防护热板法高温导热系数测定仪关键技术研究

发布时间：2018-05-09 18:54

本文选题：导热系数 + 防护热板法　；参考：《天津大学》2016年硕士论文

【摘要】：导热系数是衡量隔热材料热物性的重要参数之一,隔热材料导热系数的准确获取与航空航天、建筑节能等领域的研究和发展紧密相关。防护热板法是测量隔热材料导热系数最精确的方法,目前国内基于此方法的导热系数测定仪测量温度范围在常温附近,高温需求明显,因此实验室相继研制了第一代和第二代高温导热系数测定仪。第一代高温导热系数测定仪实现了测量功能,第二代高温导热系数测定仪在第一代的基础上对机械结构的一些不足进行了改善,提出了基于不同厚度的标定方法,但对测试栈体的温度分布和各构件的相互影响认识不足,温度控制精度有待提高、测量效率仍然较低。对这些问题涉及的关键技术进行研究具有重要的意义。本课题在第二代高温导热系数测定仪的基础上,通过有限元ANSYS软件对测试栈体的温度分布和构件布局对温度的影响进行仿真分析,从而优化机械结构;设计温度采集模块和多热电偶校准炉,实现温度的准确控制和校准;提出了基于动态周期识别的系统稳定状态判断方法,实现测量效率的提高。本文完成的主要工作有:1.介绍导热系数基本概念和主要测试方法,然后阐述了防护热板法导热仪的国内外发展现状和趋势,指出了基于防护热板高温导热系数测定仪的关键技术和实验室第二代样机的优缺点,最后说明了本课题的研究目的和内容。2.介绍傅里叶一维传热定律和导热系数计算公式,然后介绍防护热板法测量原理,最后是机械结构的设计,并对测试栈体整体温度分布、外护板对热场的影响进行了仿真分析和机械优化。3.设计了仪器的温度采集模块,包括方案选型、冷端补偿、模拟前端设计、AD采样电路、通信接口和软件设计,以及温度采集实验。4.多热电偶校准炉设计,包括对多热电偶插孔均温块、加热丝和钣金的机械设计,E5CC温控和加热电路设计,热电偶标定实验。5.仪器快速测量方法研究,介绍卡尔曼滤波理论和算法,以及基于卡尔曼滤波的PID温度控制;描述了基于动态周期识别的系统稳态判断方法,最后是人机交互软件设计和测量实验。6.结论与展望,对论文的主要结论进行总结,并指出尚存问题,以明确后期努力方向。
[Abstract]:Thermal conductivity is one of the important parameters to measure the thermal properties of thermal insulation materials. The accurate acquisition of thermal conductivity of thermal insulation materials is closely related to the research and development of aerospace, building energy conservation and other fields. The thermal plate method is the most accurate method to measure the thermal conductivity of heat insulating materials. At present, the temperature range of the thermal conductivity measuring instrument based on this method is near normal temperature, and the demand for high temperature is obvious. Therefore, the first generation and the second generation of high temperature thermal conductivity measurement instrument have been developed in the laboratory. The first generation high temperature thermal conductivity measuring instrument has realized the measuring function, the second generation high temperature thermal conductivity measuring instrument has improved some shortcomings of the mechanical structure on the basis of the first generation, and has proposed the calibration method based on different thickness. However, the temperature distribution of the test stack and the interaction of each component are not well understood, the precision of temperature control needs to be improved, and the measuring efficiency is still low. It is of great significance to study the key technologies involved in these problems. On the basis of the second generation high temperature thermal conductivity measuring instrument, this paper simulates and analyzes the temperature distribution of the test stack and the influence of the component layout on the temperature by finite element ANSYS software, so as to optimize the mechanical structure. The temperature acquisition module and multi-thermocouple calibration furnace are designed to realize the accurate temperature control and calibration, and a method for judging the stable state of the system based on dynamic cycle identification is proposed to improve the measuring efficiency. The main work accomplished in this paper is 1: 1. This paper introduces the basic concept and main testing methods of thermal conductivity, and then expounds the present situation and trend of the thermal conductivity instrument of the protective hot plate method at home and abroad. This paper points out the key technology of the high temperature thermal conductivity measuring instrument based on the protective hot plate and the advantages and disadvantages of the second generation prototype of the laboratory. Finally, the purpose and content of the research are described. This paper introduces Fourier's one-dimensional heat transfer law and calculation formula of thermal conductivity, then introduces the measuring principle of protective hot plate method, and finally, the design of mechanical structure, and the whole temperature distribution of the test stack. The influence of outer shield on thermal field is simulated and optimized. 3. 3. The temperature acquisition module of the instrument is designed, including scheme selection, cold end compensation, analog front-end design, AD sampling circuit, communication interface and software design, and temperature acquisition experiment .4. The design of multi-thermocouple calibration furnace includes the mechanical design of multi-thermocouple Jack, heating wire and sheet metal, the design of E5CC temperature control and heating circuit, and the thermocouple calibration experiment .5. This paper introduces the theory and algorithm of Kalman filter and PID temperature control based on Kalman filter, describes the method of system steady-state judgment based on dynamic period recognition. Finally, the human-computer interaction software design and measurement experiment. 6. Conclusion and prospect, the main conclusions of the paper are summarized, and the remaining problems are pointed out in order to clarify the direction of the later efforts.
【学位授予单位】：天津大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TH81

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