Numerical Analysis of Thermo-Hydraulic Performance of FLiBe Flowing Through a Louvered-Fin Compact Heat Exchanger

Abstract: The study focuses on the steady-state thermohydraulic behavior of the LiF-BeF2 (FLiBe) molten salt flowing through a compact heat exchanger with multi louvered fins in the cooling loop of a Molten Salt Reactor (MSR). This numerical benchmark study was conducted to obtain data both for baseline and cases with slow coolant circulation problems in the reactor. A series of numerical tests are conducted for low Reynolds numbers of 100 to 500 based on the louver pitch with different fin pitches and fin louver angles. The steady-state velocity profiles, temperature, and pressure fields are studied in detail. The heat transfer coefficient and pressure drop data are reported in terms of Colburn j-factor and Fanning friction factor f, and the volume goodness factor to get a performance comparison for FLiBe as the coolant in a Molten Salt Reactor. As regards findings of the analyses, when the louver angle steeps, the molten salt flow becomes more louvered direct which improves the interaction and heat transfer between the fin and molten salt. On the contrary, when the fin pitches increase, the flow becomes duct-directed that reducing the contact between fin and FLiBe which leads to a decline in thermal performance.