Additively Manufactured Lattice-Based Enhanced Heat Transfer Concepts for Superior Particle-to-Supercritical Carbon Dioxide Heat Exchanger for CSP Applications

This research investigates the enhancement of heat transfer in packed bed heat exchangers using additively manufactured novel lattice structures, with applications in concentrated solar power (CSP) plants. The study encompasses multiple stages, examining various lattice topologies and their impact on heat transfer and fluid flow characteristics.

Initially, four lattice topologies (Octet, FD-Cube, Tetrakaidecahedron, and Cube) were investigated using air as the working fluid. The research revealed that lattices provided 10-20 times higher heat transfer augmentation compared to smooth channels. A unified correlation for Nusselt numbers as a function of Reynolds numbers was developed, applicable across all studied configurations. Utilizing additively manufactured lattices in 420 Stainless Steel. The study evaluated conjugate heat transfer capabilities, effective thermal conductivity, and forced convective heat transfer performance. Results indicated that the Cube topology provided the best overall thermal hydraulic performance. Further research explored a novel moving packed bed heat exchanger with Octet lattice structures for CSP applications. Granular flow analysis, conducted through experiments and DEM-based simulations, revealed complex flow phenomena within the lattice structures.

The final stage characterized heat transfer in additively manufactured Octet-shaped lattice frame materials using particles and air as working fluids. The presence of lattices enhanced effective thermal conductivity by 2-4 times compared to particle-only packed beds, achieving high convective heat transfer coefficients ranging from 200-400 W/m²K.

This comprehensive study demonstrates the potential of additively manufactured lattice structures in significantly improving heat transfer performance in packed bed heat exchangers, with promising applications in CSP plants.