ELECTRICAL-IMPEDANCE METHOD FOR FLOW REGIME IDENTIFICATION IN VERTICAL UPWARD GAS-LIQUID 2-PHASE FLOW

A new method using an indigenously developed electronic circuit for id entifying all the flow regime transitions in a Vertical upward gas-liq uid two-phase flow is reported. The circuit basically converts the voi d fraction signal of the two-phase mixture into a series of square pul ses of varying width. The probability density function of the pulse wi dth spectra is analysed for detection of bubble-to-slug flow transitio n. Slug-to-churn flow transition is detected on the basis of liquid sl ug length measurements. Churn to annular flow transition is identified on the basis of the number of liquid bridging. Experimental analysis shows that, in bubble flow through narrow tubes, bubbles bigger than a critical size cannot exist without forming Taylor bubbles. The techni que has potential to minimize substantially the adverse effects of ele ctrode polarization, stray impedance and varying conductance of the li quid medium. The sampling time and sampling frequency can be varied in dependently. The circuit can be used for measurement of both conductin g and dielectric fluids.