Experimental and analytical investigation of the convective heat transfer potential of PEG 400 based nanocolloids with Al 2 O 3 and ZnO nanoparticles

In this paper, two types of nanoparticles were used to manufacture nanoenhanced PEG 400 fluids. Both types of nanofluids (i.e. Al 2 O 3 and ZnO with PEG 400) were experimentally studied in regard to their morphology, thermal stability, porosity and thermophysical properties. This research presents an analysis of possible behavior at heat transfer for these new fluids, based on several properties previously determined. Specifically, Prandtl number, thermal diffusivity, Mouromtseff number and pumping power were discussed for all fluids. Results demonstrated an increase up to 4% in thermal diffusivity for suspensions with ZnO, while Pr number remains the same or even decreases, proving a better heat transfer of ZnO – PEG 400 in comparison with the base fluid. For Al 2 O 3 it was noticed an increase in pumping power of up to 8.1% in laminar flow, while in turbulent regime the increase or decrease in relative Mo number is not significant. As a general outcome, it can be concluded that the best results were noticed for low concentrations of ZnO – PEG 400 nanofluids, making them a good option to increase the convection heat transfer.