Experimental study on the influence of nanoparticle PCM slurry for high temperature on convective heat transfer and energetic performance in a circular tube under imposed heat flux

Nanoparticle PCM (Phase Change Material) slurry is a dispersion where the PCM is dispersed in fluid. Compared to fluid, these nanofluids have a higher heat capacity during the phase change and a possible enhancement, as a result of this phase change, in the heat transfer phenomenon. To appreciate the merits, in terms of energy, an experimental study has been carried out with fluid based on THERMINOL 66 (T66) with NaOH KOH nanoparticles, flowing inside a horizontal tube. Pressure drop and heat transfer coefficients have been measured at different inlet temperatures (150 °C < Ti < 300 °C) and at various flow rates (2500 < Re < 25 000). The Reynolds and Nusselt numbers have been determined using thermal conductivity and viscosity measured in the same conditions as those in tests. An energy Performance Evaluation Criterion (PEC) has been defined: it is the ratio of heat transfer rate at fixed pumping power. The results obtained show an improvement of this energetic criterion at low velocity compared to the base fluid.