Hydrothermal conversion of fructose to lactic acid and derivatives:Synergies of metal and acid/base catalysts

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.

Leakage Proof,Flame-Retardant,and Electromagnetic Shield Wood Morphology Genetic Composite Phase Change Materials for Solar Thermal Energy Harvesting

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.

Laser X-ray Conversion and Electron Thermal Conductivity

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.

Understanding CO_2 decomposition by thermal plasma with supersonic expansion quench

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.

Highly Thermo-Conductive Three-Dimensional Graphene Aqueous Medium

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.

主曲线法研究亮氨酸热失重动力学

在不同升温速率条件下采用热重法(TG)研究了亮氨酸的热失重过程,得到了动力学三因子;用等转化率法求得了表观活化能Ea=(137.95±2.66)kJ.mol-1;用主曲线法确定了亮氨酸热失重过程的最可几机理函数G(α)为一维相边界反应函数,G(α)=α;再由Ea和G(α)求得指前因子ln(A/s-1)=23.81±0.10.经红外光谱分析和对比观察实验证明,该失重过程实际上是亮氨酸的升华过程.

顺丁烯二酸酐的热失重动力学

利用热分析技术研究了顺丁烯二酸酐在N2气气氛中不同升温速率条件下的热失重过程，得出失重过程的动力学方程和动力学参数。顺丁烯二酸酐在温度为110～160℃，质量损失率〉98％。通过热重-红外联用技术得出热失重过程的气体产物为顺丁烯二酸酐气体，该失重过程的实质是顺丁烯二酸酐的升华过程。在质量损失率α为0．2～0．9范围内，用迭代的等转化率法求得失重过程的活化能为（75．147±0．48）kJ／mol，与Coats-Redfem方程计算出的Ea（（75．0645±1．239）kJ／mol）吻合。由此推出，顺丁烯二酸酐的失重过程可以用单一的机理函数来描述，排除了存在多个分解反应步骤相互重叠的可能性；并用主曲线法确定了失重过程的最可几机理函数的积分式G（α）=1-（1-α）^m（m=0．8139±0．02）；由Ea和G（α）求得速率方程中的指前因子1n（A／s^-1）为23．57±0．018。

CH_2(COO)_2Cu·2H_2O热分解的非等温动力学研究

羧酸盐特别是草酸盐和乙酸盐的热分解动力学和分解机理研究已有大量报道^[1-5],丙二酸盐热分解过程的报道却并不多。Mohamed等用非等温法研究了二水合丙二酸镍及二水合丙二酸钴的失水和分解过程，比较了其在空气、氢气和氮气中的分解行为^[6、7]。Suzuki等人研究了水合二羧基锰盐在空气中的热分解过程，

Ionic thermoelectric materials and devices

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.

Design Optimization of Ocean Thermal Energy Conversion(OTEC)Considering the Off-Design Condition

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.

Assessment of the stiffened panel performance in the OTEC seawater tank design:Parametric study and sensitivity analysis

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.

Review of enhancement for ocean thermal energy conversion system

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.

Advancements in biomass gasification and catalytic tar-cracking technologies

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.

Artificial“honeycomb-honey”decorated with non-noble plasmonic nanoparticles for superior solar capture and thermal energy storage

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.

Calcium-looping based energy conversion and storage for carbon neutrality-the way forward

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.

A passive temperature regulator

Maintaining stable temperatures is crucial for civilization,but it typically requires substantial energy consumption,contributing to significant carbon footprints.Despite advancements in passive heating/cooling technologies,achieving purely passive temperature regulation in volatile environments remains a challenge due to the temporal mismatch between heating/cooling demand and passive power supply.Here,we demonstrate a passive temperature regulator that balances the power demand and supply through a tailored sandwich structure,integrating the functionalities of harvesting,storage,and release of passive solar heat and space coldness.Outdoor experiments demonstrate that the regulator maintains a target temperature for 96%(71%)of the testing period in winter(summer).Compared to conventional solar absorbers(radiative coolers),the regulator saves 56%(30%)of energy across 31 cities worldwide in achieving stable temperatures.The regulator represents an important advancement in passive temperature regulation with minimized carbon footprint and shows attractive prospects both on Earth and in outer space.

An Innovative Argon/Miller Power Cycle for Internal Combustion Engine: Thermodynamic Analysis of its Efficiency and Power Density

Increasing efficiency and reducing emissions are fundamental approaches to achieving peak carbon emissions and carbon neutrality for the transportation and power industries.The Argon power cycle(APC)is a novel concept for high efficiency and zero emissions.However,APC faces the challenges of severe knock and low power density at high efficiency.To elevate efficiency and power density simultaneously of APC,the Miller cycle is applied and combined with APC.The calculation method is based on a modification of the previous thermodynamic method.The mixture of hydrogen and oxygen is controlled in the stoichiometric ratio.The results indicate that to obtain a thermal conversion efficiency of 70%,in the Otto cycle,the compression ratio and the AR(argon molar ratio in the argon-oxygen mixture)could be 9 and 95%,respectively.In comparison,for the Miller cycle,these two parameters only need to be 7 and 91%.A lower compression ratio can reduce the negative effect of knock,and a reduced AR increases the power density by 66%with the same efficiency.The improvement effect is significant when the expansion-compression ratio is 1.5.Meanwhile,increasing the expansion-compression ratio is more effective in the argon-oxygen mixture than in the nitrogen–oxygen mixture.For the next-generation Argon/Miller power cycle engine,the feasible design to achieve the indicated thermal efficiency of 58.6%should be a compression ratio of 11,an expansion-compression ratio of 1.5,and an AR of 91%.

Development and Regeneration Performance of LaNiO_(3)Perovskite Oxides for Dry Reforming of Methane

Dry reforming of methane(DRM)process has attracted much attention in recent years for the direct conversion of CH_4 and CO_(2)into high-value-added syngas.The key for DRM was to develop catalysts with high activity and stability.In this study,LaNiO_(3)was prepared by the sol-gel,co-precipitation,and hydro-thermal methods to explore the influence of preparation methods on the catalyst structure and DRM reaction performance.The regeneration properties of the used LaNiO_(3)catalysts were also investigated under steam,CO_(2),and air atmospheres,respectively.The results showed that LaNiO_(3)prepared by sol-gel method showed the best DRM performance at 750℃.The DRM performance of the samples prepared by hydro-thermal method was inhibited at 750℃due to the residual of Na^(+)ions during the preparation process.The regeneration tests showed that none of the three atmospheres could restore LaNiO_(3)perovskite phase in the samples,but they could eliminate the carbon deposits in the samples during the DRM reaction,so the samples could maintain stable DRM performance at different cycling stages.

Optimal Offering Strategy of Virtual Power Plant with Hybrid Renewable Ocean Energy Portfolio

This paper proposes a hybrid ocean energy sys-tem to form a virtual power plant(VPP)for participating in electricity markets in order to promote the renewable ocean energy utilization and accommodation.In the proposed system,solar thermal energy is integrated with the closed-cycle ocean thermal energy conversion(OTEC)to boost the temperature differences between the surface and deep seawater for efficiency and flexibility improvements,and the thermodynamic effects of seawater mass flow rates on the output of solar-boosted OTEC(SOTEC)are exploited for deploying SOTEC as a renewable dispatchable unit.An optimal tidal-storage operation model is also developed to make use of subsea pumped storage(SPS)with hydrostatic pressures at ocean depths for mitigating the intermittent tidal range energy in order to make the arbitrage in the electricity market.Furthermore,a two-stage coordinated scheduling strategy is presented to optimally control seawater mass flow rates of SOTEC and hydraulic reversible pump-turbines of SPS for enhancing the daily VPP profit.Comparative studies have been investigated to confirm the superiority of the developed methodology in various renewable ocean energy and electricity market price scenarios.