Heat exchangers using TPMS architectures manufactured by LPBF

Overview & Synopsis

Applied to heat exchangers or reacting exchangers, Additive Manufacturing (AM) enables the development of innovative solutions, especially by use of specific internal structures and morphologies that are impossible to manufacture by traditional process routes. Among them TPMS cellular structures (triply-periodic minimal surfaces, by instance Schwartz or Gyroides) are of particular interest since gaz and liquid flows can be independent but intimately intertwined, for efficient heat exchange. AM manufacturing of such structures promotes heat exchanger integration in a system by fitting with the available design space, resulting in advantageous compacity. In addition, AM leads to monolithic manufacturing of the component (i.e. internal and external structures are built together) that simplify or remove assembly operations and consequently leakage risks. In this presentation, two use-cases will be presented to illustrate the concept : the first case is dedicated to thermal management of future electrical power sources in carbon-free aeroplanes, the second one is related to cooling circuit for engines in a transportation application. The dimensioning and sizing process - through modelling and calculations – leads to two very different configurations and architectures since: aeronautic application is an air/glycolated water system and the transportation one is a water / water glycolated system. Through these examples, we propose to discuss the issues of the dimensioning activity of such components taking account of their specifications and performances as well as AM – LPBF (laser powder bed fusion) manufacturing constraints, typically the orientation and roughness of walls. As a complement to the workflow description (initial TPMS cell design, TPMS architecture mapping into design space, numerical chain with CFD solver) one focus will be made on specific model implemented in calculations to take into account the specific roughness of surfaces produced by LPBF. Prototypes were manufactured in CEA on Poudrinnov Plateform (LPBF AlSi7Mg and LPBF SS316L respectively) and tested on experimental equipments. Some results will be presented and compared to predicted performances before conclusion and discussion on perspectives.