共线式热电发电机在侧面散热情况下的性能
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摘要
热电材料是一种环境友好型功能材料,其可以实现热能与电能的相互转化,在热电发电、热电制冷中具有许多应用.传统的热电发电机为π型结构,要求热电腿的长度相等,在某些情况该结构不利于热电发电机的优化设计.热电发电机在高温工况下会引起强烈的热应力甚至应力集中,从而缩短了其工作寿命.另外,热电发电机的工作温度于环境温度,这样必然会有一部分热量散失到环境中,从而影响热电发电机的性能.针对该现象,本文建立了考虑散热的新型共线式热电发电机模型,该模型的热电腿可以独立进行优化,基于有限元方法,对考虑侧面散热的共线式热电发电机进行了仿真模拟,分析了其在狄利克雷边界条件下的热电性能和力学性能,得到了热电发电机的温度场、电势场、应力场,探究了不同强度的对流散热系数对热电发电机热电性能和力学性能的影响.结果表明,对流散热会降低热电发电机的能量转化效率,当对流换热系数达到100 W/(m~2·°C)时,效率为0.047 9,该值比绝热状态的转化效率0.066 7低28%.对流散热使热电发电机侧面热损失增加,降低了热应力.在实际应用中,应合理优化设计隔热系统,提高能量的转化效率.
Thermoelectric material is an environment-friendly function material, which can convert energy between heat and electricity. And it holds extensive application potentiality in power generation and refrigeration. The traditional thermoelectric generator is a π-type structure, which requires the length of the thermoelectric legs to be equal. In some cases,the structure is not conducive to the optimal design of the thermoelectric generator. Intense thermal stress and even stress concentration will be induced in the thermoelectric generator due to high-temperature working condition, leading to shortening its working life. In addition, since the operating temperature of the thermoelectric generator is higher than ambient temperature, part of the heat will inevitably be dissipated to the environment, which will affect the thermoelectric performance and mechanical performance of the thermoelectric generator. Therefore, the heat dissipation cannot be neglected when analyzing this kind of problem. For these phenomena, in this work, a novel collinear-type thermoelectric generator model is proposed considering the heat dissipation in the side surface. And the legs of the proposed thermoelectric modelcan be optimized independently. Then, based on the finite element method, performance of collinear thermoelectric generator considering the heat dissipation in the side surface is simulated. And the thermoelectric performance and mechanical performance under the Dirichlet boundary condition is analyzed. Simultaneously, the temperature field, electric potential field and stress field in the thermoelectric generator are obtained. The influence of various convective heat transfer coefficient on thermoelectric performance and mechanical performance of the thermoelectric generator is investigated. The results demonstrate that thermal convection can decrease the energy conversion efficiency of the thermoelectric generator.When the convective heat transfer coefficient reaches 100 W/(m~2·°C), the efficiency is 0.047 9 which is 28% lower than the conversion efficiency of 0.066 7 in adiabatic state. Though heat loss from the side surface is increased due to heat convection, thermal stress is reduced. In practical application, proper design and improvement of the thermal insulation system should be carried out to improve the efficiency of energy conversion.
Thermoelectric material is an environment-friendly function material, which can convert energy between heat and electricity. And it holds extensive application potentiality in power generation and refrigeration. The traditional thermoelectric generator is a π-type structure, which requires the length of the thermoelectric legs to be equal. In some cases,the structure is not conducive to the optimal design of the thermoelectric generator. Intense thermal stress and even stress concentration will be induced in the thermoelectric generator due to high-temperature working condition, leading to shortening its working life. In addition, since the operating temperature of the thermoelectric generator is higher than ambient temperature, part of the heat will inevitably be dissipated to the environment, which will affect the thermoelectric performance and mechanical performance of the thermoelectric generator. Therefore, the heat dissipation cannot be neglected when analyzing this kind of problem. For these phenomena, in this work, a novel collinear-type thermoelectric generator model is proposed considering the heat dissipation in the side surface. And the legs of the proposed thermoelectric modelcan be optimized independently. Then, based on the finite element method, performance of collinear thermoelectric generator considering the heat dissipation in the side surface is simulated. And the thermoelectric performance and mechanical performance under the Dirichlet boundary condition is analyzed. Simultaneously, the temperature field, electric potential field and stress field in the thermoelectric generator are obtained. The influence of various convective heat transfer coefficient on thermoelectric performance and mechanical performance of the thermoelectric generator is investigated. The results demonstrate that thermal convection can decrease the energy conversion efficiency of the thermoelectric generator.When the convective heat transfer coefficient reaches 100 W/(m~2·°C), the efficiency is 0.047 9 which is 28% lower than the conversion efficiency of 0.066 7 in adiabatic state. Though heat loss from the side surface is increased due to heat convection, thermal stress is reduced. In practical application, proper design and improvement of the thermal insulation system should be carried out to improve the efficiency of energy conversion.
引文
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2 Chen G.Theoretical efficiency of solar thermoelectric energy generators.Journal of Applied Physics,2011,109(10):773-778
3贾磊,陈则韶,胡芃等.导体温差发电器件的热力学分析.中国科学技术大学学报,2004,34(6):684-687(Jia Lei,Chen Zeshao,Hu Peng,et al.Thermodynamic analysis of semiconductor thermoelectric generator.Journal of University of Science and Technology of China,2004,34(6):684-687(in Chinese))
4 Hadjistassou C,Kyriakides E,Georgiou J.Designing high efficiency segmented thermoelectric generators.Energy Conversion and Management,2013,66:165-172
5 Kim S.Analysis and modeling of effective temperature differences and electrical parameters of thermoelectric generators.Applied Energy,2013,102(2):1458-1463
6贾阳,任德鹏.温差发电器中热电材料物性的影响分析.电源技术,2008,32(4):252-256(Jia Yang,Ren Depeng.Effect analysis for physics characteristic of thermo-electric materials in thermo-electric generator.Journal of Power Sources,2008,32(4):252-256(in Chinese))
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10 Liu ZC,Zhu SP,Ge Y,et al.Geometry optimization of twostage thermoelectric generators using simplified conjugate-gradient method.Applied Energy,2017,190:540-552
11 Ali H,Sahin AZ,Yilbas BS.Thermodynamic analysis of a thermoelectric power generator in relation to geometric configuration device pins.Energy Conversion and Management,2014,78:634-640
12 Al-Merbati AS,Yilbas BS,Sahin AZ.Thermodynamics and thermal stress analysis of thermoelectric power generator:Influence of pin geometry on device performance.Applied Thermal Engineering,2013,50:683-692
13 Sahin AZ,Yilbas BS.The thermoelement as thermoelectric power generator:Effect of leg geometry on the efficiency and power generation.Energy Conversion Management,2013,65:26-32
14 Kim H S,Itoh T,Iida T,et al.Design of linear shaped thermoelectric generator and self-integration using shape memory alloy.Materials Science and Engineering:B,2014,183(1):61-68
15 Jia XD,Gao YW.Optimal design of a novel thermoelectric generator with linear-shaped structure under different operating temperature conditions.Applied Thermal Engineering,2015,78:533-542
16 Jia XD,Wang YJ,Gao YW.Numerical simulation of thermoelectric performance of linear-shaped thermoelectric generators under transient heat supply.Energy,2017,130:276-285
17 Yilbas BS,Akhtar SS,Sahin AZ.Thermal and stress analyses in thermoelectric generator with tapered and rectangular pin configurations.Energy,2016,114:52-63
18王长宏,李娜,林涛等.半导体P-N型温差发电器件热电性能研究.功能材料,2016,47(12):12147-12151(Wang Changhong,Li Na,Lin Tao,et al.Research on thermoelectric properties of semiconductor P-N type thermoelectric power generation device.Functional Materials,2016,47(12):12147-12151(in Chinese))
19张克实,黄世鸿,刘贵龙等.纯铜后继屈服面的测试与晶体塑性模型模拟.力学学报,2017,49(4):870-879(Zhang Keshi,Huang Shihong,Liu Guilong,et al.Measuring subsequent yield surface of pure copper by crystal plasticity simulation.Chinese Journal of Theoretical and Applied Mechanics,2017,49(4):870-879(in Chinese))
20 Drink E,Martin J,Markus B,et al.Multiphysics simulation of thermoelectric systems for comparison with experimental device performance.Journal of Electronic Materials,2009,38(7):1456-146
21龙凯,王选,韩丹.基于多相材料的稳态热传导结构轻量化设计.力学学报,2017,49(2):359-366(Long Kai,Wang Xuan,Han Dan.Structural light design for steady heat conduction using multimaterial.Chinese Journal of Theoretical and Applied Mechanics,2017,49(2):359-366(in Chinese))
22章鹏,杜成斌,江守燕.比例边界有限元法求解裂纹面接触问题.力学学报,2017,49(6):1335-1347(Zhang Peng,Du Chengbin,Jiang Shouyan.Crack face contact problem analysis using the scaled boundary finite element method.Chinese Journal of Theoretical and Applied Mechanics,2017,49(6):1335-1347(in Chinese)
2 Chen G.Theoretical efficiency of solar thermoelectric energy generators.Journal of Applied Physics,2011,109(10):773-778
3贾磊,陈则韶,胡芃等.导体温差发电器件的热力学分析.中国科学技术大学学报,2004,34(6):684-687(Jia Lei,Chen Zeshao,Hu Peng,et al.Thermodynamic analysis of semiconductor thermoelectric generator.Journal of University of Science and Technology of China,2004,34(6):684-687(in Chinese))
4 Hadjistassou C,Kyriakides E,Georgiou J.Designing high efficiency segmented thermoelectric generators.Energy Conversion and Management,2013,66:165-172
5 Kim S.Analysis and modeling of effective temperature differences and electrical parameters of thermoelectric generators.Applied Energy,2013,102(2):1458-1463
6贾阳,任德鹏.温差发电器中热电材料物性的影响分析.电源技术,2008,32(4):252-256(Jia Yang,Ren Depeng.Effect analysis for physics characteristic of thermo-electric materials in thermo-electric generator.Journal of Power Sources,2008,32(4):252-256(in Chinese))
7 Ju CJ,Dui GS,Zheng H,et al.Revisiting the temperature dependence in material performance and performance of thermoelectric materials.Energy,2017,124:249-257
8 Wang BL.A finite element computational scheme for transient and nonlinear coupling thermoelectric fields and the associated thermal stresses in thermoelectric materials.Applied Thermal Engineering,2017,110:136-143
9杜群贵,邹杰慧,陈水金等.半导体热电转换单元发电性能的变物性计算模型.华南理工大学学报,2013,41(4):47-53(Du Qungui,Zou Jiehui,Chen Jinshui,et al.Calculation model of semiconductor thermoelectric generator unit based on variable material properties.Joumal of South China University of Technology,2013,41(4):47-53(in Chinese))
10 Liu ZC,Zhu SP,Ge Y,et al.Geometry optimization of twostage thermoelectric generators using simplified conjugate-gradient method.Applied Energy,2017,190:540-552
11 Ali H,Sahin AZ,Yilbas BS.Thermodynamic analysis of a thermoelectric power generator in relation to geometric configuration device pins.Energy Conversion and Management,2014,78:634-640
12 Al-Merbati AS,Yilbas BS,Sahin AZ.Thermodynamics and thermal stress analysis of thermoelectric power generator:Influence of pin geometry on device performance.Applied Thermal Engineering,2013,50:683-692
13 Sahin AZ,Yilbas BS.The thermoelement as thermoelectric power generator:Effect of leg geometry on the efficiency and power generation.Energy Conversion Management,2013,65:26-32
14 Kim H S,Itoh T,Iida T,et al.Design of linear shaped thermoelectric generator and self-integration using shape memory alloy.Materials Science and Engineering:B,2014,183(1):61-68
15 Jia XD,Gao YW.Optimal design of a novel thermoelectric generator with linear-shaped structure under different operating temperature conditions.Applied Thermal Engineering,2015,78:533-542
16 Jia XD,Wang YJ,Gao YW.Numerical simulation of thermoelectric performance of linear-shaped thermoelectric generators under transient heat supply.Energy,2017,130:276-285
17 Yilbas BS,Akhtar SS,Sahin AZ.Thermal and stress analyses in thermoelectric generator with tapered and rectangular pin configurations.Energy,2016,114:52-63
18王长宏,李娜,林涛等.半导体P-N型温差发电器件热电性能研究.功能材料,2016,47(12):12147-12151(Wang Changhong,Li Na,Lin Tao,et al.Research on thermoelectric properties of semiconductor P-N type thermoelectric power generation device.Functional Materials,2016,47(12):12147-12151(in Chinese))
19张克实,黄世鸿,刘贵龙等.纯铜后继屈服面的测试与晶体塑性模型模拟.力学学报,2017,49(4):870-879(Zhang Keshi,Huang Shihong,Liu Guilong,et al.Measuring subsequent yield surface of pure copper by crystal plasticity simulation.Chinese Journal of Theoretical and Applied Mechanics,2017,49(4):870-879(in Chinese))
20 Drink E,Martin J,Markus B,et al.Multiphysics simulation of thermoelectric systems for comparison with experimental device performance.Journal of Electronic Materials,2009,38(7):1456-146
21龙凯,王选,韩丹.基于多相材料的稳态热传导结构轻量化设计.力学学报,2017,49(2):359-366(Long Kai,Wang Xuan,Han Dan.Structural light design for steady heat conduction using multimaterial.Chinese Journal of Theoretical and Applied Mechanics,2017,49(2):359-366(in Chinese))
22章鹏,杜成斌,江守燕.比例边界有限元法求解裂纹面接触问题.力学学报,2017,49(6):1335-1347(Zhang Peng,Du Chengbin,Jiang Shouyan.Crack face contact problem analysis using the scaled boundary finite element method.Chinese Journal of Theoretical and Applied Mechanics,2017,49(6):1335-1347(in Chinese)