Investigation of Supercritical CO₂ Thermal Hydraulic Characteristics in a Printed Circuit Heat Exchanger

Printed circuit heat exchangers are considered for use as the intermediate heat exchangers (IHXs) in high temperature gas-cooled reactors (HTGRs), molten salts reactors (MSRs) and other advanced reactors. A printed circuit heat exchanger (PCHE) is a highly integrated plate-type compact heat exchanger with high-temperature, high-pressure applications and high compactness. A PCHE is built based on the technology of chemical etching and diffusion bonding. A PCHE with supercritical carbon dioxide (CO₂) as the working fluid was designed in this study based on the theory correlations. Three-dimensional numerical analysis was then conducted to investigate the heat transfer and pressure drop characteristics of supercritical CO₂ in the designed printed circuit heat exchanger using commercial CFD code, FLUENT. The distributions of temperature and velocity through the channel were modeled. The influences of Reynolds number on heat transfer and pressure drop were analyzed. The numerical results agree well with the theory calculations.