基于电网功率分布的碳排放流计算方法

传统碳排放量的计量是通过统计数据得到,有文献提出碳排放流的概念及相应的碳流计算方法,但未考虑无功功率和网损的影响。为此,计及无功功率和网损的电力网络中碳流计算方法将更具实际物理意义。以电网电流分布理论为基础,根据发电机与负荷间的直接功率传递关系,提出了负荷从电源汲取功率的分布及电源在联络支路上的功率分布。然后,在电力系统碳排放流分析理论的基础上,根据系统潮流与碳流的关系给出负荷节点及联络支路上碳流的计算方法。采用此方法计算得到的负荷节点处的碳流不包括网损部分,从而可以通过机组总注入碳排放与负荷节点的总碳排放得到网损产生的碳排放。最后,通过IEEE 14节点系统算例验证了上述方法的正确性。

计及混合交易模式的多区域互联电力系统碳排放流计算方法

为理清在多区域互联系统中各子区域间的混合交易对碳流分布的影响,该文提出了一种计及混合交易模式的多区域互联电力系统碳排放流计算方法。首先采用分裂法的思想,将原多区域互联电力系统转化为直观的双边交易系统。再根据潮流追踪法,将联营交易等效为多笔虚拟双边交易,成功将网损分至每笔交易,实现双边交易网络与联营交易网络的解耦。然后根据每笔交易的特性,得出新交易网络的运行参数,分别计算出各网络中的支路碳流率与负荷碳流率,进而计算出原多区域互联系统的碳流分布。算例结果显示,与传统的碳流计算法相比,上述方法能够反映出不同混合交易模式对系统碳流分布的影响,有效地避免不同交易耦合所造成的“碳泄露”,并能向电力用户展示碳排放的构成信息,具有较高的实用价值。

含光伏不确定性的电力系统碳排放流分析

为分析光伏发电对电力系统的低碳贡献,提出光伏注入功率不确定性对电力系统碳排放流影响的分析方法。首先,通过光伏机组的出力与系统节点功率模型,建立光照强度与系统节点总碳流率的函数表达式。其次,使用有向通路算法计算路径输出分布因子矩阵,将光伏出力的随机性转移到平衡机组,在平衡机组与系统节点支路的碳流率关联矩阵基础上,计算光伏注入功率对节点与支路的影响因子,得到光伏注入功率下电力系统碳排放流的不确定特征。最后,以实测光照强度与IEEE14节点算例分析结果验证所述方法的正确性,计算光伏电场集中式与分布式接入电力系统的节点碳势、支路碳流率与影响因子,进而定量分析光伏接入对电力系统的低碳贡献。

电力系统碳排放流分析理论初探

采用低碳电力技术是电力行业实现可持续发展的重要举措。现有研究中,碳排放的统计量通常以宏观数据统计为主,按照一次能源消耗量转换得到。此类方法无法揭示电力系统碳排放的特点,在应用中存在着诸多局限性。文中探讨了将碳排放分析与电力系统潮流计算相结合的新思路,提出了电力系统碳排放流的概念。结合网络分析技术,提出并建立了电力系统碳排放流分析的几个基本概念与指标,初步形成电力系统碳排放流分析的理论架构。给出了一个示例系统的计算结果和直观展示,并结合电力系统潮流分析的基本原理,剖析了电力系统碳排放流分析理论的作用和意义。最后对电力系统碳排放流分析理论的应用领域和研究方向进行了展望。

计及碳减排分摊的配电网分布式储能集群配置方法

“碳排放”市场的逐步建立背景下,针对大量分布式新能源接入配电网造成的系统消纳能力与增长速度不匹配问题,提出一种考虑不同主体碳减排收益分摊的储能集群配置方法。首先,基于电网各节点电气距离及其源荷特性将所有节点划分成若干个集群区域。其次,针对新型电力系统特点改进了节点碳流率计算方法,进一步提出集群储能对配电网碳排放流的影响模型,可以基于用能角度准确核算出储能对各个用户的碳减排分摊量,计算出相应的碳减排分摊收益。接着,提出计及碳减排分摊的配电网分布式储能集群配置模型,以储能全寿命周期成本最小,考虑碳减排收益等收益最大为目标来对各个集群进行储能配置。最后,基于IEEE 33节点配电网算例验证改进的碳流计算方法的正确性以及该文集群储能配置方法的合理性与经济性。

作业车间碳排放动态特性及二阶优化调度模型

为了降低加工作业运行时间的能耗、物耗和排放,以设备运行过程中的能耗为主要碳排放因素,基于碳流率的概念,用改进甘特图表征了工件全加工链的碳排放特性。将作业车间排产划分为设备选择和作业顺序规划两个阶段进行碳排放效率优化调度,建立了一种二阶低碳优化调度模型。该模型通过优化组合设备—工件功率匹配关系,提高设备能效,缩短非加工设备等待空载运行时间,提高车间综合能效。以某机加工作业车间为例,分析并验证了优化模型的可行性。

一种面向碳中和的基于机组出力的最优碳流计算方法

提出一种基于机组出力的最优碳流计算方法,通过建立碳流率与系统决策变量的关系,优化了碳排放流模型以达到降低碳流的目的。首先以碳流计算为基础,利用潮流分布矩阵,将发电机组产生的碳排放分摊给负荷节点、支路功率以及网损,建立发电机组出力与碳流率的映射关系;以PSO-GA算法为例,将发电机组的出力作为系统决策变量,在满足潮流约束、系统功率平衡的基础上,建立最优碳流的计算模型。采用IEEE9节点系统进行测试,测试结果证明了该方法的可行性和有效性。

Supercritical Carbon Dioxide Extraction of Andrographolide from Andrographis paniculata： Effect of the Solvent Flow Rate, Pressure, and Temperature

Andrographis paniculata Nees has been extensively used for traditional medicine and help against fever dysentery, diarrhoea, inflammation, and sore throat. In this study, andrographolide, the main component of this plant was extracted from the leaves of A. paniculata using supercritical carbon dioxide. The operating pressures were varied from 7.50 to 20MPa, the temperatures were varied from 30℃ to 60℃, and the flow rates were varied from 0.5 to 4ml.min^-1. The best extraction condition occurred at 10MPa, 40℃, and a flow rate of 2ml.min^-1 for a 3g sample of A. paniculata ground-dried leaves. The measured extraction rate was found to be about 0.0174g of andrographolide per gram of andrographolide present in the leaves per hour of operation. The future studies must focus on the interaction between the various operating parameters such as temperature, pressure, and flow rate of supercritical carbon dioxide.

Electroreduction of air‐level CO_(2) with high conversion efficiency

The electrochemical conversion of carbon dioxide(CO_(2))has been attracting increasingly research interest in the past decade,with the ultimate goal of utilizing electricity from renewable energy to realize carbon neutrality,as well as economic and energy benefits.Nonetheless,the capture and concentrating of CO_(2) cost a substantial portion of energy,while almost all the reported researches showed CO_(2) electroreduction under high concentrations of(typically pure)CO_(2) reactants,and only very few recent studies have investigated the capability of applying low CO_(2) concentrations(such as~10%in flue gases).In this work,we first demonstrated the electroreduction of 0.03%CO_(2)(in helium)in a homemade gas‐phase electrochemical electrolyzer,using a low‐cost copper(Cu)or nanoscale copper(nano‐Cu)catalyst.Mixed with steam,the gas‐phase CO_(2) was directly delivered onto the gas‐solid interface with the Cu catalyst and reduced to CO,without the need/constraint of being adsorbed by aqueous solution or alkaline electrolytes.By tuning the catalyst and experi‐mental parameters,the conversion efficiency of CO_(2) reached as high as~95%.Furthermore,we demonstrated the direct electroreduction of 0.04%CO_(2) from real air sample with an optimized conversion efficiency of~79%,suggesting a promising perspective of the electroreduction ap‐proach toward direct CO_(2) conversion.

Three Stage Equilibrium Model for Coal Gasification in Entrained Flow Gasifiers Based on Aspen Plus

A three stage equilibrium model is developed for coal gasification in the Texaco type coal gasifiersbased on Aspen Plus to calculate the composition of product gas, carbon conversion, and gasification teml^erature. The model is divided into three stages including pyrolysis and combustion stage, char gas reaction stage, and gas p.hase reaction stage. Part of the water produced in thepyrolysis and combust!on stag.e is assumed to be involved inthe second stage to react with the unburned carbon. Carbon conversion is then estimated in the second stage by steam participation ratio expressed as a function of temperature. And the gas product compositions are calculated from gas phase reactions in the third stage. The simulation results are consistent with published experimental data.

A carbon-oxygen-bridged ladder-type building block for efficient donor and acceptor materials used in organic solar cells

A carbon-oxygen-bridged ladder-type donor unit （CO5） was invented and prepared via an ＂intramolecu- lar demethanolization cyclization＂ approach. Its single crystal structure indicates enhanced planarity compared with the carbon-bridged analogue indacenodithiophene （IDT）. Owing to the stronger electron-donating capability of CO5 than IDT, CO5-based donor and acceptor materials show narrower bandgaps. A donor-acceptor （D-A） copolymer donor （PCO5TPD） and an A-D-A nonfullerene acceptor （COSIC） demonstrated higher performance than IDT-based counterparts, PIDTTPD and IDTIC, respec-tively. The better performance of CO5-based materials results from their stronger light-harvesting capability and higher charge-carrier mobilities.

Photoacoustic Doppler flowmetry of carbon particles flow using an autocorrelation method

In order to measure the axial flowing velocity of carbon particle suspension with particle diameter of tens of micrometers, the photoacoustic Doppler(PAD) frequency shift is calculated based on a series of individual A scans using an autocorrelation method. A 532 nm pulsed laser with repetition rate of 20 Hz is used as a pumping source to generate photoacoustic signal. The photoacoustic signals are detected using a focused piezoelectric(PZT) ultrasound transducer with central frequency of 5 MHz. The suspension of carbon particles is driven by a syringe pump. The complex photoacoustic signal is calculated by the Hilbert transformation from time-domain photoacoustic signal, and then it is autocorrelated to calculate the Doppler frequency shift. The photoacoustic Doppler frequency shift is calculated by averaging the autocorrelation results of some individual A scans. The advantage of the autocorrelation method is that the time delay in autocorrelation can be defined by user, and the requirement of high pulse repetition rate is avoided. The feasibility of the proposed autocorrelation method is preliminarily demonstrated by quantifying the motion of a carbon particle suspension with flow velocity from 5 mm/s to 60 mm/s. The experimental results show that there is an approximately linear relation between the autocorrelation result and the setting velocity.

Circulating Fluidized Bed Gasification of Low Rank Coal：Influence of O2/C Molar Ratio on Gasification Performance and Sulphur Transformation

To promote the utilization efficiency of coal resources,and to assist with the control of sulphur during gasification and/or downstream processes,it is essential to gain basic knowledge of sulphur transformation associated with gasification performance.In this research we investigated the influence of O_2/C molar ratio both on gasification performance and sulphur transformation of a low rank coal,and the sulphur transformation mechanism was also discussed.Experiments were performed in a circulating fluidized bed gasifier with O_2/C molar ratio ranging from 0.39 to 0.78 mol/mol.The results showed that increasing the O_2/C molar ratio from 0.39 to 0.78 mol/mol can increase carbon conversion from 57.65%to 91.92%,and increase sulphur release ratio from 29.66%to63.11%.The increase of O_2/C molar ratio favors the formation of H_2S,and also favors the retained sulphur transforming to more stable forms.Due to the reducing conditions of coal gasification,H_2S is the main form of the released sulphur,which could be formed by decomposition of pyrite and by secondary reactions.Bottom char shows lower sulphur content than fly ash,and mainly exist as sulphates.X-ray photoelectron spectroscopy(XPS)measurements also show that the intensity of pyrite declines and the intensity of sulphates increases for fly ash and bottom char,and the change is more obvious for bottom char.During CFB gasification process,bigger char particles circulate in the system and have longer residence time for further reaction,which favors the release of sulphur species and can enhance the retained sulphur transforming to more stable forms.

Length-Sorted Semiconducting Carbon Nanotubes for High-Mobility Thin Film Transistors

We have developed a process for chemical purification of carbon nanotubes for solution-processable thin-film transistors （TFTs） having high mobility. Films of the purified carbon nanotubes fabricated by simple drop coating showed carrier mobilities as high as 164 cm2V-1s -1 normalized transconductances of 0.78 Sm-1 and on/off current ratios of 10^6. Such high performance requires the preparation of a suspension of micrometer-long and highly purified semiconducting single-walled carbon nanotubes （SWCNTs）. Our purification process includes length and electronic-type selective trapping of SWCNTs using recycling gel filtration with a mixture of surfactants. The results provide an important milestone toward printed high-speed and large-area electronics with roll-to-roll and ink-jet device fabrication.