An experimental study on ferrofluid flow and heat transfer in a micro-fin straight circular tube

The use of various tools to improve heat transfer in fluid flow by researchers is steadily increasing. These tools result in the use of active and passive methods. In this article, an experimental study of heat transfer and fluid flow in a micro-fin tube has been done. Using a micro-fin tube along with using magnetic nanofluid (Ferrofluid) instead of pure water in the test bed made in this research are two ways to improve the heat transfer coefficient. The magnetic nanofluid has been checked for particle size and stability before use. Validation of the results has been done and the results have shown good compliance. The Nusselt number and pressure drop for pure water and magnetic nanofluid in the micro-fin tube are reported separately. A maximum Nu number enhancement of 23% and the most pressure loss of 24.3% are recorded in this research. Two empirical correlations are presented in order to predict Nusselt in a micro-fin tube for pure water and magnetic nanofluid with a mass fraction of 1% in a laminar flow regime. Performance coefficient has been used to accurately check the effect of pressure drop and Nusselt number. The results showed that using ferrofluid in a micro-finned tube in a flow with a lower Reynolds number results in a much better performance, and as the Reynolds number increases, the performance coefficient decreases and approaches to 1.