Numerical modeling of negative corona discharge in pure carbon dioxide

10-2 10-1 0.0 0.2 0.4 0.6 0.8 1.0 1.2 e (×4) O−(×1500) O− 3(×400000) CO− 4 (×103) CO− 3 Negative ion density (108cm-3) Radial distance, r (cm) 0.8 Fig. 1: Radial distribution of electrons and negative ions at exit of the cylinder. Numerical modeling of negative corona discharge in pure carbon dioxide K.Yanallah1, F. Pontiga2, A.Fernández-Rueda2, A.Castellanos3 and Y.Meslem1 1Laboratoire de Génie Physique, Université de Tiaret, Algeria 2Dpt. Física Aplicada II and 3Dpt. Electrónica y Electromagnetismo, Universidad de Sevilla, Spain 1. Introduction Corona discharge is present in many industrial processes, such as in the treatment of polymer films, the production of ozone or the decomposition of gaseous pollutants [1]. In this paper, our attention will be focused on the use of wire-to-cylinder negative corona discharge for the decomposition of carbon dioxide. As it is well known, CO2 is a green house gas that contributes to the global warming of Earth atmosphere. In addition, this gas is the major constituent of Martian atmosphere [2]. Therefore, the study of its decomposition by means of electrical discharges and its transformation in other compounds has a double interest: it can help to the development of new technologies aiming to the reduction CO2 emissions, and it can provide important clues on the presence of trace gases in the Martian atmosphere (like ozone) that are essential for live supporting. 2. Numerical model Corona discharge is modeled as a stationary and homogeneous discharge in the axial and azimuthal directions [3]. On the basis of a hydrodynamic model, the electrical discharge is simulated using a set of continuity equations that describe the generation and destruction of charged and neutral species due to the chemical reactions at each point of the inter-electrode gap. This set of equations is coupled to Poisson’s equation and the heat equation. The chemical model includes 21 species (e, O+, O2+, O3+, CO2+, O−, O2−, O3−, CO3−, CO4−, O, O2 O3, O(1D), O2(1∆g), O(1Σg+), O2 *, O3 *, CO, C and C2O) and a total number of 47 reactions. The selection of reactions was based on the study of Soria and al. [4] and Mikoviny and al. [5]. 3. Results The numerical results presented in this section were obtained for 1 atm and 298 K. The axial gas flow rate through the cylinder was taken as Q = 100 cm3/min and the applied voltage was set to V = 6 kV. The radial distributions of electrons and negative ions at the outlet of cylinder are presented in Fig. 1. The structure of the electrical discharge is very similar to that in pure oxygen, which has been previously studied [3, 4]. The inter-electrode space is divided into three regions: active, ionization and drift region. In the drift region, the principal charge carrier is CO3−, and in lesser degree CO4− and O3−. Carbon dioxide is decomposed by the impact of energetic electron provided by the electrical discharge, e + CO2 → CO + O + e. (R1) Molecular oxygen, which is necessary for the production of ozone, is generated according to process, O + O + CO2 → O2 + CO2. (R2) Other radicals and excited species are also formed in the active region and then diffuse toward the outer electrode (see Fig. 2). Most of these radicals are also produced by direct electron impact dissociation and excitation of CO2 and O2. Finally, ozone is mainly generated via a threebody reaction of O and O2, with CO2 acting as the third body partner, O + O2 + CO2 → O3 + CO2. (R2) References [1] B Eliasson and U Kogelschatz, IEEE Trans Plasma Sci 19 1063–77 (1991). [2] L Kaltenegger, M Fridlund, J Kasting Proc of the 36th ESLAB Symp, 277-282 (2002). [3] K Yanallah et al. J Phys D: Appl Phys 41 195206 (8pp) (2008). [4] C Soria et al. Plasma Sources Sc. Technol 13 95 (2004). [5] T Mikoviny et al. J Phys D: Appl Phys 37 64 (2004). Acknowledgment This work has been supported by the Spanish Agency for International Development and Cooperation (AECID). Fig. 2: Radial distribution of neutral species at exit of the cylinder. 10-2 10-1 104 107 1010 1013 1016 1019 O2 O O(1D) O2(1Σg) CO O2(1∆g) O3 O* 2 O* 3 C C2O Neutral species density (cm-3) Radial distance, r (cm) 0.8 View publication statsView publication stats