Ultra-high pool boiling performance and effect of channel width with selectively coated open microchannels

Abstract

Recent developments in the microelectronics industry has placed increasing demand on developing high heat flux removal systems. Pool boiling offers a simple technique without introducing complicated header configurations and moving parts. Enhancement in pool boiling is achieved by delaying critical heat flux (CHF) and increasing heat transfer coefficient (HTC), which dictates the heat removal capability of a surface. This study focuses on the effect of channel width on the performance and heat transfer mechanisms on open microchannel surfaces with three coating configurations: (i) sintered-throughout, (ii) sintered-fin-tops, and (iii) sintered-channels. Pool boiling performance is obtained with water at atmospheric pressure for 300μm, 500μm and 762μm channel widths. The separate liquid–vapor pathways in narrow channels, with sintered coatings only inside the channel, yielded an unprecedented performance with a CHF of 420W/cm2 based on the 1cm2 projected area at a wall superheat of 1.7°C at the fin top surface, resulting in an HTC of 2.9MW/m2°C. High speed videos were taken to understand the underlying mechanism. Furthermore, liquid–vapor pathways were identified to explain the parametric trends observed for each selectively enhanced configuration set.