An improved design of double-layered microchannel heat sink with truncated top channels

•A novel double-layered microchannel heat sink with truncated top channel is proposed.•The new design has more uniform bottom wall temperature and lower thermal resistance.•The performance improvement is due to the weakened heating effect of top channels.•The performances of the new design are studied at various heat sink geometries.

An improved design of double-layered microchannel heat sink (DL-MCHS) with truncated top channels was proposed. The advantages of the design were studied numerically by a three-dimensional solid–fluid conjugate heat transfer model. The better performance of the design was well demonstrated by comparison with the original DL-MCHS. The results indicate that there exists an optimal truncation position for the top channel to achieve the best DL-MCHS performance, where the coolant temperature in the top channel is approximately equal to that in the bottom channel. The optimal truncation position is determined by the trade-off between the cooling effect and heating effect of the top coolant. Then the effects of individual parameters including bottom channel length (Lx), channel number (N), channel-to-pitch width ratio (β), and total pumping power (Ω) on the performance of the proposed design were investigated. It is found that for the original DL-MCHS with larger Lx, the cooling effect and heating effect of the top coolant are both enhanced compared to the design with smaller Lx. In this circumstance, an appropriate truncated design for the top channel can reduce the top coolant heating effect significantly without the loss of cooling effect. As a result, the advantages of the truncated concept become more obvious when applied in a DL-MCHS with larger Lx. As the same reason, for a specific design with larger N, smaller β or smaller Ω, the truncated design is strongly recommended to enhance the DL-MCHS performance.