Heat transfer rates for filmwise, dropwise, and superhydrophobic condensation on silicon substrates
Name
772609760-MIT.pdf
Description
Full printable version
Size
2.91 MB
Format
Adobe PDF
Checksum (MD5)
f3d8d0b37c03ca8deed1cddaba7b781b
Author(s)
Hery, Travis M
Advisor(s)
Evelyn N. Wang.
Date Issued
2011
Publisher
Massachusetts Institute of Technology
Abstract
Condensation, a two-phase heat transfer processes, is commonly utilized in industrial systems. Condensation heat transfer can be optimized by using surfaces in which dropwise condensation (DWC) occurs, and even further optimized using superhydrophobic surfaces. For superhydrophobic condensation, a structured silicon surface with pillars 2.1 p.m tall, 200 nm in diameter, and a 400 nm pitch was tested. By removing noncondensable gases (NCG) from the system by means of a steam trap, the heat transfer rates of DWC and SHC were found to be greater than that of filmwise condensation (FWC) by a factor of 2, but indistinguishable from each other. The effect of NCG leads to a 5x reduction in heat transfer rates for both DWC and SHC. DWC heat transfer rates are as much as 50 kW/m 2 less than FWC at the same temperature difference, representing a 25% reduction. However, the SHC heat transfer rates remain above those of FWC by as much as 50 kW/m² at the same temperature difference, representing a 20% improvement. These studies suggest that SHC may be a useful passive method to improve condensation heat transfer rates in the presence of NCG. However, it remains to be seen if SHC can provide better heat transfer rates than DWC under saturated steam conditions.
Description
Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2011.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 24).
Subjects
Mechanical Engineering.
MIT Department
Massachusetts Institute of Technology. Department of Mechanical Engineering
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