title: New portable instrument for the measurement of thermal conductivity in gas process conditions.
abstract: The development of high temperature gas sensors for the monitoring and determination of thermophysical properties of complex process mixtures at high temperatures faces several problems, related with the materials compatibility, active sensing parts sensitivity, and lifetime. Ceramic/thin metal films based sensors, previously developed for the determination of thermal conductivity of molten materials up to 1200 °C, were redesigned, constructed, and applied for thermal conductivity measuring sensors. Platinum resistance thermometers were also developed using the same technology, to be used in the temperature measurement, which were also constructed and tested. A new data acquisition system for the thermal conductivity sensors, based on a linearization of the transient hot-strip model, including a portable electronic bridge for the measurement of the thermal conductivity in gas process conditions was also developed. The equipment is capable of measuring the thermal conductivity of gaseous phases with an accuracy of 2%-5% up to 840 °C (95% confidence level). The development of sensors up to 1200 °C, present at the core of the combustion chambers, will be done in a near future.
authors.affiliation: Centro de Química Estrutural, Faculdade de Ciências da Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal.
authors.forename: C S G P
authors.initials: CS
authors.lastname: Queirós
authors.affiliation: Centro de Química Estrutural, Faculdade de Ciências da Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal.
authors.forename: M J V
authors.initials: MJ
authors.lastname: Lourenço
authors.affiliation: Centro de Química Estrutural, Faculdade de Ciências da Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal.
authors.forename: S I
authors.initials: SI
authors.lastname: Vieira
authors.affiliation: Instituto Dom Luiz, Faculdade de Ciências da Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal.
authors.forename: J M
authors.initials: JM
authors.lastname: Serra
authors.affiliation: Centro de Química Estrutural, Faculdade de Ciências da Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal.
authors.forename: C A
authors.initials: CA
authors.lastname: Nieto de Castro