Flow state analysis of molten salt in shell and tube heat exchanger with perforated baffles

Abstract

Addressing the issue of flow dead zones in molten salt heat exchangers in concentrating solar power generation systems, this study focuses on the conventional shell and tube heat exchanger using molten salt and heat transfer oil as the working medium. The flow dynamics of molten salt within the heat exchanger are analyzed. To quantify the volume fraction of the molten salt flow dead zones, the residence time distribution curve is employed. Four baffle salt flow configurations are comparatively assessed. Findings indicate that the four opening configurations effectively enhance the reduction of molten salt flow dead zones, with volume fraction reductions ranging from 57.8% to 68.21%. Notably, configuration 4 yields the most optimal results. Furthermore, molten salt flow states in varying regions were examined: the innermost flow dead zone exhibited the highest improvement, followed by the middle area, with the edge area showing the least enhancement. Additionally, the impact of the opening diameter on the flow dead zone was explored. The volume fraction of the molten salt flow dead zone diminishes as the opening diameter expands, with the rate of this change also decelerating. Given that molten salt at the opening manifests as a jet, enlarging the opening diameter lessens the pressure differential across the baffle, subsequently weakening the jet's intensity and its influence on the flow dead zone.