【作者】 郝丽宏；

【导师】 林凌；

【作者基本信息】 天津大学 ， 精密仪器及机械， 2004， 硕士

【摘要】 导热系数表征着物质导热能力的大小，是衡量材料热物理性质的重要参数之一，对于材料的使用具有重要指导意义。导热系数的测量方法以及仪器装置也在不断的发展和完善。其中，广为采用的保护热板法基于傅里叶一维稳态导热原理测量材料的导热系数，具有量程广、无需在测试前进行系统标定等优点。然而， 现有基于保护热板法测量材料导热系数的仪器还存在着智能化程度不高、功能单一、测量精度有待于进一步提高等问题。因此本课题研制了一种新型双平板式导热系数测定仪，可以对建筑材料为代表的隔热材料进行热阻、导热系数的高精度测量。仪器由双平板装置（炉体）和智能测控系统两部分组成，前者从结构上保证实现保护热板法要求的一维稳态导热，后者主要实现以下功能：提供人机对话界面、信号采集与处理、过程控制、参数计算。智能测控系统的设计是本文论述的主要内容，其中的测控模块的设计对导热系数的测量精度起关键作用，也是决定整机性能的关键，其工作包括：运用控制算法控制加热器、制冷器，使系统快速、稳定、准确地进入一维稳态导热，利用高精度的测量电路进行温度、功率信号的精确测量，计算得到精确的导热系数。本文从测量原理、总体设计、通用微处理器模块设计、测控模块设计、系统评估实验几方面对仪器的装置结构、硬件电路、程序设计、控制算法等逐一进行了阐述，分析了现场调试中可能存在的问题。本论文工作的突出之处主要表现在三个方面。第一，高度智能化设计使仪器不但界面友好，而且在使用功能上有所扩展：不但可以测量特定温度差和平均温度下的导热系数，而且可以测量某一温度范围内固定温差下的多个算术平均温度点的导热系数，在上述测量结束时还可以选择测量材料的热扩散特性；第二，在测控系统的电路设计上体现了“器件解决”思想，在提高测量精度的同时又大大简化了测量电路；最后，控制算法方面运用了基本PID控制与模糊控制相结合的控制算法，达到了较高的控制精度和速度，而且对于类似问题的解决具有借鉴意义。更多还原

【Abstract】 Thermal conductivity, as one of material’s thermal parameters, indicates the material’s capability of heat conduction. The measurement of thermal conductivity contributes much to new material development as well as proper use of materials, and therefore, has been a field of progressing. Double guarded hot plate apparatus has been widely used for its wide measurement range and non-demarcating, which is based on Fourier’s law of heat conduction for one dimensional steady state temperature field. At present, however, the instruments have still much to be desired, such as higher measurement precision, better performance, more flexible functions, etc. A new kind of thermal conductivity measurement instrument is, therefore, developed, which can be used to measure the thermal conductivity and the thermal resistance of heat insulation material in steady conduction state.The whole instrument is made up of double guarded hot plate apparatus (stove) and the intelligent measuring-controlling system. The former provides the conditions for heat conduction in one dimensional steady state temperature field; the latter mainly realize the following functions: man-machine interaction, signal sampling and processing, procedure control and parameter calculation. The performance of the measuring-controlling system is the key point to the whole instrument’s function realization, and its design & evaluation forms main parts of this thesis. The intelligent measuring-controlling system takes on the power-controls of the heaters and thermoelectric coolers, temperature-measurements, and calculations of the thermal conductivity and the thermal resistance.Introduced and discussed mainly in this thesis includes: the measurement principle, the whole instrument’s design, the microcontroller design, the measurement and control module design and the system evaluating experiments, and the potential problems in field debugging. The apparatus structure, detailed circuits, programs, control arithmetic can also be found in this thesis.The outstanding point lies in following three aspects: the first, the highly intelligent design not only makes the man-machine-interaction friendly but also expands its functions. The second, use of highly integrate circuit chip makes the measuring circuits simpler and improves the measurement precision. Finally, as to the control arithmetic, PID and fuzzy control are colligated to improve the control precision and speed, which is helpful for solving the similar problems.更多还原