Experimental investigation of thermal-hydraulic performance of discontinuous fin printed circuit heat exchangers for supercritical CO2 power cycles

•Thermal-hydraulic performance of rectangular and airfoil fin PCHEs was investigated.•Both the PCHEs offered significantly lower pressure drop compared to zig-zag PCHE.•Nusselt numbers of the rectangular fin PCHE are higher than the zig-zag channel PCHE.•Up to ∼25% PCHE volume reduction possible for sCO2 power cycle applications. The supercritical carbon dioxide (sCO2) Brayton cycles have the potential to attain higher cycle efficiencies than the conventional steam Rankine cycles. Using compact diffusion-bonded heat exchangers for thermal recuperation in sCO2 Brayton cycles can lead to cost-effective, simple, and compact cycle footprint. This study focuses on the experimental thermal-hydraulic performance evaluation of a set of chemically etched discontinuous offset rectangular and airfoil fin surface patterns for use in diffusion bonded heat exchangers. Local and average heat transfer coefficients and pressure drops were measured for a wide range of operating conditions relevant to the sCO2 Brayton cycles. Empirical correlations for the friction factor and the Nusselt number are proposed based on the experimental data. The friction factor correlations were able to reproduce the experimentally measured pressure drops with a standard deviation of ±13.5% and ±14.7% for the discontinuous offset rectangular and airfoil fins respectively. Nusselt number correlations were able to reproduce the experimental Nusselt numbers with standard deviation of ±15.4% and ±8% for the discontinuous offset rectangular and airfoil fins respectively.