Numerical study on a novel hyperbolic inlet header in straight-channel printed circuit heat exchanger

Printed circuit heat exchangers (PCHEs) can be used as the recuperator and condenser in the supercritical CO₂ (sCO₂) Brayton cycle of fast cooled reactor (FCR) systems. Most researchers focused on heat transfer improvement of the core structure in previous literatures. However, the flow non-uniformity may seriously decrease the comprehensive performance of PCHEs by increasing the pressure loss. The sCO₂ temperature in partial channels may be lower than the pseudo-critical temperature due to non-uniform flow distribution. Thereby, it is possible that the condenser may deviate from the steady operating condition and work inefficiently. In this paper, the flow non-uniformity of a straight-channel PCHE condenser with four different inlet headers is analyzed. Based on the streamline profile, a novel modified hyperbolic inlet header is proposed, which can reduce the flow non-uniformity by 46% compared with the current practical manufactured model. Simultaneously, the improvement of flow uniformity by the novel inlet header may increase the overall performance by 39.5%. Furthermore, the effect of core length is also investigated, and it is found that the flow non-uniformity can be minimized by varying the core length. Additionally, the relationship between the standard deviation of flow non-uniformity and the shape factor is quantitatively investigated and analyzed. Result shows that the flow non-uniformity can be expressed as a function of the shape factor and dimensionless core length. Finally, the correlations of the thermo-hydraulic performance of the straight-channel PCHE with corrections for flow non-uniformity are proposed.