Mlcak, Justin Dale (2007-05). Simulation of Three-Dimensional Laminar Flow and Heat Transfer in an Array of Parallel Microchannels. Master's Thesis. Thesis uri icon

abstract

  • Heat transfer and fluid flow are studied numerically for a repeating microchannel array with water as the circulating fluid. Generalized transport equations are discretized and solved in three dimensions for velocities, pressure, and temperature. The SIMPLE algorithm is used to link pressure and velocity fields, and a thermally repeated boundary condition is applied along the repeating direction to model the repeating nature of the geometry. The computational domain includes solid silicon and fluid regions. The fluid region consists of a microchannel with a hydraulic diameter of 85.58?m. Independent parameters that were varied in this study are channel aspect ratio and Reynolds number. The aspect ratios range from 0.10 to 1.0 and Reynolds number ranges from 50 to 400. A constant heat flux of 90 W/cm2 is applied to the northern face of the computational domain, which simulates thermal energy generation from an integrated circuit. A simplified model is validated against analytical fully developed flow results and a grid independence study is performed for the complete model. The numerical results for apparent friction coefficient and convective thermal resistance at the channel inlet and exit for the 0.317 aspect ratio are compared with the experimental data. The numerical results closely match the experimental data. This close matching lends credibility to this method for predicting flows and temperatures of water and the silicon substrate in microchannels. Apparent friction coefficients linearly increase with Reynolds number, which is explained by increased entry length for higher Reynolds number flows. The mean temperature of water in the microchannels also linearly increases with channel length after a short thermal entry region. Inlet and outlet thermal resistance values monotonically decrease with increasing Reynolds number and increase with increasing aspect ratio. Thermal and friction coefficient results for large aspect ratios (1 and 0.75) do not differ significantly, but results for small aspect ratios (0.1 and 0.25) notably differ from results of other aspect ratios.
  • Heat transfer and fluid flow are studied numerically for a repeating microchannel
    array with water as the circulating fluid. Generalized transport equations are discretized
    and solved in three dimensions for velocities, pressure, and temperature. The SIMPLE
    algorithm is used to link pressure and velocity fields, and a thermally repeated boundary
    condition is applied along the repeating direction to model the repeating nature of the
    geometry. The computational domain includes solid silicon and fluid regions. The fluid
    region consists of a microchannel with a hydraulic diameter of 85.58?m. Independent
    parameters that were varied in this study are channel aspect ratio and Reynolds number.
    The aspect ratios range from 0.10 to 1.0 and Reynolds number ranges from 50 to 400. A
    constant heat flux of 90 W/cm2 is applied to the northern face of the computational
    domain, which simulates thermal energy generation from an integrated circuit.
    A simplified model is validated against analytical fully developed flow results
    and a grid independence study is performed for the complete model. The numerical
    results for apparent friction coefficient and convective thermal resistance at the channel
    inlet and exit for the 0.317 aspect ratio are compared with the experimental data. The
    numerical results closely match the experimental data. This close matching lends credibility to this method for predicting flows and temperatures of water and the silicon
    substrate in microchannels.
    Apparent friction coefficients linearly increase with Reynolds number, which is
    explained by increased entry length for higher Reynolds number flows. The mean
    temperature of water in the microchannels also linearly increases with channel length
    after a short thermal entry region. Inlet and outlet thermal resistance values
    monotonically decrease with increasing Reynolds number and increase with increasing
    aspect ratio.
    Thermal and friction coefficient results for large aspect ratios (1 and 0.75) do not
    differ significantly, but results for small aspect ratios (0.1 and 0.25) notably differ from
    results of other aspect ratios.

publication date

  • May 2007