THERMO-FLUID AND MECHANICAL DESIGN OF AN ADVANCED PRINTED CIRCUIT HEAT EXCHANGER FOR SUPERCRITICAL CO2 BRAYTON CYCLES

A supercritical carbon dioxide (sCO2) Brayton power cycle is considered as one of the promising energy conversion systems for a number of applications such as Concentrated Solar Power (CSP) plants due to its high thermodynamic efficiency and small equipment size. The compact heat exchangers such as Printed Circuit Heat Exchangers (PCHEs) with micro-channel geometry are suitable for coupling different heat sources to a sCO2 Brayton power cycle. The objective of this study is to design and optimize an advanced PCHE micro-channel geometry and topology for a sCO2 Brayton cycle. This work is concerned with the design where both sides of the plate are etched forming a double-etched micro-channel design configuration. In this advanced micro-channel topology, shim plates are needed to construct a PCHE stack using diffusion bonding.
Thermo-hydraulic performance of semi-circular micro-channel and advanced semi-circular and circular double-etched micro-channel geometries, and maximum stress, were determined. The results obtained for the advanced double-etched microchannel geometry were compared to the “conventional” semi-circular single-etched (single-side etched) micro-channel design for the counter-flow arrangement. Using ANSYS-Workbench, a multi-objective optimization algorithm employing NSGA-II and Response Surface Approximation (RSA) as a surrogate model was used for design and optimization of the advanced double-etched micro-channel PCHE geometry.