Turbulent heat transfer with FC-72 in small diameter tubes

The heat transfer process of turbulent, single-phase forced convection of FC-72 through small diameter tubes with 1 and 1.8 mm inner diameters was experimentally investigated. The influence of Reynolds number (Red), Prandtl number (Pr), viscosity ratio (μ/μw) and ratios of heated length to inner diameter (L/d) on turbulent heat transfer was studied in detail. The experimental data were also compared with the values calculated by classical correlations for conventional sized channels. The results indicated that the classical heat transfer correlations are not adequate for calculation of the heat transfer coefficient in small diameter tubes. The Nusselt numbers (Nud) for 1 and 1.8 mm depend on Red in a different manner compared to classical correlations. The deviation from classical heat transfer correlations increased as the Red increase. The turbulent heat transfer correlation for FC-72 flow in tubes with diameters of 1 and 1.8 mm has been developed based on the experiment data. The differences between experimental and predicted Nud are within ±15%.