A new correlation of two-phase frictional pressure drop for evaporating flow in pipes

The calculation of two-phase frictional pressure drop for evaporating flow in pipes is required in many fields. Although plenty of studies associated with this issue have been carried out, an accurate correlation is still needed. In this paper, a comprehensive survey of correlations and experimental investigations of two-phase frictional pressure drop is conducted. The 2622 experimental data points of 15 refrigerants are obtained, with hydraulic diameter from 0.81 to 19.1 mm, mass flux from 25.4 to 1150 kg m−2 s−1, and heat flux from 0.6 to 150 kW m−2. There are 29 existing correlations evaluated against the experimental database. It is found that the best correlation has a mean absolute relative deviation (MARD) of 28.5%. Based on the experimental database, a new correlation is proposed, which has an MARD of 25.2%, improving remarkably the prediction of two-phase frictional pressure drop for pipe evaporating flow, especially for micro-channels.