CHAPTER FIVE Review of advances in convective heat transfer developed through additive manufacturing Karen A. Thole, Stephen P. Lynch, and Alexander J. Wildgoose Department of Mechanical Engineering, Pennsylvania State University, University Park, PA, United States Contents 1. Introduction 251 2. Metal printing methods and post-processing 253 2.1 Printing methods 253 2.2 Powdered metals and properties 255 2.3 Design considerations and process parameters 256 2.4 Part accuracy and surface morphology 260 3. Heat transfer and friction factors for small channels 267 3.1 Build orientation effects 273 3.2 Print process parameters effects 276 3.3 Correlations to predict performance for small additively manufactured channels 279 4. Noncircular channel shapes 285 4.1 Scaling friction factor and heat transfer for noncircular channel shapes 286 5. Other types of microchannels and heat transfer augmentation surfaces 294 5.1 Wavy microchannels 294 5.2 Pin fins, lattices, and triply periodic minimal surfaces 297 5.3 Thin fins 301 6. Heat exchangers 310 7. Conclusions and future needs 315 References 316 Abstract Opportunities exist to make revolutionary impacts on convective heat transfer designs for high temperature applications as the development of three-dimensional metal printing technologies continue to advance. Not only can complex heat exchange designs be further exploited because of manufacturability, but the development of these new designs can be done cheaper and faster. This chapter highlights the impor- tance of understanding the additive manufacturing (AM) processes in light of how the AM processes impact heat transfer, particularly for millimeter-sized channels and thin Advances in Heat Transfer, Volume 53 Copyright # 2021 Elsevier Inc. ISSN 0065-2717 All rights reserved. https://doi.org/10.1016/bs.aiht.2021.06.004 249