Thermal design, optimization and additive manufacturing of ceramic regular structures to maximize the radiative heat transfer

Abstract

The present study is focused on the application of a ceramic tubular high temperature heat exchanger with engineered cellular architectures. Thermal design and optimization to maximise the radiative heat transfer has been investigated both experimentally and computationally. Numerical models were designed involving various arrangements of cells and their different sizes (while the total heat transfer area remains constant). They were 3D-printed by Stereolithography (SLA) and subsequently sintered. Heat transfer tests were performed both with a high temperature pressure drop test and by CFD simulations on 2D and 3D models. The computational results agree with the experimental data. We found that radial heat transfer in a tube increases by 160% to 280%, if a ceramic lattice is inserted, in respect of an empty tube. Moreover, the arrangement of cells and their size significantly influences the radiative heat transfer showing (for a given array) its top performances above 773 K. Geometries with large cells outside and small cells inside in the radial direction allow radiation to penetrate better through the core of the porous body. With this engineered ceramic lattices it is possible to reduce the tube length by one third to obtain more compact heat exchangers than an empty tubular solution.