TY - JOUR
T1 - Condensate droplet size distribution on lubricant-infused surfaces
AU - Weisensee, Patricia B.
AU - Wang, Yunbo
AU - Qiang, Hongliang
AU - Schultz, Daniel
AU - King, William P.
AU - Miljkovic, Nenad
N1 - Funding Information:
This work was supported by the National Science Foundation Engineering Research Center for Power Optimization of Electro Thermal Systems (POETS) with cooperative agreement EEC-1449548. N. Miljkovic gratefully acknowledges the funding support from the Office of Naval Research (ONR) with Dr. Mark Spector as the program manager (Grant No. N00014-16-1-2625). N. Miljkovic gratefully acknowledges the support of the International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), sponsored by the Japanese Ministry of Education, Culture, Sports, Science and Technology.
Publisher Copyright:
© 2017 Elsevier Ltd
PY - 2017
Y1 - 2017
N2 - Condensation is a ubiquitous phenomenon in nature and industry. Heat transfer rates during dropwise condensation on non-wetting substrates can be 6-8X higher than heat transfer rates during traditional filmwise condensation on wetting substrates. Dropwise condensation on lubricant-infused surfaces (LIS, or SLIPS) is particularly interesting due to high droplet mobility on these surfaces. To accurately predict heat transfer rates during dropwise condensation, the distribution of droplet sizes must be known. Here we present condensation studies of water on aluminum-based lubricant-infused surfaces with a wide range of lubricant viscosities (12–2717 cSt) to determine droplet size distributions. Through optical imaging and microscopy, we show that the distribution of droplet sizes on LIS is independent of lubricant viscosity, and agrees well with the model developed by Rose for the distribution of droplet sizes on hydrophobic surfaces, especially in the range 10 < r < 100 µm. Using artificial sweeping experiments and numerical modeling, we investigate the dependence of sweeping rates on the distribution of droplet sizes and on average heat transfer rates. The maximum size to which droplets grow before being swept decreases rapidly with only a modest decrease in sweeping period, from 750 to 62 µm. Yet, the distribution of droplet sizes and heat transfer rates are nearly unaffected by the change in sweeping period, due to a relative insensitivity of heat transfer to droplets with radii r > 100 µm due to a high conduction resistance within these droplets. Our work provides an experimental and analytical framework to predict heat transfer and sweeping rates for water condensation on a vertical plate coated with a LIS or SLIPS surface.
AB - Condensation is a ubiquitous phenomenon in nature and industry. Heat transfer rates during dropwise condensation on non-wetting substrates can be 6-8X higher than heat transfer rates during traditional filmwise condensation on wetting substrates. Dropwise condensation on lubricant-infused surfaces (LIS, or SLIPS) is particularly interesting due to high droplet mobility on these surfaces. To accurately predict heat transfer rates during dropwise condensation, the distribution of droplet sizes must be known. Here we present condensation studies of water on aluminum-based lubricant-infused surfaces with a wide range of lubricant viscosities (12–2717 cSt) to determine droplet size distributions. Through optical imaging and microscopy, we show that the distribution of droplet sizes on LIS is independent of lubricant viscosity, and agrees well with the model developed by Rose for the distribution of droplet sizes on hydrophobic surfaces, especially in the range 10 < r < 100 µm. Using artificial sweeping experiments and numerical modeling, we investigate the dependence of sweeping rates on the distribution of droplet sizes and on average heat transfer rates. The maximum size to which droplets grow before being swept decreases rapidly with only a modest decrease in sweeping period, from 750 to 62 µm. Yet, the distribution of droplet sizes and heat transfer rates are nearly unaffected by the change in sweeping period, due to a relative insensitivity of heat transfer to droplets with radii r > 100 µm due to a high conduction resistance within these droplets. Our work provides an experimental and analytical framework to predict heat transfer and sweeping rates for water condensation on a vertical plate coated with a LIS or SLIPS surface.
KW - Dropsize distribution
KW - Dropwise condensation
KW - Heat transfer
KW - Lubricant infused surface (LIS)
KW - Slippery liquid infused porous surface (SLIPS)
KW - Sweeping
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U2 - 10.1016/j.ijheatmasstransfer.2017.01.119
DO - 10.1016/j.ijheatmasstransfer.2017.01.119
M3 - Article
AN - SCOPUS:85012053653
SN - 0017-9310
VL - 109
SP - 187
EP - 199
JO - International Journal of Heat and Mass Transfer
JF - International Journal of Heat and Mass Transfer
ER -