Smart microchannel heat exchanger based on the adaptive deformation effect of shape memory alloys

Abstract

Microchannel heat exchangers that are compact and have high efficiency have significant application value in the cooling of high-power electronic components. In this study, a smart microchannel heat exchanger with a shape memory alloy vortex generator (SMA-VG) was proposed to address the challenges associated with complex working conditions and random hotspots of electronic components. Owing to the shape memory effect, the structure of the SMA-VG can automatically adjust to change the flow characteristics of the microchannel, such that the cooling capacity and heat dissipation demand can be matched intelligently without external control. Herein, the principle underlying smart microchannel heat exchangers is analyzed, and a relationship between coil deformation and the Nusselt number (Nu) is proposed. Subsequently, the responses of the SMA-VG to different heat fluxes and Reynolds numbers are revealed, and a SMA-VG of three unequal lengths is proposed. The performance of microchannel heat exchangers with SMA-VG was investigated by combining experimental and numerical methods. The results showed that the SMA-VG adaptively adjusted its pitch configuration with changes in heat flux, improving the overall heat transfer performance of the channel in comparison to the non-deformed vortex generator (NDF-VG). The channel with the SMA-VG exhibited a stronger localized disturbance performance. When the heat flow density was 100 000 W/m2, Nu increased by 112% relative to that of the channel without a vortex generator, which was 9% higher than that of the channel with NDF-VG. Therefore, this novel heat exchanger resolves the challenges of poor automatability that are associated with traditional microchannel heat exchangers, in addition to removing random hotspots. Moreover, it facilitates the achievement of different levels of heat dissipation demands without external control, and it has potential for application in fields involving the usage of high-heat-flux chips.