用并联模型法测定泡沫塑料的导热系数

稳态热流计法操作简单,广泛用于测量保温材料的导热系数。但由于仪器设备和方法的限制,难以测试异型材料的导热系数。分别采用并联模型法和直接测量法分析了挤塑聚苯乙烯泡沫、硬质聚氨酯泡沫、橡塑泡沫在平均温度10、15、25℃下的导热系数。结果表明:在不同平均温度和不同材料中,采用并联模型法所计算的导热系数与测试结果误差较小,说明并联模型法可用于不规则泡沫塑料导热系数的测试。     

陶瓷材料导热系数测量方法

导热系数是各种材料特别是陶瓷材料的一个重要参数，对于非金属材料，特别是陶瓷材料，由于比较复杂，至今还未能精确地进行计算，基本上仍须依靠直接的测量。本文对稳态法和非稳态法测量导热系数的较有代表性的方法进行介绍。由于激光脉冲法（闪光法）具有许多独特的优点，故作比较深入的讨论。     

侧面散热对导热系数测量的影响研究

稳态平板法测量导热系数因方法简单直接在测量材料的导热系数中广泛应用。但通过数值模拟和实验发现侧面散热对导热系数测量影响明显,采用大空间自然对流换热实验关联式对实验数据处理公式进行修正,在实验中得到较满意结果。利用数值模拟和实验对影响侧面散热的主要因素如环境温度、热源温度、样品厚度、试样导热系数进行研究,发现环境温度降低、热源温度增加、试样厚度的增加以及试样导热系数的减小,都会导致传热温差增加,侧面散热的绝对量和占总传热量的比例也随之增加。     

测定材料高温导热系数的非稳态热线法

本文介绍材料高温导热系数的新型测定方法——非稳态热线法的原理,并研究使用国产仪器实现这种方法。结果表明,与国外仪器测定结果比较,符合良好。自行设计的加热炉设备为全耐火纤维炉衬、升降式结构、具有快速升温优良性能的节能电炉。用Mittenbuhler热线方法测定了四种低导热材料(聚胺酯硬质泡沫塑料、加气混凝土、轻质耐火浇注料以及轻质粘土砖),并且探索了测定高导热材料的平行热线法,测定了镁砖的导热系数,结果是令人满意的。     

并联模型法测量不规则泡沫塑料导热系数

稳态热流计法是测量保温材料导热系数的常用方法之一,但由于方法和仪器设备的限制,难以测量不规则保温材料的导热系数。本文以硬质聚氨酯泡沫为研究对象,首先在不同平均温度下验证和分析了不同拼接方式下并联模型法与整体测试结果。为了验证并联模型的可靠性和可重复性,按模型对聚苯乙烯泡沫及聚氨酯泡沫试样重复测试,并对测试结果和计算结果进行比较,结果表明,利用并联模型法计算所得的导热系数值与实测值误差小,重复性好。     

轮胎胶料的导热系数测定及误差分析

采用稳态法测量轿车轮胎和航空轮胎各部位胶料在不同温度下的导热系数。测量结果表明,轿车轮胎在20~80℃、航空轮胎在20~110℃范围内,轮胎各部位胶料的导热系数与温度呈线性关系;轿车轮胎胎侧胶导热系数较大,胎面基部胶导热系数较小,航空轮胎胎侧胶导热系数较大,胎面胶导热系数较小。试验时采取使设备和试样充分干燥、以石棉做绝热材料、保持冰端温度等措施,可使试验误差小于4%。     

纤维导热性能的研究

本文采用稳态双平板法,对几种不同纤维材料的导热系数进行测定,研究它们在不同温度下导热系数规律,同时也讨论了不同的纤维与空气的体积对比导热系数的影响。结果表明：纤维导热系数随着温度的上升,纤维与窃据的体积比的增大也会导致纤维导热系数的增加。     

串联模型热流计法测薄层泡沫塑料导热系数

稳态热流计法因方法简单,广泛应用于测量保温材料的导热系数。但因仪器设备和方法的限制,难以测试薄层材料的导热系数。本文分别以聚苯乙烯泡沫和硬质聚氨酯泡沫为研究对象,首先在不同平均温度下测试不同厚度聚苯乙烯材料的导热系数,再利用串联模型法推导计算多层材料的导热系数。为了验证串联模型的可靠性和可重复性,按模型对聚苯乙烯泡沫及聚氨酯泡沫试样重复测试,并对测试结果和计算结果进行比较,结果表明,利用串联模型法计算所得的导热系数值与实测值误差小,重复性好。     

发射药导热系数测定的影响因素

利用热流法导热系数测定仪测量了不同实验条件下双基发射药的导热系数。分析了试样高度、真空度及硝化甘油含量对测量结果的影响。结果表明,发射药试样的高度较低时,或测试过程中的真空度越高,导热系数测定值较接近其真空值。硝化甘油含量对发射药的导热系数有明显影响。     

双热流计法测定聚氨酯保温材料的导热系数

简要介绍了几种测定固体材料导热系数的方法,重点讨论了稳态双热流计法测定聚氨酯保温材料导热系数的方法原理、导热仪的结构、影响测试结果的因素,并对提高检测结果的准确性、减少误差提出了建议。     

The thermal conductivity of oils sands

Measurements have been made of the effective thermal conductivity of some samples of Athabasca oil sands using a steady state method over the temperature range 20°C – 120°C. The bitumen content of the samples was altered from its natural value by mixing with additional sand and the resulting values of the thermal conductivity were found to increase with increasing the oil content. Moreover, the effective thermal conductivity values were found to decrease with increasing temperature.     

环柱状催化剂内强放热复合反应──传质──传热耦合过程研究(Ⅰ)催化剂曲折因子、有效导热系数的测定

采用经典定态法和改进的单颗粒线反应器法（SPSRM)测定了环柱状环氧乙烷银催化剂的曲折因子,两种方法测定结果十分吻合。提出一种测定固体催化剂颗粒有效导热系数的新方法。该方法简单、方便且不改变催化剂原有的形状及物理结构,可以在催化剂允许使用的任何温度下进行测定,准确度较高。用本方法测定了环氧乙烷合成银催化剂颗粒的有效导热系数,并用于催化剂内部浓度、温度、选择性计算,计算与实验结果吻合良好。     

Thermal conductivity of plastic foams

A simple equation enabling the prediction of the thermal conductivity of plastic foams, without the aid of adjustable parameters, is proposed. The equation is based on a recurrent method, previously developed, that showed reasonable agreement with experimental results. Ways of decreasing the thermal radiation contribution are shown. In particular, the influence of cell size, radiation transmission through solid membranes, and low-emissivity boundary surfaces are analyzed. Errors involved in steady techniques of measuring the thermal conductivity associated with radiation are discussed.     

环柱状催化剂内强放热复合反应──传质──传热耦合过程研究(Ⅰ)催化剂曲折因子、有效导热系数的测定

采用经典定态法和改进的单颗粒线反应器法（SPSRM)测定了环柱状环氧乙烷银催化剂的曲折因子,两种方法测定结果十分吻合。提出一种测定固体催化剂颗粒有效导热系数的新方法。该方法简单、方便且不改变催化剂原有的形状及物理结构,可以在催化剂允许使用的任何温度下进行测定,准确度较高。用本方法测定了环氧乙烷合成银催化剂颗粒的有效导热系数,并用于催化剂内部浓度、温度、选择性计算,计算与实验结果吻合良好。     

饱和蒸气压测定方法的评述

介绍了各种对物质饱和蒸气压测定的方法,给出了各种方法的适用范围及其优缺点。特别分析了蒸气压的现代测量方法(色谱法、热重法和差示扫描量热法)和工厂常用的雷德法的特点,得出性质较为复杂的煤液化油馏分饱和蒸气压的测定宜采用拟静态法。     

稠油比热容导热系数及粘温物性参数变化研究

利用Anton Paar MCR301旋转流变仪开展了不同区块稠油粘温性的实验研究,在20～300℃,利用HA-Ⅱ型比热容测定装置及HA-Ⅱ型导热测定装置,测定了岩石、水和不同区块稠油的比热容及不同区块稠油的导热系数.研究结果表明,稠油的粘度对温度非常敏感,随温度升高而大幅度降低.在20～300℃,稠油的比热容值在1.6840～4.4939 J/(g·K)变化,变化范围较大.稠油的导热系数都有随着温度的升高而降低的规律,并且在数值上较为接近,在20～300℃,导热系数在0.1196～0.1650W/(m·K)变化,变化范围很小.     

Study of the thermal conductivity of textiles for firefighters’ uniforms

Experimental data on determination of the thermal conductivity of textiles used for sewing clothing for firemen are reported. It was shown that nonstationary methods of measuring the thermal conductivity can lead to a large error in the results if the contact thermal resistances are not taken into account in the measuring instrument; a method for excluding them is proposed. __________ Translated from Khimicheskie Volokna, No. 2, pp. 26–28, March–April, 2006.     

A new apparatus to measure the thermal conductivity and diffusivity of thermoplastic and thermosetting polymers

A new apparatus has been constructed to measure the thermal conductivity and the thermal diffusivity of reactive and nonreactive liquids and solids. The method used consists in suddenly subjecting the test specimen to a thermal flux and measuring the velocity of the heat wave across the sample. Maintaining the heat flux leads to a steady thermal gradient across the sample from which the thermal conductivity can be determined. The test duration is short relative to durations employed by existing conventional techniques and thus causes only a small thermal disturbance to the sample of the order of 1 to 2°C. Thermal properties of liquids and solids, including thermoplastics and a typical epoxy resin during cure with different equivalents of an aromatic diamine hardener have been measured near room temperature. Experimental data compare favorably with literature values for similar systems. Variations in thermal conductivity and diffusivity during cure have been obtained through a series of individual discrete measurements to cover the whole isothermal cure history. The results have been analyzed and discussed with respect to the cure characteristics of the resin and the nature of the physicochemical changes the material undergoes during cure.     

SPHERICAL FURNACE CALORIMETER FOR DIRECT MEASUREMENT OF SPECIFIC HEAT AND THERMAL CONDUCTIVITY*

A spherical calorimeter was constructed for measuring true specific heat and thermal conductivity. It was formed of two concentric spherical platinum shells, and a spherical sample was fitted into the inner shell. Electric heat was supplied at the center of the sample, and the calorimeter was housed in a spherical electric furnace. Thermal conductivity was measured by determining the inner and outer sample temperatures at steady heat flow using the equation of heat conduction in a sphere; specific heat was measured by noting the temperature rise of the sample with a known heat input while maintaining the calorimeter shells near the adiabatic condition; and a correction for heat leakage was made by using the conductivity determination to calculate this factor. Specific heat and thermal conductivity measurements were made on quartz sand, chrome refractory cement, four types of insulating firebrick, and 85% magnesia insulation over a total temperature range of 100° to 2200°F. The estimated accuracy of specific heat measurement of 3 to 5% is consistent with engineering requirements. No estimate of accuracy can be given as yet for thermal conductivity results.     

橡胶复合材料的热传导特性研究

介绍了准稳态测量橡胶复合材料热导率的原理和试验装置;对以人造丝,尼龙和聚酯增强的橡胶复合材料的热导率进行一测量,线性拟合得出了其热导率与温度的定量关系式,并将线性关系式和橡胶基体材料进行了对比。结果表明,橡胶复合材料的热导率在纤维纵向上大于橡胶的热导率;在纤维横向上基本与橡胶一致。