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

Abstract

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.