| Abstract: | Heat transfer and friction factor in a tube with turbulator internally grooved and rib are studied using numerical simulation. Two different turbulator geometries, including only groove and both groove and rib, on the tube wall are investigated. The study is developed for different parameters of turbulator including pitch ratio (PR), groove and rib height (DR), and Reynolds number in the range of 10 000 to 38 000. The results revealed that the best Nusselt number is achieved for GR turbulator and for the tube wall with PR = 2 and DR = 1. Furthermore, for a specific turbulator parameter, Nusselt number is improved by 46% compared with the experimental result. The results show that the friction factor decreases by increase of both step and height ratios. For example, based on Reynolds number, 21% to 69% reduction in the friction factor was observed for PR = 7 and DR = 3. In addition, the correlations for Nusselt number and friction factor with acceptable deviation are presented for the studied turbulators. Finally, thermal performance enhancement factor is defined to be a good criterion for selection of the optimum turbulator and their parameters. |
