Nucleate pool boiling of R-114 and R-114-oil mixtures from smooth and enhanced surfaces—I. Single tubes

• Published in: International journal of heat and mass transfer 1995, Vol.38 (8), p.1347-1361
• Main Authors: Memory, S.B., Sugiyama, D.C., Marto, P.J.
• Format: Article
• Language: English
• Subjects: Applied sciences; Devices using thermal energy; Energy; Energy. Thermal use of fuels; Exact sciences and technology; Heat exchangers (included heat transformers, condensers, cooling towers); Heat transfer; Theoretical studies. Data and constants. Metering
• ISSN: 0017-9310; 1879-2189
• DOI: 10.1016/0017-9310(94)00263-U

Measurements of pool-boiling heat-transfer coefficients in pure R-114 and R-114-oil mixtures are reported for a smooth tube and eight enhanced tubes (five finned and three re-entrant cavity). Tests were carried out at atmospheric pressure while decreasing the heat flux. For pure refrigerant, the finned tubes typically provide enhancements of between 3 and 4, whilst the re-entrant cavity tubes provide enhancements of more than 10 at low heat fluxes, decreasing to around 4 at high heat fluxes. With addition of oil, performance of the finned tubes at first increases (with 3% oil) before dropping off. For the re-entrant cavity tubes, addition of oil causes a steady drop-off in performance, especially for the porous tube where heat transfer rates similar to that of the smooth tube were obtained.