亚洲免费av电影一区二区三区,日韩爱爱视频,51精品视频一区二区三区,91视频爱爱,日韩欧美在线播放视频,中文字幕少妇AV,亚洲电影中文字幕,久久久久亚洲av成人网址,久久综合视频网站,国产在线不卡免费播放

        ?

        Selection of Working Parameter for Bladder-type Accumulators with Different Conditions

        2013-06-02 06:17:00YANGYanfang
        機(jī)床與液壓 2013年18期

        YANG Yanfang

        China University of Mining and Technology ,Yinchuan College,Yinchuan 750011,China

        1.Introduction

        Accumulator is an indispensable component of modern hydraulic technology.With the development of hydraulic control technology,the accumulator is widely adopted in the industry applications.The most important function of accumulator is to store energy in the hydraulic system and to release the energy when the system is in demand[1].

        It is important to develop a software package to design and test an accumulator by using the existing hydraulic system and accumulator theory.Wanqiang Long,who works in shanghai Mayo,developed a smart and convenient software to calculate the volume of accumulator;Par.ker Hannifin Corp designed a calculator called Sharp EL512 to assist the user to select the parameters of different accumulators[2-3].

        1.1.The classification of accumulator

        Hydraulic accumulators could be classified in terms of the energy carrier and the separating element.

        The storage of energy is one of the purposes for the hydraulic accumulators.For the mechanical accumulator,the energy is stored with a type of potential energy.On the other hand,the internal energy of separation medium could be stored for the gas-loaded accumulators.Therefore,the accumulators could be classified by either with or without a separating element[4-5].The hydraulic accumulators with a separating element could be divided into the following types:① bladder-type accumulators,② diaphragmtype accumulators,③ piston-type accumulators.

        The principle of these above accumulators is to utilize the good compressibility of gas to store some liquid fluid with worse compressibility.Usually,nitrogen is chosen as the energy carrier.Basically,a hydro-pneumatic accumulator consists of a liquid compartment,a gas compartment,and a gas-tight separating element.The liquid compartment of accumulator is connected to the hydraulic circuit.Therefore,if the pressure of hydraulic circuit gets increased,the gas in the gas compartment will be compressed and the energy could be absorbed by the compressible gas.However,once the pressure of hydraulic circuit gets decreased,the compressed gas could be expanded and the stored energy will be released to push the liquid into the system.

        1.2.The function of accumulator

        Accumulators have a wide variety of applications in hydraulic systems due to the excellent properties

        The main functions of accumulator are as follows:① Energy storage ,② Emergency operation,③Leakage fluid make-up,④Volume compensation,⑤Shock absorption,⑥Pulsation damping ,⑦ Liquid addition.

        2.Various factors influence the working parameters

        2.1.Influence of poly index

        In the charge process of accumulators,the gas index is uncertain.The gas is compressed in the energy absorption process of accumulators.If the compression process is adiabatic,the poly indexn=1.4;If the compression process is isothermal,thenn=1.In fact,the gas compression process of the accumulator is between these two cases.There are two factors which will affect the gas heat transfer.One is the thermal resistance between the gas and the surrounding media and it depends on the accumulator.Another one is the process of experience;it mainly depends on the increase rate of gas pressure.The increase rate of gas pressure will be analyzed as a main factor to affect the poly index.

        During the time period Δt,the time-averaged gas compression rate could be evaluated by the ratio of the change of volume and the original volume.Take the limitation of above equation,the compression rate of gas could be obtained as follows[6]:

        ΔVsis the absolute change of volume during the time Δt,ΔVuis the volume of liquid fluid entering into the accumulator during the time Δt,VSis the original volume of the gas,Qis the flow of liquid fluid entering into the accumulator.

        Ifn=f(ε),the charging process is isothermal:

        The charging process is adiabatic:

        For bladder accumulator,the formula is as follows:

        2.2.Influence of the temperature

        In the operation cycle,the temperature of system could be changed.Since the volume of liquid/gas is the function of temperature,the influence of temperature should be taken into account.Due to the relationship between temperature and pressure and the Lussac Law,the relationship between pressure and volume could be obtained.When the temperature of system decreases,the pressure of the charge process will be decreased,and the storage capacity of accumulator will decrease as well.

        Therefore,in order to accumulate to ΔV,greaterV0is indispensably required.The relationship between the pressure and the volume is as follows:

        T1=θ1(℃)+273=the minimal temperature(K),T2=θ2(℃)+273=the maximal temperature(K),V0is the calculation volume without temperature change(L),V0Tis the increased volume with change of temperature(L).

        2.3.The total volume formula of the accumulator

        The total volume of the accumulator could be obtained as follows:

        P0is charging pressure of the gas space with the fluid space depressurized,P1is minimum pressure required to open the valve,P2is maximum operating pressure of the hydraulic system with bladder and diaphragm accumulators,ΔVis Effective volume.

        3.Programming and implementation of accumulator selection and accumulator working parameters calculation

        3.1.Flowchart of the software

        Accumulator calculation and accumulator working parameters selection are very important part of the software package[7-10].The calculation flowchart is Fig.1.

        3.2.Calculating program of the total volume

        Based on the poly index formula(3)and the accumulator total volume formula(5),the accurate total volume and the poly index of accumulator for the volumeV0 could be obtained.The Visual Basic language was adopted to program the main interface.The corresponding functional modules were compiled according to the different requirements and the Access was used as database to collect all the data of accumulator.Based on this software package,once user confirmed all the input parameters,an appropriate accumulator could be obtained.The final result will be presented in the form of chart.

        The code of programing is as follows:

        3.3.Examples of Application

        When the accumulator is used for volume compensation,if a pipe with internal diameterd=77.7 mm and the lengthL=120 m,the oil inside the pipe flows under the pressure of 10 bar;θ1=10℃,θ2=45℃;the change range of pressure is ±8%and the working temperature is between 25℃ and 70℃.

        1)Effective volume formula is defined as follows:

        VTis the volume of pipeline(L),θ2is the maximum temperature of system(℃),θ1is the minimum temperature of system(℃),β is fluid coefficient of cubical expansion,Kbis fluid coefficient of linear expansion of pipelines.

        2)The value of each parameter:

        Fig.1 The flowchart of selection and calculation of Accumulator

        3.4.Application of the software

        1)Interface is Fig.2.

        Fig.2 The initial interface of the software

        2)Select working conditions interface is Fig.3.

        Fig.3 The interface of selecting working condition

        3)Calculate the effective volume value ΔVis Fig.4.

        Press the“Calculation”button,then a message box displays ΔV=19.066 04 L.

        Fig.4 The interface of calculating the useful volume

        4)Calculate the total volume valueV0is Fig.5.

        Fig.5 The interface of calculating the total volume

        Press the“Calculation”button,then a message box displaysV0=178.44 L.

        5)Calculate the poly index at the condition ofV0 is Fig.6.

        Fig.6 The interface of calculating the poly index of accumulator for the volume V0

        Press the“Calculation”button,then a msgbox displaysn=1.035 744.

        6)Use the Access to establish the accumulator database,and chose the matching accumulator according to theV0andP0is Fig.7[2].

        7)The detailed information of the accumulator selected is Fig.8.

        Fig.7 The interface of the matching accumulators from database

        Fig.8 The interface of the detailed information of the accumulator selected

        4.Conclusions

        In this paper,a software package for accumulator was developed,and this software can provide precise total volume value.According to the total volume value,the database will recommend a proper accumulator.The software has friendly user interface and it is easy to use and understand.

        The accumulator software package still needs further improvement.After the calculation of total volume and recommendation of matching accumulator,this software suppose to call the Simulink in Matlab to build dynamic model of hydraulic loop to dynamic analysis.And another function of this software should be improved to check whether the accumulators meets the requirements or not.It provides an accurate basis for hydraulic system to choose appropriate accumulator and made full use of accumulator.

        [1]KONG Xiangdong,QUAN Lingxiao.The History,Current Situation of Accumulator’s Research and its Vista[J].MACHINE & HYDRAULICS,J2004(6):105..

        [2]Chamberlain J,F(xiàn)lippo W.Making the choice-bladder or piston accumulator[J].HYDRAULICS & PNEUMATICS,1987(11):58-64.

        [3]Flippo W T.Sharp EL512 Calculat or Helps Size Accumulators[J].HYDRAULICS &PNEUMATICS,1985(6):106-109.

        [4]MA Yali,HUANG Zhijian.Accumulator practical techniques[M].Beijing:Chemical industry press,2007.

        [5]ZHOU Entao.The manual of designing and selecting the hydraulic system components[J].Beijing :China Machine Press,2007:740-753.

        [6]WANG Dewei.Determination of the Gas Poly tropic exponent in the Charge Process of the Energy Accumulator[J].HYDRAULICS & PNEUMATICS,2007(9):106.

        [7]ZHAO Qi.The computer aided design of accumulator and working loop[D].Qinghuangdao:Yanshan University,2001.

        [8]LI xi,ZHANG Cong,CHAI Xin.Visual Basic Programming fundamentals[M].Beijing:China Railway Publishing House,2005.

        [9]WANG Jiasong.Visual Basic development experts[M].Beijing:Publishing house of electronics industry,2008.

        [10]LI Minye,WANG Ying.The complete analysis of Visual Basic & Access database applications[M].Beijing:Posts& Telecom Press,2004.

        老妇高潮潮喷到猛进猛出| 无码伊人66久久大杳蕉网站谷歌 | 成年女人18毛片毛片免费| 亚洲禁区一区二区三区天美| 亚洲爆乳无码专区www| 久久久精品人妻一区二区三区| 亚洲大片免费| 日韩精品一区二区三区av| 久久日日躁夜夜躁狠狠躁| 免费观看又色又爽又湿的视频| 国产成人久久综合热| 日本红怡院东京热加勒比| 大量漂亮人妻被中出中文字幕| 免费观看羞羞视频网站| 亚洲网站地址一地址二| 少妇一级aa一区二区三区片| 青青草成人在线播放视频| 啦啦啦www在线观看免费视频| 亚洲欧美日韩精品高清| 成人免费视频自偷自拍| 东北女人一级内射黄片| 无码吃奶揉捏奶头高潮视频| 久久国产亚洲精品超碰热| 一区二区三区黄色一级片| 亚洲最大成人网站| 国产乱人伦在线播放| avtt一区| 日韩精品视频免费在线观看网站| av鲁丝一区鲁丝二区鲁丝三区 | 欧美午夜一区二区福利视频| 国产精品女同学| 91精品国产一区国产二区久久| 亚洲日产一线二线三线精华液| 欧美日韩亚洲色图| 久久蜜桃一区二区三区| 精品无码久久久久久久久水蜜桃| 久久99精品国产麻豆| 亚洲欧美成人在线免费| 亚洲国产av一区二区三区| 免费人成视频xvideos入口| 国产精品99精品一区二区三区∴|