Thermal and Flow Performance of a Microconvective Heat Sink With Three-Dimensional Constructal Channel Configuration

Abstract

The design, performance, manufacturing, and experimental validation of two convective heat sinks with scalable dimensions are presented. The heat sinks consist of an array of elemental units arranged in parallel. Each elemental unit is designed as a network of branching channels whose dimensions follow a group of geometric relations that have been derived from physiological fluid transport systems and the constructal method. The goal of these relations is to optimize both the point-to-point temperature difference within the heat sink and the pressure drop across the device under imposed geometric constraints. The first branching network is a generic three-dimensional (3-D) structure that was analyzed to push the limit of the heat sinks capability. The second is a heat sink that was designed specifically with the tape-casting fabrication method in mind. The heat sink has a branching network embedded within low temperature cofire ceramic (LTCC) and the same network embedded within thick film silver, which has the ability of being cofired with low temperature cofired ceramic substrates. The performance is evaluated using both a channel-level lumped model and a CFD model. The performance for different heat sink materials (low-temperature cofired ceramic and silver) is presented. The key results are then compared with the experimental results of the two scaled models. The results show good agreement within the experimental uncertainty. This validation confirms that the thermal performance and pumping efficiency of the constructal heat sink is superior compared to porous metal and conventional microchannel heat sinks under the same operating conditions, and that the designs are only limited by manufacturing techniques.