Investigation of using 60Co source and one detector for determining the flow regime and void fraction in gas–liquid two-phase flows

• 1 60Co source and 1 NaI detector were used to determine flow regime and void fraction.
• A primary ANN was used for recognizing flow regime and 3 for void fraction prediction.
• 3 extracted features from registered gamma spectrum were used as inputs of ANNs.
• Using this method just regimes of stratified and annular were identified from each other.

In this study, a simple detection system comprised of one 60Co source and just one NaI detector was investigated in order to identify flow regime and measure void fraction in gas–liquid two phase flows. For this purpose, 3 main flow regimes of two-phase flows including stratified, homogenous and annular with void fractions in the range of 5–95% were simulated by Monte-Carlo N Particle (MCNP) code. At first step, 3 features (count under full energy peaks of 1.173 and 1.333 MeV, and count under Compton continuum) were extracted from registered gamma spectrum. These 3 extracted features were used as inputs of artificial neural network (ANNs). A primary network was trained for identifying the flow regimes, but after testing many different structures, it was found that just two regimes of stratified and annular could be completely identified from each other. After identifying the mentioned two flow regimes by the first ANN, two specific ANNs were also implemented for predicting the void fraction. Using the proposed method in this work, void fraction percentages were predicted with a mean relative error (MRE) of less than only 0.42%. Using fewer detectors is of advantage in industrial nuclear gauges, because of reducing economical expenses and also simplicity of working with these systems.