Post-CHF heat transfer during two-phase upflow boiling of R-407C in a vertical pipe
نویسندگان
چکیده
1359-4311/$ see front matter 2009 Elsevier Ltd. A doi:10.1016/j.applthermaleng.2009.07.016 * Corresponding author. Tel.: +91 4422574680; fax E-mail address: [email protected] (A.R. Balakrishna This paper reports a study of heat transfer in the post-critical heat flux (post-CHF) regime under forced convective upflow conditions in a uniformly heated vertical tube of 12.7 mm internal diameter and 3 m length. Experiments were conducted with non-azeotropic ternary refrigerant mixture R-407C for reduced pressures ranging from 0.37 to 0.75, mass flux values from 1200 to 2000 kg/m s and heat flux from 50 to 80 kW/m. Data shows a considerable effect of system pressure on the post-CHF heat transfer coefficient for specified mass and heat fluxes. The post-CHF heat transfer coefficients for R-407C are compared with three existing correlations which are found to over predict the current data. A modified correlation to represent the experimental data for R-407C is presented. 2009 Elsevier Ltd. All rights reserved.
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Critical heat flux of R-407C in upflow boiling in a vertical pipe
The critical heat flux (CHF) in forced convective upflow has been investigated in a uniformly heated vertical tube of 12.7 mm internal diameter and 3 m length for different reduced pressures ranging from 0.32 to 0.98, with non-azeotropic ternary refrigerant mixture R407C as the working fluid. The onset of CHF was determined by the sudden rise in the wall temperature of the electrically heated t...
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