Effects of noise on fluidized bed characteristics measurements by electrical capacitance tomography

Abstract

Noise is inevitable in electrical capacitance tomography (ECT) measurements. This paper describes the influence of noise on ECT performance for measuring gas–solids fluidized bed characteristics. The noise distribution is approximated by the Gaussian distribution and added to experimental capacitance data with various intensities. The equivalent signal strength ($\varphi$) that equals the signal-to-noise ratio of packed beds is used to evaluate noise levels. Results show that the Pearson correlation coefficient, which indicates the similarity of solids fraction distributions over pixels, increases with $\varphi$, and reconstructed images are more deteriorated at lower $\varphi$. Nevertheless, relative errors for average solids fraction and bubble size in each frame are less sensitive to noise, attributed to noise compromise caused by the process of pixel values. These findings provide useful guidance for assessing the accuracy of ECT measurements of multiphase flows.