Multiphase modeling approach for ionic liquids (ILs) based nanofluids: Improving the performance of heat transfer fluids (HTFs)

Ionic liquids (ILs) based nanofluids was recently being considered as a heat transfer augmentation method via improving the thermal properties of heat transfer fluids (HTFs). In this study, the thermal performance of ionic liquids (ILs) based nanofluids in a circular tube was numerically analyzed using (i) a continuum based model and an (ii) eulerian based two phase model. For the continuum model, we considered ILs based nanofluids as a mixture averaged single fluid. The eulerian based model connected with two fluids multiphase model which emphasizes the dynamics of interaction between the nanoparticles and the base fluid. The study was carried out for ILs based nanofluids: a mixture of 1-butyl-3-methylimidazolium bis{(trifluoromethyl)sulfonyl} imide ([C(4)mim] [NTf2) ILs and Al2O3 nanoparticles. The numerical model was validated against the experimental data for ILs based nanofluids and the Shah's equation for base ILs. The results showed that the overall heat transfer coefficient increases significantly for Its based nanofluids for a range of Reynolds numbers. The results also suggested that the two phase eulerian model was more reliable than continuum based model for predicting the heat transfer performance under such a configuration. A parametric analysis of nanofluids volume fraction and heat flux were also analyzed. Finally, an empirical model was proposed in this study to analyze the heat transfer performance of Its based nanofluids under laminar flow conditions.