The effect of flow pulsation on Al2O3 nanofluids heat transfer behavior in a helical coil: A numerical analysis

Nanofluids heat transfer in a helical coil under pulsation condition was numerically simulated. The dynamic single phase model which considered Brownian motion effect was utilized to study the Al2O3 nanofluids heat transfer in helical coils. The reliability test results were consistent with experimental results. Then, pulsation was further imposed. The influence of the pulsation frequency on the heat transfer performance was explored. And the changes of instantaneous h with frequency were further studied to interpret the results. The axial velocity contours, axial velocity distributions, and cross-section velocity vectors at various planes along the coil were examined. The results revealed that there was an optimum pulsation frequency for heat transfer augmentation within the scope of Re. The secondary flow generated in cross region and the counter-rotating vortex formed in the axial direction all devoted to the helical coil heat transfer augmentation under pulsation. (C) 2020 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.