally friendly synthesis approach,leveraging the inherent anisotropy and unidirectional porosity of wood aerogel(nanowood)to support polyethylene glycol(PEG).The wood modification process involves the incorporation of phytic acid(PA)and MXene hybrid structure through an evaporation-induced assembly method,which could impart non-leaking PEG filling while concurrently facilitating thermal conduction,light absorption,and flame-retardant.Consequently,the as-prepared wood-based CPCMs showcase enhanced thermal conductivity(0.82 W m^(-1)K^(-1),about 4.6 times than PEG)as well as high latent heat of 135.5 kJ kg^(-1)(91.5%encapsula-tion)with thermal durability and stability throughout at least 200 heating and cooling cycles,featuring dramatic solar-thermal conversion efficiency up to 98.58%.In addition,with the synergistic effect of phytic acid and MXene,the flame-retardant performance of the CPCMs has been significantly enhanced,showing a self-extinguishing behavior.Moreover,the excellent electromagnetic shielding of 44.45 dB was endowed to the CPCMs,relieving contemporary health hazards associated with electromagnetic waves.Overall,we capitalize on the exquisite wood cell structure with unidirectional transport inherent in the development of multifunctional CPCMs,showcasing the operational principle through a proof-of-concept prototype system.展开更多
CO2 pyrolysis by thermal plasma was investigated,and a high conversion rate of 33% and energy efficiency of 17% were obtained.The high performance benefited from a novel quenching method,which synergizes the convergin...CO2 pyrolysis by thermal plasma was investigated,and a high conversion rate of 33% and energy efficiency of 17% were obtained.The high performance benefited from a novel quenching method,which synergizes the converging nozzle and cooling tube.To understand the synergy effect,a computational fluid dynamics simulation was carried out.A quick quenching rate of 10~7Ks（-1） could be expected when the pyrolysis gas temperature decreased from more than 3000 to 1000 K.According to the simulation results,the quenching mechanism was discussed as follows： first,the compressible fluid was adiabatically expanded in the converging nozzle and accelerated to sonic speed,and parts of the heat energy converted to convective kinetic energy; second,the sonic fluid jet into the cooling tube formed a strong eddy,which greatly enhanced the heat transfer between the inverse-flowing fluid and cooling tube.These two mechanisms ensure a quick quenching to prevent the reverse reaction of CO2 pyrolysis gas when it flows out from the thermal plasma reactor.展开更多
High-temperature radiative cooling is essential for solar absorbers,as it mitigates efficiency degradation resulting from thermal accumulation.While porous structures have proven effective in enhancing absorber perfor...High-temperature radiative cooling is essential for solar absorbers,as it mitigates efficiency degradation resulting from thermal accumulation.While porous structures have proven effective in enhancing absorber performance,practical manufacturing processes and prolonged operational wear inevitably introduce surface roughness and structural deviations,which profoundly impact radiative properties.This study constructs a ZnS/Ag solar absorber model with surface roughness and employs the finite-difference time-domain method to investigate how characteristic length,surface roughness,porosity,pore shape factor,and taper influence its radiative properties in the 3μm-5μm band at 750 K.Results show optimal absorption at a 1μm characteristic length with a 36.72%improvement compared to the model with l=0.25μm,increased absorption with higher porosity with a 69.29%improvement at 0.6 compared to the non-porous structure,lower circularity with a 19.03%improvement for C=0.89 compared to C=1.00,while surface roughness with a 61.24%improvement at RMS=0.031 compared to RMS=0 and taper with a 38.29%improvement at β=20°compared to β=0°also exert significant effects.This work provides engineering design guidelines for high-efficiency,low-cost absorbers.展开更多
Since the“Twelfth Five-Year Plan”,global tidal energy,tidal current energy,wave energy,ocean thermal energy conversion(OTEC),and salinity gradient power technologies have experienced a new surge in development.China...Since the“Twelfth Five-Year Plan”,global tidal energy,tidal current energy,wave energy,ocean thermal energy conversion(OTEC),and salinity gradient power technologies have experienced a new surge in development.China has also been promoting marine energy development through technology research and development,demonstration projects,and industrial planning.Against the backdrop of developing the marine economy and building a strong maritime nation,the development of ocean energy is of great significance for actively and prudently advancing carbon peaking and carbon neutrality,boosting high-quality economic and social development,and gaining an edge in the new round of technological revolution.展开更多
Highly thermo-conductive aqueous medium is a crucial premise to demonstrate high-performance thermal-related applications.Graphene has the diamond comparable thermal conductivity,while the intrinsic two-dimensional re...Highly thermo-conductive aqueous medium is a crucial premise to demonstrate high-performance thermal-related applications.Graphene has the diamond comparable thermal conductivity,while the intrinsic two-dimensional reality will result in strong anisotropic thermal conductivity and wrinkles or even crumples that significantly sacrifices its inherent properties in practical applications.One strategy to overcome this is to use three-dimensional(3D)architecture of graphene.Herein,3D graphene structure with covalent-bonding nanofins(3D-GS-CBF)is proposed,which is then used as the filler to demonstrate effective aqueous medium.The thermal conductivity and thermal conductivity enhancement efficiency of 3D-GS-CBF(0.26 vol%)aqueous medium can be as high as 2.61 W m-1 K-1 and 1300%,respectively,around six times larger than highest value of the existed aqueous mediums.Meanwhile,3D-GS-CBF can be stable in the solution even after 6 months,addressing the instability issues of conventional graphene networks.A multiscale modeling including non-equilibrium molecular dynamics simulations and heat conduction model is applied to interpret experimental results.3D-GS-CBF aqueous medium can largely improve the solar vapor evaporation rate(by 1.5 times)that are even comparable to the interfacial heating system;meanwhile,its cooling performance is also superior to commercial coolant in thermal management applications.展开更多
Biomass,heralded as sustainable“green coal”,plays a crucial role in energy conservation and achieving“dual carbon”objectives through clean conversion.This paper reviews advancements in biomass catalytic gasificati...Biomass,heralded as sustainable“green coal”,plays a crucial role in energy conservation and achieving“dual carbon”objectives through clean conversion.This paper reviews advancements in biomass catalytic gasification,a technology pivotal for converting biomass to hydrogen-rich fuel and syngas.It highlights the efficiency gains afforded by various catalysts,including natural minerals,alkali metals,nickel-based compounds,zeolites,and rare earth-modified composites.The focus is on their influence on hydrogen output,syngas quality,and tar reduction.The synthesis of these insights paves the way for novel catalyst development and optimized gasification processes,hence advancing catalytic gasification technology toward more sustainable energy solutions.展开更多
The tremendous amount of wasted heat from solar radiation and industry dissipation has motivated the development of thermoelectric concepts that directly convert heat into electricity.The main challenge in practical a...The tremendous amount of wasted heat from solar radiation and industry dissipation has motivated the development of thermoelectric concepts that directly convert heat into electricity.The main challenge in practical applications for thermoelectrics is the high cost from both materials and manufacturing.Recently,breakthrough progresses in ionic thermoelectrics open up new possibilities to charge energy storage devices when submitted to a temperature gradient.The charging voltage is internally from the ionic Seebeck effect of the electrolyte between two electrodes.Hence electrolytes with high thermoelectric figure of merit are classified as ionic thermoelectric materials.Most ionic thermoelectric materials are composed of abundant elements,and they can generate hundreds of times larger thermal voltage than that of electronic materials.This emerging thermoelectric category brings new hope to fabricate low cost and large area heat-to-energy conversion devices,and triggers a renewed interest for ionic thermodiffusion.In this review,we summarize the state of the art in the new field of ionic thermoelectrics,from the driving force of the ionic thermodiffusion to material and application developments.We present a general map of ionic thermoelectric materials,discuss the unique characters of each type of the reported electrolytes,and propose potential optimization and future topics of ionic thermoelectrics.展开更多
Ocean thermal energy conversion(OTEC)is a renewable energy source that uses differences in ocean water temperature between warm surface and cold depth to generate electricity.It is an essential link in the carbon neut...Ocean thermal energy conversion(OTEC)is a renewable energy source that uses differences in ocean water temperature between warm surface and cold depth to generate electricity.It is an essential link in the carbon neutrality chain and one of the rising sectors of the ocean energy.This paper provides an overview of studies on closed thermodynamic cycles and the numerous difficulties that OTEC technology faces.A description of the thermodynamic cycles incorporating mixed or pure working fluids,as well as the implications of different working fluids on cycle efficiency were also studied.Changes in condensing and evaporating temperatures induced by variations in heat resources affect the efficiency of cycles with pure working fluids.Several strategies,such as intermediate extraction regeneration and heat recovery of ammonia-depleted solution can increase the thermal efficiency with mixed working fluids.In addition,the impact of the ejector on the cycle’s performance is examined.Finally,the efficiency-improving strate-gies are described and summarized.Thermodynamic efficiency can increase using suitable working fluids and taking steps to maximize the rate of ocean thermal energy.To establish which approach is the most effective,different methods have been evaluated and compared under identical operating conditions.展开更多
The comprehensive optimization of thermodynamic and economic performances is significant for the engineering application of ocean thermal energy conversion(OTEC).Motivated by this,this paper develops a thermo-economic...The comprehensive optimization of thermodynamic and economic performances is significant for the engineering application of ocean thermal energy conversion(OTEC).Motivated by this,this paper develops a thermo-economic OTEC model and conducts a sensitivity analysis of the OTEC system concerning its thermodynamic and economic performances.Specifically,the impact of warm-seawater temperature and cold-seawater pumping depth on the net thermal efficiency and the total investment cost are investigated.The results indicate that,an increase in warm-seawater temperature and cold-seawater pumping depth can improve the net thermal efficiency and a higher installed capacity is beneficial to the system economics.Building on these,a design optimization method with considering the on-design and off-design conditions is proposed in this paper,and the dynamic variation of warm-seawater temperature are considered in this method.In multi-objective optimization procedure,with the objective functions being the average net thermal efficiency and unit power cost within the operational cycle,the non-dominated sorting genetic algorithm Ⅱ(NSGA-Ⅱ) is employed to maximize the net thermal efficiency and minimize the unit power investment cost,resulting in the Pareto front.The net thermal efficiencies of OTEC systems using ammonia and R245fa as working fluids are 4.13% and 3.8%,respectively.This represents an improvement of 19.4% and 57.0%,respectively,compared to traditional optimization methods that do not account for off-design conditions.展开更多
Ocean thermal energy conversion(OTEC)is a process of generating electricity by exploiting the temperature difference between warm surface seawater and cold deep seawater.Due to the high static and dynamic pressures th...Ocean thermal energy conversion(OTEC)is a process of generating electricity by exploiting the temperature difference between warm surface seawater and cold deep seawater.Due to the high static and dynamic pressures that are caused by seawater circulation,the stiffened panel that constitutes a seawater tank may undergo a reduction in ultimate strength.The current paper investigates the design of stiffening systems for OTEC seawater tanks by examining the effects of stiffening parameters such as stiffener sizes and span-over-bay ratio for the applied combined loadings of lateral and transverse pressure by fluid motion and axial compression due to global bending moment.The ultimate strength calculation was conducted by using the non-linear finite element method via the commercial software known as ABAQUS.The stress and deformation distribution due to pressure loads was computed in the first step and then brought to the second step,in which the axial compression was applied.The effects of pressure on the ultimate strength of the stiffener were investigated for representative stiffened panels,and the significance of the stiffener parameters was assessed by using the sensitivity analysis method.As a result,the ultimate strength was reduced by approximately 1.5%for the span-over-bay ratio of 3 and by 7%for the span-over-bay ratio of 6.展开更多
Phase change materials(PCMs)are popular solutions to tackle the unbalance of thermal energy supply and demand,but suffer from low thermal conductivity and leakage problems.Inspired by how honeybees store honey,we prop...Phase change materials(PCMs)are popular solutions to tackle the unbalance of thermal energy supply and demand,but suffer from low thermal conductivity and leakage problems.Inspired by how honeybees store honey,we propose artificial“honeycombhoney”for excellent solar and thermal energy storage capacity based on TiN nanoparticles decorated porous AlN skeletonsPCMs composites.The thermal conductivity of composites achieves 21.58 W/(m·K)at AlN loading of 20 vol.%,superior to the state-of-the-art ceramic-based composites.The charging/discharging time is reduced to about half of pure PCMs with shapestability and thermal reliability well maintained over 500 melting/freezing cycles.The underlying mechanism can be attributed to the combination of single-crystal AlN whiskers with few crystal defects and reduced phonon scattering,as well as vertically arranged three-dimantional(3D)heat conduction channels.A rapid and efficient solar thermal storage is also demonstrated with solar thermal storage efficiency achieving a high value of 92.9%without employing additional spectrum selective coatings.This is benefited from high thermal conductivity and full-spectrum solar absorptance of up to 95%induced by plasmonic resonances of TiN nanoparticles.In addition,by embedding LiNO3-NaCl eutectics,the phase change enthalpy of composites reaches as high as 208 kJ/kg,making high energy storage density and fast energy storage rate compatible.This work offers new routes to achieve rapid,efficient,stable,and compact solar capture and thermal energy storage.展开更多
With the global ambition of moving towards carbon neutrality,this sets to increase significantly with most of the energy sources from renewables.As a result,cost-effective and resource efficient energy conversion and ...With the global ambition of moving towards carbon neutrality,this sets to increase significantly with most of the energy sources from renewables.As a result,cost-effective and resource efficient energy conversion and storage will have a great role to play in energy decarbonization.This review focuses on the most recent developments of one of the most promising energy conversion and storage technologies-the calcium-looping.It includes the basics and barriers of calcium-looping beyond CO_(2) capture and storage(CCS)and technological solutions to address the associated challenges from material to system.Specifically,this paper discusses the flexibility of calcium-looping in the context of CO_(2) capture,combined with the use of H_(2)-rich fuel gas conversion and thermochemical heat storage.To take advantage of calcium-looping based energy integrated utilization of CCS(EIUCCS)in carbon neutral power generation,multiple-scale process innovations will be required,starting from the material level and extending to the system level.展开更多
This study investigated how biomass pyrolysis varies with the different fractions of magnesite mixing into biomass.The pyrolysis occurred with simultaneous decomposition of magnesite without use of any gasification re...This study investigated how biomass pyrolysis varies with the different fractions of magnesite mixing into biomass.The pyrolysis occurred with simultaneous decomposition of magnesite without use of any gasification reagent,and was analyzed in terms of producer gas yield and quality.As magnesite fraction increased from 0 to 30%,the yield of producer gas and its calorific value increased from 48.6%to 66.3%and 8.29 to 8.93 MJ/Nm^(3),respectively.The carbon and hydrogen conversion increased from 44.1%to 60.7%and 43.1%to 66.2%,respectively.The characterization results revealed that magnesite particles facilitated the conversion of fixed carbon and the thermal/catalytic cracking of tar to produce H-rich gas.The in-situ generated CO_(2)from magnesite decomposition could be reduced to CO/CH_(4)in the reductive atmosphere of the pyrolysis products.This study proposes the concept of converting low-energy-density biomass into gas without oxygen and provides a novel approach for producing H-rich gas from biomass.展开更多
基金the funds from National Natural Science Foundation of China (22078365, 21706290)Natural Science Foundation of Shandong Province (ZR2017MB004)+2 种基金Innovative Research Funding from Qingdao City, Shandong Province (17-1-1-80-jch)Fundamental Research Funds for the Central Universities and Development Fund of State Key Laboratory of Heavy Oil Processing (17CX02017A, 20CX02204A)New Faculty Start-Up Funding from China University of Petroleum (YJ201601059)
文摘With increasing strict regulation on single-use plastics,lactic acid(LA)and alkyl lactates,as essential monomers for bio-degradable polylactic acid(PLA)plastic products,have gained worldwide attention in both academia and industry.While LA is still dominantly produced through fermentation processes from start,chemical synthesis from cellulosic biomass remains a grand challenge,owing to poor selectivity in activating CAH and CAC bonds in sugar molecules.To our best knowledge,recent publications have been focused on hydrothermal conversion of glucose to LA,while this review summarizes the highlights on direct thermal conversion of fructose as starting material to LA and derivatives.In particular,the synergies of metal/metal cations and acid/base catalysts will be critically revised on retro-aldol and dehydration reactions.This work will provide insights into rational design of active and selective catalysts for the production of carboxylic acids from biomass feedstocks.
基金funded by Nansha District Science and Technology Project(Grant Number.2024ZD008)funded by China Geological Survey(Grant number:No.DD20230066,DD20242659).
文摘As a controllable power generation method requiring no energy storage,Ocean Thermal Energy Conversion(OTEC)technology demonstrates characteristics of abundant reserves,low pollution,and round-the-clock stable operation.The free-standing cold-water pipe(CWP)in the system withstands various complex loads during operation,posing potential failure risks.To reveal the deformation and stress mechanisms of OTEC CWPs,this study first analyzes wave particle velocity and acceleration to determine wave loads at different water depths.Based on the Euler-Bernoulli beam model,a quasi-static load calculation model for OTEC CWPs was established.The governing equations were discretized using the finite difference method,and matrix equations were solved to analyze bending deformation,bending moments,and surface stresses at discrete points along the pipe.Results indicate that water depths within 50 m represent a critical zone where wave particle velocity,acceleration,and wave loads exhibit significant variations in harmonic patterns,while beyond 50 m depth wave loads decrease linearly.Ocean currents and surface wind-driven currents substantially influence the CWP’s lateral displacement.Considering the effect of clump weights,the maximum lateral displacement occurs at 600–800 m below sea level.Utilizing large-wall-thickness high-strength pipes at the top section significantly enhances the structural safety of the CWP system.
基金supported by the National Natural Science Foundation of China(Grants No.42177431 and No.U20A2086)the Beijing Natural Science Foundation(International Scientists Project,Grant No.IS24033)+3 种基金the joint research project between UniMAP and TIIAME NRU(Grant No.INTERES 9008-00064)the series training courses(Belt&Road Talent Exchange Program,Grant No.DL2021108001L)for academic writing guidance that conducted by Prof.Harold J.Annegarnthe support from China Scholarship CouncilTYSP program to the international students and scholars。
文摘One of the solutions to the global warming risk and other climate issues is to concentrate on research and development of utilizing biomass as a fossil fuel alternative.The current estimate of cotton residue waste in the world is about 50 million tons.This massive volume of biomass waste should be turned into clean energy to avert burning the stalks in open fields after cotton harvesting.Therefore,harmful emissions such as CO_(2) will be reduced.This study aims to investigate the published literature to comprehend the bioenergy production from the thermal treatment of cotton stalks,including combustion,pyrolysis,carbonization,torrefaction,liquefaction,and gasification.Furthermore,the future outlook,utilization,and prospective challenges of agricultural biomass for biofuel production are discussed.According to the literature,biochar and bio-oil derived from cotton stalks have high heating values of about 27.5 and 37.2 MJ·kg~(–1),respectively.These values are double those of cotton stalk raw materials,which make it a good candidate for bioenergy production.This article offers valuable insight into cotton stalk utilization via thermochemical treatment and provides a solid reference for researchers,policymakers,and other stakeholders in this field.
基金the National High-Tech ICF Committee in Chinathe National Natute Science Foundation of China !(No.19735002)the Fund of C
文摘The influence of electron thermal conductivity on the laser x-ray conversion in the coupling of 3w. laser with Au plane target has been investigated by using a non-LTE radiation hydrodynamic code. The non-local electron thermal conductivity is introduced and compared with the other two kinds of the flux-limited Spitzer-Harm description. The results show that the non-local thermal conductivity causes the increase of the laser x-ray conversion efficiency and important changes of the plasma state and coupling feature.
基金funding from the National Natural Science Foundation of China(No.22268025)China Postdoctoral Science Foundation(NO.2022MD713757)+2 种基金Yunnan Provincial Postdoctoral Science Foundation(NO.34Y2022)Yunnan Province Joint Special Project for Enterprise Fundamental Research and Applied Basic Research(No.202101BC070001-016)Guangdong Basic and Applied Basic Research Foundation(No.2023A1515011985).
文摘Phase change materials(PCMs)offer a promising solution to address the challenges posed by intermittency and fluctuations in solar thermal utilization.However,for organic solid-liquid PCMs,issues such as leakage,low thermal conductivity,lack of efficient solar-thermal media,and flamma-bility have constrained their broad applications.Herein,we present an innova-tive class of versatile composite phase change materials(CPCMs)developed through a facile and environmentally friendly synthesis approach,leveraging the inherent anisotropy and unidirectional porosity of wood aerogel(nanowood)to support polyethylene glycol(PEG).The wood modification process involves the incorporation of phytic acid(PA)and MXene hybrid structure through an evaporation-induced assembly method,which could impart non-leaking PEG filling while concurrently facilitating thermal conduction,light absorption,and flame-retardant.Consequently,the as-prepared wood-based CPCMs showcase enhanced thermal conductivity(0.82 W m^(-1)K^(-1),about 4.6 times than PEG)as well as high latent heat of 135.5 kJ kg^(-1)(91.5%encapsula-tion)with thermal durability and stability throughout at least 200 heating and cooling cycles,featuring dramatic solar-thermal conversion efficiency up to 98.58%.In addition,with the synergistic effect of phytic acid and MXene,the flame-retardant performance of the CPCMs has been significantly enhanced,showing a self-extinguishing behavior.Moreover,the excellent electromagnetic shielding of 44.45 dB was endowed to the CPCMs,relieving contemporary health hazards associated with electromagnetic waves.Overall,we capitalize on the exquisite wood cell structure with unidirectional transport inherent in the development of multifunctional CPCMs,showcasing the operational principle through a proof-of-concept prototype system.
基金the funding of National Natural Science Foundation of China (Grant No.11775155)
文摘CO2 pyrolysis by thermal plasma was investigated,and a high conversion rate of 33% and energy efficiency of 17% were obtained.The high performance benefited from a novel quenching method,which synergizes the converging nozzle and cooling tube.To understand the synergy effect,a computational fluid dynamics simulation was carried out.A quick quenching rate of 10~7Ks（-1） could be expected when the pyrolysis gas temperature decreased from more than 3000 to 1000 K.According to the simulation results,the quenching mechanism was discussed as follows： first,the compressible fluid was adiabatically expanded in the converging nozzle and accelerated to sonic speed,and parts of the heat energy converted to convective kinetic energy; second,the sonic fluid jet into the cooling tube formed a strong eddy,which greatly enhanced the heat transfer between the inverse-flowing fluid and cooling tube.These two mechanisms ensure a quick quenching to prevent the reverse reaction of CO2 pyrolysis gas when it flows out from the thermal plasma reactor.
基金funded by the National Natural Science Foundation of China,grant number 52406102,received by Haiyan YuShandong Provincial Natural Science Foundation,grant number ZR2023QE258,received by Haiyan Yu.
文摘High-temperature radiative cooling is essential for solar absorbers,as it mitigates efficiency degradation resulting from thermal accumulation.While porous structures have proven effective in enhancing absorber performance,practical manufacturing processes and prolonged operational wear inevitably introduce surface roughness and structural deviations,which profoundly impact radiative properties.This study constructs a ZnS/Ag solar absorber model with surface roughness and employs the finite-difference time-domain method to investigate how characteristic length,surface roughness,porosity,pore shape factor,and taper influence its radiative properties in the 3μm-5μm band at 750 K.Results show optimal absorption at a 1μm characteristic length with a 36.72%improvement compared to the model with l=0.25μm,increased absorption with higher porosity with a 69.29%improvement at 0.6 compared to the non-porous structure,lower circularity with a 19.03%improvement for C=0.89 compared to C=1.00,while surface roughness with a 61.24%improvement at RMS=0.031 compared to RMS=0 and taper with a 38.29%improvement at β=20°compared to β=0°also exert significant effects.This work provides engineering design guidelines for high-efficiency,low-cost absorbers.
文摘Since the“Twelfth Five-Year Plan”,global tidal energy,tidal current energy,wave energy,ocean thermal energy conversion(OTEC),and salinity gradient power technologies have experienced a new surge in development.China has also been promoting marine energy development through technology research and development,demonstration projects,and industrial planning.Against the backdrop of developing the marine economy and building a strong maritime nation,the development of ocean energy is of great significance for actively and prudently advancing carbon peaking and carbon neutrality,boosting high-quality economic and social development,and gaining an edge in the new round of technological revolution.
基金the financial support from National Natural Science Foundation of China(No.51906211)the China Postdoctoral Science Foundation(No.2019M662048)+1 种基金the Key R&D Program of Zhejiang Province(No.2019C01044)the Zhejiang Provincial Natural Science Foundation of China(No.LR17E060002)。
文摘Highly thermo-conductive aqueous medium is a crucial premise to demonstrate high-performance thermal-related applications.Graphene has the diamond comparable thermal conductivity,while the intrinsic two-dimensional reality will result in strong anisotropic thermal conductivity and wrinkles or even crumples that significantly sacrifices its inherent properties in practical applications.One strategy to overcome this is to use three-dimensional(3D)architecture of graphene.Herein,3D graphene structure with covalent-bonding nanofins(3D-GS-CBF)is proposed,which is then used as the filler to demonstrate effective aqueous medium.The thermal conductivity and thermal conductivity enhancement efficiency of 3D-GS-CBF(0.26 vol%)aqueous medium can be as high as 2.61 W m-1 K-1 and 1300%,respectively,around six times larger than highest value of the existed aqueous mediums.Meanwhile,3D-GS-CBF can be stable in the solution even after 6 months,addressing the instability issues of conventional graphene networks.A multiscale modeling including non-equilibrium molecular dynamics simulations and heat conduction model is applied to interpret experimental results.3D-GS-CBF aqueous medium can largely improve the solar vapor evaporation rate(by 1.5 times)that are even comparable to the interfacial heating system;meanwhile,its cooling performance is also superior to commercial coolant in thermal management applications.
基金supported by the National Natural Science Foundation of China(52160013,51768054)Inner Mongolia Autonomous Region"Grassland Talent"Science Fund Program(CYY012057)+2 种基金Program for Young Talents of Science and Technology in Universities of Inner Mongolia Autonomous Region(NJYT22062)Inner Mongolia Natural Science Foundation(2021LHMS05026)Inner Mongolia University Research Program(2023RCTD018,2023YXXS023,2024YXXS047).
文摘Biomass,heralded as sustainable“green coal”,plays a crucial role in energy conservation and achieving“dual carbon”objectives through clean conversion.This paper reviews advancements in biomass catalytic gasification,a technology pivotal for converting biomass to hydrogen-rich fuel and syngas.It highlights the efficiency gains afforded by various catalysts,including natural minerals,alkali metals,nickel-based compounds,zeolites,and rare earth-modified composites.The focus is on their influence on hydrogen output,syngas quality,and tar reduction.The synthesis of these insights paves the way for novel catalyst development and optimized gasification processes,hence advancing catalytic gasification technology toward more sustainable energy solutions.
基金support by the French National Research Agency through grant ANR-19-CE300012by the European Research Council(ERC)through grant No.772725。
文摘The tremendous amount of wasted heat from solar radiation and industry dissipation has motivated the development of thermoelectric concepts that directly convert heat into electricity.The main challenge in practical applications for thermoelectrics is the high cost from both materials and manufacturing.Recently,breakthrough progresses in ionic thermoelectrics open up new possibilities to charge energy storage devices when submitted to a temperature gradient.The charging voltage is internally from the ionic Seebeck effect of the electrolyte between two electrodes.Hence electrolytes with high thermoelectric figure of merit are classified as ionic thermoelectric materials.Most ionic thermoelectric materials are composed of abundant elements,and they can generate hundreds of times larger thermal voltage than that of electronic materials.This emerging thermoelectric category brings new hope to fabricate low cost and large area heat-to-energy conversion devices,and triggers a renewed interest for ionic thermodiffusion.In this review,we summarize the state of the art in the new field of ionic thermoelectrics,from the driving force of the ionic thermodiffusion to material and application developments.We present a general map of ionic thermoelectric materials,discuss the unique characters of each type of the reported electrolytes,and propose potential optimization and future topics of ionic thermoelectrics.
文摘Ocean thermal energy conversion(OTEC)is a renewable energy source that uses differences in ocean water temperature between warm surface and cold depth to generate electricity.It is an essential link in the carbon neutrality chain and one of the rising sectors of the ocean energy.This paper provides an overview of studies on closed thermodynamic cycles and the numerous difficulties that OTEC technology faces.A description of the thermodynamic cycles incorporating mixed or pure working fluids,as well as the implications of different working fluids on cycle efficiency were also studied.Changes in condensing and evaporating temperatures induced by variations in heat resources affect the efficiency of cycles with pure working fluids.Several strategies,such as intermediate extraction regeneration and heat recovery of ammonia-depleted solution can increase the thermal efficiency with mixed working fluids.In addition,the impact of the ejector on the cycle’s performance is examined.Finally,the efficiency-improving strate-gies are described and summarized.Thermodynamic efficiency can increase using suitable working fluids and taking steps to maximize the rate of ocean thermal energy.To establish which approach is the most effective,different methods have been evaluated and compared under identical operating conditions.
基金supported by National Key R&D Program of China(No.2019YFB1504301).
文摘The comprehensive optimization of thermodynamic and economic performances is significant for the engineering application of ocean thermal energy conversion(OTEC).Motivated by this,this paper develops a thermo-economic OTEC model and conducts a sensitivity analysis of the OTEC system concerning its thermodynamic and economic performances.Specifically,the impact of warm-seawater temperature and cold-seawater pumping depth on the net thermal efficiency and the total investment cost are investigated.The results indicate that,an increase in warm-seawater temperature and cold-seawater pumping depth can improve the net thermal efficiency and a higher installed capacity is beneficial to the system economics.Building on these,a design optimization method with considering the on-design and off-design conditions is proposed in this paper,and the dynamic variation of warm-seawater temperature are considered in this method.In multi-objective optimization procedure,with the objective functions being the average net thermal efficiency and unit power cost within the operational cycle,the non-dominated sorting genetic algorithm Ⅱ(NSGA-Ⅱ) is employed to maximize the net thermal efficiency and minimize the unit power investment cost,resulting in the Pareto front.The net thermal efficiencies of OTEC systems using ammonia and R245fa as working fluids are 4.13% and 3.8%,respectively.This represents an improvement of 19.4% and 57.0%,respectively,compared to traditional optimization methods that do not account for off-design conditions.
基金part of the OTEC research activity"Preliminary Design of a 5 MW OTEC plant:Study case in the North Bali"research grand DIPA-124.01.1.690505/2023 conducted by the Marine Renewable Energy Conversion Technology research group,Research Center for Hydrodynamics Technology,National Research and Innovation Agency(BRIN)。
文摘Ocean thermal energy conversion(OTEC)is a process of generating electricity by exploiting the temperature difference between warm surface seawater and cold deep seawater.Due to the high static and dynamic pressures that are caused by seawater circulation,the stiffened panel that constitutes a seawater tank may undergo a reduction in ultimate strength.The current paper investigates the design of stiffening systems for OTEC seawater tanks by examining the effects of stiffening parameters such as stiffener sizes and span-over-bay ratio for the applied combined loadings of lateral and transverse pressure by fluid motion and axial compression due to global bending moment.The ultimate strength calculation was conducted by using the non-linear finite element method via the commercial software known as ABAQUS.The stress and deformation distribution due to pressure loads was computed in the first step and then brought to the second step,in which the axial compression was applied.The effects of pressure on the ultimate strength of the stiffener were investigated for representative stiffened panels,and the significance of the stiffener parameters was assessed by using the sensitivity analysis method.As a result,the ultimate strength was reduced by approximately 1.5%for the span-over-bay ratio of 3 and by 7%for the span-over-bay ratio of 6.
基金the National Key Research and Development Program of China(No.2018YFA0702300)the National Natural Science Foundation of China(Nos.51820105010 and 52076106).
文摘Phase change materials(PCMs)are popular solutions to tackle the unbalance of thermal energy supply and demand,but suffer from low thermal conductivity and leakage problems.Inspired by how honeybees store honey,we propose artificial“honeycombhoney”for excellent solar and thermal energy storage capacity based on TiN nanoparticles decorated porous AlN skeletonsPCMs composites.The thermal conductivity of composites achieves 21.58 W/(m·K)at AlN loading of 20 vol.%,superior to the state-of-the-art ceramic-based composites.The charging/discharging time is reduced to about half of pure PCMs with shapestability and thermal reliability well maintained over 500 melting/freezing cycles.The underlying mechanism can be attributed to the combination of single-crystal AlN whiskers with few crystal defects and reduced phonon scattering,as well as vertically arranged three-dimantional(3D)heat conduction channels.A rapid and efficient solar thermal storage is also demonstrated with solar thermal storage efficiency achieving a high value of 92.9%without employing additional spectrum selective coatings.This is benefited from high thermal conductivity and full-spectrum solar absorptance of up to 95%induced by plasmonic resonances of TiN nanoparticles.In addition,by embedding LiNO3-NaCl eutectics,the phase change enthalpy of composites reaches as high as 208 kJ/kg,making high energy storage density and fast energy storage rate compatible.This work offers new routes to achieve rapid,efficient,stable,and compact solar capture and thermal energy storage.
基金supported by the National Science Fund for Distinguished Young Scholars[51925604]the National Natural Science Foundation of China[52176210,51820105010]+1 种基金the Bureau of International Cooperation of Chinese Academy of Sciences[182211KYSB20170029]the Cooperation Foundation of Dalian National Laboratory for Clean Energy[DNL202017].
文摘With the global ambition of moving towards carbon neutrality,this sets to increase significantly with most of the energy sources from renewables.As a result,cost-effective and resource efficient energy conversion and storage will have a great role to play in energy decarbonization.This review focuses on the most recent developments of one of the most promising energy conversion and storage technologies-the calcium-looping.It includes the basics and barriers of calcium-looping beyond CO_(2) capture and storage(CCS)and technological solutions to address the associated challenges from material to system.Specifically,this paper discusses the flexibility of calcium-looping in the context of CO_(2) capture,combined with the use of H_(2)-rich fuel gas conversion and thermochemical heat storage.To take advantage of calcium-looping based energy integrated utilization of CCS(EIUCCS)in carbon neutral power generation,multiple-scale process innovations will be required,starting from the material level and extending to the system level.
基金supported by Basic scientific research project of colleges and universities of Liaoning Province Education Department(NO.LJKMZ20220798)Liaoning Provincial Natural Science Youth Fund(NO.LJKQZ20222279)+1 种基金Youth Fund of National Natural Science Foundation of China(NO.22108175)Foundation of National Natural Science Foundation of Xinjiang in China(NO.U190310).
文摘This study investigated how biomass pyrolysis varies with the different fractions of magnesite mixing into biomass.The pyrolysis occurred with simultaneous decomposition of magnesite without use of any gasification reagent,and was analyzed in terms of producer gas yield and quality.As magnesite fraction increased from 0 to 30%,the yield of producer gas and its calorific value increased from 48.6%to 66.3%and 8.29 to 8.93 MJ/Nm^(3),respectively.The carbon and hydrogen conversion increased from 44.1%to 60.7%and 43.1%to 66.2%,respectively.The characterization results revealed that magnesite particles facilitated the conversion of fixed carbon and the thermal/catalytic cracking of tar to produce H-rich gas.The in-situ generated CO_(2)from magnesite decomposition could be reduced to CO/CH_(4)in the reductive atmosphere of the pyrolysis products.This study proposes the concept of converting low-energy-density biomass into gas without oxygen and provides a novel approach for producing H-rich gas from biomass.
