Micro structured surfaces for thermodynamic applications: Poster presented at EUSPEN Topical Meeting "Structured and Freeform Surfaces"; 5th-6th December 2012, Teddington

Abstract

The functionality of surfaces, especially regarding heat exchange properties for thermodynamic applications, can be enhanced by help of specific surface modifications and surface micro structuring. To determine the influence on the heat transfer capability, different selected surface structures are investigated. Micro geometries produced by cutting, ablating and forming technologies are in focus of this research. A systematic design and a determination of appropriate thermodynamic micro structures can be executed by the help of FEM multiphysics simulations. During recent research and development different micro structures with high potential for convection and nucleate boiling processes were identified. Selected features were fabricated applying electrochemical and laser beam machining. Especially calottes, micro channels and micro columns were investigated. Primarily, the surface enlargement has the determining influence on the heat transfer efficiency. However, the design of the geometries and the arrangement of the structures also affect the heat transfer. A systematic analysis of the precision and the surface quality of the machined microstructures was carried out, which underlines the potential of the used processes for micro structuring of surfaces for thermodynamic applications. Following up, forming processes are particularly suitable for the production of functionally micro-structured surfaces on components or semi-finished material under economic criteria, because complex deterministic structures can be reproduced on large areas. However, it is extraordinarily important to know the transfer characteristic of the forming process exactly in order to satisfy the design specs of the surface structure. Research and development in forming of microstructures concentrates on flow behavior of metals, influences of the forming