An empirical study on heat transfer and pressure drop characteristics of CuO–base oil nanofluid flow in a horizontal helically coiled tube under constant heat flux

An experimental investigation has been carried out to study the heat transfer and pressure drop characteristics of nanofluid flow inside horizontal helical tube under constant heat flux. The nanofluid is prepared by dispersion of CuO nanoparticle in base oil and stabilized by means of an ultrasonic device. Nanofluids with different particle weight concentrations of 0.5%, 1% and 2% are used. The effect of different parameters such as flow Reynolds number, fluid temperature and nanofluid particle concentration on heat transfer coefficient and pressure drop of the flow are studied. Observations show that by using the helically coiled tube instead of the straight one, the heat transfer performance is improved. Also, the curvature of the tube will result in the pressure drop enhancement. In addition, the heat transfer coefficient as well as pressure drop is increased by using nanofluid instead of base fluid. Furthermore, the performance evaluation of the two enhanced heat transfer techniques studied in this investigation shows that applying helical tube instead of the straight tube is a more effective way to enhance the convective heat transfer coefficient compared to the second method which is using nanofluids instead of the pure liquid.