Pool Boiling on Composite Surfaces of Graphite Microfibers Imbedded in Metal Matrix
W.-J. Yang, N. Zhang, D.-F. Chao and S. Torii
The composite surfaces of graphite micro-fiber reinforced copper (Gr-Cu) or aluminum (Gr-Al) are manufactured through graphite micro-fibers of 8 to 10 micron diameter imbedded co-axially within a copper or aluminum matrix with certain percentage area fraction. This article presents an overview of pool boiling experiments on such composite surfaces employing micro-fibers in a macro-application. Scanning Electron Microscope (SEM) is employed to examine the topography of these composite surfaces for the characteristics of nucleation sites. The most important finding in pool boiling on the graphite-metal composite surfaces is a significant enhancement in performance over that on pure metal surfaces under the same operating conditions. The unique nature which is unseen in other high flux boiling surfaces has motivated over a decade study on the subject since 1991 by the authors and their associates. Results and discussion presented here include pool boiling performance, nucleation phenomena, bubble departure, hysteresis, critical heat flux, and the effects of micro-gravity conditions. The objective of this article is to utilize these composite surfaces as high heat flux surfaces for the cooling of electronic chips (very large-scale integration, VLSI) and other industrial applications including in space flights.