Ali Akbar Jamali - Imam Hossein University, Engineering faculty, Chemical Engineering Department
musa Nazari - Imam Hossein University, Engineering faculty, Chemical Engineering Department
Mehdi Saberian - Imam Hossein University, Engineering faculty, Chemical Engineering Department

In this study, nanoparticles of nickel ferrite (Ni-Fe2O4) with a mean particle size of 20 nm have been prepared by chemical precipitation method through one-step. The as-prepared samples were characterized by powder X-ray diffractometry (XRD), and transmission electron microscopy (TEM). TEM indicated that the particles were spherical with particle sizes in the range 20 nm. Heat transfer coefficient of Nickel ferrite nanofluid flowing in a double pipe heat exchanger with and without wire coil inserts are studied experimentally. The effect of different parameters such as Reynolds number from 3000 to 8000 and in volume concentration range from 2% and 5%.The nanofluid is prepared by dispersion of Ni-Fe2O4 nanoparticles in base ethylene glycol/water and stabilized by means of an ultrasonic device. The heat transfer coefficient enhancement with the use of 2% and 5% of Ni-Fe2O4 nanofluid for the same set of test conditions from 27% and 41.5% for Reynolds number 3000 and 22.3% and 36.3% for Reynolds number 8,000 compared to base fluid with inserts, respectively. The measured values of heat transfer coefficient are compared with the published literature. Based on the experimental data, generalized correlations is proposed for Nusselt number and thermal conductivity coefficients.

NiFe2O4 nano-particles, Double pipe heat exchanger, Turbulent flow, Wire coil