Space charge density in dielectric and conductive liquids flowing through a glass pipe

Flow electrification phenomena in the case of conductive and dielectric liq uids flowing through an insulating pipe are compared. A theoretical model, which takes into account the development time of the diffuse layer in the c ase of a laminar flow, is compared with streaming current measurements. Exp eriments are conducted with water (electrical conductivity 0.2 < sigma < 1. 4 mS/m) and heptane (53 < sigma < 1010 pS/m) flowing through a 32 mum-radiu s glass pipe. Evolution of the space charge density at the wall p, in funct ion of the liquid conductivity cr is analysed. Results show that the intens ity of how electrification depends mainly on the space charge density at th e wall and the liquid electrical conductivity. (C) 2001 Elsevier Science B. V. All rights reserved.