导热系数

A theoretical model is built to investigate the simulation of the infrared characteristic of the metal structure with the PCM false target.Structure parameters of the PCM false target that suit for the simulation are investigated numerically.According to the results,further request on the improvement of the thermal conductivity of PCM is presented.An experimental platform is built and the numerical model is validated experimentally.Three key thermal characteristic components of the false tank(barbette,wheel and front armor plate) are manufactured and tested,and good results are obtained.A method for the thermal conductivity enhancing of PCM by using aluminum fins is studied,the influence of the structure parameters of PCM plates to the simulation effects are investigated numerically,and the reasonable configuration parameters of the PCM plates used to simulate the steel plates of different thickness are obtained.In the study of the application of heat convection method in IR false target,a passive infrared simulation system is designed to simulate the infrared characteristic of metal constructions.The system is made up of pipe-plate,pump,receiver,and working fluid.

在相变材料应用于红外示假的研究中，通过数值模拟，研究确定了适用于制作假目标的相变材料各物性参数的范围，分析了相变材料制作假目标的可行性，并根据所得结果，选取石蜡为研究对象，建立了相变材料模拟金属构件红外特征的理论模型，研究了适用于模拟各金属构件红外特征的相变材料假目标的相关结构参数，得出了相变材料假目标模拟各金属构件红外特征的理论结果，并对相变材料的导热系数这一物性提出了进一步的改进要求；搭建了假目标实验平台，验证了所建理论模型的准确性；以坦克假目标为研究对象，制作了炮塔、负重轮和前上装甲板三个坦克假目标的关键红外热特征部件，并进行了野外实验，取得了较好的结果；以添加铝肋片作为改进相变材料导热能力的手段，理论研究了此类导热增强型相变材料的相关结构参数对模拟效果的影响，得出了模拟不同厚度钢板红外特征的导热增强型相变材料的结构参数及模拟效果。

Aluminum nitrate enneahydrate and barium hydroxide octahydrate are considered as potential phase change materials for energy storage.

用热敏电阻作加热元件和测温元件，首次测定了适合用作相变储能材料的九水合硝酸铝、八水合氢氧化钡导热系数的测定在10℃~80℃温度范围的导热系数，其实验值的不准确度分别为2.8%和3.2%。

The uncertainties of the measured thermal conductivities were estimated to be ?.8% for aluminum nitrate enneahydrate and 3.2% for barium hydroxide octahydrate, respectively.

导热系数是物质的基本物理性质之一，在储能材料研究领域的理论计算、实用储能设备的设计以及相关材料的传热学研究中，都是必不可少的热物理数据，测定导热系数具有很重要的理论和实际意义。

Taking a carborundum brick of which the thermal conduction coefficient was given as specimen, the measuring error of it is less than 8%.

通过测量已知导热系数的碳化硅砖的导热系数，得其误差小于8%；通过对同一试样的两个小试样进行平行测量，得其相对偏差小于3%。

In this paper, a high-pressure apparatus for measuring thermal conductivity was developed based on the present transient single hot-wire device of our group.

然而它们的导热系数的研究还相当欠缺，尤其是二甲氧基甲烷及其与柴油混合物的导热系数研究基本上没有人做过。

A computer data acquisition and treating system was used in the hot-wire heat transfer device to measure thermal conductivity of nonmetallic materials.

根据目前应用的热线导热仪存在的问题，提出将计算机数据采集与处理系统应用到热线导热仪上测量非金属材料的导热系数，提高导热仪的测试精度和再现性。

This article analyses the application conditions of freezing method, current research status and the problems in thisiold. It, points that it" s necessary to study deep freezing temperature field deeply and discusses the factors which influence the freezing wall such as soil" s nature, moisture content, geological conditions, etc. It introduces the theory, process of freezing method, the distribution of temperature field of freezing method and key thermotics parameters influencing freezing temperature field, it simplifies the deep freezing temperature field model. Through ANSYS, this article founds the deep freezing temperature field model, and simulates the field on vary heat conductivities. It analyzes the results of ANSYS simulation, gains the theoretical value of thermometric holes which is needed by back analysis. Using the simulation temperature and actual value, it gets the equivalent heat conductivity. Then it solves the deep freezing temperature field by the equivalent value, simulates the freezing wall development process and temperature change curve. Against the actual project, the results are favorable.

文中分析了冻结法施工的应用条件，目前对冻结法施工的研究现状和在此领域内存在的问题，指出了对深土冻结温度场进行深入研究分析的必要性；对影响冻结壁形成发展的因素如冻土土性、含水量、地质条件及施工方法等因素进行了论述；对冻结法施工的原理、过程，冻结法温度场的分布情况，影响冻结温度场分布的主要热学参数进行了综述；对深土冻土温度场模型进行了合理的简化，通过ANSYS大型有限元分析软件，建立了深土冻结温度场的模型，对不同导热系数情况下的深土冻结温度场进行了模拟；对ANSYS的模拟结果进行了定性的分析，通过对ANSYS结果的后处理取得了反分析时需要用到的测温孔理论温度值；经过对测温孔模拟温度值和实测温度值的分析，得到了冻结温度场的等效导热系数；使用等效导热系数对深土冻结温度场进行了求解，模拟了冻结壁发展情况和温度场中的温度变化曲线，用所得结果对比工程实际情况，取得了较好的效果。

The calculative results show that the efficient thermal conductivity rises as temperature rises under a constant fiber volume fraction, and it is proportional to the third power of absolute temperature; it decreases as fiber volume fraction increases under high temperature; it increases as fiber volume fraction increases under low temperature, and it is in agreement with that is described in the literature.

此式计算结果表明：在纤维体积分率一定时，其有效导热系数随温度的升高而升高，且它是绝对温度的三次方关系；在高温条件下，其有效导热系数随纤维体积分率的升高而四川大学硕土学位论文有减少趋势；在低温条件下，其有效导热系数随纤维体积分率的增大而增大，与所查文献描述规律一致。

A method using a tiny thermistor as heat transfer model was developed to measure thermophysical properties (thermal conductivity and thermal diffusivity) of three standand samples(ethanol, ethylene alcohol, solution of calcium chloride). Results showed that there was no significant difference between measurement and recommendation; results of thermal conductivity from thermistor method and heat probe method for carrot and potato samples showed no significant difference; results of thermal diffusivity between thermistor method and calculation for carrot and potato samples showed no significant difference.

在分析微珠状热敏电阻传热模型的基础上，在室温对标准样品（乙二醇、乙醇、氯化钙的水溶液）的热物性进行测定，结果显示，导热系数及热扩散系数的测量值与推荐值之间无显著性差异（p＞0.05）；热敏电阻法与热探针法对比测定胡萝卜及马铃薯两种农产品的导热系数，结果显示两种方法之间无显著性差异（p＞0.05）；热敏电阻法与常规计算对比测定胡萝卜及马铃薯两种农产品的热扩散系数，结果显示两种方法之间无显著性差异（p＞0.05）。

The main is focused on the discussion on the crystal structure, porosity, temperature profiles, thermal conductivity, salinity and density of sea ice in Liaodong Bay based on the author's research on ice temperature profile in field, thermal conductivity coefficients in field and in laboratory, and the ice structures studied under the computerized tomography scanner.

重点以作者完成的海冰现场温度场、现场冰层导热系数和实验室导热系数以及应用正交偏光和CT扫描研究冰组构等研究成果为主体，讨论了辽东湾海冰的晶体结构、孔隙率、温度场和导热系数、盐度、密度等工程海冰指标。

Breath, muscle contraction of the buttocks; arch body, as far as possible to hold his head, right leg straight towards the ceiling (peg-leg knee in order to avoid muscle tension).

呼气，收缩臀部肌肉；拱起身体，尽量抬起头来，右腿伸直朝向天花板（膝微屈，以避免肌肉紧张）。

The cost of moving grain food products was unchanged from May, but year over year are up 8%.

粮食产品的运输费用与5月份相比没有变化，但却比去年同期高8％。