【作者】 梁高卫；

【导师】 周孑民；

【作者基本信息】 中南大学 ， 动力工程及工程热物理， 2013， 博士

【摘要】 摘要：铝电解工业是能耗大户,2008年,我国电解铝总耗电量占全国电能消耗总量的5%左右,而且约一半的电能以余热方式直接散失。有效地利用铝电解余热是实现铝冶金工业节能的一个重要措施。温差发电技术利用半导体热电材料的热电效应,能够直接将热能转换为电能,具有结构简单、体积小、可靠性高、环保无污染等优点。在工业余热回收发电方面,由于传统的发电方式无法回收这部分能源,采用温差发电技术可有效地将工业余热转换为电能。本文将温差发电技术应用到铝电解槽侧壁的余热回收发电,根据铝电解槽侧壁散热孔的结构特点,设计并制作了温差发电装置,通过回收低品位电解散热达到减少余热排放的目的。本论文完成的主要研究工作和创新点如下：(1)建立了单个温差发电器的热电模型。该模型首次考虑了接触效应对温差发电器性能的影响,得出了温差发电器的电压、电流、输出功率和匹配负载的相关表达式。结果表明：接触电阻对输出功率的影响相当于增大了发电器的电源内阻；接触热阻是通过降低半导体热电偶对两端的温差来降低输出功率的；与通常的电路不同,温差发电器最大输出功率时的匹配负载并不等于发电器的总内阻。(2)通过理论分析和实验测试,研究了温差发电器串联连接和并联连接的性能。建立了温差发电器串联连接解析的模型和温差发电器并联的解析模型,得到了串联回路和并联回路的电压、电流、输出功率的近似表达式,并通过实验验证了这两个模型。研究表明：只有当回路中所有的热电模块具有相同的内在参数,且忽略接触热阻的影响时,温差发电器串联或并联回路与一般的直流电源具有相同的串联或并联性能。(3)通过理论分析和实验测试,研究了磁场对温差发电器输出性能的影响。从理论上说明磁场对温差发电器的输出性能影响很小；通过实验证明,磁电效应和热磁效应对碲化铋材料制成的温差发电器的开路性能、输出功率的影响可以忽略不计。(4)建立了温差发电器实验平台,该平台可以测试各种复杂工况下热电模块的性能。并利用实验平台,筛选出最适合在铝电解槽侧壁散热孔环境下工作的热电模块。(5)对铝电解槽侧壁余热温差发电技术进行了论证,设计并加工制作了余热发电装置,建立了余热发电系统,并在铝电解槽现场进行性能测试。结果表明：余热温差发电装置的温差能达到100℃,由18个发电装置组成的余热发电系统的输出功率为290W。本文的研究为铝电解余热利用提供了一个新的思路和方法,这种方法还可以推广到其他形式的工业余热回收应用中,具有较强的理论意义和实际应用价值。图78幅,表18个,参考文献190篇更多还原

【Abstract】 Abstract:The aluminum reduction industry is a large energy consumer. In2008, the total consumption of electrolytic aluminum is about5%of the all country current consumption, and about half of the energy dissipites from the cell to the surroundings and becomes waste heat. As a result, the effective utilization of the aluminum electrolysis waste heat is an important measure to energy saving in the aluminum metallurgical industry. Thermoelectric generation is a technology for directly converting thermal energy into electric energy by thermoelectric effect, it has no moving parts, and it is compact, quiet, highly reliable and environment friendly. In the field of industrial waste heat recovery, low temperature waste heat can not be recycled effectively by conventional methods, while thermoelectric generation can convert the low temperature waste heat into electric energy directly.In this paper, thermoelectric generation technology was applied to the waste heat recovery from aluminum reduction cell’s sidewalls. According to the structural characteristics of aluminum reduction cell’s shell, thermoelectric generators were designed and manufactured. The purpose of energy saving was achieved through the recovery of low-grade waste heat. The main contributions of this dissertation are summarized as follows:(1) Based on the actual physical structure and application, a numerical model of signal thermoelectric generator was established. The influence of contact effects was considered, and approximate expressions of output power, current and matched load were deduced by the model. The results indicate that the existence of contact electric resistance is just like the increase of the thermoelectric module’s internal resistance, which leads to the deceases of output power. The thermal contact resistance reduces the output power by reducing the temperature difference between the two sides of the thermocouples. The matched load of thermoelectric generator is not equal to the internal resistance unlike most circuit.(2) The performances of parallel thermoelectric generator and series thermoelectric generator were studied by theoretical analysis and experimental test. The analytical model of parallel thermoelectric generators and series thermoelectric generators were developed by theoretical analysis and calculation, and the two analytical models were verified by experimental test. The results indicate that only when all of the thermoelectric modules in the series or parallel thermoelectric generators have the same inherent parameters, and the influence of contact thermal resistance is ignored, the series or parallel properties of the thermoelectric generators are the same as that of common DC power.(3) The influence of the magnetic field on the output performance of thermoelectric generator was studied. It was theoretically explained that the influence of magnetic field on the output performance of thermoelectric generator is very little. To the thermoelectric generator made of bismuth telluride, it is proved by experiment test that the influence of magnetoelectric effect and thermomagnetic effects on the open circuit performance and output power of the thermoelectric generator is negligible.(4) An experimental platform was built, which can be used to test the performance of thermoelectric module in various complex cases. A thermoelectric module was selected, which is very suitable for working in the cooling holes of aluminum reduction cell.(5) The thermoelectric generators were designed and manufactured. A waste heat generating system was built, and the system was tested on the spot of aluminum reduction cell. The result shows that the temperature difference of thermoelectric generator can reach100℃, output power of the waste heat generating system made up of18thermoelectric generators is290W.The research of this dissertation provides a new idea and method of energy saving in aluminum electrolysis, the method can also be extended to the application of other industrial waste heat recovery, and it is of good significance both in theory and practice.更多还原