Void fraction and pressure drop of hydrocarbon mixture during condensation in a helically coiled tube

A study was conducted to investigate the void fraction and pressure drop characteristics of methane/propane under different mass flux, saturation pressure and heat flux in a helically coiled tube, and the effects of distribution ratio (methane/propane) 50/50, 66/34 and 80/20 mole% were also analyzed. The friction pressure drop increased with the mass flux increased. Similarly, with the decrease of saturation pressure, friction pressure drops decreased. For a different distribution ratio, the friction pressure loss increases as the propane component increased in the mixture. Meanwhile, existing correlation models of different forms were used to evaluate the void fraction, and the Ahrens model provided the best accuracy with a MARD (mean absolute relative deviation) of 2.85%. In addition, the existing pressure drop correlations were used to compare with simulated data. Friedel correlation gave a well prediction for non-annular data with a MARD of 16.1%, while Cavallini correlation can well predict annular flow data with a MARD of 16.6%. Finally, considering the influence of flow regime transition, a new frictional pressure drop correlative was proposed, which can predict the data well with MARD of 5.4%. (c) 2021 Elsevier Ltd. All rights reserved.