부산대학교 도서관

Configuration improvements are greatly important in heat transfer enhancement. In this study, TiO.sub.2/water nanofluid was used in combination with ribbed tubes for this purpose. Namely, this article presents a numerical investigation on the effect of rib geometries (trapezoidal and triangular rib shapes), number of ribs (4, 6, and 8 ribs) on heat transfer using TiO.sub.2 nanofluid in turbulent flow with Reynolds numbers of 5000-40,000. The thermal and hydraulic behavior of nanofluids was simulated utilizing single-phase approach with the assumption that the fluid properties are constant with temperature, and the flow is under uniform heat flux. The average size of the nanoparticles used in this work was 50 nm, and the nanofluid was considered at concentrations of 0.25-1.0%. The investigations were performed with the aim of establishing the impact of rib numbers and shapes on friction factor and heat transfer employing TiO.sub.2/water nanofluid as the working fluid. The results show that the helical-ribbed tube significantly improves heat transfer compared to the plain tube taking into account the shape and number of ribs. Further, by means of performance evaluation criteria, the tubes with trapezoidal ribs provide better thermal performance followed by the ones with triangular ribs compared to the plain tubes. Ultimately, the nonlinear models of Nusselt number and friction factor in the foregoing configurations were proposed with maximum deviations of ± 7.0% and ± 5.0%, respectively.
Author(s): Aadel A. R. Alkumait [sup.1], Thamir K. Ibrahim [sup.1], Maki H. Zaidan [sup.1], Ahmed T. Al-Sammarraie [sup.1] [sup.2] Author Affiliations: (1) grid.442858.7, 0000 0004 1796 0518, Mechanical Engineering Department, [...]