Numerical Study of Nanofluid Convective Heat Transfer in Sinusoidal Tubes

ABSTRACT

The waviness of tube wall and adding nanoparticles to fluid as two passive enhanced heat-transfer techniques are dully accepted; however, the combined effect of their simultaneous usage has not been dealt with, yet. Therefore in the present study, the convective heat transfer of nanofluid laminar flow inside straight tube and sinusoidal tubes under constant heat flux boundary condition was documented. The nanofluid used in this study was Al₂O₃/water with volume fractions from 0 to 4%. The effects of Reynolds number, volume fractions of nanoparticles, and the geometry of sinusoidal tubes upon the heat-transfer coefficient were investigated. The results showed that using sinusoidal tubes enhances heat-transfer coefficients. Also, it was observed that increasing Reynolds number leads to higher heat-transfer coefficients in the convergent section. Moreover, it was observed that increasing the sinusoidal wave amplitude augments the convective heat-transfer coefficients; however, the increase in Nusselt number was slight. Furthermore, adding nanoparticles enhances heat transfer especially in large wave amplitude sinusoidal tubes.