Speeding-up Scientific Knowledge Transfer and Improvement of Capabilities of emerging European National Metrology Institutes and Designated Institutes in the field of thermal measurements: Benefits and Impacts

Within the frame of a European project called Eura-Thermal, the general objective was to upgrade the regional metrological infrastructure (Bosnia & Herzegovina, Croatia, Ireland, Serbia...) with new capabilities, especially in the field of thermal measurements. This paper highlights the strategy used for improving in the short term, scientific knowledge transfer and the capabilities of different emerging institutes. Furthermore, as a main output, the impacts and benefit for Industry and for the end-users are also presented as examples. © 2018 Institute of Physics Publishing. All rights reserved.XXII World Congress of the International Measurement Confederation (IMEKO 2018

Etude et développement d'un calorimètre adiabatique pour la caractérisation du point-fixe de l'indium (application des mesures fluxmétriques à l'optimisation des cellules calorimétriques)

L Échelle Internationale de Température (EIT-90) est matérialisée par un ensemble de points fixes liés aux transitions de phases (fusion ou congélation) de métaux de hautes puretés. Ces points-fixes permettent, entre autres, d étalonner les thermomètres à résistance de platine. Ces travaux proposent une méthode alternative aux mises en œuvres classiques des points fixes, par l approche de la calorimétrie adiabatique. Le point de fusion de l indium (156,5985C) est étudié en s affranchissant de toute perturbation thermique, afin de quantifier les influences thermochimiques liés aux impuretés en présence dans le métal. Ce calorimètre adiabatique repose sur le principe d une cellule point-fixe au sein d une autre cellule point-fixe (ou cell-within-cell). Différents capteurs, thermométriques et fluxmétriques, ont permis des mesures couplées pour le développement de nouvelles approches analytiques en termes d étude énergétique et thermodynamique associées aux points-fixes de température.The International Temperature Scale (ITS-90) is materialised by a series of fixed-points which the principle is based on the phase transition (freezing or melting) of high purity metals. These fixed-points are used for calibrating platinum resistance thermometers. The purpose of these works is to propose an alternative method for realizing the fixed-points by an adiabatic calorimetric approach. The indium melting point (156.598 5 C) is studied with supressing any thermal influence, in order to quantify the thermochemical effects due to the weak impurities concentrations in the metal. This adiabatic calorimeter is based on the so-called cell-within-cell principle. Coupled measurements have been realized with both of temperature and heat flow sensors, and have given some originals analytic developements in terms of thermodynamics and energetic associated to the temperature fixed-points devices.LE MANS-BU Sciences (721812109) / SudocSudocFranceF

Interface effects on the NLO properties of guest-host materials

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Méthodes d’Auto-Validation Pour Thermocouples à Haute Température

Une des grandes difficultés dans l’utilisation de thermocouples à haute température (au-delà de 1000 °C) est de maîtriser leur dérive. Soumis à leurs températures limites de fonctionnement, les thermocouples ont tendance à dériver, principalement à cause de recombinaisons structurelles inhérentes au recuit thermique. Ceux-ci sont également exposés à des pollutions depuis leurs milieux de mise en œuvre, ce qui peut conduire à des hétérogénéités de composition sur la longueur des thermo-éléments, altérant ainsi leurs pouvoirs thermoélectriques. La solution proposée est d’embarquer, voire intégrer un point-fixe de temperature de référence au thermocouple, permettant ainsi un étalonnage in situ du capteur lorsque le procédé permet de réaliser la transition de phase (fusion et/ou congélation) du matériau point-fixe. Cet article présente quelques méthodes et techniques en cours de développement au LNE-Cnam visant à mettre en pratique des méthodes d’auto-validation de thermocouples à haute température, sous atmosphères neutres et oxydantes

Uncertainty Assessment for Very High Temperature Thermal Diffusivity Measurements on Molybdenum, Tungsten and Isotropic Graphite

International audienceAbstract The French National Metrology Institute LNE has improved its homemade laser flash apparatus in order to perform accurate and reliable measurements of thermal diffusivity of homogeneous solid materials at very high temperature. The inductive furnace and the associated infrared (IR) detection systems have been modified and a specific procedure for the in situ calibration of the used radiation thermometers has been developed. This new configuration of the LNE’s diffusivimeter has been then applied for measuring the thermal diffusivity of molybdenum up to 2200 °C, tungsten up to 2400 °C and isotropic graphite up to 3000 °C. Uncertainties associated with these high temperature thermal diffusivity measurements have been assessed for the first time according to the principles of the “Guide to the Expression of Uncertainty in Measurement” (GUM). Detailed uncertainty budgets are here presented in the case of the isotropic graphite for measurements performed at 1000 °C, 2000 °C and 3000 °C. The relative expanded uncertainty (coverage factor k = 2) of the thermal diffusivity measurement is estimated to be between 3 % and 5 % in the whole temperature range for the three investigated refractory materials

Metrological prospects for the assessment of transition plateaus

International audienceHeat flow transducers have been implemented within a thermometric fixed-point cell operated with indium. Then a local heat flow rate was monitored simultaneously with the classical temperature measurement. A specific configuration, so-called cell-within-cell, allowed us to control a melting transition plateau and to observe the behaviour of the heat exchanged during the whole process of the melting transition. Owing to their dynamic character, heat flow measurements prove to be the most appropriate for defining specific boundaries on a given transition plateau, and relevant sensors are found to be suitable tools to be coupled with enhanced temperature measurements. This piece of work is presented in two parts, with the description of the set-up and measurement results in this first paper and their subsequent thermodynamic implications in the following one

Towards a thermodynamic assessment of transition plateaus

International audienceThis second part of the work is devoted to the thermodynamic implications of the results presented in the preceding paper, as heat flow meters (HFMs) were installed within a thermometric fixed-point cell operated with indium. Then, simultaneous measurements of both temperature and heat flow allow us to pinpoint the specific boundaries (solidus and melt-off points) of a given transition plateau. To the best of our knowledge, this work is the first experimental illustration being reported on how to consider a plateau as a specific thermodynamic regime marked with a minimum amount of generated entropy in a metrological fixed-point cell. As a result, a significant relationship linking the boundaries of the plateau and the melting temperature of the material studied is presented. In order to obtain a quantitative understanding of the quality of a given transition process, straightforward thermodynamic considerations allow us to consider both theoretically and experimentally an adimensional parameter defined as the ratio of the entropy generation over the entropy change

Heat flow metric policy for dynamic monitoring of fixed-point cells

International audienceIn this paper, an original configuration, named as cell-within-cell, is described together with a specific measurement policy. To this end, concomitant temperature and heat flow assessments are carried out so as to obtain the exhaustive energy monitoring within the thermometric fixed-point cell. Two different melting schemes are investigated so as to consider an optimized control strategy in the near future