Conference Year
2021
Keywords
furcating heat exchanger, computational fluid dynamics, correlation development, supercritical carbon dioxide, topology optimization
Abstract
The thermal efficiency of indirectly heated power cycles such as supercritical carbon dioxide (sCO2) closed Brayton cycles are typically limited by their heat exchangers (HXs), which require high heat transfer effectiveness while operating for tens of thousands of hours under high temperature (>800°C) and pressure (>80 bar) conditions. Previous literature has shown that the use of nature-inspired furcating flow channels represents an exciting opportunity to improve HX thermal-hydraulic performance. In this paper, we analyze the novel multi-furcating HX manifold concept, that was previously shown experimentally to reduce HX volume and mass compared to a baseline oil cooler by 50% and 67%, respectively. Computational fluid dynamics (CFD) simulations are utilized to analyze thermal-hydraulic performance and fluid flow development. CFD-based correlations of Nusselt number and friction factor are developed for performance prediction of a full, additively manufactured HX. The developed Nusselt number and friction factor correlations predict unit cell thermal-hydraulic performance within ±3% and ±5% for all simulated Reynolds numbers, respectively. The full HX would enable increased thermal efficiency of indirectly heated power cycles to reduce both energy consumption and emissions while also allowing opportunities in advanced aerospace applications.