Numerical analysis and correlation comparison of void fraction in refrigerant two-phase flow in horizontal tubes

This study explores the void fraction in R290 refrigerant two-phase flow within small-diameter horizontal tubes through numerical simulations and correlation comparisons. Although there has been extensive research on traditional refrigerants, there is a lack of data and predictive correlations for R290, a promising low-global- warming-potential alternative. By employing the Euler model combined with the Realizable k-epsilon turbulence model, this research examines the void fraction behavior under various conditions, including vapor quality, mass flux, tube diameter, and saturation temperature. The study identifies distinct flow patterns and their impact on void fraction, providing new insights into the two-phase flow dynamics of R290. A key contribution is the evaluation of 35 void fraction correlations, with the El Hajal et al. correlation providing the best predictive accuracy for R290, achieving a Mean Relative Deviation of 1.11% and a Mean Absolute Deviation of 2.37%. This study provides numerical simulation results and a suitable correlation for R290 void fraction prediction, offering a reference for the transition to sustainable refrigerants.