Evaluation of Additively Manufactured Single-Pass and Two-Pass Enhanced Microchannel Heat Sinks

Additive manufacturing is proving to be a viable manufacturing technique to fabricate complex structures as it opens up the design space by providing improved design freedom and reduced geometric restrictions. Further, it assures to provide benefit to the heat exchanger industry which relies on novel geometric features to enhance performance and efficiency. This paper explores the heat transfer and pressure drop performance of additively manufactured microchannel heat sinks. Two types of microchannel heat sinks were tested, namely, single-pass and two-pass microchannels with heat flux provided on the bottom wall. Additionally, the microchannel geometry was enhanced by incorporating periodic secondary flow passages with an aim to enhance fluid mixing and disrupt boundary layer development. The enhanced microchannel configurations featured the oblique fin and trapezoidal fin heat sinks. Enhanced microchannels showed superior performance both thermally and hydraulically with 100% increase in heat transfer performance with negligible gain in pressure drop over the baseline straight microchannel geometry. Moreover, the performance gain was more evident for the single-pass microchannels than the two-pass configuration, which showed tremendously high pressure drop due to increase in flow length. Results showed 30% reduction in the overall thermal resistance for a constant pressure drop for the enhanced microchannels in the single pass configuration.