Review of channel flow boiling enhancement by surface modification, and instability suppression schemes

Abstract

Abstract This article provides a comprehensive review of published literature concerning enhancement of channel flow boiling heat transfer by surface modification. Addressed are macro, micro, nano, and hybrid multiscale methodologies. While the vast majority of published schemes have shown favorable heat transfer performance, evidenced by earlier onset of boiling, improved flow boiling heat transfer coefficient, and ameliorated critical heat flux (CHF), increased pressure drop is a serious concern shared by most. Nanoscale enhancement remains controversial, given that, unlike macroscale and microscale enhancement features, nanostructure topographies are prone to severe degradation after prolonged boiling. Multiscale enhancement, combining macro, micro, and nano features as well as favorable coolant flow control, is shown highly effective at tackling very high heat flux situations. Also included in this review is discussion of effective means for mitigating flow instabilities. It is concluded that the most serious obstacle to adopting surface modification techniques is absence of generalized predictive tools or robust computational models for different channel shapes, sizes, and enhancement configurations, and different fluids and operating conditions, such as tools presently available for two-phase flow and heat transfer in conventional micro-channel heat sinks.