TY - BOOK

T1 - Application of impedance tomography to measurement of temperature distributions in hot gases

AU - Baroudi, Djebar

AU - Hietaniemi, Jukka

AU - Somersalo, Erkki

PY - 1998

Y1 - 1998

N2 - This communication describes a novel technique for
measuring gas temperature distributions, based on
impedance tomography. In the method, the temperature
field in the hot gas is reconstructed from the
temperature-induced resistance changes in a grid of thin
metal wires forming the measuring device. The grid
consists of 21 filaments, arranged in groups of 7 wires
with an angle of 120º between the groups. The
reconstruction of the temperature distribution may be
reduced to the standard inversion problem of tomography.
In the present case, however, the measuring mesh is
relatively coarse, which leads to severe undetermination
of the problem, thus rendering the commonly used
inversion techniques unsuitable. Therefore, the problem
is recast in the form of a Bayesian parameter estimation
problem where Markov Chain Monte Carlo methods (MCMC) are
applied for extracting the temperature field. The
operation of the algorithm is demonstrated through an
application to synthetic data infected by noise. Results
are presented on the use of the method for measurement of
two temperature distributions above a hot-air blower, one
with a single peak and the other with two peaks lying
close to each other. The reconstructed distributions
agree well with the temperature readings measured with
auxiliary thermocouples located at several positions in
the hot gas stream. As compared to the 21-wire device
based on the principle of tomography, to achieve an equal
resolution with the point-wise thermocouples, an array of
ca. 100 sensors would have been needed, which is more
tedious to implement and operate.

AB - This communication describes a novel technique for
measuring gas temperature distributions, based on
impedance tomography. In the method, the temperature
field in the hot gas is reconstructed from the
temperature-induced resistance changes in a grid of thin
metal wires forming the measuring device. The grid
consists of 21 filaments, arranged in groups of 7 wires
with an angle of 120º between the groups. The
reconstruction of the temperature distribution may be
reduced to the standard inversion problem of tomography.
In the present case, however, the measuring mesh is
relatively coarse, which leads to severe undetermination
of the problem, thus rendering the commonly used
inversion techniques unsuitable. Therefore, the problem
is recast in the form of a Bayesian parameter estimation
problem where Markov Chain Monte Carlo methods (MCMC) are
applied for extracting the temperature field. The
operation of the algorithm is demonstrated through an
application to synthetic data infected by noise. Results
are presented on the use of the method for measurement of
two temperature distributions above a hot-air blower, one
with a single peak and the other with two peaks lying
close to each other. The reconstructed distributions
agree well with the temperature readings measured with
auxiliary thermocouples located at several positions in
the hot gas stream. As compared to the 21-wire device
based on the principle of tomography, to achieve an equal
resolution with the point-wise thermocouples, an array of
ca. 100 sensors would have been needed, which is more
tedious to implement and operate.

M3 - Report

SN - 951-38-5302-0

T3 - VTT Tiedotteita - Meddelanden - Research Notes

BT - Application of impedance tomography to measurement of temperature distributions in hot gases

PB - VTT Technical Research Centre of Finland

CY - Espoo

ER -