【作者】 罗清海；

【导师】 汤广发；

【作者基本信息】 湖南大学 ， 供热、供燃气、通风及空调工程， 2005， 博士

【摘要】 以节能紧迫性和环保的迫切性为背景,由于电子、生物、医药等领域对温度精确控制的需求推动,以及新材料和其它相关技术的渗透和促进,为热电制冷应用提供了新的发展机遇和动力,应用领域不断向广度和深度拓展。但热电制冷技术的研究目前主要集中于高性能热电制冷材料、制冷模块结构优化的研究上,而系统优化研究相对而言显得很欠缺,制约着热电制冷技术的应用发展。论文通过深入系统的文献研究,考察了近40年来,特别是近10年来热电制冷应用技术的应用与发展现状。论文对理想热电制冷循环进行了热力分析,理想热电制冷循环是指不考虑外部传热热阻的外可逆内不可逆循环。论文对热电制冷与机械压缩制冷进行了循环机理比较,二者能流载体(电子和制冷剂)在循环的基本物理过程和相应的能级变化规律上表现出可类比性。论文对热电制冷、磁制冷、吸附制冷等环境友好制冷技术作了工作原理、热力学特性、技术适用性以及发展现状等方面的深入比较,热电制冷比磁制冷、吸附制冷技术更成熟,适用更广泛,更具有竞争力。论文对实际热电制冷系统进行了热力学优化分析计算,建立了无量纲稳态系统热力学模型。并用该模型分析了优值系数、热媒温度、电流、传热热阻等参数变化对系统性能影响,以及各性能参数之间的相互制约关系。对系统能量转化、热量传递各环节的不可逆性进行了分析。论文分析了实际热电制冷系统与压缩式制冷系统在热力学特性上的定性规律一致性,热电制冷系统中有限速率热交换、焦耳热和傅立叶热分别可与机械压缩制冷系统中的不可逆传热、摩擦损失和热漏损失相类比。理论分析得出的一系列结论对于指导实际热电制冷系统的优化设计,提高性能具有重要的准则意义。建立了以水为热媒的热电制冷/热泵实验系统。探索了强化各环节传热,提高系统性能的实践途径,计算分析了冷、热侧传热面积的匹配对系统性能的影响。实验内容包括:(1)改变热媒流量; (2)改变电流大小和方向; (3)改变热媒温差; (4)改变热媒相对流向。对一种新型分体式平板型热虹吸装置进行了实验研究:包括热虹吸装置的结构形式的选择、热虹吸工质的选择、最佳充液率的确定、热传递特性等,为热电制冷系统的传热强化提供了新的技术途径。分析建筑热水能耗,探讨热水器的未来发展方向,开发了水泵循环热回收和分体热虹吸热回收两种新型热电热泵快热式热水器的样机,并作了节能性分析。开发了一种新型热电热泵烘干装置,并进行了实验研究。更多还原

【Abstract】 The development of thermoelectric (TE) refrigeration meets many new opportunities, such as pressing environment pollution and energy conservation, accurately controlling temperatures in the following fields: electronics, biology, medicine and so on, and integration of new material and other correlating technology, An increasing number and variety of promising TE products have been reported for specific applications in military, instrument, medicine and other fields. Former investigations are mostly in the development of high quality TE materials and modules, while works on the optimization of TE refrigerating systems were scarce. In this dissertation, the progresses of TE refrigerators in the past 40 years were firstly reviewed, and the recent advance in the past 10 years were especially stressed. The thermodynamic characteristics were analyzed for an ideal TE refrigerator, which is externally reversible and internally irreversible. The physical mechanisms were compared between TE refrigerators and mechanical refrigerators. Their circulation of energy carriers (electrons or refrigerants) and corresponding energy levels present comparability although their circulating patterns differ considerably. Three eco-friendly refrigeration systems: TE refrigeration, magnetic refrigeration and adsorption refrigeration were compared in the aspects of principles, thermodynamics, practicability and developments. It is found that TE refrigeration is the most well-developed, applicable and competitive technology. In this dissertation, a dimensionless thermodynamic model of TE refrigerating system was founded for steady running conditions, and its performances were analyzed by numerical calculations for different varying parameters including merit figure, temperatures of heat mediums, electrical currents and heat resistances. The correlations between above parameters were also discussed. The various irreversibility, such as Joule heat, Fourier loss and finite heat transfer, were analyzed for real TE thermodynamic cycles and energy conversion. The consistency of thermodynamic characteristics was analyzed between TE refrigerators and mechanical refrigerators. The irreversible losses of a TE refrigerating system represent the typical losses of general two-source refrigerating system. Its finite heat transfer, Joule heat and Fourier heat are respectively corresponding to the irreversible heat transfer, friction loss and heat leak of compressing refrigerating system. The conclusions are of great significance for optimizing real TE refrigerating systems. A TE refrigerating experimental system was founded in TE laboratory of Hunan University; it utilized water as heat mediums. The optimum allocation of heat transfer surface and measures intensifying heat transfer were discussed and quested for high performances. Experiments were performed with varying parameters as following: (1) flow-rates of heat mediums; (2) electrical currents; (3) temperatures of heat mediums; (4) directions of heat mediums. A panel-type separating thermo-siphon was originally developed. It offers a new approach for heat transfer intensification of TE refrigerating systems. Experiments were performed on structure type, working medium, optimum filling-rate and characteristics of heat transferring. The situations of energy consumption were analyzed for hot water in different buildings. Two novel TE heat-pump instantaneous waters and a novel TE heat-pump clothing dryer were originally developed and investigated in the TE laboratory. The originalities of the dissertation are mainly in the following: (1) Two new concepts, the permissive temperature ratio and the favorable working region, were presented as optimizing rules for TE refrigerating systems. It was pointed out that temperature ratio may better include the effect of temperatures on the performances of a TE refrigerating system than temperature difference. The optimum working point should be (εq)max, it is different from the conventional maximum points of refrigerating coefficient and capacity. (2) Another new concept, the performance pinnacle, was presented as a theoretic evidence for development of efficient TE refrigerating or heat-pump systems. (3) A panel-type separating thermo-siphon was originally developed. It offers a new approach for heat transfer intensification of TE systems. (4) Experiments offered datum reference for development of efficient TE refrigerating or heat-pump systems under near room-temperatures. The two novel water heater prototypes, compared to electrical water heaters, can reduce more than 40% or 38% of the power consumption. (5) A TE heat-pump clothing dryer was originally developed. In comparison with conventional electrical clothing dryers, it can reduce about 35% of the power consumption. As for application prospects, new materials and synthesis techniques have reawakened interest in the use of TE technology for CFCs will be prohibited as refrigerants in the whole world before long. It offers a constructive technological approach for developing distributed refrigerating or air-conditioning system inbuildings. It also offers new ideas for dispersed waste energy recovering and low-grade energy utilization. It was expected that TE cooling would be one of leading approaches of cooling electronic components. Since the merit figure of TE materials is unsatisfactory, the efforts of optimizing TE refrigerating systems should centralized on heat transfer intensification, and optimizing allocation between cold and hot sides. The system should run in the favorable working region, and the optimum working point should be (εq)max. In addition, energy recovering is of great significance to improve performance of a TE refrigerating systems.更多还原