Numerical Simulation Of Fluid Flow And Heat Transfer In Microchannel Heat-Sink

As miniaturization, reduction in products weight become the latest trend in electronic products development, traditional design methods and manufacturing technology fail to meet today's demands. Of the currently available coolers for electronic products with a high heat flux, microchannel heat sinks have been proved to be able to provide the best heat transfer performance and are one of the most promising coolers. The validity of the description of fluid flow and heat transfer in a microchannel heat sink using the Navier-stokes equation and the heat conduction equation is discussed in this paper. This paper also clarifies that the RNG k-εturbulence model can be used in the numerical simulation of the turbulent flow in a microchannel heat sink. Four coolants including water, methanol, ethanol and R113 are used in the simulation, the flow fields and temperature fields in mircochannels of different structures and sizes are simulated. Pressure losses of different parts of the microchannel and contributions to heat transfer by different surfaces within the microchannel are analyzed. For a high-power laser diode bar cooling heat sink, numerical simulations are carried out at Re=2500 (Reynolds number), ΔT_max=27℃(the maximal temperature rise at substrate surface) and P=3.6W (the pumping power), for the various width of microchannel inlets/outlets, the various width and depth of microchannels, and the various thickness of fins and substrates. The influence of various widths and depths on the heat transfer performance is analyzed and points to be considered for optimization design are discussed. Finally, strategies for improving the performance of the heat sink are presented. Different dimensions and heat load requirements are proposed for different microchannel heat sink applications. The author designs an optimization algorithm based on the characteristics of flow and heat transfer in a microchannel heat sink and writes optimization design software incorporating the algorithm. Given pumping work or the maximal temperature difference between the heat-sink surface and the coolant, the software can calculate the optimum structure dimensions and operating parameters under the restriction of the maximal temperature difference on the heat-sink surface. The software, which adopts the plural modality algorithm, carries out the optimization design of U-shaped passages and heat sinks with rectangular cross sections and plots the temperature distributions of the heat sink surfaces in a 3D figure. Material properties, boundary conditions, meshing scheme, and flow and temperature field solvers can be set through a GUI.