Analysis of a single-phase natural circulation loop with hybrid-nanofluid

A rectangular single-phase natural circulation loop (NCL) has numerous industrial applications such as nuclear reactors, geothermal systems, solar water heating systems, gas turbine blade cooling, electrical machine rotor cooling, and electronic device cooling. To establish the heat transport capability of a NCL, it is important to realize the mass flow rate. Commonly, water has been considered as working fluid. In this paper, a hybrid nanofluid (Al2O3-Cu-water) is considered as working fluid. Firstly, the governing equations are written for the NCL. Then the dimensionless form of governing equations are solved. The influence of cooler length, heater length, tubes diameter, loop height, loop inclination angle, the concentration of nanoparticles, the power of the heater and the type of working fluid on the loop temperature distribution and loop mass flow rate are scrutinized. The results illustrate that the steady-state mass flow rate goes up with augmenting the heater power, the loop height, the loop diameter and the concentration of nanoparticles whereas it abates with rising the loop inclination angle. The results discovered that the steady-state mass flow augments 34.8% if the loop diameter increases 20% at phi = 2%. Also, the Reynolds number reaches a maximum value (Re-ss = 1303.5) at phi = 6% for hybrid nanofluid.