Heat Transfer Effects on Non-Newtonian Fluids: Nanofluid Analysis in Helical Heat Exchangers

Abstract

This study investigates the heat transfer characteristics of non-Newtonian nanofluids in a helically baffled heat exchanger with elliptic tubes, combining experimental and numerical approaches. Xanthan gum (XG) aqueous solutions (0.2 wt%) serve as the non-Newtonian base liquid, with multi-walled carbon nanotubes (MWCNTs) dispersed at various weight fractions (0.2%, 0.5%, and 1.0%). Single-phase and multiphase flow models are employed to examine convective heat transfer and fluid flow dynamics in porous media. Results indicate significant enhancement in heat transfer with increasing Reynolds number and nanoparticle concentration. For nanofluids, Nusselt numbers increase by 11% to 35%, and thermal performance factors improve by 3% to 26%. Numerical simulations validate experimental findings, with strong agreement observed. Correlations for predicting Nusselt numbers, friction factors, and Euler numbers are proposed. This research highlights the importance of grid quality in simulations and offers insights into optimizing heat exchanger performance with nanofluids.