汽车尾气温差发电装置热应力分析及优化
|
摘要
自汽车诞生至今,汽乍技术经历了一个世纪的发展,汽车新技术正在向节能环保方向快速发展。当前研发汽车新技术都要在车辆的经济环保方面予以考虑,汽车燃油消耗和排放性能是国际汽车市场竞争的重要指标。在车用发动机节能环保技术登峰造极的背景下,研发新型车载节能技术可进一步提高车辆节能性能。汽车尾气温差发电技术是一项新型车载能量回收技术,该技术通过温差发电装置将尾气中的部分废热转换为电能。国内相应的研究刚刚起步,本文通过对温差发电装置构造和工作环境的研究,提出了对该装置进行热应力分析的课题。
本文主要研究温差发电装置的热应力分布,研究方法是对温差发电装置的有限元模型进行CAE分析。先使用Hypermesh对装置的几何模型进行前处理,完成几何模型离散之后,使用Fluent计算出的气箱壁面温度和恒定的水箱壁面温度作为边界条件计算出离散模型的温度场。再将计算出的温度场和装置的约束作为边界条件施加到热应力计算模型上,使用ANSYS计算出离散模型的热应力分布。计算结果表明,在施加约束处有较为明显的应力集中点,最大应力值达到320MPa。其中X方向的分应力最小,但水箱应力值较大；Y向分应力值很均匀；Z向分应力有明显的应力集中,且应力梯度很大。固定横梁的位置影响了水箱表面的应力分布,固定横梁在安装螺栓处有应力集中点。热电模块阵列边缘有明显的应力集中点。
针对装置的热应力分布提出消除气箱应力集中区域的优化目标。分析了约束对温差发电装置热应力的影响,约束模型中部一个节点的六个自由度,在相同的边界条件下计算出了模型的热应力分布。计算表明约束优化明显的消除了应力集中,模型综合应力和各向压应力值都有显著下降,拉应力只在X向有较小增加。为消除气箱棱边的应力集中区域将气箱的原棱边结构改为圆角过渡,在相同的壁面温度和约束下计算应力场。分析结果表明,优化后气箱的综合应力值、X向分应力和Y向分应力的最大值减小都较小,但Z向分应力减小了36.1MPa,基本消除了气箱的应力集中区域。另外,合理的选择箱体材料也可以减小装置的热应力。
本文采用温差发电装置能承受的最高温度作为应力计算的温度载荷,得出装置的最大稳态热应力分布,提出的热应力优化方案优化效果显著。研究表明装置不合理的安装固定会带来严重的热应力集中问题。
The vehicle industry has already developed for a century since the first car of the world has been made, and the new vehicle technology keep developing and promoting in the environmental and economical field. Now, the new technology applying to vehicles must consider the fuel consumption and air pollution. The most important norms in the international automobile market will be the energy saving and environment protecting. Therefore, in the era of the vehicle engine has the best perfonnance in energy saving, studying new board methods to make full use of the burning chemical energy could further improve vehicle energy-saving performance. Thermoelectric generator (TEG) is a new method which could turn west heat into electric power based on the material property. Domestic research on TEG technology just staring while overseas has been studied for years. After a study of the TEG device operation environment and the structure, I have put forward the analysis the thermal stress distribution on the TEG device.
This paper mainly studies the thermal stress on the TEG set. The main content is calculating the stress field with the CAE software. The preliminary CAE treatment is handled by hyermesh, a very useful engineering software, extract the middle plane and discrete the model with finite elements, use the cooling water tank and air channel's wall temperature provide by Fluent computed result as the boundary condition to compute the temperature distribution of the finite element model. Then set the temperature computed result and constraint conduction to the finite element model, analysis the thermal stress distribution by ANSYS. The thermal stress distribution result indicates a few stress concentration areas on the of the air channel, where the constraints have been set, and the X direction stress sharing has a uniform distribution with a smaller value, but the air channel get a bigger sharing. Y direction stress sharing has a smaller stress, obvious stress concentration areas with grate gradient in Z stress sharing. The fixing beams changed the stress distribute of the water tank surface, and several stress concentration points in the bolt position of the beam surface. Many stress concentration points on the boundary of thermoelectric module array.
Through rationalization analysis, put forward an optimization objective decreasing the max stress on the air channel surface. In order to achieve the target, limit the nodes's six degrees of freedom which locate on the middle of air channel. Keep other boundary all the s(?)me as the original model and calculate the thermal stress field. The stress concentration area show up around those limit nodes in the original model all has gone, the max stresses value have been decreased, as well as sharing of Y direction and Z direction. Only X direction sharing have increased a several MPa. In order to eliminating the stress concentration areas on the air channel surface, change the sharp edge to a round transition structure, calculate the thermal stress distribute with the same temperature and constraint condition. Max value of thermal stress and X direction share and Y direction share did not have changed much, but Z direction stress share decreased36.1MPa, therefore the optimization right on their target. In addition, reasonable selection of material also can reduce the thermal stress of the device.
Applying the maximum temperature which the device could bearing as boundary condition, and obtain the extreme stress value on steady state. Geometry optimization got remarkable result. Research shows that devices unreasonable installation can bring serious thermal stress concentration problems.
本文主要研究温差发电装置的热应力分布,研究方法是对温差发电装置的有限元模型进行CAE分析。先使用Hypermesh对装置的几何模型进行前处理,完成几何模型离散之后,使用Fluent计算出的气箱壁面温度和恒定的水箱壁面温度作为边界条件计算出离散模型的温度场。再将计算出的温度场和装置的约束作为边界条件施加到热应力计算模型上,使用ANSYS计算出离散模型的热应力分布。计算结果表明,在施加约束处有较为明显的应力集中点,最大应力值达到320MPa。其中X方向的分应力最小,但水箱应力值较大；Y向分应力值很均匀；Z向分应力有明显的应力集中,且应力梯度很大。固定横梁的位置影响了水箱表面的应力分布,固定横梁在安装螺栓处有应力集中点。热电模块阵列边缘有明显的应力集中点。
针对装置的热应力分布提出消除气箱应力集中区域的优化目标。分析了约束对温差发电装置热应力的影响,约束模型中部一个节点的六个自由度,在相同的边界条件下计算出了模型的热应力分布。计算表明约束优化明显的消除了应力集中,模型综合应力和各向压应力值都有显著下降,拉应力只在X向有较小增加。为消除气箱棱边的应力集中区域将气箱的原棱边结构改为圆角过渡,在相同的壁面温度和约束下计算应力场。分析结果表明,优化后气箱的综合应力值、X向分应力和Y向分应力的最大值减小都较小,但Z向分应力减小了36.1MPa,基本消除了气箱的应力集中区域。另外,合理的选择箱体材料也可以减小装置的热应力。
本文采用温差发电装置能承受的最高温度作为应力计算的温度载荷,得出装置的最大稳态热应力分布,提出的热应力优化方案优化效果显著。研究表明装置不合理的安装固定会带来严重的热应力集中问题。
The vehicle industry has already developed for a century since the first car of the world has been made, and the new vehicle technology keep developing and promoting in the environmental and economical field. Now, the new technology applying to vehicles must consider the fuel consumption and air pollution. The most important norms in the international automobile market will be the energy saving and environment protecting. Therefore, in the era of the vehicle engine has the best perfonnance in energy saving, studying new board methods to make full use of the burning chemical energy could further improve vehicle energy-saving performance. Thermoelectric generator (TEG) is a new method which could turn west heat into electric power based on the material property. Domestic research on TEG technology just staring while overseas has been studied for years. After a study of the TEG device operation environment and the structure, I have put forward the analysis the thermal stress distribution on the TEG device.
This paper mainly studies the thermal stress on the TEG set. The main content is calculating the stress field with the CAE software. The preliminary CAE treatment is handled by hyermesh, a very useful engineering software, extract the middle plane and discrete the model with finite elements, use the cooling water tank and air channel's wall temperature provide by Fluent computed result as the boundary condition to compute the temperature distribution of the finite element model. Then set the temperature computed result and constraint conduction to the finite element model, analysis the thermal stress distribution by ANSYS. The thermal stress distribution result indicates a few stress concentration areas on the of the air channel, where the constraints have been set, and the X direction stress sharing has a uniform distribution with a smaller value, but the air channel get a bigger sharing. Y direction stress sharing has a smaller stress, obvious stress concentration areas with grate gradient in Z stress sharing. The fixing beams changed the stress distribute of the water tank surface, and several stress concentration points in the bolt position of the beam surface. Many stress concentration points on the boundary of thermoelectric module array.
Through rationalization analysis, put forward an optimization objective decreasing the max stress on the air channel surface. In order to achieve the target, limit the nodes's six degrees of freedom which locate on the middle of air channel. Keep other boundary all the s(?)me as the original model and calculate the thermal stress field. The stress concentration area show up around those limit nodes in the original model all has gone, the max stresses value have been decreased, as well as sharing of Y direction and Z direction. Only X direction sharing have increased a several MPa. In order to eliminating the stress concentration areas on the air channel surface, change the sharp edge to a round transition structure, calculate the thermal stress distribute with the same temperature and constraint condition. Max value of thermal stress and X direction share and Y direction share did not have changed much, but Z direction stress share decreased36.1MPa, therefore the optimization right on their target. In addition, reasonable selection of material also can reduce the thermal stress of the device.
Applying the maximum temperature which the device could bearing as boundary condition, and obtain the extreme stress value on steady state. Geometry optimization got remarkable result. Research shows that devices unreasonable installation can bring serious thermal stress concentration problems.
引文
[1]张雄.轻型车燃油经济性及其道路测试研究[D].武汉：武汉理工大学,2007.
[2]新华网.欧盟委员会对汽车尾气排放提出新的强制便准.2007,02.http://news.qq.com/a/20070211/001370.htm
[3]鄂勇,宋国利,鄂光琪.机动车与环境[J].机动车与环境,2007,12(30).
[4]刘成.二甲醚均质压燃烧的实验和模拟研究[D].武汉：武汉理工大学.2007.
[5]史玉茜.绿色环保汽车-太阳能汽车[J].节能技术,2009,1(1).
[6]朱则刚.太阳能在汽车上的应用[J].汽车工程技术应用,2009,(4)55-56.
[7]凌凯.太阳能在汽车上的应用初探[J].节能减排及新能源汽车技术论坛,2009,115-119.
[8]袁庆强.新型混合动力轿乍动力匹配及控制策略的研究[D].武汉：武汉理工大学.2007.
[9]一种电动汽车用制动能量回收控制器的设计[J].电器传动,2011,5(41)42-46.
[10]张圆圆.汽车车体振动能量回收装置的几个关键技术问题的研究[D].天津：河北工业大学.2009.
[11]J. LaGrandeur, D. Crane, S. Hung,et al. Automotive Waste Heat Conversion to Electric Power using Skutterudite, TAGS, PbTe and BiTe[J].Visteon Corporation, BMW Technology Office,[S.1.]
[12]Douglas T. Crane, Lon E.Bell. Design to Maximize Performance of a Thermoelectric Power Generator With a Dynamic Thermal Power Source[J].MARCH,,2009,131.
[13]周子鹏.半导体温差发电装置的研制[D].天津：河北工业大学.2008.
[14]郭殉,邓亚东,苏楚奇,等.汽车排气废热温差发电技术研究[J].节能减排及新能源汽车技术论坛,[2009],120-124.
[15]Sales.B.C,Mandrus.D,Williams.R.K. et al. Fille skutterudite antimonides:a new class of thermoelectric materials[J].science, 1996.
[16]J.Yang.Potential Applications of Thermoelectric Waste Heat Recovery in the Automotive Industry[J].Clemson University,U.S.A:IEEE,154-160.
[17]李义.半导体热电模块热分析与优化设计[D].上海：同济大学.2008.
[18]Robert F. Temperature Rises for Devices That Turn Heat Into Electricity [J]. Science,2004,Oct29.
[19]Tritt, TM.Thermoelectric Phenomena, Materials, and Applications[J].Annual Review of Materials Research,2011 (41),432-448.
[20]Lon E.Bell.Cooling,Heating,Generating Power,and Recovering Waste Heat With Thermoelectric Systems[J].Science,2008,321(TN.5895).
[21]Kushch AS,BassJC,GhamatyS, et al. Thermoelectric Development at Hi-Z Technology[J]. TWENTIETH INTERNATIONAL CONFERENCE ON THERMOELECTRICS, PROCEED INGS.2001,422-430.
[22]张征,曾美琴,司广树.温差发电技术及其在汽车发动机排气余热利用中的应用[J].能源技术,2004,3(25)120-123.
[23]N.ESPINOSA, M.LAZARD, L.AIXALA. Modeling a Thermoelectric Generator Applied to Diesel Automotive Heat Recovery [J].Electronic materials,2010,9(39).
[24]Quazi Hussain, David Brigham, Clay Maranville. A Model Based Approach to Exhaust Heat Recovery using Heat Recovery Using Thremoelectrics[J]. Research & Advanced Engineering Ford Motor CoMPany.[S.1.]
[25]李影.基于汽车尾气余热回收的温差发电研究[D].成都：电子科技大学.2010.
[26]于广,黄维军,余流,张征.车用内置式温差发电器换热性能的数值模拟[J].节能技术,2008,5(26)：436-442.
[27]屈健,李茂,德乐伟,林泉.半导体温差发电器的工作性能优化[J].低温工程,2005(2)：20-23.
[28]郑文波,王禹,吴知非,黄志勇,周世新.温差发电器热电性能测试平台的搭建[J].实验技术与管理,2006,11(23)：62-65.
[29]凌凯.基于汽车尾气废热温差发电的42V动力系统建模与仿真[D].武汉：武汉理工大学,2011.
[30]K.M.Saqr,M.K.Mansour,M.N.Musa.Thermal Design of Automobile Exhaust Based Thermoelectric Generators:Objectives and Challenges [J]. International Journal of Automotive Technology,2008,2(9)154-160.
[31]杨双亮,张红,许辉.车用温差发电装置换热性能的数值模拟研究[J].制冷技术,211,5(39)47-52.
[32]杨凤.汽轮机转子的热应力分析和疲劳寿命研究[D].沈阳：沈阳工业大学.2007.
[33]陈弦,杨杰,蒲健,等.平板式SOFC结构热应力的有限元分析[J]1无机材料学,2007.2(22)339-343.
[34]刘占生,顾卫东,朱自明,等.超临界汽轮机高压缸有限元热应力分析[J].汽轮机技术,2002.1(44)23-25.
[35]郭运强.某型发动机火焰筒非均匀温度场下热应力分析[D].西安：西北工业大学,2004.
[36]Bin zhao. Thermal stress analysis of ceramic-coated diesel engine pistons based on the wavelet finite-element method [J]. Journal of engine mechanics.2012,143-149.
[37]王翔宇.某大型柴油机消声器结构热应力和内部流动研究[D].哈尔滨：哈尔滨工程大学,2009.
[38]夏凯.汽车发动机废弃余热温差发电装置结构优化设计[D].武汉：武汉理工大学,2010.
[39]郭殉.汽车排气废热发电系统与发动机消声器一体化研究[D].武汉：武汉理工大学,2010.
[40]赵镇南.传热学[M].北京：高等教育出版社,2002.
[41]于秋红.热工基础[M].北京：北京出版社,2009.
[42]严宗达,王洪礼.热应力[M].1991.
[43]刘志恩.汽油机缸盖不稳定传热三维有限元分析[D].武汉：华中科技大学,2003.
[44]丁厚福,王立人.工程材料[M].武汉：武汉理工大学出版社,2001.
[45]李金龙.汽车排气系统结构强度及焊接疲劳分析[D].武汉：武汉理工大学,2001.
[46]于开平,周传月,谭惠丰,等Hypermesh从入门到精通[M].北京：科学出版社,2005：82-140.
[47]小飒工作室编.最经典的ANSYS及Workbench教程[M].北京：电子工业出版社,2004：479-525.
[48]刘涛,杨凤鹏主编.精通ANSYS[M]北京清华大学学研大厦：清华出版社,2002：344-368.
[49]李庆龄ANSYS中网格划分方法研究[J].上海机电学院学报,2006,5(9)28-30.
[2]新华网.欧盟委员会对汽车尾气排放提出新的强制便准.2007,02.http://news.qq.com/a/20070211/001370.htm
[3]鄂勇,宋国利,鄂光琪.机动车与环境[J].机动车与环境,2007,12(30).
[4]刘成.二甲醚均质压燃烧的实验和模拟研究[D].武汉：武汉理工大学.2007.
[5]史玉茜.绿色环保汽车-太阳能汽车[J].节能技术,2009,1(1).
[6]朱则刚.太阳能在汽车上的应用[J].汽车工程技术应用,2009,(4)55-56.
[7]凌凯.太阳能在汽车上的应用初探[J].节能减排及新能源汽车技术论坛,2009,115-119.
[8]袁庆强.新型混合动力轿乍动力匹配及控制策略的研究[D].武汉：武汉理工大学.2007.
[9]一种电动汽车用制动能量回收控制器的设计[J].电器传动,2011,5(41)42-46.
[10]张圆圆.汽车车体振动能量回收装置的几个关键技术问题的研究[D].天津：河北工业大学.2009.
[11]J. LaGrandeur, D. Crane, S. Hung,et al. Automotive Waste Heat Conversion to Electric Power using Skutterudite, TAGS, PbTe and BiTe[J].Visteon Corporation, BMW Technology Office,[S.1.]
[12]Douglas T. Crane, Lon E.Bell. Design to Maximize Performance of a Thermoelectric Power Generator With a Dynamic Thermal Power Source[J].MARCH,,2009,131.
[13]周子鹏.半导体温差发电装置的研制[D].天津：河北工业大学.2008.
[14]郭殉,邓亚东,苏楚奇,等.汽车排气废热温差发电技术研究[J].节能减排及新能源汽车技术论坛,[2009],120-124.
[15]Sales.B.C,Mandrus.D,Williams.R.K. et al. Fille skutterudite antimonides:a new class of thermoelectric materials[J].science, 1996.
[16]J.Yang.Potential Applications of Thermoelectric Waste Heat Recovery in the Automotive Industry[J].Clemson University,U.S.A:IEEE,154-160.
[17]李义.半导体热电模块热分析与优化设计[D].上海：同济大学.2008.
[18]Robert F. Temperature Rises for Devices That Turn Heat Into Electricity [J]. Science,2004,Oct29.
[19]Tritt, TM.Thermoelectric Phenomena, Materials, and Applications[J].Annual Review of Materials Research,2011 (41),432-448.
[20]Lon E.Bell.Cooling,Heating,Generating Power,and Recovering Waste Heat With Thermoelectric Systems[J].Science,2008,321(TN.5895).
[21]Kushch AS,BassJC,GhamatyS, et al. Thermoelectric Development at Hi-Z Technology[J]. TWENTIETH INTERNATIONAL CONFERENCE ON THERMOELECTRICS, PROCEED INGS.2001,422-430.
[22]张征,曾美琴,司广树.温差发电技术及其在汽车发动机排气余热利用中的应用[J].能源技术,2004,3(25)120-123.
[23]N.ESPINOSA, M.LAZARD, L.AIXALA. Modeling a Thermoelectric Generator Applied to Diesel Automotive Heat Recovery [J].Electronic materials,2010,9(39).
[24]Quazi Hussain, David Brigham, Clay Maranville. A Model Based Approach to Exhaust Heat Recovery using Heat Recovery Using Thremoelectrics[J]. Research & Advanced Engineering Ford Motor CoMPany.[S.1.]
[25]李影.基于汽车尾气余热回收的温差发电研究[D].成都：电子科技大学.2010.
[26]于广,黄维军,余流,张征.车用内置式温差发电器换热性能的数值模拟[J].节能技术,2008,5(26)：436-442.
[27]屈健,李茂,德乐伟,林泉.半导体温差发电器的工作性能优化[J].低温工程,2005(2)：20-23.
[28]郑文波,王禹,吴知非,黄志勇,周世新.温差发电器热电性能测试平台的搭建[J].实验技术与管理,2006,11(23)：62-65.
[29]凌凯.基于汽车尾气废热温差发电的42V动力系统建模与仿真[D].武汉：武汉理工大学,2011.
[30]K.M.Saqr,M.K.Mansour,M.N.Musa.Thermal Design of Automobile Exhaust Based Thermoelectric Generators:Objectives and Challenges [J]. International Journal of Automotive Technology,2008,2(9)154-160.
[31]杨双亮,张红,许辉.车用温差发电装置换热性能的数值模拟研究[J].制冷技术,211,5(39)47-52.
[32]杨凤.汽轮机转子的热应力分析和疲劳寿命研究[D].沈阳：沈阳工业大学.2007.
[33]陈弦,杨杰,蒲健,等.平板式SOFC结构热应力的有限元分析[J]1无机材料学,2007.2(22)339-343.
[34]刘占生,顾卫东,朱自明,等.超临界汽轮机高压缸有限元热应力分析[J].汽轮机技术,2002.1(44)23-25.
[35]郭运强.某型发动机火焰筒非均匀温度场下热应力分析[D].西安：西北工业大学,2004.
[36]Bin zhao. Thermal stress analysis of ceramic-coated diesel engine pistons based on the wavelet finite-element method [J]. Journal of engine mechanics.2012,143-149.
[37]王翔宇.某大型柴油机消声器结构热应力和内部流动研究[D].哈尔滨：哈尔滨工程大学,2009.
[38]夏凯.汽车发动机废弃余热温差发电装置结构优化设计[D].武汉：武汉理工大学,2010.
[39]郭殉.汽车排气废热发电系统与发动机消声器一体化研究[D].武汉：武汉理工大学,2010.
[40]赵镇南.传热学[M].北京：高等教育出版社,2002.
[41]于秋红.热工基础[M].北京：北京出版社,2009.
[42]严宗达,王洪礼.热应力[M].1991.
[43]刘志恩.汽油机缸盖不稳定传热三维有限元分析[D].武汉：华中科技大学,2003.
[44]丁厚福,王立人.工程材料[M].武汉：武汉理工大学出版社,2001.
[45]李金龙.汽车排气系统结构强度及焊接疲劳分析[D].武汉：武汉理工大学,2001.
[46]于开平,周传月,谭惠丰,等Hypermesh从入门到精通[M].北京：科学出版社,2005：82-140.
[47]小飒工作室编.最经典的ANSYS及Workbench教程[M].北京：电子工业出版社,2004：479-525.
[48]刘涛,杨凤鹏主编.精通ANSYS[M]北京清华大学学研大厦：清华出版社,2002：344-368.
[49]李庆龄ANSYS中网格划分方法研究[J].上海机电学院学报,2006,5(9)28-30.