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Design Optimization and Operating Performance of S-CO_(2) Brayton Cycle under Fluctuating Ambient Temperature and Diverse Power Demand Scenarios

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Journal of Thermal Science 2024年第1期33卷 190-206页

作者： YANG Jingze YANG Zhen duan yuanyuan Key Laboratory for Thermal Science and Power Engineering of MOE Beijing Key Laboratory for CO_(2) Utilization and Reduction TechnologyTsinghua UniversityBeijing 100084China

The supercritical CO_(2)(S-CO_(2)) Brayton cycle is expected to replace steam cycle in the application of solar power tower system due to the attractive potential to improve efficiency and reduce *** the concentrated solar power plant with thermal energy storage is usually located in drought area and used to provide a dispatchable power output,the S-CO_(2) Brayton cycle has to operate under fluctuating ambient temperature and diverse power demand *** addition,the cycle design condition will directly affect the off-design *** this work,the combined effects of design condition,and distributions of ambient temperature and power demand on the cycle operating performance are analyzed,and the off-design performance maps are proposed for the first time.A cycle design method with feedback mechanism of operating performance under varied ambient temperature and power demand is introduced *** show that the low design value of compressor inlet temperature is not conductive to efficient operation under low loads and sufficient output under high ambient *** average yearly efficiency is most affected by the average power demand,while the load cover factor is significantly influenced by the average ambient *** multi-objective optimization,the optimal solution of designed compressor inlet temperature is close to the minimum value of35℃ in Delingha with low ambient temperature,while reaches 44.15℃ in Daggett under the scenario of high ambient temperature,low average power demand,long duration and large value of peak load during the peak temperature *** the cycle designed with compressor inlet temperature of 35℃ instead of 44.15℃ in Daggett under light industry power demand,the reduction of load cover factor will reach 0.027,but the average yearly efficiency can barely be improved.

关键词： supercritical CO_(2)Brayton cycle ambient temperature fluctuating power demand scenarios design optimization off-design performance

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Structure and flow calculation of cake layer on microfiltration membranes

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Journal of Environmental Sciences 2017年第6期29卷 95-101页

作者： Yadong Yu Zhen Yang yuanyuan duan Key Laboratory for Thermal Science and Power Engineering of MOE Beijing Key Laboratory for CO2 Utilization and Reduction TechnologyTsinghua UniversityBeijing 100084China

Submerged membrane bioreactors （SMBR） are widely used in wastewater treatment. The permeability of a membrane declines rapidly because of the formation of a cake layer on the membrane surface. In this paper, a multiple staining protocol was conducted to probe the four major foulants in the cake layer formed on a filtration membrane. Fluorescent images of the foulants were obtained using a confocal laser scanning microscope （CLSM）. The three dimensional structure of the cake layer was reconstructed, and the internal flow was calculated using computational fluid dynamics （CFD）. Simulation results agreed well with the experimental data on the permeability of the cake layer during filtration and showed better accuracy than the calculation by Kozeny-Carman method. B-D-Glucopyranose polysaccharides and proteins are the two main foulants with relatively large volume fractions, while a-D-glucopyranose polysaccharides and nucleic acids have relatively large specific surface areas. The fast growth of B-D-glucopyranose polysaccharides in the volume fraction is mainly responsible for the increase in cake volume fraction and the decrease in permeability. The specific area, or the aggregation/dispersion of foulants, is less important to its permeability compared to its volume fraction.

关键词： Membrane fouling CLSM Cake layer CFD Permeability

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Multiparameter optimization and configuration comparison of supercritical CO_(2) Brayton cycles based on efficiency and cost tradeoff

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Science China(Technological Sciences) 2021年第10期64卷 2084-2098页

作者： LIU TianYe YANG JingZe YANG Zhen duan yuanyuan Key Laboratory for Thermal Science and Power Engineering of MOE Beijing Key Laboratory for CO_(2)Utilization and Reduction TechnologyTsinghua UniversityBeijing 100084China

Supercritical CO_(2)Brayton cycle has high efficiency,compactness,and excellent power generation *** the design of the cycle,some parameters,such as recuperator pinch point temperature difference(ΔTrec,pp),turbine inlet temperature(Ttur,in),and maximum cycle pressure(pmax),are often preset without ***,different preferences on efficiency and cost tradeoff can significantly affect the optimal design of the cycle,and the influence of different parameters on the design condition and the optimum cycle configuration becomes unclear as the preference *** this study,different preferences on efficiency and cost tradeoff are considered,and the effects of cycle configuration and optimization parameter addition on the tradeoff are *** addition,four configurations under different preferences on tradeoff are *** show that the design condition parametersΔT_(rec,pp) decrease and T_(tur,in) and pmax increase as the preference of thermal efficiency(W_(th))*** optimized parameters affect the results of the design point and cycle *** addition,the simple recuperative cycle and reheating cycle are recommended when low cycle initial cost dominates(W_(th)0.701).The decision maker can select appropriate configuration according to specific preferences.

关键词： supercritical CO_(2)Brayton cycle multi-objective optimization decision preference optimized parameter analysis cycle configuration comparison

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Ultrathin planar broadband absorber through effective medium design

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Nano Research 2016年第8期9卷 2354-2363页

作者： Dong Liu Haitong Yu Zhen Yang yuanyuan duan School of Energy and Power Engineering Nanjing University of Science & Technology Nanjing 210094 China Key Laboratory of Thermal Science and Power Engineering of Ministry of Education Key Laboratory for CO2 Utilization and Reduction Technology Tsinghua University Beijing 100084 China

Ultrathin planar absorbers hold promise in solar energy systems because they can reduce the material, fabrication, and system cost. Here, we present a general strategy of effective medium design to realize ultrathin planar broadband absorbers. The absorber consists of two ultrathin absorbing dielectrics to design an effective absorbing medium, a transparent layer, and metallic substrate. Compared with previous studies, this strategy provides another dimension of freedom to enhance optical absorption; therefore, destructive interference can be realized over a broad spectrum. To demonstrate the power and simplicity of this strategy, we both experimentally and theoretically characterized an absorber with 5-nm-thick Ge, 10-nm-thick Ti, and 50-nm-thick SiO2 films coated on an Ag substrate fabricated using simple deposition methods. Absorptivity higher than 80% was achieved in 15-nm-thick （1/50 of the center wavelength） Ge and Ti films from 400 nm to near 1 btm. As an application example, we experimentally demonstrated that the absorber exhibited a normal solar absorptivity of 0.8 with a normal emittance of 0.1 at 500 ~C, thus demonstrating its potential in solar thermal systems. The effective medium design strategy is general and allows material versatility, suggesting possible applications in real-time optical manipulation using dynamic materials.

关键词： ultrathin planar film broadband absorber effective medium design solar energy

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Power Generation Systems Using Continuous Blowdown Waste Heat from Drum Boilers Driving an Organic Rankine Cycle

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中国电机工程学报 2013年第35期33卷 I0001-I0014页

作者： LIU Qiang duan yuanyuan WAN Xucai Tsinghua University CPECC Southwest Electric Power Design Institute

提出了一种利用汽包锅炉排污系统余热的有机朗肯循环发电系统,有机工质回收扩容器疏水的热量,并通过气轮机发电。建立了系统的热力性能分析模型,并对R227ea、RC318、R236ea、R245fa、R245ca、R123和R113等7种工质的热力性能进行了优化... 详细信息

提出了一种利用汽包锅炉排污系统余热的有机朗肯循环发电系统,有机工质回收扩容器疏水的热量,并通过气轮机发电。建立了系统的热力性能分析模型,并对R227ea、RC318、R236ea、R245fa、R245ca、R123和R113等7种工质的热力性能进行了优化。结果表明,临界温度高的工质,其o2循环的最佳主气温度（蒸发温度）反而低；亚临界循环采用干流体时,过热不利于余热的利用；超临界循环可以改善热源与工质间的温度匹配,有利于增大系统输出功,但是其运行压力高、大比热区的传热恶化等问题是实际运行和设计需要考虑的因素；R236ea的热力性能优于其余6种工质。

关键词：朗肯循环余热驱动连续排污发电系统锅炉燃煤电厂标准煤耗率发电量

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CO_2 Mitigation in Coal Gasification Cogeneration Systems with Integration of the Shift Reaction, CO_2 Absorption and Methanol Production

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Journal of Thermal Science 2004年第3期13卷 193-198页

作者： yuanyuan duan Jin ZHANG Key Laboratory of Thermal Science and Power Engineering, Department of Thermal Engineering, Tsinghua University, Beijing 100084, China Key Laboratory of Thermal Science and Power Engineering Department of Thermal Engineering Tsinghua University Beijing China

Cogeneration of electricity and liquid fuel can achieve higher efficiencies than electricity generation alone in Integrated Gasification Combined Cycle (IGCC), and cogeneration systems are also expected to mitigate CO2 emissions. A proposed methanol-electricity cogeneration system was analyzed in this paper using exergy method to evaluate the specified system. A simple cogeneration scheme and a complicated scheme including the shift reaction and CO2 removal were compared. The results show that the complicated scheme consumes more energy, but has a higher methanol synthesis ratio with partial capture of *** those methanol and electricity cogeneration systems, the CO2 mitigation is not merely an additional process that consumes energy and reduces the overall efficiency, but is integrated into the methanol production.

关键词： cogeneration system methanol synthesis CO2 mitigation exergy analysis

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Analysis of the thermodynamic performance limits of the organic Rankine cycle in low and medium temperature heat source applications

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Science China(Technological Sciences) 2021年第8期64卷 1624-1640页

作者： YANG FuBin YANG FuFang LI Jian HU ShuoZhuo YANG Zhen duan Yuan Yuan Key Laboratory for Thermal Science and Power Engineering of Ministry of Education Beijing Key Laboratory for CO_(2) Utilization and Reduction TechnologyTsinghua UniversityBeijing100084China Faculty of Environment and Life Beijing University of TechnologyBeijing100124China Center for Energy Resources Engineering(CERE) Department of Chemical and Biochemical EngineeringTechnical University of Denmark2800Kgs.LyngbyDenmark

In this paper,an exploration of the practical thermodynamic performance limits of the organic Rankine cycle(ORC)under working fluid and cycle parameter restrictions is *** performance limits are more realistic benchmarks for the thermodynamic cycle than the efficiency of the Carnot *** ORC configuration with four typical case studies that are related to temperature ranging from 373.15 to 673.15 K is taken into *** ORC is defined by its cycle parameters and working fluid characteristic *** cycle parameters involve evaporation temperature(T_(eva)),condensation temperature(T_(con))and superheat degree(ΔT_(sup)),while the working fluids are represented by the characteristic properties including critical temperature(T_(c)),critical pressure(p_(c)),acentric factor(ω),and molar ideal gas isobaric heat capacity based on the principle of corresponding ***,Pareto optimum solutions for obtained hypothetical working fluids and cycle parameters are achieved using multi-objective optimization method with the consideration of both thermal efficiency(η_(th))and volumetric power output(VPO).Finally,sensitivity analysis of the working fluid characteristic properties is conducted,and the second law of thermodynamics analysis,especially the applicability of entropy generation minimization,is *** results show that the current commonly used working fluids are widely scattered below the Pareto front that represents the tradeoff betweenη_(th) and VPO for obtained hypothetical fluids.T_(eva) and T_(con) are the most dominant cycle parameters,while T_(c) and ωtend to be the most dominant characteristic property *** entropy generation minimization does not give the same optimal results.

关键词： organic Rankine cycle thermodynamic performance limit working fluids cycle parameters

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Spectral matching based remote sensing identification of two main crop rotation patterns in a large irrigation district

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中国水利水电科学研究院学报（中英文） 2024年第6期22卷 640-650页

作者： duan yuanyuan CHEN Xiuhua LIU Jun YE Mao LU Wenjing LIU Hongjie China Institute of Water Resources and Hydropower Research Beijing 100038China Application Center of Remote Sensing Technology Research Center on Flood&Drought Disaster Prevention and Reduction of the Ministry of Water ResourcesBeijing 100038China Qingdao Comcore Technologies Co. LtdShandong Qingdao 266000China Sucheng District Water Resources Bureau Jiangsu Suqian 223800China

The rapid identification of planting patterns for major crops in a large irrigated district has vital importance for irrigation management,water fee collection,and crop yield *** this study,the OTSU algorithm and Mean-Shift algorithm were employed to automatically determine threshold values for mapping two main rotated crop patterns at the pixel scale.A time series analysis was conducted to extract the spatial distribution of rice-wheat and wheat-maize rotations in the Chuanhang irrigation district from 2016 to *** results demonstrate that both threshold segmentation algorithms are reliable in extracting the spatial distribution of the crops,with an overall accuracy exceeding 80%.Additionally,both Kappa coefficients surpass 0.7,indicating better performance by OTSU *** the period from 2016 to 2020,the area occupied by rice-wheat rotation cropping ranged from 12500 to 14400 hm 2;whereas wheat-maize rotation cropping exhibited smaller and more variable areas ranging from 19730 to 34070 hm *** findings highlight how remote sensing-based approaches can provide reliable support for rapidly and accurately identifying the spatial distribution of main crop rotation patterns within a large irrigation district.

关键词： Chuanhang irrigation district rotate crop pattern spectral matching OTSU algorithm Mean-Shift algorithm

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Happy life expectancy in China

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China Population and Development Studies 2020年第2期3卷 218-236页

作者： yuanyuan duan Wei Chen Center for Population and Development Studies Renmin University of ChinaNo.59 Zhongguancun StreetHaidian DistrictBeijing 100872China Macquarie Business School Macquarie UniversityBalaclava RoadNorth RydeSydneyNSW 2109Australia

Utilizing multiple-wave data from Chinese General Social Survey and the life table method,this study assesses the happy life expectancy of Chinese population aged 18 and older over *** also use the decomposition method to further iso-late the happiness effect and mortality effect on temporal changes and gender *** results suggest that,Chinese adults,in general,live a great proportion of their lives happily,and the happy life expectancy increases pronouncedly over time in both absolute and relative terms.A rapidly rising level of happiness provides the major contribution to the temporal increase in happy life *** exceed men in the length of happy life expectancy,and the gender difference enlarges over *** gender gap in happy life expectancy mainly reflects a mortality *** results also indicate that with the increase of age,there is an increasing propor-tion of happy life years lived among the Chinese elderly,which is in sharp contrast with the decreasing proportion of healthy life years lived by this population,as sug-gested by previous studies on health life *** conclude that a combina-tion of healthy life expectancy and happy life expectancy can provide a fuller and more comprehensive reflection on people’s overall quality of life.

关键词： Quality of life Subject wellbeing Happy life expectancy The Sullivan method

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Thermophysical Properties of a New Environment FriendlyAlternative - Trifluoroiodomethane

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Journal of Thermal Science 1999年第2期8卷 73-78页

作者： duan yuanyuan Shi Lin Zhu Mingshan Han Lizhong(Department of Thermal Engineering, Tsinghua University, Beijing 100084, China) Department of Thermal Engineering Tsinghua University Beijing China

Trifluoroiodomethane (CF3l) is consider as a Promising refrigerant alternative, especially as a component inmixtures, to replare CFC-12. But reliable thermophysical propelty data for CF3I are still limited. The investigationson thermophysical Propelties of CF3I developed by us are summarized in this paper. Experimental data of criticalParamethe, and the condations of saturated liquid and vapor density, enthaipy of vaporization, vapor pressurs,PVT prowtes, second vinal coefficient ideal-gas heat capacity, surface tension, viscosity and thermalconduchvity are given in the Present paper.

关键词： trifluoreiodomethane CF3I thermodynamic properties transport properties refrigerant alternative

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