Fundamental Study on Tracer Response Analysis for Water-Steam Flow Accompanied by Boiling in a Porous Medium

Abstract

This paper describes a tracer response analysis for water-steam flow through a porous medium. The experiments are carried out by using a packed, glass beads bed submerged horizontally in a thermostat at a temperature of more than 373K. Water is injected continuously into the bed under a constant pressure gradient and is heated from the surrounding, and a part of the water vaporizes in the bed. When the temperature and the flow rates of steam and hot water attain to be steady, 0.5 cm³ of ammonia water solution (about five volume percent of NH₃) is injected into the bed as a tracer by using a syringe for a few seconds. The tracer vaporizes in the bed, and ammonia gas flows out of the bed with steam. Then, the NH₃ content in the exit gas is measured by a gas chromatography every a few minutes. The experimental results of tracer response are analyzed by a onedimensional, mathematical model which describes mass transfer in water-steam flow under the boiling condition.
The conclusions are as follows:
(1) The mathematical model proposed in this paper describes experimental tracer response in gas phase of water-steam flow accompanied by boiling.
(2) The analysis of the tracer response gives the leading edge of boiling (the position at which water starts to boil in a porous medium).
(3) The theoretical value of the leading edge of boiling is consistent with the experimental one.