Steam-water Two-phase Flow Research Articles

Void Fraction and Vapor and Liquid Temperatures: Local Measurements in Two-Phase Flow Using a Microthermocouple

A technique is described which enables the detection of the phase (liquid or vapor) in steam-water two-phase flow and the temperature measurement of each phase, using the hot junction of a microthermocouple. The signals are processed with a multichannel analyzer in order to obtain the amplitude histograms of the temperature. Significant results are obtained in pool boiling, forced convection subcooled boiling, and flashing flow of water.

Metering of Steam-Water Two-Phase Flow by Sharp-Edged Orifices

This paper describes work conducted on the passage of steam-water mixtures through standard sharp-edged orifices for the prediction of flow conditions. When the stagnation enthalpy or alternatively the dryness fraction at the orifice is known, it is shown that the mass flow rate can be approximately determined. For the case where a steam-water mixture passes through a pipeline to the atmosphere or to a low-pressure receiver so that critical flow occurs at the outlet, both the mass flow rate and the stagnation enthalpy may be approximately evaluated using an orifice meter in series with a pressure tapping located at the point of critical flow. In this case, a trial-and-error method is necessary. The experimental results were within a range of dryness fractions from 1 per cent to 56 per cent, orifice pressures from 75 to 275 lb/in2 abs., differentials from 15 to 780 mmHg under water and flow rates from 54 700 to 508 000 lb/h. Orifices of 5.591 and 6.615 in diameter were installed in 7.9-in diameter pipes which were equipped with radius ( D and D/2) taps. The method employs a correlation between the homogeneous dryness fraction x, and a corrected dryness fraction x m necessary for evaluating the two-phase density used in the conventional single-phase meter equation.