Perpustakaan Digital ITB

ThorCon Molten Salt Reactor (MSR) converts fission heat to electricity through four loops: a primary loop inside the can, a secondary salt loop, a solar loop, and a supercritical steam loop. The secondary salt loop uses the natural circulation phenomenon inside a Natural Circulation Loop (NCL) to circulate coolant salt from the primary heat exchanger to the secondary heat exchanger. Several studies on NCL Computational Fluid Dynamics (CFD) simulation have been done in the recent years, but none of those discusses the optimal geometrical design of the NCL. Moreover, flow modeling using molten salts as a working fluid is also yet to be done previously. Therefore, this study aimed to determine the most optimum geometrical parameters of NCL and investigate the effect of working fluid. The simulation process started with constructing a 3D model by using Solidworks 2023 Student Version. Secondly, the 3D model was meshed into smaller partitions using Ansys Mechanical. After that, simulation setup was assigned into the meshed model with series of features in Ansys Student R2 2023 (Fluent). The first simulation was carried out to validate the developed model by comparing simulation results with available experimental data. The second simulation aimed to determine the most optimum geometrical parameters with considering hot leg length, cold leg length, pipe inclination as the variables. Meanwhile, for the third simulation, working fluid was varied to investigate the effects of working fluid. The study on model validation demonstrated a deviation of 5.7% from the experimental results obtained by Britsch et al.. Subsequently, a simulation for geometrical optimization was conducted using the validated model, and it was found that the FP8 design (1.34 m hot leg length, 1.66 m cold leg length, 72.97 pipe inclination) produced the highest average velocity for the molten salt. Thus, the FP8 design was considered the optimal geometrical model, with average velocity of 0.8661 m/s. The impact of the working fluid was analyzed using the FP8 design, and it was observed that FLiNaK salt exhibited the highest average salt velocity of 0,09107 m/s.