Numerical study on flow and heat transfer of non Newtonian fluids in coiled micro tube

In the present study, an attempt was made to explore the flow behavior of non-Newtonian fluids in coiled micro tube. The non-Newtonian fluids were aqueous solutions of carboxymethylcellulose (CMC), a polymer, with concentrations of 0.1 wt% and 0.5 wt%. Initially, the numerical procedure was validated by comparing the present predicted pressure drop of Newtonian fluid flowing in straight micro tube with known experimental data. Numerical computations were then carried out to characterize velocity field and temperature field of the non-Newtonian fluids flowing in coiled and straight micro tube. Friction factor and Nusselt numbers were computed and compared with the existing correlations for conventional tubes for the flow range of 500≤ NRe ≤1000. The results showed that the pressure drop in micro coiled tube was higher than the conventional tube. The heat transfer performance of coiled micro tube was more significantly enhanced for Newtonian fluids. Further work was carried out to study the effect of heat transfer for pseudo plastic fluids. It was found that the heat transfer performance of coiled micro tube increased with increase in pseudo plasticity of fluid.