80平方米浮头式换热器设计【说明书+CAD】
收藏
资源目录
压缩包内文档预览：
编号：120936189
类型：共享资源
大小：1.63MB
格式：ZIP
上传时间：2021-04-11
上传人：221589****qq.com
认证信息
个人认证
李**（实名认证）
湖南
IP属地：湖南
40
积分
- 关 键 词：
-
80
平方米
头式
换热器
设计
说明书
CAD
- 资源描述：
-
80平方米浮头式换热器设计【说明书+CAD】,80,平方米,头式,换热器,设计,说明书,CAD
- 内容简介：
-
SHELL SIDE NUMERICAL ANALYSIS OF A SHELL AND TUBE HEATEXCHANGER CONSIDERING THE EFFECTS OF BAFFLEINCLINATION ANGLE ON FLUID FLOWbyRajagapal THUNDIL KARUPPA RAJ*and Srikanth GANNESchool of Mechanical and Building Sciences,Vellore Institute of Technology, Vellore, Tamil Nadu, IndiaOriginal scientific paperDOI: 10.2298/TSCI110330118RIn this present study, attempts were made to investigate the impacts of various baf-fle inclination angles on fluid flow and the heat transfer characteristics of ashell-and-tube heat exchanger for three different baffle inclination angles namely0, 10, and 20. The simulation resultsfor various shell and tube heat exchangers,one with segmental baffles perpendicular to fluid flow and two with segmental baf-fles inclined to the direction of fluid flow are compared for their performance. Theshell side design has been investigated numerically by modeling a small shell-and-tubeheatexchanger.Thestudyisconcernedwithasingleshellandsinglesidepass parallel flow heat exchanger. The flow and temperature fields inside the shellare studied using non-commercial computational fluid dynamics software toolANSYS CFX12.1.Foragivenbafflecutof36%,theheatexchangerperformanceisinvestigated by varying mass flow rate and baffle inclination angle. From the com-putationalfluiddynamicssimulationresults,theshellsideoutlettemperature,pres-sure drop, re-circulation near the baffles, optimal mass flow rate and the optimumbaffle inclination angle for the given heat exchanger geometry are determined.Key words: shell-and-tube heat exchanger, computational fluid dynamics,conjugate heat transfer, pressure drop, baffle inclination angleIntroductionHeat exchangers have always been an important part to the lifecycle and operation ofmany systems. A heat exchanger is a device built for efficient heat transfer from one mediumtoanother in order to carry and process energy. Typically one medium is cooled while the other isheated. They are widely used in petroleum refineries, chemical plants, petrochemical plants,natural gas processing, air-conditioning, refrigeration, and automotive applications. One com-monexampleofaheatexchanger istheradiatorinacar,inwhichittransfersheatfromthewater(hot engine-cooling fluid) in the radiator to the air passing through the radiator.There are two main types of heat exchangers:direct contact heat exchanger, where both media between which heat is exchanged are indirect contact with each other, andThundil Karuppa Raj, R., et al.: Shell Side Numerical Analysis of a Shell and Tube Heat .THERMAL SCIENCE: Year 2012, Vol. 16, No. 4, pp. 1165-11741165*Corresponding author; e-mail: thundil.rajagopalvit.ac.in, ganne2020indirect contact heat exchanger, where both media are separated by a wall through whichheat is transferred so that they never mix.A typical heat exchanger, usually for higher pressure applications up to 552 bar, is theshellandtubeheatexchanger.Shellandtubetypeheatexchangerisanindirectcontacttypeheatexchanger as it consists of a series of tubes, through which one of the fluids runs. The shell is acontainer for the shell fluid. Usually, it is cylindrical in shape with a circular cross-section, al-though shells of different shapes are used in specific applications. For this particular study Eshellisconsidered, whichisgenerallyaonepassshell.Eshellisthemostcommonlyusedduetoits low cost and simplicity, and has the highest log-mean temperature-difference (LMTD) cor-rection factor. Although the tubes may have single or multiple passes, there is one pass on theshell side, while the other fluid flows within the shell over the tubes to be heated or cooled. Thetube side and shell side fluids are separated by a tube sheet, 1-3. The heat exchanger modelused inthis studyisasmallsized one, ascomparedtothe mainstream,all ofthe leakage and by-pass streams do not exist or are negligible, 4-6. Baffles are used to support the tubes for struc-tural rigidity, preventing tube vibration and sagging and to divert the flow across the bundle toobtain a higher heat transfer coefficient. Baffle spacing (B) is the centre line distance betweentwo adjacent baffles, 7-9. Baffle is provided with a cut (Bc) which is expressed as the percent-age of the segment height to shell inside diameter. Baffle cut can vary between 15% and 45% ofthe shell inside diameter, 10-12. In the present study 36% Bc is considered. In general, con-ventional shell and tube heat exchangers result inhigh shell-side pressure drop and formationofre-circulation zonesnearthebaffles.Mostoftheresearchesnowadayarecarriedonhelicalbaf-fles, which give better performance then single segmental baffles but they involve high manu-facturing cost, installation cost and maintenance cost. Theeffectiveness and cost aretwoimpor-tant parameters in heat exchanger design. So, In order to improve the thermal performance at areasonable cost of the shell and tube heat exchanger, baffles in the present study are providedwithsomeinclination inordertomaintainareasonablepressuredropacrosstheexchanger13.The complexity with experimental techniques involves quantitative description offlow phenomena using measurements dealing with one quantity at a time for a limited range ofproblem and operating conditions. Computational fluid dynamics (CFD) is now an establishedindustrial design tool, offering obvious advantages 14. In this study, a full 360 CFDmodelofshell and tube heat exchanger is considered. By modeling the geometry as accurately as possi-ble, the flow structure and the temperature distribution inside the shell are obtained.Computational modeling and simulationIn this study six baffles are placed along the shell in alternating orientations with cutfacing up, cut facing down, cut facing up again etc., in order to create flow paths across the tubebundle. The geometric model is optimized by varying the baffle inclination angle i. e., 0, 10,and 20. The computational modeling involves pre-processing, solving and post- processing.The geometry modeling of shell and tube heat exchanger is explained below.Geometry modelingThe model is designed according to TEMA (Tubular Exchanger Manufacturers Asso-ciation) Standards Gaddis (2007), using Pro/E Wildfire-5 software as shown in fig. 1. Designparameters and fixed geometric parameters have been taken similar to Ozden et al. 4, as indi-cated in tab. 1.Thundil Karuppa Raj, R., et al.: Shell Side Numerical Analysis of a Shell and Tube Heat .1166THERMAL SCIENCE: Year 2012, Vol. 16, No. 4, pp. 1165-1174Table 1. Geometric dimensions of shell and tube heat exchangerHeat exchanger length, L600 mmShell inner diameter, Di90 mmTube outer diameter, do20 mmTube bundle geometry and pitch triangular30 mmNumber of tubes, Nt7Number of baffles. Nb6Central baffle spacing, B86 mmBaffle inclination angle, q0, 10, and 20Grid generationThe 3-D model is then discretized in ICEM CFD. In order to capture both the thermaland velocity boundary layers the entire model is discretized using hexahedral mesh elementswhich are accurate and involve less computation effort. Fine control on the hexahedral meshnearthewallsurfaceallowscapturingtheboundarylayergradientaccurately.Theentiregeome-try is divided into three fluid domains Fluid_Inlet, Fluid_Shell, and Fluid_Outlet, and six soliddomains namely Solid_Baffle1 to Solid_Baffle6 for six baffles, respectively. The heatexchanger is discretized into solid and fluid domains in order to have better control over thenumber of nodes.The fluid mesh is made finer then solid mesh for simulating conjugate heat transferphenomenon. The three fluid domainsareasshown in fig. 2. The firstcell height in the fluid do-main from the tube surface is maintained at 100 microns to capture the velocity and thermalboundary layers. The discretized model is checked for quality and is found to have a minimumThundil Karuppa Raj, R., et al.: Shell Side Numerical Analysis of a Shell and Tube Heat .THERMAL SCIENCE: Year 2012, Vol. 16, No. 4, pp. 1165-11741167Figure 1. Isometric view of arrangement of baffles and tubes of shell andtube heat exchanger with 20 baffle inclinationangle of 18 and min determinant of 4.12. Once the meshes are checked for free of errors andminimum required quality it is exported to ANSYS CFX pre-processor.Governing equationsThe 3-D flow through the shell-and-tube heat exchanger has been simulated by solv-ingtheappropriategoverning equations, eq.(1)toeq.(5).viz.conservation ofmass,momentumand energy using ANSYS CFX code. Turbulence is taken care by shear stress transport (SST)k-wmodelofclosurewhichhasablending functionthatsupportsStandardk-wnearthewallandStandard k-e elsewhere.Conservation of mass: ?()r?V0(1)x-momentum:? ?()rtttupxxyz?Vxxyxzx(2)y-momentum:? ?()rtttrupyxyz?Vgxyyyzy(3)z-momentum:? ?()rtttupzxyz?Vxzyxzz(4)Energy:? ? ?()rfepk Tq?VV +() +(5)Thundil Karuppa Raj, R., et al.: Shell Side Numerical Analysis of a Shell and Tube Heat .1168THERMAL SCIENCE: Year 2012, Vol. 16, No. 4, pp. 1165-1174Figure 2. Discretized fluid domain with non-uniform mesh for capturing boundary layerBoundary condition set-upIn ANSYS CFX pre-processor, the various fluid and solid domains are defined. Thedetails of the domains created with the corresponding fluid-solid & fluid-fluid interfaces areprovided in tab. 2, respectively. The flow in this study is turbulent, hence SST k-w turbulencemodelischosen. The boundary conditions are specified in ANSYSCFXpre-processor and thenthefileisexportedtotheANSYSCFX.Thesameprocedureisadoptedfortheothertwomodels.Table 2. Various domains and interfaces created in ANSYS CFX pre-processorDomain locationDomain typeDomain interfaceInterface typeFLUID_INLETFluidFLFL_INLET_SHELLFluid FluidFLUID_OUTLETFluidFLFL_OUTLET_SHELLFluid FluidFLUID_SHELLFluidFLFL_INLET_SHELLFluid FluidFLFL_OUTLET_SHELLFluid FluidFLSL_SHELL_BAFFLE1Fluid SolidFLSL _SHELL_BAFFLE2Fluid SolidFLSL _SHELL_BAFFLE3Fluid SolidFLSL _SHELL_BAFFLE4Fluid SolidFLSL _SHELL_BAFFLE5Fluid SolidFLSL_SHELL_BAFFLE6Fluid SolidSOLID_BAFFLE1SolidFLSL_SHELL_BAFFLE1Fluid SolidSOLID_BAFFLE2SolidFLSL _SHELL_BAFFLE2Fluid SolidSOLID_BAFFLE3SolidFLSL _SHELL_BAFFLE3Fluid SolidSOLID_BAFFLE4SolidFLSL _SHELL_BAFFLE4Fluid SolidSOLID_BAFFLE5SolidFLSL _SHELL_BAFFLE5Fluid SolidSOLID_BAFFLE6SolidFLSL_SHELL_BAFFLE6Fluid SolidBoundary conditions:the working fluid of the shell side is water,the shell inlet temperature is set to 300 K,the constant wall temperature of 450 K is assigned to the tube walls,zero gauge pressure is assigned to the outlet nozzle,the inlet velocity profile is assumed to be uniform,no slip condition is assigned to all surfaces, andThe zero heat flux boundary condition is assigned to the shell outer wall (excluding thebaffle-shell interfaces), assuming the shell is perfectly insulated.Thundil Karuppa Raj, R., et al.: Shell Side Numerical Analysis of a Shell and Tube Heat .THERMAL SCIENCE: Year 2012, Vol. 16, No. 4, pp. 1165-11741169Results and discussionValidationSimulation results are obtained for different massflow rates of shell side fluid rangingfrom0.5kg/s,1kg/s,and2kg/s.Thesimulatedresultsfor0.5kg/sfluidflowrateformodelwith0 baffle inclination angle are validated with the data available in 4. It is found that the exittemperature at the shell outlet is matching with the literature results and the deviation betweenthe two is less than 1%.Thesimulationresultsfor0.5kg/smassflowrateformodelswith0,10,and20baf-fle inclination are obtained. It is seen that the temperature gradually increases from300 K at theinlet to 340 K at the outlet of the shell side. The average temperature at the outlet surface isnearly 323 K for all the three models. There is no much variation of temperature for all the threecases considered.The maximumpressure for models with 0, 10 and 20 baffle inclinations are 94 .43,91.05, and 79.19 Pa, respectively. The pressure drop is less for 20 baffle inclination comparedto other two models due to smoother guidance of the flow. The maximum velocity is nearlyequal to 0.302 m/s for all the three models at the inlet and exit surface and the velocity magni-tude reduces to zero at the baffles surface. It can be seen that compared to 0 baffle inclinationangle, 10, and 20 baffle inclination angles, provide a smoother flow with the inclined bafflesguiding the fluid flow.From the stream line contour of fig. 3-5, it is found that recirculation near the bafflesinducesturbulenceeddieswhichwouldresultinmorepressuredropformodelwithq=0whereas re-circulations are lesser for model with q = 10 and the re-circulations formed for modelwith q = 20 are much less in comparison to the other two models which indicates the resultingpressure drop is optimum as shown in fig. 6.Thundil Karuppa Raj, R., et al.: Shell Side Numerical Analysis of a Shell and Tube Heat .1170THERMAL SCIENCE: Year 2012, Vol. 16, No. 4, pp. 1165-1174Figure 3. Variation of streamlines along the shell for 0 baffle inclination angleFromtheCFDsimulationresults,forfixedtubewallandshellinlettemperatures,shellside outlet temperature and pressure drop values for varying fluid flow rates are provided in tab.3 and it is found that the shell outlet temperature decreases with increasing mass flow rates asexpected even the variation is minimal as shown in fig. 6. It is found that for three mass flowrates 0.5 kg/s, 1 kg/s, and 2 kg/s there is no much effect on outlet temperature of the shell evenThundil Karuppa Raj, R., et al.: Shell Side Numerical Analysis of a Shell and Tube Heat .THERMAL SCIENCE: Year 2012, Vol. 16, No. 4, pp. 1165-11741171Figure 4. Variation of streamlines along the shell for 10 baffle inclination angleFigure 5. Variation of streamlines along the shell for 20 baffle inclination anglethough thebaffleinclination isincreasedfrom0to20.Howevertheshell-sidepressuredropisdecreasedwithincreaseinbaffleinclination anglei.e.,astheinclination angleisincreasedfrom0 to 20. The pressure drop is decreased by 4 %, for heat exchanger with 10 baffle inclinationangle and by 16 % for heat exchanger with 20 baffle inclination compared to 0 baffle inclina-tion heat exchanger as shown in fig. 7. Hence it can be observed that shell and tube heatexchanger with 20 baffle inclination angle results in a reasonable pressure drop. Hence it canbe concluded shell and tube heat exchanger with 20 baffle inclination angle results in betterperformance compared to 10 and 0 inclination angles.ConclusionsThundil Karuppa Raj, R., et al.: Shell Side Numerical Analysis of a Shell and Tube Heat .1172THERMAL SCIENCE: Year 2012, Vol. 16, No. 4, pp. 1165-1174Figure 6. Variation of temperaturewith baffle inclination angle (forvarious mass flow rates)Figure 7. Variation of pressuredrop with baffle inclination angle(for mass flow rates of 0.5 kg/s,1 kg/s, and 2 kg/s)Table 3. Outlet temperature and Shell-side pressure drop values for various baffle inclinationsand mass flow ratesBaffleinclinationangledegreesMass flow rate = 0.5 kg/sMass flow rate = 1 kg/sMass flow rate = 2 kg/sOutlettemperatureKPressuredifferencePaOutlettemperatureKPressuredifferencePaOutlettemperatureKPressuredifferencePa0323.3094.43322.28377.14321.371507.6410323.6291.05322.62362.12321.701459.89?The shell side of a small shell-and-tube heat exchanger is modeled with sufficient detail toresolve the flow and temperature fields.?The shell side of a small shell-and-tube heat exchanger is modeled with sufficient detail toresolve the flow and temperature fields.?For the given geometry the mass flow rate must be below 2 kg/s, if it is increased beyond2 kg/s the pressure drop increases rapidly with little variation in outlet temperature.?The pressure drop is decreased by 4%, for heat exchanger with 10 baffle inclination angleand by 16 %, for heat exchanger with 20 baffle inclination angle.?The maximumbaffle inclination angle can be 20, if the angle is beyond 20, the centre rowof tubes are not supported. Hence the baffle cannot be used effectively.?Hence it can be concluded shell and tube heat exchanger with 20 baffle inclination angleresults in better performance compared to 10 and 0 inclination angles.References1Gaddis, D., Standards of the Tubular Exchanger Manufacturers Association, TEMA Inc, 9thed.,Tarrytown, N. Y., USA, 20072Schlunder,E.V.,HeatExchanger DesignHandbook,HemispherePublishingCorp., BureauofEnergy Ef-ficiency, New York, USA, 19833Mukherjee, R., Practical Thermal Design of Shell-and-Tube Heat Exchangers, Begell House. Inc., NewYork, USA, 20044Ozden, E., Tari, I., Shell Side CFD Analysis of a Small Shell-and-Tube Heat Exchanger, Energy Conver-sion and Management, 51 (2010), 5, pp. 1004-10145Kapale,U.C., Chand, S.,ModelingforShell-SidePressureDropforLiquidFlowinShell-and-Tube HeatExchanger, International Journal of Heat and Mass Transfer, 49 (2006), 3-4, pp. 601-6106Thirumarimurugan, M., Kannadasan, T., Ramasamy, E., Performance Analysis of Shell and Tube HeatExchanger Using Miscible System, American Journal of Applied Sciences, 5 (2008), 5, pp. 548-5527Sparrows, E. M., Reifschneider, L. G., Effect of Inter Baffle Spacing on Heat Transfer and Pressure Dropin a Shell-and-Tube Heat Exchanger, International Journal of Heat and Mass Transfer, 29 (1986), 11, pp.1617-16288Li, H., Kottke, V., Effect of Baffle Spacing on Pressure Drop and Local Heat Transfer in Shell-and-TubeHeat Exchangers for Staggered Tube Arrangement, Int. J. Heat Mass Transfer, 41 (1998), 10, pp.1303-13119Than, S. T. M., Lin, K. A., Mon, M. S., Heat Exchanger Design, Engineering and Technology, 46 (2008),22, pp. 604-61110
- 温馨提示:
1: 本站所有资源如无特殊说明，都需要本地电脑安装OFFICE2007和PDF阅读器。图纸软件为CAD,CAXA,PROE,UG,SolidWorks等.压缩文件请下载最新的WinRAR软件解压。
2: 本站的文档不包含任何第三方提供的附件图纸等，如果需要附件，请联系上传者。文件的所有权益归上传用户所有。
3.本站RAR压缩包中若带图纸，网页内容里面会有图纸预览，若没有图纸预览就没有图纸。
4. 未经权益所有人同意不得将文件中的内容挪作商业或盈利用途。
5. 人人文库网仅提供信息存储空间，仅对用户上传内容的表现方式做保护处理，对用户上传分享的文档内容本身不做任何修改或编辑，并不能对任何下载内容负责。
6. 下载文件中如有侵权或不适当内容，请与我们联系，我们立即纠正。
7. 本站不保证下载资源的准确性、安全性和完整性, 同时也不承担用户因使用这些下载资源对自己和他人造成任何形式的伤害或损失。
人人文库网所有资源均是用户自行上传分享，仅供网友学习交流，未经上传用户书面授权，请勿作他用。
川公网安备: 51019002004831号