Synthesis of phase change nanocapsule and use in nanofluid preparation

In this study nano capsules with polyurethane shell and n-nonadecane core were synthesized using interface polymerization technique. Density, viscosity, heat transfer coefficient and heat capacity of the solutions with 0,42%, 0,84%, 1,68% volume fraction were measured. Solutions were prepared with two different base fluids which were water and ethylene glycol. Heat transfer experiments were conducted with water based nanofluids at double pipe heat exchanger system. Melting and freezing points and phase change entalpies of polyurethane/nanodecane nanocapsules were measured with DSC analysis are 31.90°C -30.34°C ve 92.846 J/g-91.862 J/g, respectively. It is experimentally determined that the average nanocapsule size is 100 nm, changing in the range of 55-165 nm. It was observed that viscosities of water based and ethylene glycol based solutions are higher than base fluids. Viscosity of the solutions was increased with higher volumetric mass fraction. Viscosity of the solutions was decreased with higher temperature. Measured heat transfer coefficients were between 0,527-0,656 W/mK for water based fluids and 0,247-0,255 W/mK for ethylene glicol based fluids. Impovement ratio for Nusselt number is 18% for maximum solid rate.