Latest progress on nanotechnology aided boiling heat transfer enhancement: A review

Boiling heat transfer has drawn continuous attention owing to its wide range of applications in the energy fields. In the boiling process, the heat transfer coefficient (HTC) enhancement is needed for better energy conversion efficiency, and the critical heat flux (CHF) enhancement is needed to avoid boiling crises. With the advancement of nanotechnology, nanoscale surface modifications and nanofluids have shown great boiling enhancement potential. Furthermore, the coupled methods, which refer to the adoption of more than one method for boiling heat transfer enhancement, provide a novel way for possibly enhancing the HTC and CHF simultaneously. This work aims to provide the latest review of boiling enhancement using nanotechnology and its coupled methods. The nanotechnology-based methods on boiling enhancement including nanoscale modified surfaces and nanofluids are summarized. Furthermore, different coupled methods, including (a) hybrid nanofluids; (b) combined methods of using both nanofluid and surface modification; (c) bi-feature surfaces with multi-wettability (biphilic), multi-material, or multi-scale coating for surface modification, are discussed. Biphilic surfaces refer to surfaces with both hydrophilic and hydrophobic regions. Multi-materials surfaces refer to surfaces adopting two coating materials in the fabrication process, and multi-scale surfaces refer to nano/microscale surfaces in this review. The CHF and the HTC enhancement of pool and flow boiling are discussed, and conclusions and recommendations for future work are presented. (C) 2020 Elsevier Ltd. All rights reserved.