Problems of Measuring Gas Content in Oil in a Two-Phase Flow: A Review

In view of the necessity of measuring the air content in oil in two-phase flows in the context of general industry, a review of the most popular methods of measuring the air content in oil was carried out. This review includes an assessment of their advantages and disadvantages and of whether they meet criteria such as the degree of filling, the size and number of bubbles, verification, the absence of additional pressure drops, simplicity, and repeatability. In the review, the following methods were examined: the classic trapping method, a modified trapping method, a trapping method using hydrostatic pressure loss, the pressure loss due to frictional flow resistance, the pressure loss with a rapid increase in diameter, the pressure drop in a Venturi tube, the pressure drop in an orifice, a method using the Coriolis effect, the electrical resistance method, the electrical conductivity method, the electromagnetic method, the electrical capacitance method, the thermal anemometry method, the liquid–solid contact electrification method, the photographic method, holography, light scattering, sound dispersion, the ultrasonic transit-time method, X-ray radiation, gamma radiation, neutron radiation, and fiber-optic methods.