Optimization Design Study of a Radiant Heat Exchanger for a Small-Scale Underwater Nuclear Power Plant’s Residual Heat Removal System

Abstract With the continuous development of small-scale underwater nuclear power plants, the need to develop residual heat removal systems for underwater nuclear power plants has become urgent. The efficient and lightweight residual heat removal system is one of the key research directions that need to be developed. The mass and volume of the heat exchanger of a small-scale underwater nuclear power plant account for a large proportion of the residual heat removal system. The heat exchanger in the residual heat removal system in the liquid metal-cooled nuclear reactor of a small-scale underwater nuclear power plant adopts radiant heat exchange, and the fins of the radiant heat exchanger are made of graphite carbon fiber composite material with a rectangular structure. The heat exchanger and heat trap are filled with nitrogen gas. This paper proposes to replace the rectangular cross-section structure of the radiant fins with the triangular structure of the heat exchanger fins. The heat transfer performance of the optimized structure of the radiant heat exchanger is investigated using Fluent. The results show that the optimized triangular fin structure of the radiant heat exchanger makes the residual heat removal system have a better performance of the radiant heat exchanger. The weight of the optimized system is reduced by 16.53%.