Large eddy simulation of mixed convection of hybrid nanofluid containing nano-encapsulated phase change material in a vertical channel

The large Eddy Simulation approach is applied to simulate turbulent mixed convection of nanofluid through a vertical channel. Nanofluid consists of nano-encapsulated phase change material (NEPCM) nanofluid (5% n-octadecane/water) and hybrid nanofluid (1% CuO + 5% n-octadecane/water). The wall-adapting local eddy-viscosity model is used. The computations are performed at a friction Reynolds number of 180. The turbulence statistics quantities including normalized mean velocity and temperature, root mean square of velocity and temperature fluctuations, Reynolds shear stress and turbulent heat flux are estimated. The agreement between computed mean velocity and temperature profiles and turbulence statistics by direct numerical simulation data is good. The present numerical results show that addition of nanoparticles into pure water increases normalized mean stream-wise velocity, fluctuations of velocity and temperature, Reynolds shear stress and turbulent heat flux. By adding NEPCM and CuO nanoparticles into pure water normalized velocity fluctuations grow in three directions, as a result of which normalized Reynolds shear stress augments. Enhancement of normalized root mean square of velocity fluctuations can cause a strengthening exchange of mass and momentum, and leads to augmentation of heat transfer. The average decrease in normalized mean temperature is 8.5% for NEPCM nanofluid and 12% for hybrid nanofluid. The results indicate that hybrid nanofluid containing CuO and NEPCM nanoparticles shows a better thermal performance than nanofluid containing only NEPCM nanoparticles and pure water. This makes hybrid nanofluid in presence of NEPCM particles to be a possible choice in cooling process applications.