Comparison Between Wire Mesh Sensor Technology And Gamma Densitometry

S. Sharaf1, M. Da Silva2, U. Hampel2, C. Zippe2, B. Azzopardi1, M. Beyer2

1 Department of Chemical and Environmental Engineering, University of Nottingham, Nottingham, NG7 2RD, UK (Corresponding author: enxss10@nottingham.ac.uk)

2 Institute of Safety Research, Forschungszentrum Dresden-Rossendorf (FZD), Germany

ABSTRACT

Wire mesh sensors (WMS) are fast imaging instruments that are used for gas-liquid and liquid-liquid two-phase flow measurements and experimental investigations. Experimental tests were conducted at FZD to test both the capacitance and conductance WMS against a gamma densitometer (GD). A small closed loop gas-liquid test facility was utilised. This consisted of a vertical round pipe approximately 1 m in length, and 50 mm internal diameter. A 16x16 WMS was used with high spatial and temporal resolutions. Air-deionised water was the two-phase mixture. The gas superficial velocity was varied between 0.05 m/s to 1.4 m/s at two liquid velocities of 0.2 and 0.7 m/s. The GD consisted of a collimated source and a collimated detector. The GD was placed on a moving platform close to the plane of wires of the sensor, in order to align it accurately using a counter mechanism, with each of the wires of the WMS, and the platform could scan the full section of the pipe. Although measurements were taken for all 16 wires using both the conductance and capacitance WMS, one half of the pipe i.e. 8 wires of the sensor were evaluated with capacitance WMS and GD, and the other half of the pipe i.e. 8 wires of the sensor was evaluated with conductance WMS and GD. For the cross-sectional void (time and space averaged), along each wire, there was good agreement between WMS and the GD chordal void fraction near the centre of the pipe, however there wasn’t a good agreement near the edge of the pipe. There was consistent agreement between the capacitance and conductance WMS throughout the experiment.

Keywords Gas-Liquid Flow, Wire Mesh Sensor (WMS), Capacitance, Conductance, Gamma Densitometer (GD)