Study on particle deposition performance in liquid lead-bismuth eutectic and supercritical CO2 heat exchanger

Abstract

Lead-bismuth eutectic (LBE) and supercritical CO2 (SCO2) heat exchangers are highly recommended and designed due to their compactness and high thermal efficiency. During heat exchanger operation, however, undesired particle impurities are generated, which deposit on the surface and degrade heat transfer. To predict the deposition distribution, a tube-shell heat exchanger was proposed with LBE as the heat source and SCO2 as the cool source. Based on this proposal, a three-dimensional model was established, and particle deposition characteristics were studied numerically. The results indicated that the inlet section had a high concentration and deposition rate. At the inlet, the deposition rate in LBE was higher than SCO2. Specifically, particle deposition in LBE was concentrated mainly in the inlet section, while it occurred throughout the entire channel in SCO2. An increase of particle diameter and concentration contributed to deposition on both sides. The average deposition rates of LBE and SCO2 showed an increase of 1.04 times and 2.76 times, respectively, when the particle diameter was varied from 2 μm to 6 μm. Similarly, an increase in concentration from 1 % to 2.5 % resulted in an increase of deposition rates of LBE and SCO2 by 3.75 times and 3.68 times, respectively. This implied that the concentration had a stronger impact on deposition. The deposition characteristics of particle species differed in LBE and SCO2. As the particle density increased, the deposition rate decreased in LBE but increased in SCO2. The particle deposition mechanism in LBE and SCO2 was revealed by analyzing the forces acting on particles.