Authors: Rita Lamosa, Ana Moita, Antonio Moreira, Artem Nikulin, Helder Santos

In this paper the flow and the heat transfer of C60/tetralin nanofluid is investigated in a horizontal, circular, smooth, mini-tube with 3.5 mm of inner diameter, under an imposed constant heat flux, for laminar, transition and turbulent flow regimes. Three mass concentrations of nanofluid (0.10%, 0.30% and 0.66 mass%) as well as pure tetralin were experimentally tested at different mass flow rates and at three different inlet temperatures (25ºC, 35ºC and 45ºC). Experimental measurements were taken, allowing to determine friction factors and convective heat transfer coefficients. The results revealed that the pressure drop raises with the increase in mass concentration of the nanoparticles and with temperature. It was also found that, in the laminar flow regime the Nusselt number is not affected by the addition of the nanoparticles. However, in the turbulent region, the Nusselt number increases with the increase in mass concentration of the nanoparticles, being this augmentation more pronounced as the temperature increases. The results also revealed that the addition of C60 nanoparticles allows to decrease the critical Reynolds number for the start of transition from laminar to turbulent.

Rita Lamosa¹ | Ana Moita^1,2 | Antonio Moreira¹| Artem Nikulin³ | Helder Santos⁴
1 IN+, Center for Innovation, Technology and Policy Research, IST, Universidade de Lisboa, Portugal
2 CINAMIL – Centro de Investigação Desenvolvimento e Inovação da Academia Militar, Instituto Universitário Militar, Lisboa, Portugal
3 Centre for Cooperative Research on Alternative Energies (CIC energiGUNE), Basque Research and Technology Alliance (BRTA), AlavaTechnology Park, Spain
4 ADAI-LAETA, Delegação do IPLeiria, Escola Superior de Tecnologia e Gestão do Politécnico de Leiria, Portugal