Table 1.

A brief review of holdup measurement in horizontal two-phase flow using two-electrode capacitance system.

Authors	Electrode Design	Guard Electrodes	Inner Diameter of Pipe	Two-Phase Components
Geraest and Borst [24]	Helical	Yes	5 mm and 50 mm	Air-water
Tollefsen and Hammer [23]	Concave and helical	No	82 mm	Gas-oil, gas-water
Ahmed [25], Ahmed and Ismail [26]	Concave and ring	No	12.7 mm	Air-oil
Caniere et al. [27]	Concave	Yes	9 mm	Air-water
Demori et al. [9] and Strazza et al. [5]	Concave	Yes	21 mm	Oil-water
De Kerpel et al. [28]	Concave	Yes	8 mm	Vapour-liquid
dos Reis and da Silva Cunha [29]	Concave, helical, and ring	No	33.85 mm	Air-water
An et al. [21]	Concave	Yes	10 mm	Oil-water
Zhai et al. [30]	Helical	Yes	20 mm	Oil-water
This paper	Helical	No	28.38 mm	Air-water, oil-water