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Browsing by Author "Chen, Renkun"

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    Critical heat flux of pool boiling on Si nanowire array-coated surfaces
    (2011-12-01)
    Lu, Ming-Chang
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    Chen, Renkun
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    Srinivasan, Vinod
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    Carey, Van P.
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    Majumdar, Arun
    Pool boiling of saturated water on plain Si surfaces and surfaces covered with a dense array of Si nanowires (SiNWs) has been studied. Measured CHF and heat transfer coefficient (HTC) values of about 223 +/- 5.61 W/cm(2) and 9 +/- 1.60 W/cm(2) K. respectively, on the nanowire array-coated surface are among the highest reported in boiling heat transfer. Meanwhile, the CHFs on both nanowire-coated and Plain Si surfaces show a similar heater size dependence - the CHF increases as heater size decreases. The measured CHFs on both types of surfaces are approximately following the prediction of the hydrodynamic theory assuming the Helmholtz wavelength equal to the corresponded heater length. It suggests that the CHFs on both types of surfaces might be limited by pool hydrodynamics. (C) 2011 Elsevier Ltd. All rights reserved.
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    Phase transformation and thermoelectric properties of bismuth-telluride nanowires
    (2013)
    Hsin, Cheng-Lun
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    Wingert, Matthew
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    Huang, Chun-Wei
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    Guo, Hua
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    Shih, Ten-Jen
    Thermoelectric materials have attracted much attention due to the current interest in energy conversion and recent advancements in nano-engineering. A simple approach to synthesize BiTe and Bi2Te3 micro/nanowires was developed by combining solution chemistry reactions and catalyst-free vapor-solid growth. A pathway to transform the as-grown BiTe nanostructures into Bi2Te3 can be identified through the Bi-Te phase diagram. Structural characterization of these products was identified using standard microscopy practices. Meanwhile, thermoelectric properties of individual Bi-Te compound micro/nanowires were determined by the suspended microdevice technique. This approach provides an applicable route to synthesize advanced high performance thermoelectric materials in quantities and can be used for a wide range of low-dimensional structures.