Thermal-hydraulic correlations for zigzag-channel PCHEs covering a broad range of design parameters for estimating performance prior to modeling

Abstract

Printed circuit heat exchangers (PCHEs), with supercritical carbon dioxide (sCO2) as the working fluid, are being considered for use as recuperators and condensers in Brayton cycles for Next Generation Nuclear Plant (NGNP) projects. Many experimental and numerical studies are being conducted to characterize and optimize sCO2 PCHE performance and develop correlations to describe their thermal-hydraulic performance. This paper seeks to develop the Nusselt number (Nu) and Fanning friction factor (f) correlations for zigzag-channel PCHEs that account for changes in geometric parameters as well as fluid properties. Data from a previous zigzag-channel PCHE factor sensitivity study was used to develop these correlations. The sensitivity study analyzed 20 factors by using computational fluid dynamics (CFD) to model 50 test cases determined with design of experiments methodology. The Gauss-Newton nonlinear regression method was applied to this data to create best fit correlations. The developed correlations for hot and cold channel Nu and f were validated against experimental data and were found to model the data within ±30%. The new correlations predicted the numerical results from inlet parameters with an average error of approximately ±30%. These correlations appear to provide the best estimate, over current leading correlations, of PCHE thermal-hydraulic performance from inlet parameters prior to any simulation or experimentation.