Flow boiling heat transfer of carbon dioxide with PAG-type lubricating oil in pre-dryout region inside horizontal tube

A flow boiling heat transfer model for horizontal tubes is proposed for CO2 with entrained polyalkylene glycol (PAG) type lubricating oil in the pre-dryout region. A general power law-type model with a power number of 3 is used together with the average thermodynamic properties of the CO2-oil mixture. A convective enhancement factor (F) is recommended according to the relationship between the Lockhart-Martinelli parameter and the ratio alpha(tp)/alpha(1), which was obtained based on previous experimental results for CO2 and oil. A new suppression factor (S) is introduced that comprises a suppression term for forced convection and oil concentration term for bubble generation. A comparison of six correlations showed that the proposed correlation can depict the influence of the mass and heat fluxes on both nucleate and convection boiling reasonably well. Crown Copyright (C) 2013 Published by Elsevier Ltd and IIR. All rights reserved.