Direct Measurements of Permittivity of Plasma-Assisted Combustion Using Electrical Capacitance Tomography

Abstract

The permittivity distribution and the flame development in a closed plasma-assisted combustor were investigated using an electrical capacitance tomography system. The experiments were conducted at a pressure of 1 atm and at different equivalence ratios. I-V curves measured by the Langmuir probe were utilized to estimate the floating potential (−40 to −10 V) and the electron local parameters (T e and n e ) in the plasma-assisted flames. The results showed that the electron concentration reached the maximum at a location close to the plasma injection point where the primary reaction region of the CH 4 -air premixed flame was located. Major species measurement by emission spectrometer combined with the probe measurement revealed that the kinetic enhancement was more significant than the thermal enhancement in the plasma-assisted combustion. Moreover, the dependence of combustion kinetics including electron/ion concentration and temperature on the flame permittivity was verified. The quantitative permittivity data obtained in this study provide a good validation target for modeling of the electric field in plasma-assisted combustion.

Monitoring and Characterizing the Flame State of a Bluff-Body Stabilized Burner by Electrical Capacitance Tomography

“…The ECT is based on 'soft-field' sensing, and the electric field The cross-sectional permittivity distribution image is reconstructed using the Calderonmethod based image reconstruction algorithm on the computer [23]. The traditional reconstruction method is usually used for reconstructing the permittivity distribution of a circular region [24][25][26], while the measurement area in the present study is an annular region with a rod in the center to support the bluff-body. Therefore, the reconstruction method needs to be modified.…”

Electrical Capacitance Tomography Using Incomplete Measurement Set

“…Being inexpensive, non-intrusive and non-radioactive, ECT technique is suitable for imaging the industrial processes, in which fast-going multi-phase flow is frequently met. The applications of ECT can be found in the circulating fluidized bed [1]- [3], trickle-bed reactor, temperature measurement [4], flame detection [5], [6] and multi-phase flow rate measurement [7], [8].…”