Thermal Performance Analysis of Nanofluids In Turbulent Forced Convection Flows

In this research the enhancement of nanofluids convective heat transfer through a circular tube with a constant heat flux condition in the turbulent flow regime is numerically studied. All of the nanofluid properties depend on temperature and nanoparticle volume concentration. The incompressible and steady-state forms of continuity, Navier-Stokes and energy equations have been discretized using finite volume approach by solving the SIMPLER algorithm. In order to demonstrate the validity and precision of the numerical procedure, calculated friction factors and Nusselt numbers have been compared with the experimental data and existing correlations. To attain the best prediction, the different turbulent models are examined and it has been observed that the best model to predict the near wall treatment is based on enhanced wall function in the K-ε turbulent model. The effects of nanoparticle concentrations (1-10% Al2O3), Reynolds and Prandtl numbers are investigated in EG/water mixture and a dimensionless effectiveness quantity has been defined to measure the thermal performance of nanofluid with respect to base fluid. From the results, it can be deduced that, convective heat transfer enhances considerably with increasing the particle concentration. Also the values of nanofluids effectiveness are observed to be positive and desirable; this illustrates the improvement of the thermal performance and reduction in the maximum wall temperature.

کلیدواژه ها:

Nanofluid ، Nanoparticles ، Convective heattransfer coefficient ، Effectiveness ، Al2O3