SUBCOOLED JET IMPINGEMENT BOILING ENHANCED BY POROUS SURFACE WITH MICROCOLUMN ARRAY

Abstract

Thermal management of electronic devices has been a key problem, especially as the heat flux of these devices increases continuously. Jet impingement boiling is an effective cooling technique for electronic devices, the enhancement of which still remains an urgent requirement. In particular, lowering the wall temperature and increasing the critical heat flux (CHF) are known to enhance cooling performance. In this paper, we propose a new jet impingement cooling method: applying the porous surface with a microcolumn array. This special porous structure is fabricated via the template method by using nano/microparticles. The enhancements of the jet impingement cooling performance with deionized water on the porous surfaces are investigated. The CHF and the heat transfer coefficient (HTC) increase with decreasing distance between the microcolumns. A high CHF of 548 W/cm2 is attained at the wall superheat of 34.5°C, and 36% enhancement is gained compared with the smooth porous surface. Meanwhile, a maximum HTC of 8.63 W/(cm2K) is achieved, two and a half times as large as that on the smooth copper surface. To understand the underlying mechanism, we analyze the bubble diameter during the growth time and the bubble departure time. On the porous surface with microcolumn array, the bubble grows and departs faster due to the extra contact line and microlayer area. The thermal resistance at the edge of the microlayer can be extremely small, and the evaporation of the thin film accelerates the growth and departure of the bubble.