Semnan University Press Journal of Heat and Mass Transfer Research 2345-508X 6 1 2019 05 01 Investigation on Turbulent Nanofluid Flow in Helical Tube in Tube Heat Exchangers 31 39 3101 10.22075/jhmtr.2018.12696.1191 EN Puriya Mohamad Gholy Nejad University of Isfahan Ali Reza Solaimany Nazar University of Isfahan Zohreh Rahimi Ahar University of Isfahan Hajar Rajati University of Isfahan Journal Article 2017 11 04 In this study, the thermal characteristics of turbulent nanofluid flow in a helical tube in the tube heat exchanger (HTTHE) were assessed numerically through computational fluid dynamics (CFD) simulation. The findings of both the turbulent models: realizable k-epsion (k-ε) and re-normalisation group (RNG) k-epsilon were compared. The temperature distribution contours show that realizable and RNG k-ε models, together with the swirl dominated flow are of more uniform temperature distributions. The proper prediction of two layer theory leads to having a uniform temperature distribution and proper dimensionless wall distance (Y+). The turbulent flow and heat transfer of two nanofluids (SiO₂, Al₂O₃) and base fluid with respect to swirl dominated flow was simulated through the RNG model. The effects of the concentration of nanoparticles on heat transfer characteristics in HTTHE and two turbulent models were analyzed in a comprehensive manner. It is concluded that up to 1% concentration of SiO₂ and 1% concentration of Al₂O₃, similar heat transfer characteristics are observed. Comparison between the CFD results with the predicted values for friction factor coefficient (f) and Nusselt number (Nu) calculated through experimental correlations indicate the maximum errors of 6.56% and 0.27%, respectively. https://jhmtr.semnan.ac.ir/article_3101_56d085546ae515f2e4c3ded4a5644f96.pdf