Investigation of a correlation based model for sCO2 compact heat exchangers

Motivated by the Fukushima accident, innovative heat removal systems for nuclear power plants are currently under investigation. One of them is the supercritical carbon dioxide (sCO2) heat removal system, a closed Brayton cycle with sCO2 as working fluid. ATHLET (Analysis of THermal-hydraulics of LEaks and Transients) has been used to simulate the interaction of the heat removal system with the nuclear power plant. However, the component models need further development and validation. In this paper, a general approach for the simulation of heat exchangers is applied to a compact heat exchanger (CHX), including the heat transfer and pressure drop correlations used in ATHLET. Based on stationary experiments of a two-plate CHX, dimensionless form loss coefficients for the sCO2 inlet and outlet plenum are derived. In a second step, these coefficients are used as input values for a model, which solves the conservation equations for momentum and energy for a representative H2O/sCO2 channel pair. The results of the ATHLET simulations are in good agreement with the experiments. Compared to the mean values of the experiments, almost all simulated cases yield a deviation of less than 10 %, concerning transferred power and the pressure drop on the sCO2-side.