• <tr id="yyy80"></tr>
  • <sup id="yyy80"></sup>
  • <tfoot id="yyy80"><noscript id="yyy80"></noscript></tfoot>
  • 99热精品在线国产_美女午夜性视频免费_国产精品国产高清国产av_av欧美777_自拍偷自拍亚洲精品老妇_亚洲熟女精品中文字幕_www日本黄色视频网_国产精品野战在线观看 ?

    M icroscopic M echanism on the Incipient Pyrolysis of Insulation Paper

    2017-07-19 12:07:46WANGXueleiWANGShuoZHUWenbingZHOUJiabinXUWei
    山東電力技術(shù) 2017年6期
    關(guān)鍵詞:絕緣紙微觀機(jī)理

    WANG Xuelei,WANG Shuo,ZHUWenbing,ZHOU Jiabin,XUWei

    (State Grid Shandong Electric Power Research Institute,Jinan 250003,China)

    M icroscopic M echanism on the Incipient Pyrolysis of Insulation Paper

    WANG Xuelei,WANG Shuo,ZHUWenbing,ZHOU Jiabin,XUWei

    (State Grid Shandong Electric Power Research Institute,Jinan 250003,China)

    By investigating the microscopic pyrolysismechanism of the insulation paper,especially on the incipient pyrolysis stage,it can reveal potential guiding values,such as further understanding on the pyrolysis process in internal insulation system of a transformer undergoing overheating defects and early evaluations of insulation deterioration and life expectancy.To this end,the way of experiment combined with simulation was adopted in this article.Firstly,the GC/MS experiment on cellulose under 350~900℃ was conducted,and it is found that allose was the product of the highest ration and it is also the most important product for diagnosing the degree of deterioration on the incipient stage.For further clarification of the formation mechanism and the following rules of the pyrolysis of allose,the high temperature reactive molecular dynamics simulation for the pyrolysis of cellobiose which is the constitutional unit of the paper cellulose was investigated and discussed in this article. By tracking the visual decomposition process of the cellulose and observing the splitting and forming rules of the bonds at different time,it is found that allose was generated by the split of C′4-O glucosidic bond and C1-O5bond at the 1-pyranoid ring.The small molecules generated during pyrolysis are measured by velocitron and can be used as micro-features in diagnosing thermal faults of the power transformers.

    insulation paper;incipient pyrolysis;reactivemolecular dynamics;microscopicmechanism;allose

    0 Introduction

    With the rapid development of our power industry,electrical power transformer as a key element among the power transmission and transformation equipment,is developing towards the direction of the ultra-h(huán)igh voltage and large capacity.Once the transformer fails to work,it will ravage the electricity grid and cause huge economic losses.Oil and paper are the main insulating materials for oil-immersed transformers.When the transformer undergoes some partial defects,such as a local overheating defect,it will generate heat high enough to endanger the stability of the oil/paper insulating structure.If not dispatched in time,the heat is able to rise the local temperature to a high level in the transformer and cause oil/paper fastpyrolysis[1-2].The transformer oil/paper cracking is a very complicated process of chemical change,involving electrical,material,chemical,and many other disciplines.The existingmacroscopic experimental study on insulation defects is not sufficient to explain the indepth mechanism of the pyrolysis process of oil/paper insulation from the microscopic mechanism point of view.

    For the past few years,with the quantum mechanics theory gradually improving,continuous development and update of the force field and the popularity of the computing speed and capacity promotion of the computers,the theory and methods ofmolecular simulation was developing rapidly.In the physical,chemical,material and life science and many other fields,it plays an increasingly important role,and has gradually formed a specialdiscipline-themolecularsimulation[3-5]. Simulation of the molecular structures and behaviors based on molecular model on the atomic level,it can not only precisely calculate the micro parameters of the insulatingmaterial,but also help analyzing themicroscopic mechanism of all kinds of complicated phenomenon,so as to explain the relationship betweenmicrostructure and macro properties for insulating material.

    For themicroscopic degradationmechanism of the transformer oil/paper insulation,some explorations are already invested.The molecular dynamics simulation is carried out to investigate the thermal degradation process of cellulose molecules in insulation paper in paper[6-7].It is found that joint ofβ-1-4 glycosidic bond on the main chain of the cellulose molecules is mostly prone to rupture and lead to reduction the degree of polymerization.Thermal stability of cellulose molecular is studied in paper[8]and it is found that the stability of the structure and machinery of the insulation paper are significantly affected by cellulose internal hydrogen bond.Themolecular simulation of the oil conformation in the cellulosemolecules on different surfaces is analyzed in paper[9]and it is found that the oilmolecular on the surface of cellulose amorphous region appreciate vertical conformation and are most likely to produce charge at the interface.In paper[10],aided by Material Studio software and COMPASS force field,the effects of oxygen,water and hydronium on insulation paper aging degradation are analyzed from cellulose chain conformation,flexibility,and small molecule diffusion coefficient and other parameters.All the above studiesmainly focused on the physics calculations ofmolecular dynamics,and have not involved the chemical reactionmechanism of cellulose pyrolysis process.In paper[11],the cellulose pyrolysis process at high tem perature is simulated.To reduce the time consumption on the simulation,the temperature is set to 1 900 K in the simulation,in which,the cracking reaction is so fast that it is unable to elaborate pyrolysis law for early cracking.So it will be useful if a further study on themicro crackingmechanism of cellulose,especially the early cracking mechanism is carried out.This study will provide further understanding on the pyrolysis process of the transformer’s internal insulating system under overheating defects,potentially valuable in the early evaluation of insulation cracking and insulation life assessment.

    To this end,this paper combines the experiment and simulation method.Firstly,cellulose pyrolysis experiment at 350~900℃ is carried out to analyze the cracking process,especially the main product at the early stage.Then,based on the experimental study,the targeted pyrolysis simulation of cellulose is carried out. Through tracing the paths of themain products during the early stage,the law of cellulose pyrolysis is analyzed and detailed in this paper.

    1 Insulation Paper Pyrolysis Experim ent Based on Py-GC/MS Technology

    In the recent few years,pyrolysis chromatography mass spectrometry(Py-GC/MS)is an effective tech nology to study the pyrolysismechanism[12-13].Py technology has the advantage of ultra-fast heating of the sample to the specified temperature and low speed of the continuous decomposition in the process of heating.Meanwhile,the technology of GC/MS can analyze the components of the pyrolysis products more accurately and obtain the semi-quantitative data.Therefore,using Py-GC/MS to analyze the components and relative contents of the transformer insulation paper’s thermal cracking products can not only verify the effectiveness of the previous simulation of reaction kinetic thermal cracking in paper[11],butalso have great significance for further exploring insulation paper’s thermal cracking mechanism.

    1.1 Experimentalequipments and materials

    The Py-GC/MSused in this experiment is generated by CDS 5000 pyrolysis apparatus manufactured by CDS Company and Agilent 7890A-5975C gas chroma tograph-mass spectrometer made by Agilent Company in the United States.The equipment and lab setup is shown in Figure 1.The wire cracking is used in CDS 5000 pyrolysis apparatus for fast pyrolysis. Pyrolysis probe on the platinum filament can be quickly heated to the specified temperature for thermal cracking,up to the highest temperature of 1 500℃. The pyrolysis products are analyzed on line through HP-5MS elastic capillary column(60m×0.25 mm× 0.25 m)in Agilent 7890A-5975C GC/MS.The temperature of the connector between chromatography and mass spectrum is 300℃.The mass-to-charge ratio in mass spectrometer is 35~400 amu.The sampling frequency is 4 Hz.NIST database is used for production determination.

    Figure 1.Pyrolysis-GC/MS analysis meter

    The insulation paper used in this experiment is from transformer made by Weidmann.The thickness of the paper is 0.5mm.Main components in the insulation paper includeα-cellulose mass fraction 89%~91%,hemicellulose 6%~7%and lignin 3%~4%.

    1.2 Experiment procedure

    During the experiment,about 5 mg of insulation paper powder was placed in a quartz tube,and both ends of the tubewere fixed by quartz cotton.The quartz tube filled with insulation paper was placed in platinum coil,as shown in Figure 2.And then start the thermal crack ing test under high-purity nitrogen(99.999% )environment in the cracking chamber. Comparisons among the insulation paper’s cracking products at different temperatures are made in this experiment.The cracking temperature is holding at 350℃,500℃,700℃ and 900℃ on different stage during the test.The initial temperature of the plat inum wire is 150℃ and then rising to 350℃,500℃,700℃ and 900℃ with the rising rate 10℃/ms,holding for 12 s at each target temperature.The insulation paper begins to crack at the target temperature and forms fugitive constituent.The product will first enter the adsorption vessel and then be desorbed until the cracking reaction is completed.Then all the cracking fugitive constituent are moved into the connected chromatographic mass spectrometer to analyze the products,the whole process shown in Figure 3.To prevent the cracking product from condensing,the temperature of the external transfer line is maintained at 250℃.

    Figure 2.The pyrolysis probe

    Figure 3.Experimental flow diagram

    1.3 Thermal cracking products analysis of insulation paper

    The GC/MS spectrum of the pyrolysis products for the insulation paper at the set temperature is shown in Figure 4.The X-axis represents the retention time correspondent with the products,in which the heavier the relative molecular mass of the products is,the longer retention time.The Y-axis represents relative value of ion current which is proportional to the content of related product.Since the relative peak area is linearly related to the gas production,in this paper,the relative peak area is used to characterize the change of the product composition during the pyrolysis.At first,area normalization method is used to calculate the peak area of each component and then sum them,and calculate its percentage in total peak area,which can contribute to the qualitative analysis of the pyrolysis products’GC/MS spectrum.

    Itcan be seen from Figure4 that the decomposition is insignificant when the temperature is 350 ℃ . However when the temperature rises to 500℃,the amount of pyrolysis product is evidently more than that in 350℃.During temperature rising from 500℃to 900℃,the amount ofmicromolecule pyrolysis product is increasing significantly and the amount of macromolecule is reducing gradually.

    As shown in Figure 4,the main products from insulation paper pyrolysis include allose,CO2,glycolic aldehyde,formic acid,furfural,1-Hydroxy-2-butanone,5-hydroxymethylfurfural,which are marked at the corresponding peak position in Figure 4.As the main production,CO2,glycolic aldehyde and formic acid are analyzed inpaper[11]bymoleculardynamicssimulation and their generating paths are traced.None of these is the focuse in this paper.From the statistics obtained from the experiment,it is found that allose is the highestquantity of products in the experiments,but the content declines rapidly with the temperature increasing especially after 700℃.This indicates that allose is extremely unstable at high temperature and break down into smallermolecules quickly.This is why it is not found in the previous researches of high temperature simulations[11].

    Figure 4.GC/MS spectrogram for insulation paper pyrolysis

    For the early evaluation of insulation cracking,it isofvital importance to clarify thegeneratingmechanism of allose and explore the early stage cracking law of cellulose.To this end,reaction molecular dynamics simulation method is used in this research to simulate the early stage cracking of cellulose under high temperature,aiming at exploring the generating ways of allose and the initial crackingmechanism of insulation paper at the atomic level.

    2 Molecular Dynam ics Simulation of Cellulose Pyrolysis at High Temperature

    2.1 Molecularmodel construction

    The main component of insulation paper in the transformer is cellulose,which is a linear polymer compound combined withβ-glycosyl group and D-glycosyl group under the help of 1-glycosidic bond and 4-glycosidic bond.Its repeating unit is cellobiose. After using different length of cellulose chains for simulations,it is found that amorphous area models composed with different lengths have no significant difference regardless the molecular conformation,physical and chemical properties[14-18].As cellobiose is the repeating unit of cellulose and for the time sake,cellobiose is used for themodel as shown in Figure 5(a).For easy understanding,this paper is going to name each atom of cellobiose using the method introduced in[19].As shown in the figure,in order to distinguish the two pyran rings of cellobiose,on the right side of the figure is 4-pyran ring which is connected with glycosidic bond’s O atoms via C′4,on the left side is 1-pyran ring which is connected with glycosidic bond’s O atoms via C1.Builder Model in the ADF software package is used to build the molecular model.The molecular model of cellobiose is shown in Figure 5(b),in which the white atoms represent H,the red atoms representO,and the gray atoms represent C.

    2.2 Pyrolysis simulation methods and details

    In this paper,ADF software is used to simulate the thermal degradation mechanism of cellulose.After using Builder command establish amorphous cells,the simulation of cracking reaction for cellobiose can be done under the ReaxFF force field.Different force fields are set in ReaxFF according to the differences of simulation elements.And cellobiose includes C,H and O three types of atoms,so CHO.ff force field is chosen in this paper.The canonical ensemble with the fixed N(number of particles)V(volume)T(temperature)is used during the simulation process.

    Figure 5.Sturctural formula and moecularmodel

    In order to balance the time and the accuracy of the simulation,and make sure the time consumption of the entire simulation is in a reasonable range,the parameters are set following the guidance of paper[11],in which,the pyrolysis process of the amorphous cells (simulation unit)containing three cellobiose molecules is emulated.The density of the unit is set to 1.599/cm3(actual cellulose density),air pressure is 0.1 MPa,and the temperature is 1 700 K.The simulation is repeated 16 times to ensure the reliability of the simulation results.For each simulation,the pyrolysis time is 100 ps,time step 0.1 fs,and thetrajectory file is saved for each 0.01 ps.

    2.3 Simulation results analysis

    According to the pyrolysis experiment results in chapter 1.3,the percentage of the peak area for each product is calculated,in which the main products at 900℃are shown in table 1,and are compared with the simulation results.

    Table 1.Main products ofinsulation paperpyrolysis in 900℃

    34 Allose C6H12O6 11.82 √32 Pyrocatechol C6H6O2 1.52 √33 5-Hydroxymethy lfurfural C6H6O3 1.62 √30 Phenol C6H6O 1.32 √31 Methyl cyclopentenolone C6H8O2 0.98 √28 1,2-Ring glutaric ketone C5H6O2 1.66 √29 5-Methyl furan aldehyde C6H6O2 1.01 √26 Furfuryl alcohol C5H6O2 0.54 √27 Peroxide acetylacetone C5H8O3 0.47 √N(yùn)umber Name Formula Area ratio/%ReaxFF

    It can be seen from the statistics shown in the table above that 34 main products measured in the experiment,except benzene and toluene,are all observed in the simulations.This indicates that simulation is highly consistent with the experiment results and the simulation is reliable and very accurate.

    From the previous experimental study it is found that allose is the product with the most generation amount during the early pyrolysis of cellulose.In order to clarify its pyrolysis mechanism and the later cracking law,by observing brakeage and generation of glycosidic bond and following the visible decomposition of cellulose,the main generating paths of allose are made clear in this paper,which is shown in Figure 6 and Figure 7.The atoms of the micromolecule products are identified from their colors.The blue ones are C atoms,the pink ones are O atoms,and the green ones are H atoms.Dotted line shows the broken bond’s location during the generating process of the main products.Red subscripts represent the atomic number in the chemical structure.

    Figure 6.Generate path 1 for allose

    Figure 7.Generate path 2 for allose

    As shown in Figure 6 and Figure 7,allose are all generated after glucosidic bond C′4-O breakage (5 ps in Figure 6 and 52.9 ps in Figure 7)and 1-pyranoid ring C1-O5bond breakage(7 ps in Figure 6 and 52.9 ps in Figure 7).As the decomposition continued,the final products are 1,2-dihydroxy ethylene(the generating path is shown in Figure 6:C′5-C′6bond breakage,generate a double bond between C′4and C′5,and C′1-C′2separate from 4-pyranoid ring),CO2(the generation path is shown in Figure 7:C′5-O′5separate from 4-pyranoid ring to creat C′1=O′5).

    In addition,taking the statistics of cellobiose bond rupture at the initial cracking stage,the location data of the bond breakage is shown in Table 2.

    The table above shows that the initial breakage position ismainly at O atoms of glycosidic bond,which shows that the glycosidic bond is a weak point in cellobiose structure.And this is consistent with the theoretical derivation that glycosidic bond is the first breaking point during cellulose’s pyrolysis process,which is mentioned in paper[20].Jiang Yuanye[21]used density functional theory to calculate the thermodynamic energy of cellobiose pyrolysis in different location.His conclusion indicates that glycosidic bonds cracking is superior to other positions in thermodynamics,which is consistent with the simulation results presented in this paper.

    The table also shows that except glycosidic bonds,the oxygen atoms at the two pyran rings are easy to break free from the bond of C′5-O′5and C1-O5. This is also consistent with the conclusion of paper[13]which believes that pyran ring’s C1-O5is a breakage point from bond energy point of view.Because C1-O5on glycosidic bond and pyran rings is easy to break,and allose is generated after the breakage.This also supported the fact of allose’s mass production during the early stage of pyrolysis.

    The research above shows that allose is similar to furfural that they are both the product during the cracking process of the insulation paper.In practical applications,there are two ways to test allose during transformer insulation aging process—off-line and online test.The off-line test requires the oil samples from the site for analysis using mass spectrometer in the laboratory.The on-line test can be realized by installing the built-in sensors for monitoring purposes aiming at specific chemicals.Because of that the producing of allose is at an earlier stage compared to the furfural during insulation paper pyrolysis,it is more accurate to assess the insulating aging process from the trend of the allose production,especially for early stage.

    3 Conclusions

    In this article,the way of experiment combined with simulation was adopted to analyze the cellulose’s initial pyrolysis mechanism,the distributing pattern and generating ways of main products from atomic level.

    Insulation paper pyrolysis experiment shows that the main products include allose,CO2,glycolic aldehyde,formic acid,furfural,1-Hydroxy-2-butanone,5-hydroxymethylfurfural,etc.Among them,allose is the highest generating product but with the temperaturerising,the amount of allo se reduces rapidly.This indicates that allose is the most important product to characterize the degree of the early insulating pyrolysis.

    Table 2.Statisticaloverview of bond initial rupture location for the cellobiose

    Reactive molecular dynamic simulation at high temperature is done for researching the pyrolysis mechanism of cellobiose in insulation paper.Theways of generating allose isanalyzed and detailed by tracing the visible cellulose decomposition process and observing bonds’breakageand generation atdifferent times.

    The micro mechanism of cellulose’s pyrolysis from the atomic level is explored in this paper.It can be a theoretical support for deeper understanding to the pyrolysis process of the insulation paper during overheating defect in transformer and assessment of the insulation aging.

    [1]WU G.N.,CUIY.G.,WANG X.J.“Evaluation of Water Content in Insulation Paper of Different Aging Degrees Using Acid Value in Oil”,High Voltage Engineering,Vol.41,No.1,pp.115-122,2015.

    [2]ZHOU Y.X.,HUANG J.W.,SHA Y.C.“Electrical Properties of Oil-Paper Affected by Water Conductivity During Paper-Making Process”,High VoltageEngineering,Vol.41,No.2,pp.382-387,2015.

    [3]SCHERAGA H A,KHALILI M,LIWO A.“Protein-Folding Dynamics:Overview of Molecular Simulation Techniques”,Annual Review of Physical Chemistry,Vol.58,No.1,pp.57-83,2007.

    [4]CHENOWETH K,VANDUIN A C T,GODDARD W A.“Reaxff Reactive Force Field for Molecular Dynamics Simulations of Hydrocarbon Oxidation”,The Journal of Physical Chemistry A,Vol.112,No.5,pp.1 040-1 053,2008.

    [5]WANG Q D,WANG J B.“Reactive Molecular Dynamics Simulation and Chemical Kinetic Modeling of Pyrolysis and Combustion of N-Dodecane”,Combustion and Flame,Vol.158,No. 2,pp.217-226,2011.

    [6]LU Y.C.“Study on diffusion behavior of gas and mechanics of oilpaper aging using molecular simulation”,Chongqing,Chongqing University,2007.

    [7]YANG L.,LIAO R.,SUN C.“Influence of Vegetable Oil on The Thermal Aging of Transformer Paper and Its Mechanism”,IEEE Transactions on Dielectrics and Electrical Insulation,Vol.18,No. 3,pp.692-700,2011.

    [8]LIAO R.J.,ZHU M.Z.,ZHOU X.“Molecular Dynamics Simulation of the Diffusion Behavior ofWater Molecules in Oil and Cellulose Composite Media”,Acta Physico-Chimica Sinica,Vol.27,No.4,pp.815-824,2011.

    [9]LIAO R.J.,HU J.,YANG L.J.“Molecular Simulation for Thermal Degradative Micromechanism of Power Transformer Insulation Paper”,HighVoltageEngineering,Vol.35,No.7,pp.1565-1570,2009.

    [10]HU J.“Molecular Simulation Studies on Aging Mechanism in Crazing Zone of the Insulation Paper in Power Transformers”,Chongqing,Chongqing University,2009.

    [11]YAN J.,WANG X.,LIQ.“Molecular Dynamics Simulation on the Pyrolysis of Insulation paper”,Proceedings of the CSEE,Vol.35,No.22,pp.5 941-5 949,2015.

    [12]LIAO Y.,LUO Z.,WANG S.“Mechanism of Rapid Pyrolysis of CelloluseⅠ.Experimental Research”,Journal of Fuel Chemistry and Technology,Vol.31,No.2,pp.133-138,2003.

    [13]WANG S.,LIAO Y.,TAN H.“Mechanism of Rapid Pyrolysis of CelloluseⅡ.Mechanism Analysis”,Journal of Fuel Chemistry and Technology,Vol.14,No.31,pp.317-321,2003.

    [14]ZHU M.“Molecular dynamics study of thermal aging of oilimpregnated insulation paper”,Chongqing,Chongqing University,2011.

    [15]ZHANG L.,Zybin S V,van Duin A C T.“Carbon Cluster Formation During Thermal Decomposition of Octahydro-1,3,5,7-Tetranitro-1,3,5,7-Tetrazocine and 1,3,5-Triamino-2,4,6-Trinitrobenzene High Explosives from Reaxff Reactive Molecular Dynamics Simulations”,The Journal of Physical Chemistry A,Vol. 113,No.40,pp.10 619-10 640,2009.

    [16]STRACHAN A,VAN DUIN A C T,CHAKRABORTY D.“Shock Waves in High-Energy Materials:The Initial Chemical Events in Nitramine RDX”,Physical Review Letters,Vol.91,No.9,pp. 10 619-10 640,2003.

    [17]GUO F.,ZHANG H,CHENG X.“Molecular Dynamic Simulations of Solid Nitromethane under High Pressures”,Journal of Theoretical and Computational Chemistry,Vol.9,No.1,pp.315-325,2010.

    [18]CHENOWETH K,DUIN A C T,PERSSON P.“Development and Application of A Reaxff Reactive Force Field for Oxidative Dehydrogenation on Vanadium Oxide Catalysts”,The Journal of Physical Chemistry C,Vol.112,No.37,pp.14 645-14 654,2008.

    [19]PEI J.“Chemistry of Plant Fiber”,Beijing:China Light Industry Press,2012.

    [20]RICHARDS G N.“Glycoaldehyde from Pyrolysis of Cellulose”,Journal of Analytical and Applied Pyrolysis,Vol.10,No.2,pp.251-255,1987.

    [21]JIANG Y.,YU H.,F(xiàn)U Y.“Theoretical Study on Thermodynamic Properties of Pyrolysis of Cellulose Dimer Model Compound”,Acta Chimica Sinica,Vol.71,No.12,pp.1 611-1 619,2013.

    Accepted date:2017-04-01

    絕緣紙熱裂解初期微觀機(jī)理研究

    王學(xué)磊,王 碩,朱文兵,周加斌,許 偉

    (國網(wǎng)山東省電力公司電力科學(xué)研究院,山東 濟(jì)南 250003)

    探究絕緣紙的微觀熱裂解機(jī)理,特別是初期裂解機(jī)理,對于深入認(rèn)識變壓器內(nèi)部絕緣系統(tǒng)過熱缺陷下的裂解過程以及絕緣裂化的早期評價與絕緣壽命評估具有潛在的指導(dǎo)價值。為此,采取實(shí)驗(yàn)與仿真相結(jié)合的手段,首先,對纖維素進(jìn)行了350~900℃下的氣相色譜/質(zhì)譜聯(lián)用實(shí)驗(yàn),研究表明,阿洛糖是實(shí)驗(yàn)中生成量最高的產(chǎn)物,是絕緣裂化初期表征裂化程度最重要的產(chǎn)物。為了進(jìn)一步厘清阿洛糖裂解生成機(jī)理以及后續(xù)裂解規(guī)律,對絕緣紙纖維素中的結(jié)構(gòu)單元纖維二糖的裂解進(jìn)行了高溫反應(yīng)分子動力學(xué)模擬。通過跟蹤可視化的纖維素分解過程,觀測不同時刻鍵的斷裂和生成規(guī)律,發(fā)現(xiàn)阿洛糖生成由最易發(fā)生斷裂的糖苷鍵C′4-O鍵斷裂和1-吡喃環(huán)上C1-O5鍵兩化學(xué)鍵斷裂而來。裂解小分子產(chǎn)物作為新的微觀特征量,可通過質(zhì)譜儀測得并進(jìn)行趨勢分析,在變壓器過熱故障診斷中具有潛在應(yīng)用價值。

    絕緣紙;初始裂解;反應(yīng)分子動力學(xué);微觀機(jī)理;阿洛糖

    TM211;TM853

    A

    1007-9904(2017)06-0008-09

    ei(1986)

    the B.S.M.E.and Ph.D.degree in electrical engineering from Shandong University,China,during 2005-2015.He is now working in the State Grid Shan Dong Electric Power Research Institute.His main research interest is transformer fault diagnosis and condition evaluation.

    猜你喜歡
    絕緣紙微觀機(jī)理
    隔熱纖維材料的隔熱機(jī)理及其應(yīng)用
    納米SiO2 改性絕緣紙的機(jī)械老化與電老化性能研究
    絕緣紙耐熱助劑的制備及應(yīng)用研究
    中國造紙(2020年10期)2020-11-04 07:46:14
    絕緣紙的制備及耐熱性能
    煤層氣吸附-解吸機(jī)理再認(rèn)識
    中國煤層氣(2019年2期)2019-08-27 00:59:30
    纖維素納米晶體對變壓器絕緣紙性能的影響
    天津造紙(2019年2期)2019-01-14 21:21:06
    一種新的結(jié)合面微觀接觸模型
    霧霾機(jī)理之問
    微觀的山水
    詩選刊(2015年6期)2015-10-26 09:47:10
    微觀中國
    浙江人大(2014年8期)2014-03-20 16:21:15
    天堂影院成人在线观看| 女人被狂操c到高潮| 精品久久久久久成人av| 9191精品国产免费久久| 久久婷婷成人综合色麻豆| 亚洲视频免费观看视频| 免费搜索国产男女视频| 很黄的视频免费| 免费观看精品视频网站| 亚洲成人免费电影在线观看| 婷婷六月久久综合丁香| 日韩欧美免费精品| 日本撒尿小便嘘嘘汇集6| 免费在线观看日本一区| 国产亚洲精品久久久久久毛片| 久久人人精品亚洲av| 日韩欧美一区视频在线观看| 俄罗斯特黄特色一大片| 99久久精品国产亚洲精品| 久久青草综合色| 国产一区二区三区视频了| 1024香蕉在线观看| 一级片免费观看大全| 婷婷丁香在线五月| 不卡av一区二区三区| 国产三级在线视频| 国产精品精品国产色婷婷| 久久久久久久久免费视频了| 两性午夜刺激爽爽歪歪视频在线观看 | 欧美日韩乱码在线| av片东京热男人的天堂| 精品国产国语对白av| 欧美亚洲日本最大视频资源| 久热这里只有精品99| 最近最新中文字幕大全免费视频| 精品午夜福利视频在线观看一区| 又黄又粗又硬又大视频| 亚洲欧美日韩无卡精品| 中文字幕另类日韩欧美亚洲嫩草| 一级作爱视频免费观看| 免费不卡黄色视频| 少妇 在线观看| 久久精品国产综合久久久| 十分钟在线观看高清视频www| 久久久久久久午夜电影| 久久久久久免费高清国产稀缺| 中文字幕最新亚洲高清| 黄频高清免费视频| 久久精品aⅴ一区二区三区四区| 侵犯人妻中文字幕一二三四区| 午夜成年电影在线免费观看| 久久久精品国产亚洲av高清涩受| 免费搜索国产男女视频| av视频免费观看在线观看| 自线自在国产av| 看片在线看免费视频| 欧美日韩福利视频一区二区| 久久精品国产亚洲av高清一级| 老熟妇仑乱视频hdxx| 亚洲 国产 在线| av视频免费观看在线观看| 黄色视频不卡| 一个人观看的视频www高清免费观看 | 色综合婷婷激情| 久久人妻av系列| 日日爽夜夜爽网站| 老鸭窝网址在线观看| 亚洲全国av大片| 久久 成人 亚洲| 一本久久中文字幕| av欧美777| 9热在线视频观看99| 香蕉久久夜色| 在线观看日韩欧美| 女警被强在线播放| 欧美成人免费av一区二区三区| xxx96com| 欧美国产精品va在线观看不卡| 欧美日韩黄片免| 国产亚洲精品av在线| 成年人黄色毛片网站| 国产一卡二卡三卡精品| 老汉色av国产亚洲站长工具| 日韩免费av在线播放| 亚洲国产看品久久| www.999成人在线观看| 亚洲中文av在线| 大型av网站在线播放| 两性夫妻黄色片| 美女 人体艺术 gogo| 91麻豆av在线| 黄色丝袜av网址大全| 免费一级毛片在线播放高清视频 | 日韩视频一区二区在线观看| 啪啪无遮挡十八禁网站| 可以在线观看的亚洲视频| 99久久综合精品五月天人人| 丁香六月欧美| 亚洲三区欧美一区| 亚洲国产精品sss在线观看| 日本免费a在线| 精品日产1卡2卡| 欧美激情久久久久久爽电影 | 怎么达到女性高潮| 日韩精品青青久久久久久| 国内毛片毛片毛片毛片毛片| 人妻久久中文字幕网| 777久久人妻少妇嫩草av网站| 丰满的人妻完整版| 久久午夜亚洲精品久久| 看片在线看免费视频| 男女午夜视频在线观看| 狠狠狠狠99中文字幕| 亚洲avbb在线观看| 亚洲五月色婷婷综合| 岛国视频午夜一区免费看| 国产欧美日韩一区二区精品| 韩国av一区二区三区四区| 国产在线观看jvid| 久久精品91无色码中文字幕| 黄色a级毛片大全视频| 午夜精品国产一区二区电影| 成在线人永久免费视频| 中文字幕色久视频| 变态另类成人亚洲欧美熟女 | 91九色精品人成在线观看| 国产又爽黄色视频| a在线观看视频网站| 欧美一级a爱片免费观看看 | 国产成人欧美在线观看| 老熟妇乱子伦视频在线观看| 男女床上黄色一级片免费看| x7x7x7水蜜桃| 欧美日韩精品网址| 亚洲视频免费观看视频| 久99久视频精品免费| 咕卡用的链子| 久久亚洲精品不卡| 男人操女人黄网站| 又黄又粗又硬又大视频| 宅男免费午夜| 非洲黑人性xxxx精品又粗又长| 成人永久免费在线观看视频| 国产av一区二区精品久久| 久久九九热精品免费| 麻豆一二三区av精品| 欧美日本亚洲视频在线播放| 亚洲精品久久国产高清桃花| 99国产精品99久久久久| 国产又色又爽无遮挡免费看| 亚洲色图 男人天堂 中文字幕| 一区二区三区国产精品乱码| 午夜福利欧美成人| 欧美乱妇无乱码| 欧美日本视频| 免费av毛片视频| 一区在线观看完整版| 9191精品国产免费久久| 国产免费av片在线观看野外av| 国产欧美日韩一区二区精品| 日韩国内少妇激情av| 国产免费av片在线观看野外av| 好男人在线观看高清免费视频 | 男女午夜视频在线观看| 在线观看午夜福利视频| 色播在线永久视频| 男人舔女人下体高潮全视频| 99国产综合亚洲精品| av超薄肉色丝袜交足视频| 国产区一区二久久| 两个人看的免费小视频| 国产视频一区二区在线看| 亚洲精品久久成人aⅴ小说| 制服丝袜大香蕉在线| 中文字幕人妻熟女乱码| 9色porny在线观看| 成人特级黄色片久久久久久久| 亚洲欧美日韩无卡精品| 丝袜美腿诱惑在线| 老司机午夜十八禁免费视频| 色av中文字幕| 亚洲av成人一区二区三| 国产精品香港三级国产av潘金莲| 欧美色视频一区免费| 女人爽到高潮嗷嗷叫在线视频| av视频免费观看在线观看| 可以在线观看的亚洲视频| www日本在线高清视频| 亚洲,欧美精品.| 性少妇av在线| 国产视频一区二区在线看| 国产精品爽爽va在线观看网站 | 亚洲第一电影网av| 乱人伦中国视频| a级毛片在线看网站| 久久 成人 亚洲| av欧美777| 可以在线观看的亚洲视频| 亚洲午夜精品一区,二区,三区| 亚洲熟妇中文字幕五十中出| 老司机午夜福利在线观看视频| 一区二区三区激情视频| 中文字幕另类日韩欧美亚洲嫩草| 精品久久久久久久久久免费视频| 国产xxxxx性猛交| 久9热在线精品视频| 少妇熟女aⅴ在线视频| 国产精品二区激情视频| www国产在线视频色| 亚洲三区欧美一区| 18禁美女被吸乳视频| 伦理电影免费视频| 天天躁夜夜躁狠狠躁躁| 亚洲国产精品成人综合色| 久久影院123| 国产欧美日韩一区二区三区在线| 日日干狠狠操夜夜爽| 级片在线观看| 午夜视频精品福利| 18禁美女被吸乳视频| 最近最新中文字幕大全电影3 | 精品不卡国产一区二区三区| 91成年电影在线观看| 91麻豆av在线| 黄色 视频免费看| 国产精品精品国产色婷婷| 国内久久婷婷六月综合欲色啪| 亚洲成人久久性| 精品国产乱码久久久久久男人| 国产片内射在线| 国产欧美日韩一区二区三区在线| 男女下面插进去视频免费观看| 精品国产乱子伦一区二区三区| 欧美日本亚洲视频在线播放| 在线观看免费日韩欧美大片| 又黄又粗又硬又大视频| 99国产精品免费福利视频| 国产97色在线日韩免费| 亚洲电影在线观看av| 黄色视频,在线免费观看| 日本三级黄在线观看| 欧美一区二区精品小视频在线| 亚洲七黄色美女视频| 91老司机精品| 国产成人系列免费观看| 一区在线观看完整版| 天天一区二区日本电影三级 | 国产99久久九九免费精品| 搡老岳熟女国产| 一本久久中文字幕| 无限看片的www在线观看| 亚洲成人国产一区在线观看| 欧美中文日本在线观看视频| 色哟哟哟哟哟哟| 午夜亚洲福利在线播放| 脱女人内裤的视频| 一区福利在线观看| 日本一区二区免费在线视频| 国产精品一区二区精品视频观看| 成人免费观看视频高清| 亚洲精品国产色婷婷电影| 大型黄色视频在线免费观看| 亚洲五月天丁香| 看黄色毛片网站| 日韩欧美一区视频在线观看| 欧美丝袜亚洲另类 | av天堂在线播放| 男女做爰动态图高潮gif福利片 | 欧美激情极品国产一区二区三区| a在线观看视频网站| 欧美一级毛片孕妇| 99国产精品一区二区三区| 精品人妻1区二区| a级毛片在线看网站| 91麻豆av在线| 又紧又爽又黄一区二区| 亚洲精品国产区一区二| 国产伦人伦偷精品视频| 久久草成人影院| 黑人操中国人逼视频| 美女免费视频网站| 国产高清有码在线观看视频 | 亚洲自偷自拍图片 自拍| 一区二区三区高清视频在线| 国产av精品麻豆| 夜夜夜夜夜久久久久| 亚洲色图av天堂| 日本 av在线| 午夜精品在线福利| 亚洲一区二区三区不卡视频| 国产又色又爽无遮挡免费看| 国产精品久久视频播放| 精品一区二区三区av网在线观看| 欧美精品亚洲一区二区| 日本欧美视频一区| 久久性视频一级片| 成人18禁高潮啪啪吃奶动态图| 999精品在线视频| 亚洲无线在线观看| 国产区一区二久久| 国产精品国产高清国产av| 国产成人系列免费观看| 麻豆av在线久日| 99久久99久久久精品蜜桃| 午夜影院日韩av| 麻豆av在线久日| 可以在线观看毛片的网站| www.自偷自拍.com| а√天堂www在线а√下载| 午夜福利成人在线免费观看| 身体一侧抽搐| 在线天堂中文资源库| 精品熟女少妇八av免费久了| 一本综合久久免费| 日韩欧美一区视频在线观看| 香蕉国产在线看| 久久精品国产综合久久久| 久久婷婷人人爽人人干人人爱 | 国语自产精品视频在线第100页| 欧美在线黄色| 欧美成狂野欧美在线观看| 脱女人内裤的视频| 久久国产乱子伦精品免费另类| 满18在线观看网站| 国产aⅴ精品一区二区三区波| 伊人久久大香线蕉亚洲五| 精品久久久久久久毛片微露脸| 欧美日韩亚洲国产一区二区在线观看| 一级a爱视频在线免费观看| 国产欧美日韩精品亚洲av| 成人国语在线视频| 少妇 在线观看| 亚洲中文av在线| 亚洲免费av在线视频| 老熟妇乱子伦视频在线观看| 国产黄a三级三级三级人| 女人被狂操c到高潮| 亚洲欧美激情在线| 国产一区二区激情短视频| aaaaa片日本免费| 麻豆成人av在线观看| 午夜免费观看网址| 日韩一卡2卡3卡4卡2021年| 日韩精品中文字幕看吧| 久久久久久久午夜电影| www.精华液| 精品电影一区二区在线| 淫秽高清视频在线观看| 亚洲欧美精品综合久久99| 亚洲三区欧美一区| 成在线人永久免费视频| 久久热在线av| 真人一进一出gif抽搐免费| 久久久久久亚洲精品国产蜜桃av| 亚洲人成电影观看| 淫妇啪啪啪对白视频| 村上凉子中文字幕在线| www.www免费av| 免费在线观看日本一区| 免费看a级黄色片| 欧美成人性av电影在线观看| 成人18禁高潮啪啪吃奶动态图| 久99久视频精品免费| 久久精品亚洲精品国产色婷小说| 午夜a级毛片| 久久午夜亚洲精品久久| 可以在线观看毛片的网站| 欧美+亚洲+日韩+国产| 亚洲成av人片免费观看| 真人做人爱边吃奶动态| 天天躁狠狠躁夜夜躁狠狠躁| 国产精品久久视频播放| 日韩欧美国产在线观看| 久久久久国产精品人妻aⅴ院| 免费在线观看影片大全网站| 90打野战视频偷拍视频| 人妻久久中文字幕网| 亚洲精品中文字幕在线视频| 亚洲人成77777在线视频| 亚洲免费av在线视频| 999久久久精品免费观看国产| 成人免费观看视频高清| 97超级碰碰碰精品色视频在线观看| 亚洲午夜精品一区,二区,三区| 99在线人妻在线中文字幕| 色综合欧美亚洲国产小说| 韩国精品一区二区三区| av超薄肉色丝袜交足视频| 国产精品99久久99久久久不卡| a级毛片在线看网站| 黑人巨大精品欧美一区二区mp4| a在线观看视频网站| 精品国产亚洲在线| 欧美日韩福利视频一区二区| 人人妻人人澡欧美一区二区 | 天天躁夜夜躁狠狠躁躁| 亚洲成a人片在线一区二区| 久久久国产欧美日韩av| 欧美另类亚洲清纯唯美| 久久精品国产清高在天天线| 久久青草综合色| 琪琪午夜伦伦电影理论片6080| 午夜日韩欧美国产| 亚洲七黄色美女视频| 欧美日韩精品网址| 久久九九热精品免费| 每晚都被弄得嗷嗷叫到高潮| 日韩有码中文字幕| 午夜影院日韩av| 婷婷丁香在线五月| 久久精品国产清高在天天线| 午夜福利免费观看在线| 两性午夜刺激爽爽歪歪视频在线观看 | 婷婷精品国产亚洲av在线| 操美女的视频在线观看| 亚洲成人精品中文字幕电影| 日本三级黄在线观看| 宅男免费午夜| 久久国产亚洲av麻豆专区| 大陆偷拍与自拍| 超碰成人久久| 欧美成人一区二区免费高清观看 | 国产97色在线日韩免费| 精品一品国产午夜福利视频| 国产精品一区二区免费欧美| 成人亚洲精品一区在线观看| 两性午夜刺激爽爽歪歪视频在线观看 | 美女午夜性视频免费| 多毛熟女@视频| 黄片小视频在线播放| 午夜免费鲁丝| 嫩草影院精品99| 在线十欧美十亚洲十日本专区| 亚洲精华国产精华精| 在线观看www视频免费| 久99久视频精品免费| 18禁观看日本| 国产麻豆69| 丁香欧美五月| 欧美大码av| 国产黄a三级三级三级人| 91在线观看av| 久久久久久久久久久久大奶| 亚洲电影在线观看av| 欧美日韩福利视频一区二区| 天天躁狠狠躁夜夜躁狠狠躁| 级片在线观看| 琪琪午夜伦伦电影理论片6080| 女人爽到高潮嗷嗷叫在线视频| 国产成人精品无人区| 一级a爱视频在线免费观看| 香蕉国产在线看| 黑人巨大精品欧美一区二区蜜桃| 自拍欧美九色日韩亚洲蝌蚪91| 国产在线观看jvid| 最新在线观看一区二区三区| 女人被躁到高潮嗷嗷叫费观| 日本免费a在线| 人妻丰满熟妇av一区二区三区| 亚洲第一av免费看| 久99久视频精品免费| 少妇 在线观看| av在线天堂中文字幕| 亚洲情色 制服丝袜| 久久人人精品亚洲av| 国产精品 国内视频| 高潮久久久久久久久久久不卡| 一卡2卡三卡四卡精品乱码亚洲| 国产精品一区二区精品视频观看| 免费高清视频大片| 桃色一区二区三区在线观看| 国产高清视频在线播放一区| 两性夫妻黄色片| 身体一侧抽搐| 久久九九热精品免费| 中文亚洲av片在线观看爽| а√天堂www在线а√下载| 欧美国产精品va在线观看不卡| 少妇被粗大的猛进出69影院| 日本vs欧美在线观看视频| 国产亚洲精品久久久久久毛片| 亚洲国产精品成人综合色| 又黄又粗又硬又大视频| 免费看美女性在线毛片视频| 亚洲精品av麻豆狂野| 国产一区在线观看成人免费| tocl精华| 一边摸一边做爽爽视频免费| 在线永久观看黄色视频| 女警被强在线播放| 国产精品99久久99久久久不卡| 久久精品人人爽人人爽视色| 亚洲男人的天堂狠狠| 日本欧美视频一区| 欧美一级毛片孕妇| 午夜福利欧美成人| 日韩欧美在线二视频| 国产免费av片在线观看野外av| 久久久久精品国产欧美久久久| 国产免费av片在线观看野外av| 正在播放国产对白刺激| 色综合亚洲欧美另类图片| 午夜久久久久精精品| 欧美黄色片欧美黄色片| 我的亚洲天堂| 十八禁网站免费在线| 亚洲色图综合在线观看| АⅤ资源中文在线天堂| 久久国产亚洲av麻豆专区| av有码第一页| 正在播放国产对白刺激| 国产亚洲精品第一综合不卡| 一区在线观看完整版| av免费在线观看网站| 亚洲人成77777在线视频| 欧美久久黑人一区二区| 丁香欧美五月| 欧美色欧美亚洲另类二区 | 日本精品一区二区三区蜜桃| 成人国语在线视频| 欧美日韩黄片免| 久久久精品欧美日韩精品| 9色porny在线观看| 日本 av在线| 少妇的丰满在线观看| 国产高清视频在线播放一区| 国产国语露脸激情在线看| 日本黄色视频三级网站网址| 亚洲精华国产精华精| 麻豆成人av在线观看| 99riav亚洲国产免费| 久久久久久免费高清国产稀缺| 欧美黄色淫秽网站| 欧美激情 高清一区二区三区| 咕卡用的链子| 91国产中文字幕| 亚洲欧美日韩无卡精品| 午夜免费鲁丝| 99国产精品一区二区蜜桃av| 一进一出抽搐gif免费好疼| 中出人妻视频一区二区| 天堂√8在线中文| 欧美精品啪啪一区二区三区| av福利片在线| 国产av一区二区精品久久| 色综合婷婷激情| 又大又爽又粗| 久久国产乱子伦精品免费另类| 久久久久久久久免费视频了| 一夜夜www| 久久婷婷成人综合色麻豆| 欧美成人免费av一区二区三区| 欧美日本中文国产一区发布| 老司机在亚洲福利影院| 精品国产一区二区久久| 宅男免费午夜| 免费在线观看视频国产中文字幕亚洲| 国产色视频综合| 国产一区在线观看成人免费| 国产成人免费无遮挡视频| 一级,二级,三级黄色视频| 韩国精品一区二区三区| 久久影院123| 一夜夜www| 一进一出抽搐gif免费好疼| √禁漫天堂资源中文www| 精品久久久久久久毛片微露脸| 亚洲人成网站在线播放欧美日韩| 久久久国产成人精品二区| 国产一区二区三区综合在线观看| 一边摸一边抽搐一进一出视频| 国产麻豆成人av免费视频| 日韩欧美一区视频在线观看| 韩国av一区二区三区四区| 欧美成狂野欧美在线观看| 久久狼人影院| 国产亚洲精品综合一区在线观看 | 欧美在线一区亚洲| 此物有八面人人有两片| 久久影院123| 亚洲精品中文字幕一二三四区| 纯流量卡能插随身wifi吗| 亚洲国产精品久久男人天堂| 国产av精品麻豆| 麻豆久久精品国产亚洲av| 免费久久久久久久精品成人欧美视频| 国产精品爽爽va在线观看网站 | 涩涩av久久男人的天堂| 啦啦啦观看免费观看视频高清 | 午夜福利高清视频| 欧美日本中文国产一区发布| 国语自产精品视频在线第100页| 性少妇av在线| www.999成人在线观看| 国语自产精品视频在线第100页| 操美女的视频在线观看| www.999成人在线观看| 国产乱人伦免费视频| 夜夜夜夜夜久久久久| 99在线人妻在线中文字幕| 在线观看66精品国产| www国产在线视频色| 琪琪午夜伦伦电影理论片6080| 中文亚洲av片在线观看爽| av片东京热男人的天堂| 国产欧美日韩精品亚洲av| 国产精品免费视频内射| 欧美中文日本在线观看视频| av有码第一页| 亚洲电影在线观看av| 亚洲国产中文字幕在线视频| 精品久久久久久久毛片微露脸| 国产一区二区三区视频了| 久久伊人香网站| 制服丝袜大香蕉在线|