Computational study of rib shape and configuration for heat transfer and fluid flow characteristics of microchannel heat sinks with fan-shaped cavities

Abstract

Cavities and ribs are usually utilized in the design of microchannel heat sink systems, and their combination may lead to the optimum overall performance. However, it remains unclear how different combination methods contribute to the performance and efficiency of the systems. Computational fluid dynamics simulations were conducted to identify the optimum rib shape and configuration for the systems with fan-shaped cavities. The ribs are rectangular, diamond, hexagonal, or elliptic in cross-section. The effects of rib shape, dimensions, and configuration are investigated, and the optimum comprehensive performance was determined. The results indicated that the shape, dimensions, and configuration of ribs are important factors that affect performance and heat transfer efficiency. The shape and position of ribs must be optimized to minimize pressure drop while maximizing heat removal efficiency. The shape of ribs can be an important factor in obtaining high efficiency of heat removal while limiting the pressure drop across the channels. When the ribs are rectangular in shape, the maximum pressure drop occurs but the maximum relative Nusselt number is achieved. The maximum comprehensive performance factor is achieved when the ribs are elliptic in shape and the Reynolds number is highest. Further improvement in performance can be achieved by choosing particular rib dimensions and configuration. In order to provide appropriate benefit to such a microchannel heat sink system without inducing additional pressure drop that reduces the performance of the system, it is desirable to properly shape and position the ribs relative to the cooling flow and the cavities in a way that takes best advantage of the benefits provided by the combination of cavities and ribs. The effect of trailing edge vortexes on heat transfer performance is significant. A maximum comprehensive performance factor of 1.96 is achieved when the Reynolds number of the laminar flow is 460.