Session 19: Metrology in Thermal Sciences
Chairs:
Alcir de Faro Orlando
Pontificia Universidade Católica
do Rio de Janeiro
Edson Del Rio Vieira
Unesp
João Nildo Vianna
Universidade de Brasília Departamento
de Engenharia Mecânica
Luís Fernando Alzuguir Azevedo
Departamento de Engenharia Mecânica
PUC-RIO
Juliano Augusto Dillenburg
- dill@mecanica.ufrgs.br
Universidade Federal do
Rio Grande do Sul, Departamento de Engenharia Nuclear
Av. Osvaldo Aranha 99, 4º
andar, CEP: 90460-900 Porto Alegre, RS, Brasil.
Milton Antonio Zaro - zaro@mecanica.ufrgs.br
Universidade Federal do
Rio Grande do Sul, Departamento de Engenharia Mecânica
Rua Sarmento Leite, 425,
CEP: 90050-170, P. Alegre, RS, Brasil.
Horácio Antonio Vielmo
- vielmoh@mecanica.ufrgs.br
Universidade Federal do
Rio Grande do Sul, Departamento de Engenharia Mecânica
Rua Sarmento Leite, 425,
CEP: 90050-170, P. Alegre, RS, Brasil.
Calibration and characterization procedures for single waveband infrared pyrometers are proposed. Regardling the fact that doesn't exist a brazilian normatization and the fact that the international normatization ASTM E1256-95 is incomplete, it's expected that these considerations will produce a discussion about the creation of a brazilian normatization for the use of such technique.
Keywords: Calibration, Temperature,
Pyrometry, Emissivity, Radiation.
HELBER S.HUAQUIPACO - e-mail
sucah@hotmail.com
ALCIR F.ORLANDO - e-mail
afo@mec.puc-rio.br
Pontifícia Universidade
Católica do Rio de Janeiro - PUC-Rio
Departamento de Engenharia
Mecânica
R.Marquês de S. Vicente
225, Gávea, 22453-900, Rio de Janeiro, Brasil
ALBERTO J.F.Orlando - e-mail
albfrida@directnet.com.br
Instituto Tecnológico
de Aeronáutica
Departamento de Engenharia
Eletrônica
LUIZ C.CIPRIANO -
INMETRO
The water content in air
or in other gases is important for controlling biological, chemical and
physical processes, Measurements are made in industry within a wide range
of humidity. They contribute to the composition of the final cost and quality
of products, health and safety. The present work deals with a measurement
technique for the water content in air. The resonance frequency of a rectangular
cavity, designed for a fundamental frequency of 2,45 GHz (dry air), was
measured by a spectrum analyser for different values of the water content.
A standard dew point apparatus was used in INMETRO for measuring the partial
pressure of water vapor in air inside the cavity. The partial pressure
of water vapor in air was calculated by na existing theory as a function
of temperature and resonance frequency of the cavity, and it was compared
to the measured one. The resulting second degree polynomial curve fit between
the two values reflects the deviation from ideality of the real cavity,
suggesting that all cavities should be calibrated before being used. The
uncertainty of measurement was estimated together with the influence of
several parameters on the equipment response, which was compared to the
available ones. This completes the metrological qualification of the device.
As a result, it was demonstrated that the uncertainty of the dew point
measurement by the standard apparatus is the parameter that mostly affects
the overall uncertainty of the calibration.