Manyetik nanoakışkan bazlı tek fazlı doğal taşınım döngüsünün sayısal incelenmesi

Single-Phase Natural Circulation Loop (SPNCL) systems are widely used passive heat transfer systems, and the density gradient caused by temperature difference and resulting buoyancy forces are the driving heat transfer mechanism. In this study, it is aimed to propose a Single-Phase Natural Circulation mini Loop (SPNCmL) under the influence of external magnetic field. This system works with a temperature sensitive ferrofluid under an external magnetic field which manipulates the ferrofluid flow propagation and temperature distribution by mangetic volume force and heat source effects. Within this scope, a numerical model is developed in COMSOL Multiphysics by coupling magnetic field (no currents), heat transfer in fluids and laminar flow modules. A NdFeB permanent magnet with a remanence of 1.22 T is located at the outlet of the cooler-end since the higher magnetization is obtained at lower temperatures. SPNCmL system is working with DIW-based Fe3O4 ferrofluids' (1-3 vol%.) concentration under the conditions of different heater powers (30 and 50 W). Applying an external magnetic field dramatically affects the system performance in terms of increase in ΔTheater and ε up to 34% and 25% compared to water. Higher Tmax values (up to 9%) are obtained for Fe3O4 ferrofluids compared to water, in contrast applying magnetic field results in an increment up to 5%. Additionally, the effect of magnetic field on the temperature distribution and flow propagation are evaluated by dimensionless temperature and velocity distributions at critical cross-sections of the cooler-end for better understanding.