Abstract Calorimetric emissometers measure total hemispherical emissivity by measuring the heat transferred from a heated sample to its surroundings under a vacuum. The accuracy of emissometers standardized by the ASTM C835-06 are well understood. This work uses the Guide to the Evaluation of Uncertainty in Measurement (GUM) for the propagation uncertainties for an ASTM compliant emissometer. The GUM method was able to develop a measurement model and expressions to determine the uncertainty for other emissometers of this type. Data on ‘as-received’ Hastelloy X was used to develop a detailed uncertainty analysis of the emissivity measurement. Data on ‘as-received’ SS 347 and sandblasted A387 Gr. 91 and previous data by the group on A508/A533B were used to determine uncertainty over the ranges 0.16 to 0.81. For all samples, relative uncertainties in emissivities varied from 0.77% to 2.5% when using a fluxgate magnetometer sensor (FMS) to measure the DC heating current. Data on Hastelloy X using a Hall-effect sensor for DC current and low alloy steel showed the DC current and voltage across the test section to be dominate sources of uncertainty. When these sources were reduced, the specimen temperature and the surface area of the test sections were main sources of uncertainty in the emissivity, especially at higher temperatures. As thermal expansion of the surface was considered in the calculations, correlation between specimen temperature and surface area was examined. It was found to be a small contribution to emissivity's uncertainty despite the differences in linear CTE and its uncertainty for the materials analyzed in this study. For low temperatures, the chamber temperature can be a significant source of uncertainty if not sufficiently cooled. The GUM was also briefly compared to uncertainty from the 2nd and 3rd expansions of the Taylor series. The results were the same when rounding to two significant figures.

中文翻译：

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热丝式量热发射计稳态测量的不确定度分析

摘要 量热发射计通过测量在真空下从加热样品传递到其周围环境的热量来测量总的半球发射率。由 ASTM C835-06 标准化的发射计的精度是众所周知的。这项工作使用测量不确定度评估指南 (GUM) 来确定符合 ASTM 标准的辐射计的传播不确定度。GUM 方法能够开发测量模型和表达式来确定其他此类发射计的不确定度。“原样”哈氏合金 X 的数据被用于对发射率测量进行详细的不确定性分析。“原样” SS 347 和喷砂 A387 Gr 的数据。91 和该小组之前在 A508/A533B 上的数据用于确定 0.16 至 0.81 范围内的不确定性。对于所有样本，当使用磁通门磁力计传感器 (FMS) 测量直流加热电流时，发射率的相对不确定性从 0.77% 到 2.5% 不等。使用霍尔效应传感器检测直流电流和低合金钢的 Hastelloy X 数据表明，测试部分的直流电流和电压是不确定性的主要来源。当这些来源减少时，试样温度和测试部分的表面积是发射率不确定性的主要来源，尤其是在较高温度下。由于在计算中考虑了表面的热膨胀，因此检查了试样温度和表面积之间的相关性。尽管本研究中分析的材料的线性 CTE 和不确定性存在差异，但发现它对发射率不确定性的贡献很小。对于低温，如果没有充分冷却，腔室温度可能是一个重要的不确定性来源。还简要地将 GUM 与泰勒级数的第二次和第三次扩展的不确定性进行了比较。当四舍五入为两位有效数字时，结果相同。