Thermodynamic optimization of water–Al2O3 nanofluid flows through a helical pipe in laminar regime

Nanofluids, i.e. fluid suspensions of nanometer-sized solid particles are the new generation of heat transfer fluids for various industrial applications because of their excellent thermal performance.This study analytically examines the effects of adding nanoparticles on the entropy generation ofwater–Al2O3 nanofluid flows through a helical pipe under constant wall heat flux thermalboundary condition in laminar regime. It is found that adding nanoparticles improves the thermalperformance of water–Al2O3 flow with Re numbers less than 6000. Also it is shown that adding nanoparticles leads to increased entropy generation in the cases that fluid flow (pressure drop)irreversibility is dominant. The Dean number and radius ratio in which the entropy generation isminimum, decreases by increasing nanoparticles volume concentration from about 3175 and 14.5for pure water to 2965 and 5.3 for 5 Vol% Al2O3 nanoparticles in the based fluid of water respectively. Moreover optimum conditions of radius ratio and Dean Number for laminar nanofluid flow are obtained.

Keywords:

Entropy generation , thermodynamic optimization , nanofluid , helical pipe , laminar regime