【作者】 李涛；

【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， 2010， 博士

【摘要】 从1821年Seebeck首次发现热电现象,时至今日已经有近两百年的历史。然而热电现象被深入研究并展开应用的历史却并不长。第二次世界大战中,苏联学者Ioffe才正式开启了对热电学的全面应用研究。随着热电材料研究的快速发展,尤其是以半导体材料为代表的新型热电材料的出现,热电学应用发展开始蓬勃兴起。以美国探月和火星探测中使用的同位素发电器为代表,二十世纪六十年代热电学应用研究活动进入颠峰时期,此后热电学应用在转化效率方面的进步逐渐放缓,随后相关方面的各项研究活动显著下降并持续了近三十年。在最近的十来年间,热电研究的相关活动持续在增长。这可以主要归功于以下三方面的因素：一、全球变暖给地球带来的不良影响已日渐引起了人们对此问题的密切关注；二、对一种新的更持续的电力能源的需求,包括核燃料驱动产生的电能；三、集成电路和传感器日趋小型化。热电技术应用能够为满足以上三方面的需求做出一定贡献。在西方发达国家,热电热回收已经广泛应用于工业和汽车的废热回收发电,尽管发电效率不高,但通过利用废热而产生的经济性很高。随着中国城市化的不断深入,可持续发展的理念日渐深入人心,低品位的建筑废热能的回收利用也开始兴起。热电学起源于与热电转换有关的主要四个基本效应,塞贝克效应、帕尔贴效应、汤姆逊效应和傅立叶效应。塞贝克效应是热能转换为电能的现象。帕尔贴效应则主要表征为电能向热能的转化现象。四个基本效应直接影响热电发电和热电制冷中的热电转换。热电转换过程的本质是固体中载流子和声子的输运及其相互作用。材料的热电性能的高低主要取决于塞贝克系数、电导率和热导率三个参量。因此,弄清这三个参量的物理本质并加以定量描述,对于寻找热电性能高的材料或作材料工程设计以提高热电特性的研究,有着重要的指导意义。中国经过三十年的改革开放,人民生活水平不断提高,家用空调开始被广泛应用,随之而来的空调电力能耗也日益攀升。2003年SARS爆发后,空调房间的新风供应对空气品质的改善作用被普遍重视。新风供应而造成的空调负荷增加,必将加重空调电力能耗的负担。本论文研究的创新性和创新成果有以下五个方面：(1)基于热电效应的制冷、制热同时产生的特点,并结合空调房间排风的热回收需求,成功的构想出一款利用热电制冷、制热效应,既能处理新风又能实现对空调房间的排风热回收的热电新风机,并申请国家发明专利,目前已获得发明专利授权。(2)本研究中将热电新风机定位在家用开发方向。这款家用新风机的风量和新风被处理后的热舒适参数被系统分析确定,结合了室内空气品质分析,空调房间新风量需求,空调房间热舒适设计指标及国家相关节能设计要求。家用新风机的新风、排风的进出口布置和新风机在房间中的安放位置也通过优化设计确定。(3)为强化热电新风机工作效能,新风机工作模块采用一组板翅式换热器和一组热电模块换热器组合而成。对板翅式换热器和热电模块换热器分别进行了相应的传热分析,构建相应的数学模型,通过计算分析为相关器件进行参数选型。通过多个样机模型的实验对比,确定板翅式换热器和热电模块换热器均采用菱形结构的优化设计方案。(4)在现有家用热电新风机设计风量和工作电压范围下,通过多组风量和工作电压的组合实验对比,分别确定了新风机工作参数在冬季和夏季的最佳工作参数组合。冬季和夏季的实验中,新风机的功效比都在2.5以上,新风被处理的热舒适性基本满足空调房间热舒适要求。(5)热电热回收烘干机的研究进一步深入,由单一注重烘干加热能效,深化到同时注重对减少烘干排气的热湿污染。热回收型热电烘干机分别设计了开放式烘干、封闭式烘干、改进型封闭式烘干三种不同形式的实验。开放式侧重提高烘干加热能效兼顾水蒸气冷凝收集,烘干机加热效率比电热烘干机提高20%以上。后两种类型注重水蒸气全面冷凝收集,烘干排气湿污染零排放,烘干加热效率提高10%以上根据不同烘干形式的特点,分析指出了其相适应的应用形式。更多还原

【Abstract】 It had been about 200 years, since 1821 Seebeck effect was found by Seebeck. The history of application of thermoelectric effects had been not too long. The technology of thermoelectricity began during the "Great Patriot War" when the Soviet Union, under Academician Ioffe’s inspiration, produced thermoelectric generators to be included in a mess kit and capable of powering a small radio from a small cooking fire. Spurred by major advances in semiconductor technology, discovery of more efficient thermoelectric semiconductor alloys, and advances in thermoelectric theory, the 1950s and 1960s witnessed significant efforts to further develop thermoelectric technology. Notable were the radioisotope thermoelectric generators providing critical power for NASA missions on the moon and on Mars and for spectacular successful outer-planetary exploration missions such as VoyagerⅠandⅡ. Despite successful use of radioisotope thermoelectric generators, basic thermoelectric science continued to decline. Following decades, scientific progress, publications, and meeting activity declined.During the recent decade, activities in thermoelectircs had increased substantially. This was primarily due to three major factors:increasing awareness of the deleterious effect of global warming on the planet’s environment, a renewed requirement for long-life electrical power source, including nuclear fueled, and the increasing miniaturization of electronic circuits and sensors. Thermoelectrics was able to make a contribution to meeting the requirements of all three activities.Substantial progress had been made in employing thermoelectrics as an environmentally friendly method of recovering industrial and automobile waste heat, the development of high-performance functionally graded and segmented thermoelements for power source applications, and in the fabrication of reliable thin-film generating, cooling, and sensing devices in the developed countries. China is during its peak period of urbanization now. Substantial development concept had been accepted by more and more people in China. Recovery of waste heat from buildings has been paid more attention now.Thermoelectrics was founded by four basic effects, Seebeck effect, Peltier effect, Thomson effect, and Kelvin effect. Seebeck effect was about energy conversion from heat to electricity. Peltier effect was about energy conversion from electricity to heat. Above four basic effects could be important factors to thermoelectric application. Thermoelectricity was based on the solid carriers and phonon’s delivering and interaction. Thermoelectric materials’merit of figure was defined by Seebeck coefficient, thermal conductivity, and electrical conductivity. Clearing the relationship of three coefficients contributed to the high performance thermoelectric materials.Chinese people’s living condition have been improved greatly, since China’s reforms and opening up from 1978. Domestic air-conditioners have been used in more and more ordinary families now. Power consumption of domestic air-conditioners had been a big burden for power supply, especially in summer and winter. Further more, power consumption of air-conditioner caused by heat load of fresh air supply couldn’t be neglected. Especially, it was proved that sufficient fresh air supply could be an efficient method to prevent SARS outbreak.The innovations and originalities of this dissertation had been are included as following:(1) A prototype of thermoelectric ventilator with heat recovery from exhaust of air-conditioned room had been invented successfully. This ventilator could be used to ventilate and improve the thermal comfort of fresh air. Protection of patent for this ventilator had been authorized.(2) As an original invention, all the coefficients of this ventilator had been studied and defined. Volume of ventilation was the basic coefficient for thermoelectric ventilator. Based on occupants’ health requirement of fresh air supply, volume of ventilation was defined in some scale. Following government policy of energy saving, final coefficient of volume was followed central authority’s energy saving requirement for fresh air supply of air conditioned room.Thermal comfort of fresh air had been paid attention for its effect to occupants. Energy saving and comfort were considered together here. In order to meet these two goals, final thermal comfort coefficient of fresh air had been defined by central authority’s energy saving requirement for thermal comfort coefficient of air-conditioned room.As a domestic application, Chinese families’small apartments had been considered also. In order to use this ventilator easily, this ventilator had been designed to be compact enough.Ventilator’s fixing and its’inlet and outlet distribution had been all considered in order to realize efficient organized ventilation. (3) A cross flow flat-fin heat exchanger had been originally combined with a thermoelectric heat exchanger as the major function part of this thermoelectric ventilator. Based on the heat transfer theory, two heat exchangers had been studied and their heat transfer models had been constructed respectively.In order to transfer the original concept of this thermoelectric ventilator to be a real prototype, several real ventilator models had been produced to be tested. Ventilator’s structure had been optimized through models producing. Optimized performance and structure coefficients of ventilator had been collected through whole test.(4) In order to find the best running coefficient of this prototype, ventilator had been tested its performance in summer and winter, respectively. Through different volumes and thermoelectric power input combined, comparing prototype’s heating(cooling) power, coefficient of power, temperature difference of fresh air, optimized running coefficient of this prototype had been set. The test result showed the prototype’s coefficient of power could be above 2.5.As an original thermoelectric ventilator with heat recovery, its performance had been compared with traditional ventilator with heat recovery. This ventilator’s cost return model had been built and its outlook had been made too. Further improvement of this ventilator had been suggested in this study.(5) A thermoelectric dryer with heat recovery had been studied. Its study had been based on the thermoelectric heat-pump dryer and expanded to focus on heat recovery in order to decrease vapor pollution of dryer exhaust. This thermoelectric dryer with heat recovery had been investigated on three different work modes, opening mode, closed mode, improving closed mode. Through different thermoelectric power input and volume combined, the relationship between dryer’s coefficient of power and its running coefficient was found. All three work modes could be used to decrease vapor pollution of dryer exhaust. Opening mode’s COP could be advanced traditional dryer 20% to 30%. Under closed mode, vapor pollution of dryer exhaust could be declined to zero with COP value about 1.8. All three work modes’proper application had been suggested in the study.更多还原