Flow Electrification of an Electrically Charged Liquid
P. D. S. Clermont1,2, T. Paillat1, Y. Duval2, J. Rivenc2, and G. Peres2
1Institut PPRIME, CNRS UPR 3346 - University of Poitiers - ISAE/ENSMA, France
2Airbus Group Innovations, France
Abstract- The contact of a liquid with a solid induces a polarization of the interface between the two materials due to the Electrical Double Layer (EDL) that is developed with charges of one sign on the solid and charge of the opposite sign distributed in the liquid. Part of the charge in the liquid is mobile and can be convected by the liquid flow and breaks the static equilibrium of the EDL. A continuing charge generation process will then take place to replace the convected charge as long as the flow is held; which will eventually lead to a new electrodynamic equilibrium. This process is known as "flow electrification" and is usually studied experimentally via streaming current measurements (electrical current of the charge convected by the liquid flow) of an electrically neutral liquid flowing inside solid duct. Flow electrification can be characterized via two parameters (specific to each solid/liquid couple) ρw ∞ and K which are, respectively, the maximum charge density when the EDL is fully developed and a kinetics coefficient of the physicochemical reactions generating the charge in the EDL. In this paper, flow electrification is studied for the case of an electrically charged liquid flowing inside a solid duct in order to analyze the impact of charge already present in the liquid on the development of the EDL at the solid/liquid interface. Analytical models are proposed for such study in the context of a laminar flow of liquid within a cylindrical geometrical configuration. The analytical models were supported by experimental results obtained with n-Heptane flowing through conductive cylindrical ducts. The results show that the flow electrification phenomenon is limited by the level and the sign of the charge already present in the liquid before it enters the solid test duct.
Keywords-Flow electrification, electrostatic hazard, charged liquid