Experimental analysis of gas-liquid dispersion in mechanically stirred tank by means of quantitative Electrical Resistance Tomography

Electrical Resistance Tomography (ERT) is adopted extensively to measure fundamental dispersion properties in dense multiphase systems, where other techniques are either impossible to use (e.g. optical techniques), or very expensive (CT, PEPT, especially at large scales). Quite satisfying qualitative results can be obtained by ERT (sufficient for the accurate assessment of regime transitions or blending times), but the ability to reconstruct quantitative data has still to be fully addressed. In this paper, a practical method for obtaining quantitative data from ERT measurements is proposed and validated through experimental data. Several aspects are addressed: the effect of iterative vs non-iterative conductivity tomogram algorithms, determination of the optimal iteration number for iterative procedures and the choice of the most suitable conductivity-holdup relation. The general method proposed is applied to the dispersion of gas in a mechanically stirred tank agitated by a pitched blade turbine, finally resulting in affordable data for CFD models validation.