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Selection and Evaluation of Dry and Isentropic Organic Working Fluids Used in Organic Rankine Cycle Based on the Turning Point on Their Saturated Vapor Curves

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Journal of Thermal Science 2019年第4期28卷 643-658页

作者： ZHANG Xinxin ZHANG Congtian HE Maogang WANG Jingfu MOE key Laboratory of Enhanced Heat Transfer and Energy Conservation College of Environmental and Energy EngineeringBeijing University of TechnologyBeijing 100124China beijing key Laboratory of Heat Transfer and Energy Conversion College of Environmental and Energy EngineeringBeijing University of TechnologyBeijing 100124China MOE key Laboratory of Thermo-Fluid Science and Engineering School of Energy and Power EngineeringXi'an Jiaotong UniversityXi’an 710049China

The organic Rankine cycle(ORC)is a popular technique used in the utilization of low-grade thermal *** wet,dry,and isentropic organic working fluids,the latter two types are more appropriate for ORC *** this paper,the definition of turning point on saturated vapor curve of dry fluid and isentropic fluid was given according to the shape of the saturated curve of working fluids in a T-s *** this basis,the model of near-critical region triangle was *** this model,the thermodynamic performance of 57 kinds of dry and isentropic organic working fluids in ORC was *** performance includes the relation between turning point temperature and cycle thermal efficiency,the relation between near-critical region triangle area and cycle thermal efficiency,the relation between near-critical region triangle area and exergy at turning point temperature,the relation between near-critical region triangle area and reciprocal value of slope of saturated vapor ***,working fluid selection was also conducted in terms of heat source *** was found through theoretical analysis results that the popular R123 is an acceptable choice especially for the utilization of closed type heat *** it will be phased out in near future,then cis-butene,butane,trans-butene,and isobutene are worth studying as its *** is worthy of attention and further research and it can be a good choice for utilization of open type heat source.

关键词： dry fluid isentropic fluid turning point saturated vapor curve near-critical region triangle Organic Rankine Cycle

Drain-engineered carbon-nanotube-film field-effect transistors with high performance and ultra-low current leakage

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Nano Research 2020年第7期13卷 1875-1881页

作者： Lijun Liu Chenyi Zhao Li Ding Lianmao Peng Zhiyong Zhang key Laboratory far the Physics and Chemistry of Nanodevices and Department of Electronics Peking UniversityBeijing 100871China

A small bandgap and light carrier effective mass(mo)lead to obv ous ambipolar transport behavior in carbon nanotube(CNT)fild-effect transistors(FE Ts),including a high off-state current and severe degradation of the subthreshold swing(SS)with increasing drain bias *** demonstrate a drain-engineered method to cope with this common problem in CNT-film FETs with a sub-μum channel length,i.e.,suppressing the ambipolar behavion while maintaining high on-state performance by adopting a feedback gate(FBG)structure to extend the drain region from the CNT/metal contact to the proximate CNT channels to suppress the tunneling ***-400-nm-channel-length FETs with a FBG structure statistially present a high on/off ratio of up to 10*and a sub-200 mV/dec SS under a high drain bias of up to-2 V whle maintaining a high on-state current of 0.2 mA/μm or a peak transconductance of 0.2 mS/*** lowering the supply voltage to 1.5 V,FBG CNT-fim FETs can meet the requirement of standard-pertormance ultra large scale integrated circuits(ULSICs).Therefore,the introduction of the drain engineering structure enables applications of CNT-film-based FETs in ULSICs and could also be widely extended to other small-bandgap semiconductor-based FETs for an improvement in their off-state property.

关键词： carbon nanotube field-effect transistor current leakage subthreshold swing small bandgap semiconductor

Concurrent catalytic removal of typical volatile organic compound mixtures over Au-Pd/α-MnO2 nanotubes

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Journal of Environmental Sciences 2018年第2期30卷 276-288页

作者： Yunsheng Xia Lu Xia Yuxi Liu Tao Yang Jiguang Deng Hongxing Dai College of Chemistry and Chemical Engineering Bohai University Jinzhou 121013 China key Laboratory of beijing on Regional Air Pollution Control Beijing Key Laboratory for Green Catalysis and Separation MOE Laboratory of Enhanced Heat Transfer and Energy Conservation and College of Environmental and Energy Engineering Beijing University of Technology Beijing 100124 China Mechanical Engineering Department University of Aveiro 3810-193 Aueiro Portugal

α-MnO2 nanotubes and their supported Au-Pd alloy nanocatalysts were prepared using hydrothermal and polyvinyl alcohol-protected reduction methods, respectively. Their catalytic activity for the oxidation of toluene/m-xylene, acetone/ethyl acetate, acetone/m-xylene and ethyl acetate/m-xylene mixtures was evaluated. It was found that the interaction between Au-Pd alloy nanoparticles and α-MnO2 nanotubes significantly improved the reactivity of lattice oxygen, and the 0.91 wt.% Au0.48 Pd/α-MnO2 nanotube catalyst outperformed the α-MnO2 nanotube catalyst in the oxidation of toluene, m-xylene, ethyl acetate and acetone. Over the0.91 wt.% Au0.48 Pd/α-MnO2 nanotube catalyst,（i） toluene oxidation was greatly inhibited in the toluene/m-xylene mixture, while m-xylene oxidation was not influenced;（ii） acetone and ethyl acetate oxidation suffered a minor impact in the acetone/ethyl acetate mixture; and（iii） m-xylene oxidation was enhanced whereas the oxidation of the oxygenated VOCs（volatile organic compounds） was suppressed in the acetone/m-xylene or ethyl acetate/m-xylene mixtures. The competitive adsorption of these typical VOCs on the catalyst surface induced an inhibitive effect on their oxidation, and increasing the temperature favored the oxidation of the VOCs. The mixed VOCs could be completely oxidized into CO2 and H2 O below 320°C at a space velocity of 40,000 m L/（g·hr）. The 0.91 wt.% Au0.48 Pd/α-MnO2 nanotube catalyst exhibited high catalytic stability as well as good tolerance to water vapor and CO2 in the oxidation of the VOC mixtures. Thus, the α-MnO2 nanotube-supported noble metal alloy catalysts hold promise for the efficient elimination of VOC mixtures.

关键词： Volatile organic compound mixture Manganese dioxide nanotubes Supported gold–palladium alloy catalyst Catalytic oxidation Competitive adsorption

Ultraviolet/ozone and oxygen plasma treatments for improving the contact of carbon nanotube thin film transistors

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Science Bulletin 2018年第12期63卷 802-806页

作者： Qi Huang Jiye Xia Jie Zhao Guodong Dong Fang Liu Hu Meng Xuelei Liang key Laboratory for the Physics and Chemistry of Nanodevices and Department of Electronics Peking UniversityBeijing 100871China BOE Technology Group Co. Ltd.Beijing 100176China

Carbon nanotube thin film transistor （CNT-TFF） is an emerging technology for future macroelectronics, such as chemical and biological sensors, optical detectors, and the backplane driving circuits for flat panel displays. The mostly reported fabrication method of CNT-TFT is a lift-off based photolithography process. In such fabrication process, photoresist （PR） residue contaminates the interface of tube-metal contact and deteriorates the device performance. In this paper, ultraviolet ozone （UVO） and oxygen plasma treat- ments were employed to remove the PR contamination. Through our well-designed experiments, the UVO treatment is confirmed an effective way of cleaning contamination at the tube-metal interface, while oxygen plasma treatment is too reactive and hard to control, which is not appropriate for CNT-TFTs. It is determined that 2-6 rain UVO treatment is the preferred window, and the best optimized treatment time is 4 rain, which leads to 15% enhancement of device performance.

关键词： Carbon nanotube Thin film transistor Contact UVO Oxygen plasma

The high catalytic activity and strong stability of 3%Fe/AC catalysts for catalytic wet peroxide oxidation of m-cresol: The role of surface functional groups and FeO_(x) particles

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Chinese Journal of Chemical Engineering 2022年第4期35卷 105-114页

作者： Peiwei Han Chunhua Xu Yamin Wang Chenglin Sun Huangzhao Wei Haibo Jin Ying Zhao Lei Ma beijing key Laboratory of Fuels Cleaning and Advanced Catalytic Emission Reduction Technology/College of Chemical Engineering Beijing Institute of Petrochemical TechnologyBeijing 102617China Shandong key Laboratory of Water Pollution Control and Resource Reuse School of Environmental Science and EngineeringShandong UniversityQingdao 266237China Dalian Institute of Chemical Physics Chinese Academy of SciencesDalian 116023China

FeO;supported on activated carbon(AC) has been shown to be an ideal catalyst for catalytic wet peroxide oxidation(CWPO) due to its high CWPO reaction activity and stability. Although there have been some studies on the mechanism of Fe/AC catalysis in CWPO, the specific contribution of each component(surface oxygen groups and FeOxon AC) inside an Fe/AC catalyst and their corresponding reaction mechanism remain unclear, and the reaction stability of CWPO catalysts has rarely been discussed. Then the optimal CWPO catalyst in our laboratory, 3%Fe/AC, was selected.(1) By removing certain components on the AC through heat treatment, its contribution to the reaction and the corresponding reaction mechanism were investigated. With the aid of temperature-programmed desorption–mass spectrometry(TPD–MS) and the CWPO reaction, the normalized catalytic contributions of components were shown to be: 37.3%(carboxylic groups), 5.3%(anhydride), 19.3%(ether/hydroxyl),-71.4%(carbonyl groups) and 100%(FeOx),respectively. DFT calculation and EPR analysis confirmed that carboxylic groups and Fe_(2)O_(3) are able to activate the H_(2)O_(2) to generate·OH.(2) The catalysts at were characterized at different reaction times(0 h, 450 h, 900 h, 1350 h, and 1800 h) by TPD–MS and M?ssbauer spectroscopy. Results suggested that the number of carboxylic goups gradually increased and the size of paramagnetic Fe_(2)O_(3) particle crystallites gradually increased as the reactions progressed. The occurrence of strong interactions between metal oxides and AC was also confirmed. Due to these effects, the strong stability of 3%Fe/AC was further improved. Therefore, the reasons for the high activity and strong stability of 3%Fe/AC in CWPO were clearly shown. We believe that this work provides an idea of the removal of cresols from wastewater into the introduction to show the potential applications of CWPO.

关键词： Catalytic wet peroxide oxidation Fe/AC catalyst Surface functional groups Reaction mechanism

Emerging probing perspective of two-dimensional materials physics:terahertz emission spectroscopy

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Light(Science & Applications) 2024年第7期13卷 1278-1298页

作者： Yifei Wu Yuqi Wang Di Bao Xiaonan Deng Simian Zhang Lin Yu-chun Shengxian Ke Jianing Liu Yingjie Liu Zeli Wang Pingren Ham Andrew Hanna Jiaming Pan Xinyue Hu Zhengcao Li Ji Zhou Chen Wang State key Laboratory of New Ceramics and Fine Processing Key Laboratory of Advanced Materials of Ministry of EducationSchool of Materials Science and EngineeringTsinghua University100084 BeijingChina beijing Advanced Innovation Center for Integrated Circuits 100084 BeijingChina

Terahertz(THz)emission spectroscopy(TES)has emerged as a highly effective and versatile technique for investigating the photoelectric properties of diverse materials and nonlinear physical processes in the past few ***,research on two-dimensional(2D)materials has experienced substantial growth due to their atomically thin structures,exceptional mechanical and optoelectronic properties,and the potential for applications in flexible electronics,sensing,and ***,these materials offer advantages such as tunable bandgap,high carrier mobility,wideband optical absorption,and relatively short carrier *** applying TES to investigate the 2D materials,their interfaces and heterostructures,rich information about the interplay among photons,charges,phonons and spins can be unfolded,which provides fundamental understanding for future *** it is timely to review the nonlinear processes underlying THz emission in 2D materials including optical rectification,photon-drag,high-order harmonic generation and spin-to-charge conversion,showcasing the rich diversity of the TES employed to unravel the complex nature of these *** applications based on THz emissions,such as THz lasers,ultrafast imaging and biosensors,are also *** further,we analyzed the unique advantages of spintronic terahertz emitters and the future technological advancements in the development of new THz generation mechanisms leading to advanced THz sources characterized by wide bandwidth,high power and integration,suitable for industrial and commercial *** continuous advancement and integration of TES with the study of 2D materials and heterostructures promise to revolutionize research in different areas,including basic materials physics,novel optoelectronic devices,and chips for post-Moore’s era.

关键词： optoelectronic versatile exceptional

Combustion characteristics and kinetics of anthracite with added chlorine

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International Journal of Minerals,Metallurgy and Materials 2017年第7期24卷 745-755页

作者： Cui Wang Jian-liang Zhang Guang-wei Wang Ke-xin Jiao Zheng-jian Liu Kuo-chih Chou School of Metallurgical and Ecological Engineering University of Science and Technology Beijing Beijing 100083 China State key Laboratory of Advanced Metallurgy University of Science and Technology Beijing Beijing 100083 China

The combustion process of Yangquan anthracite（YQ） with the addition of 0.045wt%, 0.211wt%, 1.026wt%, and 2.982wt% chlorine was investigated using a thermogravimetric method from an ambient temperature to 1173 K in an air atmosphere. Results show that the YQ combustion characteristics are not significantly affected by an increase in chlorine content. Data acquired for combustion conversion are then further processed for kinetic analysis. Average apparent activation energies determined using the model-free method（specifically the KAS method） are 103.025, 110.250, 99.906, and 110.641 k J/mol, respectively, and the optimal kinetic model for describing the combustion process of chlorine-containing YQ is the nucleation kinetic model, as determined by the z（α） master plot method. The mechanism function of the nucleation kinetic model is then employed to estimate the pre-exponential factor, by making use of the compensation effect. The kinetic models to describe chlorine-containing YQ combustion are thus obtained through advanced determination of the optimal mechanism function, average apparent activation energy, and the pre-exponential factor.

关键词： chlorine anthracite combustion characteristics kinetics

New discovery of Palaeontinid fossils from the Middle Jurassic in Daohugou, Inner Mongolia (Homoptera, Palaeontinidae)

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Science China Earth Sciences 2007年第4期50卷 481-486页

作者： SHIH ChungKun College of Life Science Capital Normal University

Three new species of fossil Palaeontinidae are described from Daohugou Village, Inner Mongolia, China: Daohugoucossus shii sp. nov., D. parallelivenius sp. nov., D. lii sp. nov. The diagnosis of Daohugoucossus Wang, Zhang and Fang, 2006 is revised. These materials are the first complete fossil palaeontinids in the Middle Jurassic of the world. Based on observation of these new specimens, Sc of this new genus has the following combined characters: joined with R at base, diverged near M separation, coalesced with R before the nodal line, extended beyond the nodal line and fused with R1 before distal end. Due to the Sc characteristics mentioned above, the genus Liaocossus Ren, Yin and Dou, 1998 can be well distinguished from “Ilerdocosus-complex”.

关键词： Palaeontinidae new species fossil Middle Jurassic Inner Mongolia

An improved constraint method in optimal estimation of CO2 from GOSAT SWIR observations

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Science China Earth Sciences 2017年第2期60卷 286-296页

作者： ZOU MingMin CHEN LiangFu LI ShenShen FAN Meng TAO JinHua ZHANG Ying State key Laboratory of Remote Sensing Science Institute of Remote Sensing and Digital Earth Chinese Academy of Sciences Beijing 100101 China

We propose an algorithm that combines a pre-processing step applied to the a priori state vector prior to retrievals, with the modified damped Newton method （MDNM）, to improve convergence. The initial constraint vector pre-processing step updates the initial state vector prior to the retrievals if the algorithm detects that the initial state vector is far from the true state vector in extreme cases where there are CO2 emissions. The MDNM uses the Levenberg-Marquardt parameter ~,, which ensures a positive Hessian matrix, and a scale factor a, which adjusts the step size to optimize the stability of the convergence. While the algorithm iteratively searches for an optimized solution using observed spectral radiances, MDNM adjusts parameters ）, and a to achieve stable convergence. We present simulated retrieval samples to evaluate the performance of our algorithm and comparing it to existing methods. The standard deviation of our retrievals adding random noise was less than 3.8 ppmv. After pre-processing the initial estimate when it was far from the true value, the CO2 retrieval errors in the boundary layers were within 1.2 ppmv. We tested the MDNM algorithm＇s performance using GOSAT Llb data with cloud screening. Our preliminary validations comparing the results to TCCON FTS measurements showed that the average bias was less than 1.8 ppm and the correlation coefficient was approximately 0.88, which was larger than for the GOSAT L2 product.

关键词： Retrieve Optimal estimation CO2 GOSAT