Single-phase and Two-phase Flow and Heat Transfer in Microchannel Heat Sink with Various Manifold Arrangements

The manifold microchannel (MMC) heat sink, which possesses better heat transfer performance and less pressure drop than the traditional microchannel heat sink, has attracted much attention from researchers in recent years. But not much of them, either single-phase or two-phase ones, focused on the problems about flow maldistribution and wall temperature nonuniformity that might ultimately lead to system breakdown. To investigate the flow distribution in the MMC heat sink, six types of manifold, namely Z-type, C-type, H-type, U-type, ZU-type, and HU-type are considered in the current study. All six manifolds are investigated in single-phase cases with water, while the latter three are adopted in two-phase cases with HFE7100. The cases are solved with the self-developed codes based on the OpenFOAM package. The manifold arrangement has a strong impact on the overall heat transfer performance and pumping power required. The HU-type and ZU-type MMC heat sinks are recommended to be fabricated in the single-phase heat transfer application due to their small thermal resistance lower than 2×10−5 m2·K/W and pressure drop less than 500 Pa. Besides, if the pumping power is not a restriction factor in the system, Z-type MMC is also recommended. In the two-phase cases, the flow distribution is naturally not uniform within a parallel microchannel system, and the microchannels with large flow velocity appear to have higher wall temperatures. The authors recommend using HU-type MMC heat sink in the flow boiling application due to its bottom wall temperature distribution is relatively uniform with a difference of less than 2 K.