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Development of analytical equations for void fraction in biphasic systems using gamma radiation and MCNP6 code
W L Salgado1, R S F Dam1, C M Salgado1
1Instituto de Engenharia Nuclear - (IEN), Rua Hélio de Almeida 75, 21941-906, Cidade Universitária, RJ, Brazil.
Summary
New mathematical equations accurately calculate void fractions in pipes using gamma densitometry. This method, validated with simulations, offers precise measurements for two-phase flow systems.
Area of Science:
- Nuclear Engineering
- Fluid Dynamics
- Computational Physics
Background:
- Accurate void fraction measurement is crucial for characterizing two-phase flow in industrial processes.
- Existing methods for void fraction determination can be complex or lack precision.
- Gamma densitometry offers a non-intrusive approach for fluid property analysis.
Purpose of the Study:
- To develop and validate novel mathematical equations for calculating void fractions in pipes using gamma densitometry.
- To assess the accuracy of these equations across various pipe geometries and flow regimes.
- To compare the performance of the new equations against existing literature methods.
Main Methods:
- Monte Carlo simulations using the MCNP6 code were employed to model a gamma densitometry setup with a Cesium-137 (Cs-137) source and Sodium Iodide (Thallium-doped) [NaI(Tl)] detector.
- Biphasic water-gas flow models were simulated in square and cylindrical tubes of varying diameters.
- Gamma-ray transmission measurements using Americium-241 (Am-241), Cesium-137 (Cs-137), and Cobalt-60 (Co-60) sources were used to validate the void fraction calculation equations.
Main Results:
- The void fractions calculated from simulated gamma-ray transmission photopeaks closely matched the actual void fractions in the models.
- The developed equations demonstrated high accuracy, with a maximum mean relative error of only 0.21% for cylindrical tubes.
- The equations performed well across stratified and annular flow regimes, indicating robustness.
Conclusions:
- The proposed mathematical equations provide a reliable and accurate method for determining void fractions in pipes via gamma densitometry.
- This approach is effective for various pipe geometries, radiation sources, and flow conditions.
- The findings contribute to improved monitoring and control of two-phase flow systems.
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