Contribution to the study of nanofluid thermophysical properties with the objective of enhancing the heat transfer

Abstract

In this thesis we provided an overview of fundamental heat transfer principles, including conduction and convection, emphasizing the utilization of nanofluids to improve heat transfer across diverse engineering applications. Essential applications, principles, and physical characteristics of nanoparticles were explored, alongside strategies and methodologies for preparing nanofluids and assessing nanoparticle stability. The experimental setup, featuring a square-shaped spiral heat exchanger, and associated measurement equipment was detailed. Mathematical equations relevant to heat transfer with nanofluids were examined, and modeling equations were formulated incorporating mass, momentum, and energy conservation principles. The numerical methodology used to solve these equations under specific boundary conditions was explained, along with a comprehensive overview of the steps for conducting CFD simulations with ANSYS Fluent, including mesh generation, boundary conditions, solution selection, and convergence criteria. The results of experimental work on the square-shaped spiral heat exchanger and numerical simulations were presented, demonstrating significant improvements in heat transfer flux and Nusselt numbers with nanofluids compared to pure water. Notably, a 13.46% increase in heat transfer flux was observed with a 5% nanofluid concentration and a 4.3 L/m flow rate. Additionally, there were significant increases in Nusselt numbers and heat transfer coefficients for nanofluids, indicating enhanced heat exchange performance with higher nanofluid concentration or flow Reynolds numbers