A Reduced-Order Framework for the Thermo-hydraulic Design of Additively Manufactured Compact Heat Exchangers

Abstract

The increasing electrification of aircraft subsystems and the integration of high-power-density components are creating significant challenges for onboard thermal management systems. These key subsystems are reaching their performance limits, motivating the development of new advanced solutions. One promising option is the adoption of innovative heat exchanger concepts featuring complex internal geometries, such as strut-based lattice structures, and triply periodic minimal surfaces (TPMS), that are only feasible to manufacture through additive processes. The aim of this work is to develop a systematic methodology to characterize the thermo-hydraulic performance of advanced heat transfer structures based on periodic unit cell (Representative Volume Elements) simulations. The resulting numerical data are then used to calibrate reduced order models suitable for the preliminary design of heat transfer devices. More in detail, the study focuses on the characterization of four heat transfer topologies over a wide range of Reynolds and Prandtl numbers and structure porosities. The performance data from the simulations were used to derive empirical correlations for the friction factor and Nusselt number as a function of the topology porosity. These correlations were then implemented into an $\epsilon-NTU$-based model to support preliminary design activities. To verify this methodology, a cold plate was analyzed and the results were validated against CFD simulations. The methodology showed adequate accuracy for preliminary design, providing reliable predictions where CFD is computationally prohibitive. Future work will expand geometric inputs beyond porosity to broaden the design space of additively manufactured heat transfer devices.