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International Society for Industrial Process Tomography

10th World Congress on Industrial Process Tomography

New Method to Correct Energy Losses of Wire-Mesh Sensor Data

F. A. Dias1*, P. Wiedemann1, E. Schleicher1, M.J. da Silva2 and U. Hampel1

1Institute of Fluid Dynamics, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstr. 400, 01328 Dresden, Germany

2 Department of Electrical Engineering (CPGEI), Federal University of Technology Parana, Brazil

*Email: f.dias@hzdr.de



ABSTRACT

Capacitance wire-mesh sensor is a multielectrode instrument for the measurement of multiphase flows. Since it was originally designed to measure fluids with no or very small conductivities, the sensor may suffer from energy losses when used to measure mixtures with conductivity greater than 100 ┬ÁS/cm. Consequently, when derived flow parameters are estimated from WMS raw data, unphysical results may be obtained, i.e. negative phase fraction. Threshold methods are commonly employed to cut-off such negative values. However, such approaches work well only for flow regimes where the phases are almost binary, e.g. stratified flows. For this reason, we present a new arrangement and a new method to correct energy losses of a capacitance WMS, which generates reliable data also for complex phase fraction distributions. In the new arrangement, an additional transmitter wire is placed outside the flow domain forming external flow-independent crossing-points. Thus, the change in readings of the external crossing points are used to estimate the loss factor of each receiver wire, which in turn are employed to compensate the energy loss of each local measurement. Experimental and numerical results suggest that the new method is fundamental to expand the conductivity range of capacitance WMS and to measure complex flow structures, i.e. emulsions, foam, ionic tracers, etc. In the examples presented in this paper, deviations of some local measurements were reduced from the range of 20% to less than 3.3%.

Keywords: wire-mesh sensor; multiphase flow; energy loss correction

Industrial Application: General

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