Date of Award
Master of Science (MS)
This thesis presents a numerical investigation of laminar and turbulent fluid flow and convective heat transfer of nanofluids in the entrance and fully developed regions of flow in a channel and a pipe. In recent years, nanofluids have attracted attention as promising heat transfer fluids in many industrial processes due to their high thermal conductivity. Nanofluids consist of a suspension of nanometer-sized particles of higher thermal conductivity in a liquid such as water. The thermal conductivity of nanoparticles is typically an order-of-magnitude higher than the base liquid, which results in a significant increase in the thermal performance of the nanofluid even with a small percentage of nanoparticles (~4% by volume) in the base liquid. In this study, Al2O3, CuO and carbon nanotube (CNT) nanoparticles with the particle concentration ranging from 0 to 4 % by volume suspended in water are considered as nanofluids. Entrance flow field and heat transfer of nanofluids in a channel and pipe are computed using the commercially available software ANSYS FLUENT 14.5. Both constant wall temperature and constant heat flux boundary conditions are considered. An unstructured two-dimensional mesh is generated by the software ICEM. For turbulent flow simulations, two-equation k-epsilon, standard k-omega and SST k-omega models as well as the one-equation Spalart-Allmaras models are employed. The results are validated and compared using the experimental data and other empirical correlations available in the literature. The entrance length of laminar and turbulent flows in a circular pipe and channel are calculated and compared with the established correlations in the literature. The effect of particle concentrations, Reynolds number and type of the nanoparticles on the forced convective heat transfer performance are estimated and discussed in detail. The results show significant improvement in heat transfer performance of nanofluids, especially the CNT nanofluids, compared to the conventional base fluids.
Ramesh K Agarwal
Kenneth Jerina Swami Karunamoorthy