Investigating the orientation of the heater and cooler on the performance of a mini natural circulation loop with Water-Cu nanofluid

Todays, natural circulation loops (NCLs) are used in various industrial applications such as nuclear reactors, geothermal systems, electronic device cooling and so on. In a natural circulation loop, working fluid receives heat from a heat source (heater) and rejects it to a heat sink (cooler). The main objective of this paper is to investigate the effects of orientation of heater and cooler on the mass flow rate and temperature distribution in the natural circulation loop since the mass flow rate of the natural circulation loop is directly related to the heat transfer rate .The governing equations of the natural circulation loop are written as dimensionless form Cu-Water nanofluid considered as the working fluid and the effect of nanoparticles percentage on mass flow rate is investigated. Also, the effects of other parameters such as pipe diameter, height of the loop, loop inclination angle and the heater power on the mass flow rate of the loop and temperature distribution are investigated. The results show that increasing the diameter of the pipes, the percentage of nanoparticles, and the heater power increase the mass flow rate. However, the mass flow rate decreases with increasing loop inclination angle. The mass flow rate may be decreased or increased with increasing height depending on the orientation of the heater and cooler. In a constant heater power, the increase in the temperature of the nanofluid is much higher than other orientations when both the heater and the cooler are in the vertical position.