International Society for Industrial Process Tomography

Detection of Bubbles in Cryogenic Liquids using
Electrical Capacitance Tomography

C. Kandlbinder-Paret^1*, A. Fischerauer¹, G. Fischerauer¹

¹Chair of Measurement and Control Systems,
Center for Energy Technology (ZET),
Universität Bayreuth, Universitätsstr. 30, 95447 Bayreuth, Germany

^*Email: mrt@uni-bayreuth.de

ABSTRACT

The control of cryogenic liquid propellants used in heavy-lift launchers requires a thorough understanding of fluid phenomena and in particular of bubble formation and local boiling effects under microgravity conditions. This contribution reports on an electrical capacitance tomography (ECT) system that can observe the behaviour of those liquids. A cylindrical polycarbonate cylinder was submerged into liquid nitrogen (LN2) to monitor the location and size of bubbles. The capacitances were measured by a commercial capacitance sensor. Finite-element (FE) simulations in Ansys were used to calculate the sensitivity matrix. The projected Landweber algorithm served to reconstruct images of the permittivity distribution. For validation purposes, visual images of bubbles and bubble streams were recorded with a camera. The experimental results of the ECT system agreed well with these visual observations. The system recognized bubbles with diameters down to about 15 mm or bubble streams containing multiple smaller bubbles with identical dimensions.

Keywords Bubbles, Cryogenic, ECT

Industrial Application Space