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In situ Raman imaging of high-temperature solid-state reactions in the CaSO4-SiO2 system

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International Journal of Coal Science & Technology 2019年第2期6卷 247-259页

作者： Nadine Bohme Kerstin Hauke Manuela Neuroth Thorsten Geisler Institut fiir Geowissenschaften und Meteorologie Universitat Bonn Poppelsdorfer Schloss Meckenheimer Allee 169 53115 Bonn Germany rwe power ag F und E Kraftwerk NiederauBem Bergheim Germany

The deposition of mineral phases on the heat transfer surfaces of brown coal power plants may have a negative effect on power plant boilers. The paragenesis of these deposits contains information about the actual temperature prevailed during the combustion of lignite, if the temperature-dependences of distinct mineral transformations or reactions are known. Here, we report results of a sintering study (to ?1100℃) with samples containing anhydrite, quartz, and gehlenite, which are typical components of Rhenish lignite ashes. Thermal decompositions and solid-state reactions were analyzed (1) in situ and (2) both in situ and after quenching using confocal hyperspectral Raman imaging. This novel application of confocal Raman spectroscopy provides temperature-and time-resolved, 2-dimensional information about sintering processes with a micrometer-scale resolution. In the course of the sintering experiments with anhydrite and quartz with a weight ratio of 2:1 both polymorphs wollastonite and pseudowollastonite were identified in situ at about 920 and 1000℃, respectively. The formation of pseudowollastonite was thus observed about 120℃ below the phase transition temperature, demonstrating that it can form metastably. In addition,α′L-Ca2SiO4 was identified at about 1100℃. In samples containing equal weight fractions of anhydrite and quartz that were quenched after firing for 9h at about 1100℃,β-Ca2SiO4 (larnite) crystallized as rims around anhydrite grains and in direct contact to wollastonite. We furthermore observed that, depending on the ratio between quartz and anhydrite, wollastonite replaced quartz grains between 920 and 1100℃., i.e., the higher the quartz content, the lower the formation temperature of wollastonite.

关键词： Ash deposition Calcium silicate Calcium sulfate High-temperature Raman imaging

Analysis of arch dam deformations

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Frontiers of Structural and Civil Engineering 2010年第1期4卷 102-108页

作者： Franz PERNER Pius OBERNHUBER Verbund-Austrian Hydro power ag ViennaAustria

Predicting“regular”dam deformations for prevailing conditions and comparing them with observed deformations is an essential part of dam *** many cases prediction and comparison are carried out automatically and an alarm is triggered in the case of larger *** main contributors to the deformations of arch dams are water loading and the fluctuation of concrete *** general,the deformations exhibit an instantaneous elastic part,a time dependent reversible part and an irreversible *** of dam deformations can be based on deterministic models,purely statistical models or so-called hybrid models,which are a combination of the first *** models rely on static analyses,statistical models on the statistical analysis of previous deformation *** annual reservoirs,both water loading and temperature vary in cycles over a period of one year and it is extremely difficult to identify the various factors contributing to an observed *** is particularly true for time-dependent reversible displacements due to the water loading and the portion caused by temperature *** present article deals with the analysis of arch dam deformations based on hybrid *** attention is given to the analysis of the deformations due to temperature fluctuation and to the long-term *** proposed procedure is employed for the analysis of the deformations of the 186 m high Zillergruendl arch dam.

关键词： arch dam analysis Zillergruendl concrete temperature hybrid model

Improvement of Thermal Performance of ag Nano Fluid Combined with Carbon Nano-Tube

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Journal of Wuhan University of Technology(Materials Science) 2014年第3期29卷 463-467页

作者：吴迪刘石 School of Energy Power and Mechanical Engineering North China Electric Power University

The thermal performance of nano fluid containing ag NPs with different stabilizers was studied in detail. The wall temperature distributions of the heat pipe containing pure water and a small amount of PAN/ag, PVP/ag, L-cys/ag, and OA/ag were determined, respectively. With the addition of a small amount ofag NPs in the pure water, the heat pipe wall temperature became lower than that of pipes filled with pure water. The efficiency under the same conditions was ranked as PVP/ag 〉 L-cys/ag 〉 PAN/ag 〉 OA/ ag. After adding a small amount of CNT in the mixture, the effect was enhanced further. As more CNT became dispersed in the working fluid, the opposite effect was observed. Therefore, the optimal amount is 4 mg/L CNT in nano-fluid. ag nano fluid could form the multi-scaled surface with higher wettability and spreadability. The wettability of nano-fluid was improved with the addition of a small amount of CNT in the mixture. However, the spreadability of the mixture would decrease significantly in the presence of more CNT.

关键词： nano fluid ag wettability and spreadability CNT

A robust interface enabled by electrospun membrane with optimal resistance in lithium metal batteries

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Journal of Energy Chemistry 2021年第4期30卷 1-9页

作者： Chen Dong Zhenkang Lin Yuxin Yin Yaoxuan Qiao Wei Wang Qibing Wu Chengxiang Yang David Rooney Cheng Fan Kening Sun Beijing Key Laboratory for Chemical power Source and Green Catalysis School of Chemistry and Chemical EngineeringBeijing Institute of TechnologyBeijing 100081China State Key Laboratory of Advanced Chemical power Sources Guizhou Meiling Power Sources Co.Ltd.Zunyi 563003GuizhouChina School of Chemistry and Chemical Engineering Queen’s University BelfastBelfast BT95AGUnited Kingdom

A uniform diffusion layer is essential for non-dendritic deposition of lithium in high-density lithium ***,natural pristine solid electrolyte interface(SEI)is always porous and inhomogeneous because of repeated breakdown and repair cycles,whereas ideal materials with excellent mechanical property for artificial SEIs remain a ***,a robust and stable interface is achieved by spinning soft polymer associated with few MoO_(3) into fibers,and thus mechanical property of fibers other than materials determines mechanical performance of the interface which can be optimized by adjusting ***,lithium deposited underneath the layer is enabled by constructing an optimal resistance to make the membrane serve as an artificial SEI rather than lithium *** a result,dendritefree lithium was observed underneath the membrane,and stable interface for long-term cycling was also indicated by EIS *** lithium iron phosphate(LiFePO_(4))full-cell with coated electrode demonstrated an initial capacity of 155.2 m Ah g^(-1),and 80%of its original capacity was retained after 500 cycles at 2.0℃ without any additive in carbonate-based electrolyte.

关键词： Lithium metal battery Dendrite-free Interfacial stability Uniform diffusion layer Deposition site

Numerical Simulation of Nanofluid-Based Parallel Cooling Photovoltaic Thermal Collectors

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Journal of Thermal Science 2023年第4期32卷 1644-1656页

作者： WANG Jiangjiang QIN Yanbo HUO Shuojie XIE Kangzhen LI Yiming Hebei Key Laboratory of Low Carbon and High Efficiency power Generation Technology North China Electric Power UniversityBaoding071003China

A novel hybrid cogeneration system based on a parallel-cooled photovoltaic/thermal(PV/T)module is presented in this *** temperature of the parallel-cooled PV/T module is more uniform due to the parallel cooling fluid of air mixed with water or nanofluids(SiO2,CuO,ag,and Al_(2)O_(3)).The results show that the overall temperature of the PV cell in the parallel-cooled module is about 2 K lower than that in the single-cooled module,with a 9.01%improvement in thermal efficiency and a 0.09%enhancement in electrical *** PV/T module with nanofluid shows a significant improvement in thermal and electrical *** thermal and electrical efficiencies of the parallel-cooled PV/T module consisting of Al_(2)O_(3)nanofluid and air are 89.21%and 9.84%,*** with the non-nanofluid parallel cooling scheme,the cooling method consisting of 1 wt%,3 wt%,or 5 wt%Al_(2)O_(3)and air,the thermal efficiency of PV/T was improved by 5.47%,5.30%,and 3.93%,respectively with the solar radiation of 800 W/m^(2)and the flow rate of 0.10 m/s,while the electrical efficiency was improved by 0.026%,0.027%,and 0.034%,*** addition,when the solar radiation is 1000 W/m^(2)with a flow rate of 0.025 m/s,the air-water parallel cooling PV/T module achieves a maximum exergy efficiency of 11.74%.

关键词： PV/T parallel cooling exergy efficiency nanofluid numerical simulation

Performance Assessment and Improvement of Photovoltaic-Thermal System based on Energy, Exergy, Economic and Environment Analysis

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Journal of Thermal Science 2024年第6期33卷 2166-2178页

作者： ZHOU Yuan WANG Jiangjiang QIN Yanbo LIU Boxiang Hebei Key Laboratory of Low Carbon and High Efficiency power Generation Technology North China Electric Power UniversityBaoding 071003Chin

A photovoltaic thermal(PV/T)system with parallel cooling channels was designed in this work to decrease the PV panel temperature and improve its photoelectric conversion efficiency.A 4E analysis method(includes energy,exergy,economic,and environmental aspects)was formulated to comprehensively evaluate the performances of the PV/T system,combining experimental and simulation ***,the experiment was performed using water as the cooling *** show that the PV/T system can reduce daily CO_(2) emissions by 1682.47-1705.98 g,and compared to the PV system,the added cooling module can increase electrical efficiency and environmental performance by 12.19%and 6.2%,*** the mass flow of water rose from 0.017 kg/s to 0.023 kg/s,the electrical,thermal,and overall efficiencies were improved by 3.82%,11.36%,and 8.27%,***,a numerical simulation model was constructed based on the experimental results to predict operations of the presented PV/T system using nanofluids as the cooling medium,including ag,Al_(2)O_(3),and SiO_(2).Simulation results show that the Al_(2)O_(3)-nanofluid-based PV/T system has a higher application value,enabling an electrical efficiency of up to 15.13%.Its thermal efficiency can be enhanced by 5.43%when the volume fraction of Al_(2)O_(3);increases from 1%to 5%.

关键词： photovoltaic/thermal system parallel cooling channels 4E analysis method nanofluid numer analysis

Conductive and tribological properties of TiN-ag composite coatings under grease lubrication

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Friction 2021年第4期9卷 774-788页

作者： Feihu LIN Yanqiu XIA Xin FENG School of Energy power and Mechanical Engineering North China

TiN-ag composite coatings were prepared by pulsed bias arc ion plating.X-ray diffraction(XRD)and energy dispersive X-ray spectroscopy(EDS)were applied to analyze the compositions of the *** properties of the coatings were studied using an MFT-R4000 ball-on-disk friction tester in the presence of lubricating greases containing multilayer *** electron microscopy(SEM),Raman spectroscopy,and X-ray photoelectron spectroscopy(XPS)were used to analyze the worn surface compositions of the lubricating *** results show that with the decrease in ag in the film,hardness increased but electrical conductivity *** coating with 10 at%ag content shows the best friction-reducing and anti-wear properties,which can be attributed to the moderate content of ag embedded in the TiN crystal gap that enhanced the grain bonding force to improve the anti-wear and self-lubricating *** can be adsorbed on the coating as a solid lubricant.

关键词： silver tribology contact resistance lubricating grease

Sharing Economy in Local Energy Markets

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Journal of Modern power Systems and Clean Energy 2023年第3期11卷 714-726页

作者： Zhaoyuan Wu Jianxiao Wang Haiwang Zhong Feng Gao Tianjiao Pu Chin-Woo Tan Xiupeng Chen Gengyin Li Huiru Zhao Ming Zhou Qing Xia School of Economics and Management North China Electric Power UniversityBeijing 102206China State Key Laboratory of Alternate Electrical power System with Renewable Energy Sources North China Electric Power UniversityBeijing 102206China National Engineering Laboratory for Big Data Analysis and Applications Peking UniversityBeijing 100871China State Key Lab of power Systems Department of Electrical EngineeringTsinghua UniversityBeijing 100084China Department of Industrial Engineering and Management College of EngineeringPeking UniversityBeijing 100871China China Electric power Research Institute Beijing 100192China Department of Civil and Environmental Engineering Stanford UniversityPalo AltoCA 94305USA Engineering and Technology Institute Groningen University of Groningen9742 AG Groningenthe Netherlands

With an increase in the electrification of end-use sectors,various resources on the demand side provide great flexibility potential for system operation,which also leads to problems such as the strong randomness of power consumption behavior,the low utilization rate of flexible resources,and difficulties in cost *** the core idea of“access over ownership”,the concept of the sharing economy has gained substantial popularity in the local energy market in recent ***,we provide an overview of the potential market design for the sharing economy in local energy markets(LEMs)and conduct a detailed review of research related to local energy sharing,enabling technologies,and potential *** paper can provide a useful reference and insights for the activation of demand-side flexibility ***,this paper can also provide novel insights into the development and further integration of the sharing economy in LEMs.

关键词： Energy sharing flexibility potential local energy market information and communication technology sharing economy

Narrow-Band Thermal Radiation Based on Microcavity Resonant Effect

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Chinese Physics Letters 2014年第9期31卷 79-82页

作者：黄金国宣益民李强 School of Energy and power Engineering Nanjing University of Science and Technology Nanjing 210094 School of Energy and power Engineering Nanjing University of Aeronautics and Astronautics Nanjing 210016

The microcavity resonant effect is used to realize narrow-band thermal radiation~ Periodic circular aperture arrays with square lattice are patterned on Si substrates by using standard photolithographic techniques and reactive ion etching techniques. ag films are deposited on the surface of Si substrates with aperture arrays to improve the infrared reflectance. On the basis of the micromachining process, an ag/Si structured surface exhibiting narrow-band radiation and directivity insensitivity is presented. The emittance spectra exhibit several selective emittance bands attributed to the microcavity resonance effect. The dependence of emittance spectra on sizes and direction is also experimentally examined. The results indicate that the emittance peak of the ag/Si structured surface can be modulated by tailoring the structural sizes. Moreover, the emittance peak is independent of the radiant angle, which is very important for designing high-performance therma/emitters.

关键词： HEAT -- Radiation & absorption RESEARCH PHOTOLITHOGRAPHY CIRCULAR aperture MICROMACHINING SILVER films (Metal coating)