TURBULENT HEAT TRANSFER FOR INTERNAL FLOW OF ETHYLENE GLYCOL-AL2O3 NANOFLUID IN A SPIRAL GROOVED TUBE WITH TWISTED TAPE INSERTS

Numerical investigation for turbulent flow of nanofluid (Ethylene glycol/water-Al2O3) is carried out with a volume fraction of 0.5%, 1%, and 1.5%. The diameter of solid nanoparticles is equal to 20 nm. The range of Reynolds number in this simulation is from 6300 to 27500 through a three-dimensional steel corrugated spirally tube. For enhancement of the heat transfer performance in internal flow through the horizontal tube, the tube is combined with aluminum twist tape of a thickness of 0.8 mm and a width of 10 mm along the spirally corrugated tube. In the present work, the same twisted ratios TR=(y/w) are implemented for corrugated tube and tape. The predicted results showed that there is a clear increase in the values of heat transfer and the pressure drop in the direction of flow. Furthermore, the friction factor is increased because of the grooved and twisted tape which rise the resistance of the fluid flow. The values of Nusselt number are increased with the VOF of nanofluid. These numerical results are compared with the experiment found in the literature and showed a good agreement.