Advances in Void Fraction, Flow Pattern Maps and Non-Boiling Heat Transfer Two-Phase Flow in Pipes with Various Inclinations

Void fraction correlations for various pipe inclinations, both theoretical and empirical, that are widely available in the literature are compared with experimental data from various sources with different experimental facilities. The study produced a recommendation of six void fraction correlations and a proposed improved general void fraction correlation for horizontal to vertical pipe orientations. Further investigation has also been done specifically on the performances of available void fraction correlations with available experimental data for upward vertical two-phase flow. The work demonstrated that more accurate predictions can be obtained by giving attention to specific pipe inclination and ranges of void fraction. The result is a recommendation of a void fraction correlation that performs satisfactorily on the entire range of void fraction for upward vertical flow. Flow pattern maps of different pipe inclinations and gas-liquid combinations available in the literature are compared and discussed. The validity and limitations of the numerous two-phase non-boiling heat transfer correlations that have been published in the literature over the past six decades are discussed. Practical heat transfer correlations for a variety of gas-liquid flow patterns and pipe inclination angles are recommended.