Abstract
Abstract. The TIR100-2 emissometer (manufactured by Inglas GmbH & Co.KG) is an emissivity measurement device used by several producers of thermal insulation products for buildings and by some organizations certifying performance of insulation products. A comparison of emissivity measurements on low-emissivity foils involving different measurement techniques, including the TIR100-2 emissometer, gave widely dispersed results; the discrepancies were not explained. The metrological performance of the TIR100-2 emissometer and the uncertainties for measurement on reflective foils was not known, which could be detrimental to users. In order to quantify the performance of TIR100-2 devices for measurement of total near-normal emissivity of low-emissivity foils, the Laboratoire National de Métrologie et d'Essais (LNE) analyzed in detail the measuring principle and listed the associated assumptions and uncertainty sources. A TIR100-2 emissometer actually measures the reflectance and, for opaque materials, the emissivity is calculated from the measured reflectance. The parameters analyzed experimentally are the temperature stability and uniformity of the thermal radiation source, the emissivity of the radiation source, the response function linearity and the spectral sensitivity of the radiometric detection system measuring the reflected radiation, the size of the measurement area, and the measurement repeatability and reproducibility. A detailed uncertainty budget was established. The uncertainty sources taken into account are the uncertainties of the emissivities of the two calibrated standards used for calibration, the stability and uniformity of the radiation source temperature, the non-linearity and the spectral sensitivity of the radiometric detection system, the specific measurement condition related to the radiation source temperature, the uncertainties related to the temperatures of the standards and the sample, the noises on results, and the non-homogeneity in emissivity of the tested material. The combined measurement uncertainty was calculated for different types of reflective foils; the expanded uncertainty is around 0.03 for total near-normal emissivity measurements on smooth low-emissivity foils. A measurement campaign on five types of low-emissivity foils, involving four TIR100-2 emissometers, and a comparison to a primary reference setup at the Physikalisch-Technische Bundesanstalt (PTB) confirmed the uncertainties assessed.
Highlights
Low-emissivity surfaces are sometimes used in association with thin air or vacuum space to create resistance to heat transfer
This paper focuses on the measurements of total near-normal emissivity of very reflective foils
From the standard uncertainties quantified for each source of uncertainty, the combined standard uncertainty was quantified for the measurement of the total near-normal emissivity of the reflective foils with a TIR100-2 emissometer
Summary
Low-emissivity surfaces are sometimes used in association with thin air or vacuum space to create resistance to heat transfer. The standard EN 16012+A1 defines, among other things, the methods for measuring the emissivities of low-emissivity thermal insulation products (CEN, 2015). At the request of the working group CEN/TC89/WG12, the research project EMIRIM “Improvement of Emissivity Measurements on Reflective Insulation Materials” was carried out to improve the measurements of total hemispherical emissivity on the low-emissivity foils found as external surfaces on some thermal insulation products for buildings (JRP EMIRIM, 2017). In the EMIRIM project, the Physikalisch-Technische Bundesanstalt (PTB) performed a detailed analysis of the measurement field size of a TIR100-2 device, tested the effect of using different sets of standards for calibration and compared the results to results from the primary emissivity measurement setup EMAF at the PTB (Kononogova et al, 2019). In the study presented here, LNE (Laboratoire National de Métrologie et d’Essais) characterized in detail a TIR100-2 device with the objective of establishing an uncertainty budget for measurement of total near-normal emissivity on lowemissivity foils. The calculation of total hemispherical emissivity from the total near-normal emissivity result is beyond the scope of this publication
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
