Thermal hydraulic characteristics of turbulent single-phase flow in an enhanced tube using louvered strip insert with various slant angles

Effect of slant angle (α) of louvered strip insert on single-phase forced convection heat transfer and friction factor of internal flow was investigated experimentally. The parameter of slant angles (α) 15°, 20° and 25° was examined at the Reynolds number (Re) of 5300-17,500. The plain tube was also performed for comparison. The results show that the louvered strip insert provided the increases in heat transfer and friction factor up to 77.02% and 3.35 times above the plain tube. The results also indicate that heat transfer and friction factor increased with increasing slant angle. The highest slant angle yielded the highest thermal performance factor in the value of 1.12. Empirical correlations were also developed for Nusselt number and friction factor based on experimental data.