多组分合成气强化换热器壳程传热的数值模拟

第42卷第10期热力发电Vol 42 No 102013年10月THERMAL POWER GENERATIONOct.2013多组分合成气强化换热器壳程传热的教值模拟李彦1,2,姜秀民3,任建兴12,吴江11.上海电力学院能源与机械工程学院,上海2000902.上海发电环保工程技术研究中心,上海2000903.上海交通大学燃煤污染物减排国家工程实验室,上海200240[摘要]采用多孔介质模型对 ASPEN软件设计的高压多组分合成气换热器进行了三维数值模拟,分析了不同的几何结构对壳程流体的传热和压降的影响规律。分析结果表明,采用 ASPEN软件设计的换热器具有较妤的流动和换热特性;多孔介质模型可用于模拟净燃气过热器壳程流体的流动和换热;在其它参数不变情况下换热器折流板的圆缺度由20%减至15%对壳程流体的换热影响不大,但增加了壳程流体的压降[关键词]管壳式换热器;多组分合成气;多孔介质;壳程;流速;强化传热; ASPEN软件中图分类号]TK124[文献标识码]A[文章编号]10023364(2013)10-0021-05[DOⅠ编号]10.3969/.isn.1002-3364.2013.10.021Numerical simulation on heat transfer enhancement in shellside of multi-component synthetic gas heat exchangerLI Yan. 2, JIANG Xiumin, REN Jianxing, 2, WU Jiang, 21. College of Energy and Mechanical Engineering, Shanghai University of Electric Power, Shanghai 200090, Chir2. Shanghai Engineering Research Center of Power Generation Environment Protection, Shanghai 200090, ChinaNational Engineering Laboratory of Coal-fired Pollutants Emission Reduction, School of Mechanical EngineeringShanghai Jiao Tong University, Shanghai 200240, ChinaAbstract: The porous media model was employed to conduct three-dimensional numerical simulation on a high pressure multi-component syngas heat exchanger designed by AsPen software.The effect of different geometric structures on heat transfer and pressure drop of shell side fluidwas investigated. The results showed that, the heat exchanger designed by the asPen softwarehad good flow and heat transfer performance; the temperature distribution of the high pressuremulti-component syngas at shell side obtained by the porous medium model agreed well with thatdesigned by the aspen software; keeping the other parameters as constants and decreasing thesegmental orifice degree of the baffle plate in heat exchanger from 20% to 15% had little effect onheat transfer behavior of the shell side fluid, but the pressure drop was increasedKey words shell and tube heat exchanger; multi-component syngas; porous medium; shell side;flow rate; heat transfer; enhancement; ASPEN收稿日期:2012-10-31基金项目:国家863高技术基金项目(2007AA05Z247);上海高校青年教师培养资助计划(sd1008);上海市教委重点学科(第五期)(J51304);上海发电环保工程技术研究中心项目(1ldz2281700)。作者简介:李彦(1978-),女,副教授辽宁丹东人,从事lGCC系统内换热器强化传热及E-mail:yli@shiep.edu.cnTHS中国煤化工CNMHG热力发电2013年管壳式换热器是目前整体煤气化燃气蒸汽联合1模型建立循环(IGCC)系统中主要的换热器形式。近年来,许多学者研究了换热器结构与换热器性能之间的关高压多组分合成气换热器的结构如图1所示,系口12。古新等研究了斜向流管壳式换热器壳程净燃气走管程,水走壳程,中间布置有隔板,考虑到的折流栅等结构参数对流体的换热和流阻的影响规固定板结构的温差应力过大,选用管程可拆式U型律,分析了其温度和速度梯度的协同程度。Peng管式结构。换热器属于双壳程双管程结构。Z轴为等设计出一种防短路的折流板结构新型防短路合成气和水的流动方向,Y轴为合成气和水的进出螺旋折流板在原扇形折流板的基础上将两侧直边同口方向,该布置方式是根据 ASPEN设计计算结果时加宽1排或2排管距宽度,相邻2块扇形板的直得出的最优布置方式。边以交叉重叠方式连接。该结构有助于正向流动,防止上游螺旋通道内的流体通过三角区向下游通道逆向泄漏。赵本华等5研究对比了旋向自交叉转子、同向转子的换热器和光管的传热性能,发现在同等条件下,旋向子交叉转子的换热器具有较好的换热性能。何雅玲等6研究了压力场和速度场的场协同效应,得出速度矢量与压力梯度之间的夹角越大,压力场与流场的协同性越好,流动产生的压降越小,流动损失越小。董其伍等把周期性和对称性简化手段应用于管壳式换热器数值模拟中,提出了图1高压多组分合成气换热器结构几何原型周期段模型和单元流道模型简化方法,并Fig 1 Schematic diagram of the high pressure基于整体的对称性,仅取简化模型的一半进行计算,multicomponent synthetic gas heat exchanger大大降低了计算量。 Hilbert r等通过改变结构布置来优化传热、降低阻力。刘伟等0设计了一种壳侧采用多孔介质模型的控制方程组 RNG k-e新型的折流杆-扰流叶片组合式换热器,建立了相应模型进行计算。其中经验常数为:C=0.0845,的物理和数学模型,并对其传热与流动特性进行了=1.42,Ca=1.68,B=0.012,7=4.38,ak=计算模拟,认为该新型换热器壳程的对流换热系数=1.39。与折流杆换热器相当,但流动阻力远小于折流杆换首先给出管侧流体温度的初值,并设其为线性热器,综合性能优于折流杆换热器。夏翔鸣等从分布,通过多孔介质模型得到壳程流体的温度分布,场协同原理出发,提出了基于场协同理论的无因次根据壳程流体的吸热量等于管程流体的放热量迭代性能因子来综合评价换热表面的强化传热效果。本计算管侧流体温度直至满足收敛要求。管程流体文采用多孔介质模型对IGCC系统中的净燃气过热的物性通过 ASPEN PLUS进行计算,对于具体的器进行模拟,探讨了其采用的高压多组分合成气换工况其值为常数。热器的换热机理,对比分析了不同折流板圆缺度对模拟用简化净燃气过热器的主要几何和运行参数见表1、表2。合成气换热器换热的影响规律。表1模拟用简化净燃气过热器主要几何参数Table 1 Main geometric parameters of the simplified clean synthetic gas superheater项目数值项目数值壳体内1300折流板间距/mm30壳体长度/mm折流板数壳体进出口内径/mm折流板圆缺度/%管子外径/mm第1块折流板距离管板/m管子内径/mm管子根数2172管间距/mm管子排列方式中国煤化工CNMHGhttp:/www.rlfd.comcnhttp:/rlfd.periodicals.net.cn第10期李彦等多组分合成气强化换热器壳程传热的数值模拟表2模拟用简化净燃气过热器主要运行参数Table 2 Main operation parameters of the simplifiedclean synthetic gas superheater壳侧管侧内容项目内容进口介质水进口介质合成气进口介质温度/℃240进口介质温度/C144.1流量/kghi9020流量/kg·h150140工作压力/MPa10‖出口介质温度/℃160入2计算方法和边界条件采用 gambit进行网格划分,采用 Fluent6.1进图3换热器壳程流体速度分布Fig 3 Velocity profile of the shell-side fluid行模拟,多孔度、分布阻力和分布热源采用用户自定义函数耦合进 Fluent中进行计算。采用 SIMPLEC方法求解方程。动量、能量方程采用二级差分,压力方程采用 Standard边界条件为:给定换热器进口压力、流量和温度,其出口速度由质量守恒确定,出口压力和温度根据局部单向化确定;换热器外壳采用不可渗透、无滑移和绝热条件图2为换热器的网格布置。采用782228网格划分方式对换热器进行计算,其计算误差约为2%。图4换热器壳程流体流线Fig 4 Streamlines of the shell-side fluid图5为壳程流体在x=0平面的压力分布(单位:Pa,下同)。由图5可见,换热器入口处的压力较高,流体沿流动方向压力逐渐降低,出口处压力最低。流体进、出口大约有26Pa的压降。沿流体流动方向,折流板正向的压力较大,背侧压力较小图2网格布置Fig 2 Mesh generation of the clean synthetic gas superheater3结果与讨论3.1基准工况计算结果图3、图4分别为换热器壳程流体的速度分布和流线。由图3可见,流体沿着换热器壳体从入口流向出口,折流板处流速较小,相应地增加了流体的停留时间。由图4可见,换热器壳程流体的流线较为顺畅,基本无流动漩涡。面的压力外和Fig 5中国煤化CNMHGhttp:www.rlfd.com.cnhttp:/rlfd.periodicalsnet.cn热力发电2013年图6为壳程流体在x=0平面的温度分布(单位:K,下同)。由图6可见,壳程流体的入口温度为513K,出口温度为419K,这与 ASPEN设计计算的出口温度(417.44K)接近。流体入口处温度降低较多,换热较强。图8折流板圆缺度为15%时壳程流体速度分布ig. 8 Velocity distribution of the shell-side fluid in heatexchanger with baffle segmental degree of 15%图6x=0平面的温度分布入口Fig 6 Temperature distribution of the shell-side fluidin cross section where x=0图9折流板圆缺度为15%时壳程流体流线3.2换热器结构对换热性能的影响Fig9 Streamlines of the shell-side fluid in heat exchanger图7为折流板圆缺度为15%时换热器的结构。ith baffle segmental degree of 15%图8、图9分别为该结构换热器的壳程流体速度分图10为折流板圆缺度为15%的换热器壳程流布和流线。由图8图9可见,折流板附近的流体流体在x=0平面的压力分布速较小,出、人口的流体流速较大。由于折流板圆缺度的减小,在增加了流体扰动性的同时,折流板之间也产生了大量的漩涡,漩涡处流体的流速较小。流动漩涡的存在导致流体在该位置下形成流动死区,影响了壳程流体与管程流体之间的换热。图10折流板圆缺度为15%时壳程流体在x=0平面的压力分布图7折流板圆缺度为15%时换热器结构Fig 10distribution of the shelk-side fluid inFig 7 Structure of the heat exchanger with baffle中国煤化he bafflesegmental degree of 15%CNMHGhttp:/www.rlfd.comcnhttp:/rlfd.periodicals.net.cn第10期李彦等多组分合成气强化换热器壳程传热的数值模拟比较图5、图10发现,折流板的圆缺度从20%减至板的圆缺度,相应增加了壳程流体的压降,但对壳程15%后,壳程流体的入口压力从2.66Pa增至流体的换热影响不大。26Pa,壳程流体的压降从26Pa增至38Pa,符合减少折流板圆缺度流体的压降增加的规律。流体流向[参考文献]折流板侧压力较高,背流侧压力较低[1]江泽民.对中国能源问题的思考[J].上海交通大学学图11为折流板圆缺度为15%的换热器壳程流报,2008,42(3):345-359体在x=0平面的温度分布。比较图6、图11发现JIANG Zemin. Reflections on energy issues in折流板的圆缺度从20%减至15%后,壳程流体的出[J]. Journal of Shanghai Jiaotong University42(3):345-359.口温度基本不变。可见,减少折流板的圆缺度对壳[2]焦树建整体煤气化燃气蒸汽联合循环[M].北京:中程流体的换热影响不大,但可增加壳程流体的压降国电力出版社,1996JIAO Shujian. Integrated gasification combined cycle[M]. Beijing China Electric Power Press. 1996(in Chi[3]古新,董其伍,刘敏珊等导向型折流栅强化换热器壳程传热的数值模拟[冂].核动力工程,2010,31(2):113117GU Xin, DONG Qiwu, LIU Minshan, et al. Numericalsimulation on heat transfer enhancement in shell side ofer with lebaffles[J]. Nuclear Power Engineering, 2010, 31(2):113-117[4] Zhang C, Xie G N, Luo L Q, et al. Astudy of shell- and-tube heat exchanges with continu-ous helical baffles [J]. Technical Briefs. 2007, 1291426-1431图11折流板圆缺度为15%时壳程流体在x=0平面的[5]赵本华,何雪涛,阎华等换热管内旋向自交又转子强温度分布化传热性能研究[].热能动力工程,2012,27(3):307Fig. 11 Temperature distribution of the shellside fluidin cross section where x=0 with the baffleZHAO Benhua, HE Xuetao, YAN Hua, et al. Study ofsegmental degree of 15%the intensified heat transfer performance of a heat exhanger tube inner rotation direction self-cross rotor4结论[J]. Journal of Engineering for Thermal Energy and采用多孔介质模型以及分布阻力、分布热源关Power,2012,27(3):307-311系式,对高压多组分合成气换热器壳程流体的流动6]何雅玲,雷勇刚,田丽享等高效低阻强化换热技术的和传热进行了三维数值模拟,并分析了折流板的圆三场协同性探讨[J.工程热物理学报,2009,30(11)1904-1906缺度对换热器换热性能的影响结果表明HE Yaling, LEI Yonggang, TIAN Liting, et al. An a-(1)采用 ASPEN软件设计的换热器具有较好alysis of three-field synergy on heat transfer augmen的流动和换热特性。tation with low penalty of pressure drop[J]. Journal of(2)采用多孔介质模型模拟得到的净燃气过热2009,30(11):1904-1906器壳程流体的温度分布与采用 ASPEN软件的设计[7 Dong Q W, Liu m s, Zhao XD. Research on the char-结果相近,说明多孔介质模型可用于模拟净燃气过acteristic of shellside support structures of heat ex热器壳程流体的流动和换热。changer with longitudinal flow of shellside fluid[J](3)对于本文给定的运行条件和参数,减少折流IASME Transactions, 2005,8(2): 1491-1498中国煤化工转第31页)CNMHGhttp://www.rlfd.comcnhttp:/rlfd.periodicalsnet.cns 10 #y LI Yan et al Numerical simulation on heat transfer enhancement in shell side of multi-component synthetic gas heat exchangerteristicschanger tube inner rotation direction self-cross rotor(2)Temperature distribution of the shell-side[J]. Journal of Engineering for Thermal Energy andfluid in clean synthetic gas superheater which wasPower,2012,27(3):307-311simulated by the porous medium model was similar[6] HE Yaling, LEI Yonggang, TIAN Liting, et al. An analysis of three-field synergy on heat transfer augerto that designed by the ASPEN software, demontation with low penalty of pressure drop[]. Journal ofstrating that the porous medium model can be usedEngineering Thermophysics, 2009, 30(11): 1904-to simulate the flow and heat transfer of the shell-1906side fluid in clean synthetic gas superheat[7] Dong Q W, Liu M S, Zhao X D. Research on the char-(3)For the given operation conditions and paacteristic of shellside support structures of heat ex-rameters in this study, the pressure drop of thchanger with longitudinal flow of shellside fluid[J].shell-side fluid increased when decreasing the baf-IASME Transactions, 2005,8(2): 1491-1498tal degree[8] WU Jinxing, DONG Qiwu, LIU Minshan, et al. Numer-ical simulation on the turbulent flow and heat transferReferencesin the shell side of the rod baffle heat exchanger[J][1] JIANG Zemin. Reflections on energy issues in ChinaJournal of Chemical Engineering of Chinese Universi[T. Journal of Shanghai Jiaotong University, 2008, 42ties,2006,20(2):213-216(3):345-359[9] Hilbert R, Janiga G, Baron R, et al. Multi-objective[2] JIAO Shujian Integrated gasification combined cycleshape optimization of a heat exchanger using parallel[MI. Beijing: China Electric Power Press, 1996(ingenetic algorithms [J]. International Journal of Heatand Mass Transfer, 2006, 49: 2567-25773] GU Xin, DONG Qiwu, LIU Minshan, et al. Numerical [10] LIU Wei, LIU Zhichun, WANG Shuangying, et alulation on heat transfer enhancement in shell sideStrengthening heat transfer research and spoiler mech-of shell-and-tube heat exchanger with leading typeanism in longitudinal bundles of tube-and-shell heatshutter baffles[ J]. Nuclear Power Engineering, 2010exchanger[J]. Science in China(Series E: Technologi31(2):113-117al sciences),2009,39(11):1850-1856[4] Zhang C, Xie G N, Luo L Q, et al. An experimental [11] XIA Xiangming, ZHAO Liwei, XU Hong, et al. Overallstudy of shell- and- tube heat exchanges with continu-performance factor for evaluating intensified heat conous helical baffles [J]. Technical Briefs, 2007, 129duction based on the fieldheory[J]. Jou1426-1431of Engineering for Thermal Energy and Power, 2011[5 ZHAO Benhua, HE Xuetao, YAN Hua, et al. Study of26(2):197-201the intensified heat transfer performance of a heat ex-上接第25页[8]吴金星,董其伍,刘敏珊,等.折流杆换热器壳程湍流和学,2009,39(11):1850-1856传热的数值模拟[].高校化学工程学报,2006,20(2)LIU Wei, LIU Zhichun, WANG Shuangying, et al.213-216Strengthening heat transfer research and spoiler mechWU Jinxing, DONG Qiwu, LIU Minshan, et al. Numer-anism in longitudinal bundles of tube-and-shell heat ex-ical simulation on the turbulent flow and heat transferhanger[J]. Science in China( Series E: Technologicalin the shell side of the rod baffle heat exchanger[J]Sciences),2009,39(11):1850-1856Journal of Chemical- ngineering of Chinese Universi-[11]夏翔鸣,赵力伟,徐宏,等.基于场协同理论的强化传热ties,2006,20(2)213-216综合性能评价因子[J].热能动力工程,2011,26(2)[9] Hilbert R, Janiga G, Baron R, et al. Multi-objective197-201shape optimization of a heat exchanger using parallXIA Xiangming, ZHAO Liwei, XU Hong, et al. Overallgenetic algorithms [J]. International Journal of Heatrformance factor for evaluating intensified heat con-and Mass Transfer, 2006, 49: 2567-2577duction based on the field synergy theory [J]. Journal[10]刘伟,刘志春,王英双,等.管壳式换热器纵流管束内的of Engineering for Thermal Energy and Power, 2011扰流机制与传热强化研究[J].中国科学E辑:技术科26(2):1中国煤化工CNMHGhttp∥www.rfdcom. cnhttp:l/rlfd.periodicalsnet.cn第42卷第10热力发电vo.42No.102013年10月THERMAL POWER GENERATIONOct.2013Numerical simulation on heat transfer enhancement in shellside of multi-component synthetic gas heat exchangerLI YanZ, JIANG Xiumin, REN Jianxing, 2, WU Jiang, 21. College of Energy and Mechanical Engineering, Shanghai University of Electric Power, Shanghai 200090, china2. Shanghai Engineering Research Center of Power Generation Environment Protection, Shanghai 200090, China3. National Engineering Laboratory of Coal-fired Pollutants Emission Reduction, School of Mechanical engineeringShanghai Jiao Tong University, Shanghai 200240, ChinaAbstract: The porous media model was employed to conduct three-dimensional numerical simulation on ahigh pressure multi-component syngas heat exchanger designed by asPen software. The effect of differentgeometric structures on heat transfer and pressure drop of shell side fluid was investigated. The resultsshowed that, the heat exchanger designed by the aspen software had good flow and heat transfer performance; the temperature distribution of the high pressure multi-component syngas at shell side obtainedy the porous medium model agreed well with that designed by the aspen software keeping the other pa-rameters as constants and decreasing the segmental orifice degree of the baffle plate in heat exchanger from20% to 15% had little effect on heat transfer behavior of the shell side fluid, but the pressure drop was in-creasedKey words: shell and tube heat exchanger; multi-component syngas; porous medium; shell side; flow rateheat transfer; enhancement; ASPENAs the major heat exchanger type in the inte- verlapped and connected This structure helped tograted gasification combined cycle(IGCC) system, flow forwardly and prevented the upstream fluid inshell and tube heat exchanger has drawn much at- a spiral channel from reversely leaking to thetention in recent years, especially the relationship downstream channel through the triangle area.between the heat exchanger structure and the heat Zhao Benhua et all5] investigated and compared thetransfer performance has been widely investigated heat transfer performance of heat exchangers withby many researchers-23. Gu Xin et all3 studied the rotary self-cross rotor, co-rotating rotor andeffect of baffle structure parameters on heat trans- smooth pipe. They found that the rotary self-crossfer and flow resistance of the fluid in oblique flow rotor heat exchanger had better heat transfer pershell and tube heat exchanger, and analyzed the formance under the same conditions. He yaling etsynergy degree of the temperature and the velocity all studied the synergy effect of the pressure fieldgradient. Peng et al designed a short-circuit pre- and velocity field. They found that with an increaseventing baffles On the basis of the original sectorangle between the velocity vector and the presbaffles, the two straight edges were widened for sure gradient, the cooperativitythe pressuretube spacing width of one or two rows. The two field and the flow field got better, and the pressurestraight edges of the adjacent fan-shaped plates o- drop and flow loss decreased. Dong Qiwu and WuSupported by: National High Technology Research and Development Program of China(863 Program)(2007AA05Z247): Funding Scheme for Training Young Teachers in Shanghai Colleges(sdl11008); Key disciplines of Shanghai Education Commission(The Fifth Period)(J51304): Shanghai Engineering Research Center(11dz2281700)Correspondingauthor.E-mail:yli@shiep.edu.cnTH中国煤化工 onment ProtectionCNMHGsB 10 M LI Yan et al Numerical simulation on heat transfer enhancement in shell side of multi-component synthetic gas heat exchangerJinxing et al[7-8]applied the periodicity and symme- plate structure, the dismountable U-type tubulartry reduction methods to conduct numerical simu- structure was applied. The heat exchanger adoptedlation on a shell and tube heat exchanger Moreo- double-shell and double-tube structure. The synver, they proposed a geometric prototype of period- thetic gas and water flows along the Z axis, whilemodel and a simplified method of unit duct mohe y axis is their inflow and outflow directionel. On the basis of the overall symmetry, the com- This arrangement is the optimal configuration ac-putation amount was reduced significantly by tak- cording to the ASPEN calculation results.ing half of the simplified model to calculate. Hil-bertR et al] optimized the heat transfer and reduced the resistance by changing the structure ar-rangement. Liu Wei et allo] designed a new type ofrod baffle-spoiler blade combined heat exchangerand established the corresponding physical andmathematical model. Besides, the characteristics ofheat transfer and flow were simulated. They reported that the convective heat transfer coefficient inshell-side of this new heat exchanger was equivant to thebaffle heat exchanger, but the flowFig. 1 Schematic diagram of the high pressuremulticomponent synthetic gas heat exchangerfar less. Therefore, the comprehenive performance of the new heat exchanger wasFor calculation in the shell side, control equabetter than that of the rod baffle heat exchanger. tions of the porous medium model and the rNG k-eXia Xiangming et ali put forward a field synergy model were used. The empirical constants in theprinciple based dimensionless performance factor torng k-E model were as follows. C.=0.084 5,evaluate the effect of heat transfer enhancement Cle=l 42, Cze=1.68,P=0.012,o=4. 38,akcomprehensively In this paper, a porous medium=1.39model was applied to simulate the flow and heatAn initial temperature value of the tube-sidetransfer characteristics of the shell-side fluid in a fluid was given and its distribution was supposedclean synthetic gas superheater of the IGCC sys- to be linear. Temperature distribution of the shell-tem. The heat transfer mechanism of high pressure side fluid was obtained through the porous mediummulticomponent synthetic gas heat exchanger wasmodel Because the heat transfer of the shell-sidediscussed. Furthermore, the effect of baffle seg- fluid was equal to the heat release of the tube-sidemental degree on heat transfer of the synthesis gas fluid, the tube--side fluid temperature was iterative-heat exchanger was comparedly calculated till the convergence requirements1 Model establishmentwere satisfied. The physical properties of the tubeside fluid were calculated by the ASPEN PLUSThe structure of the high pressure multicom-software and in specific operation conditions theyponent synthetic gas heat exchanger is shown inwere considered as constantsFig. 1. The clean synthetic gas flows in the pipeThe main geometric parameters of the simpliand the water flows in the shell equipped withfied clean synthetic gas superheater are shown insome baffles in the middle. Considering the overTable 1 and table 2large temperaturess in the fixedH中国煤化工CNMHGhttp:www.rlfd.comcnhttp:/rlfd.periodicals.net.cn热力发电2013年Table 1 Main geometric parameters of the simplified clean synthetic gas superheaterItemvalueItemInner diameter of the shell side/mm1 300 Baffle spacing/mn2 360 Baffle number6Inner diameter of the shell-side fluid at inletand outlet/mn200 Baffle segmental degree/The tube outer diameter/mmDistance between the first baffle and the tubeplate/mmThe tube inner diameter/mm14‖ Tube number2172ch/mm25 Tube arrangementTriangularTable 2 Main operation parameters of the simplified clean synthetic gas superheaterShell sideTube sideItemValueItemInlet mediumWater‖ Inlet mediumSynthetic gaInlet medium temperature/CInlet medium temperature/C144.Flux/kg·h-19020Fux/kg·h-1150140Operation pressure/MPaOutlet medium temperature /C2 Calculation method and the boundaryseen that, the water flows from the entrance to theconditionsexit along the shell. The flow rate around the baf-The gambit software was employed to generfles is low. Correspondingly, the residence time ofate the meshes, and the Fluent 6. 1 was adopted tothe fluid is prolonged. Seen in Fig. 4, the shell-sidefluid has smooth streamlines with almost no flconduct the simulation. The porosity, the resistancevortexdistribution and the heat source distribution werecoupled into the Fluent by applying thee user-de-fined function By SIMPLEC method, the equationswere solved. The second difference was used forthe momentum and energy equations and theStandard was employed for the pressure equation.The boundary conditions were: the pressureflux and temperature at the heat exchanger inletwere given; the outlet velocity was determined according to the mass conservation; the outlet pressure and temperature were determined according to Fig. 2 Mesh generation of the clean synthetic gas superheaterthe local unidirectional the outer shell of the heatexchanger adopted impermeable, no slip and adia-batic conditionsFig 2 shows mesh generation of the heat exchanger. The 782 228 mesh division method was a-dopted to conduct the calculation The grid computing error of this method was about 2%let3 Results and discussion3.1 Calculation results in the reference conditions IFig. 3 and Fig 4 show the velocity distributionand streamlines of the shell-side fluid. It can beYH中国煤化工elk-side fluidCNMHGhttp:www.rlfd.comcnhttp:/rlfd.periodicalsnetcn9 10 LI Yan et al Numerical simulation on heat transfer enhancement in shell side of multi-component synthetic gas heat exchangerThe temperature drop of the fluid at inlet is largeindicating severe heat transfer occursin letFig 4 Streamlines of the shelF-side fluidFig. 5 in which the unit is Pa, shows the pressure distribution of the shell-side fluid in cross secDtion where x=0. It can be seen that, the highestoutletfluid pressure appears at the heat exchanger en-trance. Then the pressure decreases gradually a-long the flow direction and reaches the lowest atFig 6 Temperature distribution of the shell-side fluidin cross section where x=0the outlet. The pressure drop between the inlet andoutlet is about 26 Pa. Along the fluid flow direc-3. 2 Effect of heat exchanger structure on heation, the pressure at the baffle plate forward direc-transfer per formancetion is higher than that at the dorsal side of theFig 7 shows structure of the heat exchangerbaffleswith baffle segmental degree of 15%. Fig 8andFig 9 are the velocity distribution and streamlinesof the shell-side fluid in heat exchanger with thisnew structure. Seen in Fig. 8 and Fig 9, the fluidvelocity around the baffle plates is low, while thatat the entrance and the exit is high. This is becausethe decrease in baffle segmental degree increasethe fluid disturbance, meanwhile, a large number ofvortexes also formed between and among the baffleplates, causing the flow dead zone appears, whichaffects the heat transfer between the shell-side flu-id and the tube-side fluidFig. 5 Pressure distribution of the sheell-side fluidin cross section where x=0Fig. 6 in which the unit is K shows the shell-side fluid temperature distribution in cross sectionwhere x=o As shown in Fig. 6, the entrance tem-perature of the shell-side fluid is 513 K and theoutlet temperature is 419 K, which is close to theFig. 7oh中国煤化工-ith bafflecalculated temperature (417. 44 K)by ASPENCNMHGhttp:/www.rlfd.comcnhttp://rlfd.perionet cn热力发电2013年Fig 8 Velocity distribution of the shell-side fluid in heatexchanger with baffle segmental degree of 15%outletFig 10 Pressure distribution of the shell-side fluid incross section where x=0 with the bafflesegmental degree of 15%nletoutletFig. 9 Streamlines of the shell-side fluid in heat exchangerwith baffle segmental degree of 15%Fig. 10 shows pressure distribution of theshell-side fluid in cross section where x=0, withbaffle segmental degree of 15%. Comparison be-tween Fig. 5 and Fig 10 indicates that, with an de-crease in baffle segmental degree from 20% to15%, the inlet pressure of the shell-side fluid increases from 2. 66 Pa to 26 Pa, and the fluids pressure drop increases from 26 Pa to 38 Pa, whichaccordance with the general law that the fluid'spressure drop increases with the decrease of theFig. 11 Temperature distribution of the shell-side fluidbaffle segmental degree. The pressure at the bafflein cross section where x= with the bafflesegmental degree of 15%plate forward direction is higher than that at thedorsal side of the baffles4 ConclusionsFig 11 shows temperature distribution of theThe 3D numerical simulation on flow and heatshell-side fluid in cross section where x=0 with transfer oof the shell-side fluid in high pressurethe baffle segmental degree of 15%. Comparison multicomponent synthetic gas heat exchanger wasbetween Fig. 6 and Fig. 11 indicates that, with the conducted by adopting the porous medium modelbaffle segmental degree decreases from 20%distributed resistance and distributed heat source15%, the outlet temperature of the shell-side fluid relationships. The influence of the baffle segmentalchanges little. Decrease in baffle segmental degree degree on heat transfer performance was also in-has nearly no effect on heat transfer of the shell- vestigated. It could be concluded thatside fluid, but it can increase pressure drop of the(1)1中国煤化工 ned by aspenshell-side fluidsoftwareCNMHGransfer charachttp:/www.rlfd.comcnhttp:/rlfd.periodicalsnet.cns 10 #y LI Yan et al Numerical simulation on heat transfer enhancement in shell side of multi-component synthetic gas heat exchangerteristicschanger tube inner rotation direction self-cross rotor(2)Temperature distribution of the shell-side[J]. Journal of Engineering for Thermal Energy andfluid in clean synthetic gas superheater which wasPower,2012,27(3):307-311simulated by the porous medium model was similar[6] HE Yaling, LEI Yonggang, TIAN Liting, et al. An analysis of three-field synergy on heat transfer augerto that designed by the ASPEN software, demontation with low penalty of pressure drop[]. Journal ofstrating that the porous medium model can be usedEngineering Thermophysics, 2009, 30(11): 1904-to simulate the flow and heat transfer of the shell-1906side fluid in clean synthetic gas superheat[7] Dong Q W, Liu M S, Zhao X D. Research on the char-(3)For the given operation conditions and paacteristic of shellside support structures of heat ex-rameters in this study, the pressure drop of thchanger with longitudinal flow of shellside fluid[J].shell-side fluid increased when decreasing the baf-IASME Transactions, 2005,8(2): 1491-1498tal degree[8] WU Jinxing, DONG Qiwu, LIU Minshan, et al. Numer-ical simulation on the turbulent flow and heat transferReferencesin the shell side of the rod baffle heat exchanger[J][1] JIANG Zemin. Reflections on energy issues in ChinaJournal of Chemical Engineering of Chinese Universi[T. Journal of Shanghai Jiaotong University, 2008, 42ties,2006,20(2):213-216(3):345-359[9] Hilbert R, Janiga G, Baron R, et al. Multi-objective[2] JIAO Shujian Integrated gasification combined cycleshape optimization of a heat exchanger using parallel[MI. Beijing: China Electric Power Press, 1996(ingenetic algorithms [J]. International Journal of Heatand Mass Transfer, 2006, 49: 2567-25773] GU Xin, DONG Qiwu, LIU Minshan, et al. Numerical [10] LIU Wei, LIU Zhichun, WANG Shuangying, et alulation on heat transfer enhancement in shell sideStrengthening heat transfer research and spoiler mech-of shell-and-tube heat exchanger with leading typeanism in longitudinal bundles of tube-and-shell heatshutter baffles[ J]. Nuclear Power Engineering, 2010exchanger[J]. Science in China(Series E: Technologi31(2):113-117al sciences),2009,39(11):1850-1856[4] Zhang C, Xie G N, Luo L Q, et al. An experimental [11] XIA Xiangming, ZHAO Liwei, XU Hong, et al. Overallstudy of shell- and- tube heat exchanges with continu-performance factor for evaluating intensified heat conous helical baffles [J]. Technical Briefs, 2007, 129duction based on the fieldheory[J]. Jou1426-1431of Engineering for Thermal Energy and Power, 2011[5 ZHAO Benhua, HE Xuetao, YAN Hua, et al. Study of26(2):197-201the intensified heat transfer performance of a heat ex-上接第25页[8]吴金星,董其伍,刘敏珊,等.折流杆换热器壳程湍流和学,2009,39(11):1850-1856传热的数值模拟[].高校化学工程学报,2006,20(2)LIU Wei, LIU Zhichun, WANG Shuangying, et al.213-216Strengthening heat transfer research and spoiler mechWU Jinxing, DONG Qiwu, LIU Minshan, et al. Numer-anism in longitudinal bundles of tube-and-shell heat ex-ical simulation on the turbulent flow and heat transferhanger[J]. Science in China( Series E: Technologicalin the shell side of the rod baffle heat exchanger[J]Sciences),2009,39(11):1850-1856Journal of Chemical- ngineering of Chinese Universi-[11]夏翔鸣,赵力伟,徐宏,等.基于场协同理论的强化传热ties,2006,20(2)213-216综合性能评价因子[J].热能动力工程,2011,26(2)[9] Hilbert R, Janiga G, Baron R, et al. Multi-objective197-201shape optimization of a heat exchanger using parallXIA Xiangming, ZHAO Liwei, XU Hong, et al. Overallgenetic algorithms [J]. International Journal of Heatrformance factor for evaluating intensified heat con-and Mass Transfer, 2006, 49: 2567-2577duction based on the field synergy theory [J]. Journal[10]刘伟,刘志春,王英双,等.管壳式换热器纵流管束内的of Engineering for Thermal Energy and Power, 2011扰流机制与传热强化研究[J].中国科学E辑:技术科26(2):1中国煤化工CNMHGhttp∥www.rfdcom. cnhttp:l/rlfd.periodicalsnet.cn