Abstract
Surface structure and intrinsic wettability are both important for boiling heat transfer. While superhydrophilic micro, nano, and hierarchical surfaces are widely used for boiling enhancement, in which the surface structure and intrinsic wettability usually couple together. This study aims to decouple their influences on boiling heat transfer. Copper meshes are utilized as the microporous structures, and conformal superhydrophilic films of TiO2 are deposited by atomic layer deposition (ALD). Although ALD coatings for boiling have been done on flat surfaces, this study separates the influence of surface structure from that of intrinsic wettability on a three-dimensional microporous surface. By comparing two and four layer meshes, we show that the surface structure has no obvious influence on the critical heat flux (CHF), but can significantly enhance the heat transfer coefficient (HTC). The intrinsic superhydrophilicity dramatically increases the CHF due to the fast rewetting of dryout regions. Our conclusion is that fast rewetting is critical to increase the CHF, while large surface areas are vital to enhance the HTC.
Original language | English |
---|---|
Article number | 253901 |
Journal | Applied Physics Letters |
Volume | 112 |
Issue number | 25 |
DOIs | |
State | Published - Jun 18 2018 |
Externally published | Yes |
Funding
This work was supported by the startup funds of the University of South Carolina (UofSC) to Dr. Chen Li. The authors gratefully acknowledge Professor Steven George’s group and Professor Ronggui Yang’s group at University of Colorado Boulder in preparation of ALD TiO2 coatings. The authors also thank Dr. Miao Yu and Mr. Lei Wang from Department of Chemical Engineering at UofSC in the help of characterizing ALD TiO2 coatings. The authors appreciate Dr. Alam Tamanna in Department of Mechanical Engineering at UofSC and Mr. Tom Bassett in IFM USA (Columbia, SC) for the professional proofreading. This work was supported by the startup funds of the University of South Carolina (UofSC) to Dr. Chen Li. The authors gratefully acknowledge Professor Steven George's group and Professor Ronggui Yang's group at University of Colorado Boulder in preparation of ALD TiO2 coatings. The authors also thank Dr. Miao Yu and Mr. Lei Wang from Department of Chemical Engineering at UofSC in the help of characterizing ALD TiO2 coatings. The authors appreciate Dr. Alam Tamanna in Department of Mechanical Engineering at UofSC and Mr. Tom Bassett in IFM USA (Columbia, SC) for the professional proofreading.