Effect of Inner Fin Tube Structure on Comprehensive Performance of Supercritical Carbon Dioxide and Lead Bismuth Eutectic Heat Exchanger

In the combined system of lead cooled fast reactor (LFR) and supercritical carbon dioxide (S-CO₂) Brayton cycle, the intermediate heat exchanger plays a key role in the whole power system. However, the existing heat exchanger can not meet the trend of miniaturization of lead cooled fast reactor. Considering the thermo-physical properties and heat transfer behaviors in both S-CO₂ and liquid lead bismuth eutectic (LBE) are significantly different, an asymmetric compact coupled heat exchanger learning from Honeycomb structure is proposed. Through numerical simulation, it is found that the thermal resistance mainly exists in the cold side. In order to enhance the heat transfer at the S-CO₂ side, the fin tube is adopted at the cold side. The results show that the heat transfer performance and friction factor of the heat exchanger increase with the increase of fin height, width and number of fins due to the increase of heat transfer area. When the fin height is increased, PEC gradually increases at low inlet velocity, and then decreases at high inlet velocity; When the fin width is increased, PEC increases first and then decreases at low inlet velocity, and decreases gradually at high inlet velocity; With the increase of the number of fins, PEC showed an increasing trend at different inlet velocities.