Design and validation methods for additively manufactured heat exchangers

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Metal additive manufacturing (AM) is viewed as a key enabling technology for the next generation of thermal management solutions (e.g. heat exchangers). Heat exchangers, used to transfer heat between two fluids, are essential components in many engineering systems in sectors such as aerospace, automotive and energy. The harmony between AM and heat exchangers arises through the relative ease with which complex and intricate internal geometries (channels) can be produced without the need for costly fabrication stages. As such, these heat exchangers have already established themselves as highly performant, compact and lightweight alternative to traditional heat exchanger concepts.However, AM presents significant challenges in terms of development costs and time, particularly where iterative production might be expected. A typical, single machine facility is likely to cost in the range of £1 million, and titanium powder feedstock costs approximately £400/kg. A heat exchanger with dimensions of 200 x 200 x 200mm would take approximately 10 days to produce. As such, to iteratively develop a new heat exchanger concept using this technology would easily exceed the £100k mark in terms of development cost.The aim of this project is to develop a methodology that enables the user to rapidly and iteratively design a heat exchanger core that meets a set of heat transfer and pressure drop requirements, whilst adhering to spatial constraints. The current vision is to combine novel heat transfer modelling with an algorithmic design approach. This will be used to automate the design of the core geometry and therefore reduce the engineering overhead and reduce the time required to reach a new proposition. A heat exchanger test bed will also be designed and built to validate the modelling work but also to form an integral part of the design methodology by using it as hardware-in-the-loop. It is expected that this research will play a role in the current trends of reduction in emissions in the aforementioned industries, owing to a reduced mass and therefore energy/fuel savings. In addition, enhanced performance will also help to recover and harness wasted heat within these systems. Looking further, it is thought that this could help make future aircraft propulsion and power generation systems viable, such as hydrogen fuel cells and widespread electrification.