Abstract
Enhancing low surface tension liquid condensation is critical for achieving high energy efficiency and reducing the size of thermal energy systems. Extensive research has focused on promoting dropwise condensation of these liquids using state-of-the-art coatings on plain surfaces. However, maintaining dropwise condensation with low surface tension fluids is challenging due to rivulet formation, resulting in wetted tails that transition to filmwise condensation at elevated heat fluxes. To address this issue, we uncover the role of surface structures and surface chemistry in the dropwise condensation of low surface tension ethanol on slippery rough surfaces (SRS). High-performance dropwise condensation has been achieved on slippery microchannels grafted with perfluoropolyether. The SRS uniquely facilitates rapid lateral droplet removal, enabling faster directional droplet shedding without rivulet formation. The resulting higher droplet removal frequency on SRS leads to heat transfer coefficients 100 % and 500 % higher than conventional dropwise and filmwise condensation on plain surfaces, respectively. Our findings uncover the pivotal role of rapid droplet removal through slippery microchannels in sustaining dropwise condensation of low surface tension liquids. This study introduces a new paradigm for promoting dropwise condensation using engineered SRS that incorporates surface structure and surface chemistry. The work will provide fundamental design guidelines to design efficient and compact condensers that use costly or flammable low global warming potential refrigerants in future refrigeration systems.
| Original language | English |
|---|---|
| Article number | 127105 |
| Journal | International Journal of Heat and Mass Transfer |
| Volume | 247 |
| DOIs | |
| State | Published - Sep 1 2025 |
Funding
D.M. and X.D. acknowledge the National Science Foundation Faculty Early Career Development Program (Award No. 2044348). P.S.D. and X.D. acknowledge the Department of Energy (Award No. DE-EE0011217). K.W. and X.D. acknowledge the DARPA Young Faculty Award (Award No. D23AP00160). D.B. acknowledges the Department of Energy Innovation in Buildings (IBUILD) Graduate Research Fellowship. This manuscript has been authored by UT-Battelle, LLC, under contract DE-AC05-00OR22725 with the US Department of Energy (DOE). The US government retains and the publisher, by accepting the article for publication, acknowledges that the US government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for US government purposes. DOE will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads/doe-public-access-plan). D.M. and X.D. acknowledge the National Science Foundation Faculty Early Career Development Program (Award No. 2044348 ). P.S.D. and X.D. acknowledge the Department of Energy (Award No. DE-EE0011217 ). K.W. and X.D. acknowledge the DARPA Young Faculty Award (Award No. D23AP00160 ). D.B. acknowledges the Department of Energy Innovation in Buildings (IBUILD) Graduate Research Fellowship. This manuscript has been authored by UT-Battelle, LLC, under contract DE-AC05-00OR22725 with the US Department of Energy (DOE). The US government retains and the publisher, by accepting the article for publication, acknowledges that the US government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for US government purposes. DOE will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads/doe-public-access-plan).
Keywords
- Dropwise condensation
- Heat transfer coefficient
- Low surface tension liquid
- Microchannels
- Slippery rough surfaces