Enhancement factor measurements under atmospheric conditions - Article pour le 18th International Congress of Metrology, Paris, septembre 2017
Résumé et principaux résultats
Abstract: Within JRP ENV58 METEOMET, LNE-CETIAT is developing a facility which leads to the assessment of the enhancement factor under atmospheric conditions, i.e. reduced pressure and low temperature. The saturation vapour pressure of water in a gas mixture is not the same as saturation vapour pressure of pure water. The water vapour enhancement factor is used in the humidity field calculations to correct the non ideality in air water mixtures. The published data for the vapour enhancement factor in air are scarce and have been obtained mainly in the last century, the most recent publication being in the 90's. These experimental data have then been used in theoretical models of the literature. As it has been pointed out, there are some doubts on the reliability of the experimental data below 0 °C and no experimental data underpinning theoretical models for enhancement factor. When an inert, non-reacting, gas is added to a system in which a liquid or a solid is in equilibrium with its vapour, the vapour pressure of the condensed substance changes. It is due to three effects: The Poynting effect, the change of chemical potential because of interactions between the vapour and the inert gas and Henry's law effect. This project deals with the Essentials Climate Variables in the upper atmosphere, which may be mainly considered within troposphere and stratosphere. The facility developed in this task aims to cover the temperature range (i.e. typically from -60 °C up to +30 °C) and pressure range. Thus this work presents the principle of facility used and preliminary assembly for measuring enhancement factor. This work was funded by the JRP ENV58 METEOMET of the EMRP. The EMRP is jointly funded by the EMRP participating countries within EURAMET and the European Union.Titre : Mesures du facteur d'augmentation en conditions atmosphériquesTitre : Mesures du facteur d'augmentation en conditions atmosphériques
Thème
Méthodes et matériels de mesure
Mots-clés
Mesure d'humidité des gaz
Auteurs
GEORGIN Eric