Comsol Simulations as a Tool in Validating a Measurement Chamber

Research output: Contribution to journalArticleScientificpeer-review

Researchers

  • Antti Lakka

  • Hannu Sairanen
  • Martti Heinonen
  • Richard Högström

Research units

  • VTT MIKES Metrology

Abstract

The Centre for Metrology and Accreditation (MIKES) is developing a temperature–humidity calibration system for radiosondes. The target minimum air temperature and dew-point temperature are -80∘C and -90∘C, respectively. When operating in this range, a major limiting factor is the time of stabilization which is mainly affected by the design of the measurement chamber. To find an optimal geometry for the chamber, we developed a numerical simulation method taking into account heat and mass transfer in the chamber. This paper describes the method and its experimental validation using two stainless steel chambers with different geometries. The numerical simulation was carried out using Comsol Multiphysics simulation software. Equilibrium states of dry air flow at -70∘C with different inlet air flow rates were used to determine the geometry of the chamber. It was revealed that the flow is very unstable despite having relatively small Reynolds number values. Humidity saturation abilities of the new chamber were studied by simulating water vapor diffusion in the chamber in time-dependent mode. The differences in time of humidity stabilization after a step change were determined for both the new chamber model and the MIKES Relative Humidity Generator III (MRHG) model. These simulations were used as a validation of the simulation method along with experimental measurements using a spectroscopic hygrometer. Humidity saturation stabilization simulations proved the new chamber to be the faster of the two, which was confirmed by experimental measurements.

Details

Original languageEnglish
Pages (from-to)3474-3486
Number of pages13
JournalINTERNATIONAL JOURNAL OF THERMOPHYSICS
Volume36
Issue number12
Publication statusPublished - 1 Dec 2015
MoE publication typeA1 Journal article-refereed

    Research areas

  • Adsorption, Fluid flow, Mass transfer, Numerical simulation, Radiosonde

ID: 10225061