Meta-analysis of CO_(2) conversion,energy efficiency,and other performance data of plasma-catalysis reactors with the open access PIONEER database

This paper brings the comparison of performances of CO_(2)conversion by plasma and plasma-assisted catalysis based on the data collected from literature in this field,organised in an open access online database.This tool is open to all users to carry out their own analyses,but also to contributors who wish to add their data to the database in order to improve the relevance of the comparisons made,and ultimately to improve the efficiency of CO_(2)conversion by plasma-catalysis.The creation of this database and database user interface is motivated by the fact that plasma-catalysis is a fast-growing field for all CO_(2)conversion processes,be it methanation,dry reforming of methane,methanolisation,or others.As a result of this rapid increase,there is a need for a set of standard procedures to rigorously compare performances of different systems.However,this is currently not possible because the fundamental mechanisms of plasma-catalysis are still too poorly understood to define these standard procedures.Fortunately however,the accumulated data within the CO_(2)plasma-catalysis community has become large enough to warrant so-called“big data”studies more familiar in the fields of medicine and the social sciences.To enable comparisons between multiple data sets and make future research more effective,this work proposes the first database on CO_(2)conversion performances by plasma-catalysis open to the whole community.This database has been initiated in the framework of a H_(2)0_(2)0 European project and is called the“PIONEER Data Base”.The database gathers a large amount of CO_(2)conversion performance data such as conversion rate,energy efficiency,and selectivity for numerous plasma sources coupled with or without a catalyst.Each data set is associated with metadata describing the gas mixture,the plasma source,the nature of the catalyst,and the form of coupling with the plasma.Beyond the database itself,a data extraction tool with direct visualisation features or advanced filtering functionalities has been developed and is available online to the public.The simple and fast visualisation of the state of the art puts new results into context,identifies literal gaps in data,and consequently points towards promising research routes.More advanced data extraction illustrates the impact that the database can have in the understanding of plasma-catalyst coupling.Lessons learned from the review of a large amount of literature during the setup of the database lead to best practice advice to increase comparability between future CO_(2)plasma-catalytic studies.Finally,the community is strongly encouraged to contribute to the database not only to increase the visibility of their data but also the relevance of the comparisons allowed by this tool.

Experimental Study on Conversion Efficiency of A Floating OWC Pentagonal Backward Bent Duct Buoy Wave Energy Converter

Wave tank tests were carried out to evaluate the total efficiency of a floating OWC Pentagonal Backward Bent Duct Buoy (PBBDB). Two kinds of turbine generators were used in tests. The incident wave power, pneumatic power and electricity were measured. The test results show that the primary efficiency can reach up to 185.98% in regular waves and 85.86% in irregular waves. The total efficiency from wave to wire with Wells turbine-generator set is 33.43% in regular waves and 15.82% in irregular waves. The peak total efficiency of the PBBDB with check valves equipped with the impulse turbine-generator set is 41.68% in regular waves and 27.10% in irregular waves. The efficiency of the turbine-generator set is about 30% in the tests. Obviously, the total efficiency can be further improved with the increasing of turbine efficiency.

Experimental Research on A New Type of Floating Breakwater for Wave-Absorbing and Energy-Capturing

To avoid the damage caused by big wind and wave in cage culture, and to solve the problem of energy supply faced by automatic breeding equipment, a new type of floating breakwater, named as Savonius double buoy breakwater(SDBB), is proposed in the paper. The floating breakwater is composed of HDPE cylindrical double buoys and horizontal axis Savonius rotors, and has the functions of wave-absorbing and energy-capturing. Based on the linear wave theory and energy conservation law, the Fourier Transform was applied to separate the two-dimensional wave frequency domain, and the energy captured by the rotors and absorbed by the floating breakwater were calculated.Experiments were conducted in a two-dimensional wave-making flume, and the transmitted waves at different wave heights and periods, the tension of mooring lines, and the rotational torque exerted on the Savonius rotor were measured. A series of performance comparison tests were also performed on the new floating breakwater and the traditional double-floating breakwater. Results show that the new floating breakwater is better than the traditional one in terms of reducing wave transmittance, and the combination of the floating breakwater with Savonius rotors can provide for marine aquaculture equipments with green power supply to a certain degree of self-sufficiency.

Study on Performance of Savonius Rotor Type Wave Energy Converter Used in Conjunction with Floating Breakwater

In the present study,the performance characteristics of a Savonius rotor type wave energy converter used in conjunction with a conventional double-buoy floating breakwater is investigated using physical model studies.The Savonius rotor type converter is suspended under the double-buoy floating breakwater to achieve wave attenuation while generating electricity,thereby enhancing the overall wave-elimination effect of the combination.The Savonius rotor is tested with different water submergence depths,and a reasonable relative submergence depth is determined within the scope of the research parameters.The hydrodynamics and energy capture performance of the combined breakwater with four different sizes of Savonius rotor under different wave conditions are studied,and the transmission coefficient of the experimental device is analyzed.The results show that when the optimal relative submergence depth is 0.65D,where D is the impeller diameter,there is a correspondence between the optimal performance of Savonius rotor with different rotor sizes and the wave period and wave height.The optimal energy capture efficiency of the wave energy converter reaches 17%−20.5%,and the transmission coefficient is reduced by 35%−45%compared with the conventional double-buoy breakwater.

Industrial Progress:New Energy-Efficient Absorbents for the CO_(2) Separation from Natural Gas,Syngas and Flue Gas

The CO2 separation from natural gas, syngas or flue gas represents an important industrial field of applications. An economic and energy-efficient CO2 separation from these gas streams is a prerequisite for sustainable industry contributions to the megatrends resource efficiency and globalization of technologies. One way of reducing operational expenditure for these separation processes is the development of better performing CO2 absorbents. Although a number of absorbents for the separation of CO2 from process gas streams exist, the need for the development of CO2 absorbents with an improved absorption performance, less corrosion and foaming, no nitrosamine formation, lower energy requirement and therefore less operational expenditure remains. Recent industrial activities have led to the development of novel high-performance CO2 scrubbing agents that can be employed in numerous industrial processes such as natural gas treatment, purification of syngas and the scrubbing of flue gas. The objective of this paper is to introduce these new high-performance scrubbing agents and to compare their performance with other state-of-the-art absorbents. It turned out, that the evaluated absorbents offer high cyclic capacities in the range of 2.4 to 2.6 mol CO2/kg absorbent and low absorption enthalpies (–30 kJ/mol) allowing for distinctive savings in the regeneration energy of the absorbent. Calculations with the modified Kremser model resulted in a reduction of the specific reboiler heat duty of 55%. Furthermore, the absorbents are less corrosive than standard amines as indicated by the measured corrosion rates of 0.21 mm/y versus 1.18 mm/y for a piperazine/methyldiethanolamine mixture. Based on new experimental results it is shown how substantial savings in operational and capital expenditure can be realized due to favorable absorbent properties. The novel high-performance CO2 system solutions meet recent industrial absorbent requirements and allow for more efficient or new CO2 separation processes.

Sustainable Cement Production with Improved Energy Efficiency and Emerging CO₂Mitigation

This paper studies the current strategies of energy efficiency improvement, CO2 capture in cement production and fly ash blended cement and concrete. Application of updated technology in newly industrialized countries (especially China) has improved energy efficiency due to their (its) dominant global cement production shares. Waste heat recovery (WHR) increases its energy efficiency. CO2 capture from cement plants will be more efficient than that from pulverized coal fired power plant. This paper might serve as a guide for the technology improvement, energy policy making and environmental protection in cement production.

Floating Wind Turbine Motion Suppression Using an Active Wave Energy Converter

This paper proposes a new concept of an actively-controlled wave energy converter for suppressing the pitch and roll motions of floating offshore wind turbines.The wave energy converter consists of several floating bodies that receive the wave energy,actuators that convert the wave energy into electrical energy and generate the mechanical forces,and rigid bars that connect the floating bodies and the wind turbine platform and deliver the actuator forces to the platform.The rotational torques that are required to minimize the platform pitch and roll motions are determined using a linear quadratic regulator.The torques determined in this manner are realized through the actuator forces that maximize the wave power capture as well.The performance of the proposed wave energy converter in simultaneously suppressing the platform pitch and roll motions and extracting the wave energy is validated through simulations.

Experimental Study on Conversion Characteristics of Dual-Mode OWC Models Appropriate for Voyaging

Freely movable wave energy converters(WECs) will greatly improve their adaptability to the marine environment.In this paper, a dual-mode oscillating water column(OWC) WEC with potential sailing capability is proposed. By opening and closing a gate on the side facing the waves, the WEC converts wave energy in the vertical duct(called VD mode) with low sailing resistance or in the backward bend duct(called BBD mode) with high sailing resistance.A small model and a medium model were designed and manufactured. The capture width ratio(CWR) of the small model in the two modes was experimentally studied. The CWR under bidirectional airflow and conversion characteristics under unidirectional airflow of the medium model in the BBD mode were obtained. Tests of the small model show that the peak CWR is 145.2% under regular waves and 90.1% under random waves in BBD mode, and in VD mode the peak CWR is about 60% of that in the BBD mode. Tests of the medium model show that the peak CWR is 228.96% under regular waves, the maximum wave-to-battery efficiency is 63.36% under regular waves and 30.17%under random waves, respectively.

浮球覆盖下水面能量平衡再建与蒸发模型研究

针对干旱区平原水库蒸发强烈导致水资源利用率低的问题,选用黑色高密度聚乙烯(HDPE)浮球作为干旱区平原水库节水材料。通过理论分析、建模与室外试验三者结合,对完整非冰冻期内浮球覆盖下水面蒸发、水体能量平衡组分变化分布的响应机理进行研究,并在此基础上建立相应的水面蒸发量计算模型。结果显示:相较于自由水面,73%的浮球覆盖率下的整体水面净辐射吸收率减小约12.6%,其月均蒸发所需潜热通量减少了61.8%,约为148.73 W/m^(2),水体的感热通量和蓄热通量也有较大的变化。通过对彭曼模型的能量项和空气动力项进行修正,建立的覆盖条件下的水面蒸发量计算模型具有较高的精度。

基于非线性摆杆刚度机构的点吸式波能转换器

为了稳定捕获海洋低频波能,设计了一种基于非线性摆杆刚度机构的点吸式波能转换器.通过在摆杆间添加简单的拉伸弹性元件,制作了紧凑的摆杆刚度装置.对非线性刚度结构进行了受力分析,结合Cummins方程,建立了非线性波能转换器的时域动力学模型,并分析了规则波作用下点吸式波能转换器的波能转换特性.数值仿真结果表明,引入合适的非线性摆杆刚度机构可以提升系统在波浪激励下的运动响应,降低系统在波浪激励下运动响应峰值对应的频率,从而提高系统对于低频能量的捕获效率.

相交圆柱摆式波能装置俘获效率数值分析

摆式波能装置具有结构简单和转化效率高等特点,本文应用AQWA软件基于势流理论对相交圆柱摆式波能装置进行了数值模拟研究,分析了轴间距比、结构阻尼、净浮力比、水深、波浪特性及吃水深度等主要参数对相交圆柱摆式波能装置俘获效率的影响,并与直板摆式波能装置的俘获效率进行了对比。结果表明:同样条件下,相交圆柱摆式波能装置往往比直板摆式波能装置的俘获效率更高;在研究范围内,轴间距比越大俘获效率越高;潮汐导致的水深变化对底铰摆式波能装置的俘获效率具有明显的影响,在工程应用中应采取适当的措施进行处理。

振荡水翼弦向主动变形提高获能效率的机理研究

为探明振荡水翼弦向主动变形对获能效率的影响机理,应用结构变形方程结合动网格方法对水翼弦向变形进行主动控制,并通过求解雷诺平均纳维-斯托克斯(Reynolds-averaged Navier-Stokes, RANS)方程和Spalart-Allmaras(S-A)湍流模型,对具有不同变形程度的振荡水翼获能过程进行数值模拟。分析了振荡水翼弦向主动变形对获能效率的影响规律,提出了考虑水翼运动和弦向柔性变形的有效攻角计算公式,并从一个周期内不同时刻漩涡同水翼相互作用、弦向压力分布以及有效攻角变化等角度对水翼获能差异进行分析,探讨水翼弦向主动变形影响下获能效率变化的根本原因。研究结果表明:相较于刚性水翼,振荡水翼弦向主动变形可以显著提高效率,可达19%,由结构变形引起的漩涡强度变化是获能效率提升的原因之一,但其作用比较有限,由结构变形导致有效攻角增大是效率提升的主要原因。

燃煤电厂CO_(2)捕集的减排效率研究与展望

为了客观评价不同CO_(2)捕集技术的能耗水平,判别CO_(2)捕集技术的有效性和经济性,提出减排效率概念和计算模型。CO_(2)减排效率表示某种CO_(2)捕集技术的有效减排能力,即捕集单位CO_(2)所发生的CO_(2)有效减排量,减排效率模型对CO_(2)捕集技术的能耗进行归集和平准化计算,其值越大表明减排效果越佳。利用减排效率模型测算,目前我国燃煤电厂CO_(2)捕集技术的减排效率理论极值为98%,燃烧前、燃烧中和燃烧后捕集技术的减排效率分别达到80%、70%和58%~68%。经工程应用实践验证,减排效率模型能满足评价要求。最后对CO_(2)捕集技术的发展进行了展望,认为未来随着捕集技术的不断进步和创新,CO_(2)减排效率将超过90%。

一种多浮体铰接式波浪能装置的运动分析与俘获特性研究

基于线性势流理论,利用总模态法对多浮体铰接波浪能装置“海星号”在波浪中的运动开展水动力学系数计算;然后基于矢量力学建立多浮体刚体运动学方程,并结合几何约束条件开展动态响应计算,获得最优俘获效率和最优负载阻尼;最后比较并分析“海星”波浪能装置的多浮体俘获效率,获得“海星”多浮体做功的俘获特性。研究表明:“海星”波浪能装置的多浮体四向迎波设计可拓宽装置最优俘获频带宽度,提高装置整体俘获效率;正向迎波与背向迎波俘获波浪能方式相比,小周期情况下,正向吸波浮体俘获效率较高,随着周期增大,正向吸波浮体俘获效率开始降低,背向吸波浮体俘获效率开始增大,极大周期情况下,正向吸波浮体和背向吸波浮体俘获效率趋于一致且趋近于零。

碳捕集、利用与封存技术的现状及前景

碳捕集、利用与封存(CCUS)是一种有效的碳处理技术。在碳中和背景下,中国CCUS技术将迎来万亿级产业风口。目前,CCUS技术各环节均取得了显著进展,但大规模应用仍面临诸多挑战。通过调研国内外CCUS技术文献以及全球正在运行和计划建设的CCUS项目,总结了国内外CCUS技术的发展现状和研究进展,进一步明确CCUS面临的挑战及未来发展前景。研究表明:目前碳捕集效率不足90%,碳捕集成本占CCUS项目总成本的60%~85%,碳捕集技术的研发重点应以燃烧前捕集(如乙醇、合成氨和天然气加工等行业)以及燃烧后捕集等以提高碳捕集效率、降低碳捕集成本为主;CO_(2)利用技术目前处于工业示范阶段,突破高温、高压环境瓶颈,寻找合适的催化剂提高碳利用效率是CO_(2)利用技术下一阶段的重点研究方向;CO_(2)在油气田和咸水层封存应围绕CO_(2)驱提高油气采收率和增加CO_(2)封存潜力开展进一步研究;CCUS项目需要克服实现经济盈利、技术创新、降本增效、政策补贴激励等挑战;CCUS耦合氢能、油气田地热能等新能源将成为未来CCUS推广的新模式。该研究对于准确把握CCUS技术研究方向,推动CCUS技术进步与创新,加速CCUS跨越式发展具有借鉴意义。

基于多目标优化的风储一次调频控制策略

风储联合参与电网一次调频能够较好地利用风电和储能的优势进行调频控制,逐渐成为一种新的趋势。为了使风储在协同控制中发挥更好的作用,兼顾风能捕获效率、频率控制效果和储能循环使用寿命等重要因素,提出一种基于多目标优化的风储一次调频控制策略。通过构建风储参与一次调频的多目标优化数学模型,采用多目标粒子群算法求解最优参数组合。文章通过仿真对比所提控制策略与传统控制策略的风能捕获效率和调频效果,验证了所提控制策略的有效性和优越性。

非线性铰接浮体波能转换器的动力学特性研究

针对传统铰接浮体波能转换器捕获效率低、频带窄的瓶颈,提出一种新型高效波能捕获仿生非线性连接结构。该连接结构具有转动负刚度效应,可起到被动相位控制作用,提高系统的波能捕获效率。首先,基于海蛇脊柱骨结构的柔性约束机理,设计了一种高效波浪能捕获仿生连接结构,该结构由球窝结构、球头、翅状突出物和类肌肉柔性结构组成;其次,基于线性波浪理论和Cummins方程,建立两模块非线性波能转换器的动力学模型,并采用谐波平衡法解析求解非线性控制方程;最后,开展了数值模拟研究,分析了规则波激励下该新型波能转换器的波能转换特性。结果表明:通过引入新型高效仿生连接结构,可有效降低系统的等效固有频率;当连接器的负刚度结构调整到合适参数时,系统的弹性力可以在纵摇相平面上形成一个椭圆势阱,其椭圆势阱的长轴接近铰接浮体系统相对纵摇运动的模态方向,由此驱动两个模块的相对纵摇运动趋于反相,起到被动相位控制的作用。

风电机组的提效与降载一体化技术研究

目前对大型风力机的研究在追求风能捕获效率的同时往往容易忽视载荷性能的问题,本文研究了能同时优化风力机提效与降载的一体化技术。首先,阐述了目前工程中常用的最优功率曲线法的原理及存在的问题;其次,针对该问题在控制回路中引入一阶低通滤波器,以滤除高频风能对风力机载荷特性的影响,并修改最优功率曲线,进一步基于正弦风验证了改进方法的机理与应用效果。最后,采用MATLAB/Simulink对金风3MW风力机进行建模,验证了改进法的优越性与工程应用价值。研究表明:改进法能提升大型风力机风能捕获效率,并使载荷降低,在一定程度上延长了风力机的全生命周期。

兼具防波与发电的集成系统能量特性试验研究

基于模型试验法,研究PTO阻尼力、浮子底部形状对波能装置-浮式防波堤集成系统发电与防波性能的影响,并将单浮体型集成系统与双浮体型混合系统进行对比,分析防波堤对波能浮子发电性能的影响。结果表明:三角加挡板形浮子的发电与防波性能均优于方箱形和三角形浮子;相比于单浮体型集成系统,双浮体型混合系统的发电与防波性能显著提高,但当发生窄缝共振时,具有三角加挡板形浮子的双浮体型混合系统的发电性能显著降低。

微藻光合固碳效能研究:进展、挑战和解决路径

微藻固碳被认为是一种环境友好性较高的碳捕集技术,但其规模化发展遇到生产率低的瓶颈问题。为突破这一技术障碍,需要从机理层面深入研究微藻光合固碳的效能问题。本文围绕这一问题,首先综述了学界在生物特征、反应特征和效能特征3个层面的代表性研究,评述了技术发展趋势和局限性。其后,针对效能研究的跨学科特点,对3个主要挑战展开概述,并以典型制约因素的归纳展示了效能研究在方法论层面的复杂性。最后,为应对微藻光合固碳效能研究中的核心挑战,提出了对效能问题的再认识、跨学科特征的再把握和技术框架的再设计3条解决路径,并对涉及的关键技术进行了梳理,讨论了多学科和多尺度下、研究内容的串联和融合对效能研究的突破性意义。