• Login
    View Item 
    •   SMARTech Home
    • Georgia Tech Theses and Dissertations
    • Georgia Tech Theses and Dissertations
    • View Item
    •   SMARTech Home
    • Georgia Tech Theses and Dissertations
    • Georgia Tech Theses and Dissertations
    • View Item
    JavaScript is disabled for your browser. Some features of this site may not work without it.

    Transport Characteristics of Pin Fin Enhanced Microgaps under Single and Two Phase Cooling

    Thumbnail
    View/Open
    WAN-DISSERTATION-2016.pdf (7.171Mb)
    Date
    2016-05-06
    Author
    Wan, Zhimin
    Metadata
    Show full item record
    Abstract
    Microfluidic convection cooling is a promising technique for future high power microprocessors, radio-frequency (RF) transceivers, solid-state lasers, and light emitting diodes (LED). Three-dimensional (3D) stacking of chips is a configuration that allows many performance benefits. A microgap with circulating fluid is a promising cooling arrangement that can be incorporated within a 3D chip stack. Although studies have examined the thermal characteristics of microgaps under both single-phase and two-phase convection, the characteristics and benefits of microgaps with surface enhancement features have not been fully explored. In this work, firstly, the single phase thermal/fluid characteristics of microgaps with staggered pin fin arrays are studied. The effects of the pin fin dimensions including diameter, transversal and longitudinal spacing, and height are investigated computationally and experimentally over a range of Reynolds number (Re) 22-357. Micropin fin arrays investigated have pin diameter of 100 μm, pitch/ diameter ratios of 1.5 ~ 2.25, and height/ diameter ratios of 1.5 ~ 2.25. Correlations of friction factor (f) and Colburn j factor for these dense arrays of micro pins have been developed. Subsequently, microfluidic cooling with staggered pin fin arrays is employed in functional 3D integrated circuit (ICs). Thermal and electrical performance of a CMOS chip in terms of temperature and leakage power under realistic operating conditions are studied. Both experimental and modeling results show that microfluidic cooling could significantly decrease the chip temperature and leakage power, thus increasing the chip performance. Lastly, two-phase cooling is studied with dielectric fluid HFE-7200 as a baseline with mass flux from 354.5 kg/m2-s to 576.3 kg/m2-s. Critical heat flux (CHF) increases with increasing mass flux but decreases with decreasing gap height. Nonuniform heating will cause nonuniform flow with a decrease of mass flux in high power area, which decreases the thermal performance. The effects of fluid mixture (HFE-7200/Methanol) on thermal performance are studied with mass fraction of Methanol from 8.5% to 35.8%. A very small amount of addition of Methanol (8.5% mass fraction) can significantly increase the thermal performance due to the sharp decrease of saturation temperature and increase of effective thermal conductivity and latent heat. However, the Marangoni effect caused by the concentration gradient deteriorates the CHF.
    URI
    http://hdl.handle.net/1853/55480
    Collections
    • Georgia Tech Theses and Dissertations [23877]
    • School of Mechanical Engineering Theses and Dissertations [4086]

    Browse

    All of SMARTechCommunities & CollectionsDatesAuthorsTitlesSubjectsTypesThis CollectionDatesAuthorsTitlesSubjectsTypes

    My SMARTech

    Login

    Statistics

    View Usage StatisticsView Google Analytics Statistics
    facebook instagram twitter youtube
    • My Account
    • Contact us
    • Directory
    • Campus Map
    • Support/Give
    • Library Accessibility
      • About SMARTech
      • SMARTech Terms of Use
    Georgia Tech Library266 4th Street NW, Atlanta, GA 30332
    404.894.4500
    • Emergency Information
    • Legal and Privacy Information
    • Human Trafficking Notice
    • Accessibility
    • Accountability
    • Accreditation
    • Employment
    © 2020 Georgia Institute of Technology