Numerical design analysis of a lead-lithium/supercritical CO2 printed circuit heat exchanger at demo power conversion ranges

Abstract

One of the key issues of fusion technology is the efficient recovery of the fusion power extracted by heat transfer fluids in the breeding blanket. The Spanish National Programme Tecno_Fus is exploring the functionalities of dual-coolant breeding blanket design concept and its plant auxiliary systems for a future power reactor (DEMO), with lead-lithium eutectic as main primary nuclear power recovering fluid. Supercritical CO2 is chosen for the secondary circuit, since its high efficiency at significantly lower temperature than for the Brayton helium cycle due to low compression work near the critical point and with additional major benefits in terms of tritium control. Other CO2 advantages are its moderate value of the critical pressure, stability, relative inertness and low cost. The more attractive design option is a liquid metal/supercritical CO2 printed circuit heat exchanger (PCHE), which is supported by the advantages of its compactness and its adaptability for control/passive removing of tritium from the secondary circuit. This work presents a design of the heat exchanger and a definition of its main geometric and working parameters with a main goal of sizing of such auxiliary system. A CFD analysis of the design is also included.