Palko, J.W., Zhang, C., Wilbur, J.D., Dusseault, T.J., Asheghi, M., Goodson, K.E., and Santiago, J.G., 2015, “Approaching the Limits of Two-Phase Boiling Heat Transfer:  High Heat Flux and Low Superheat,” Applied Physics Letters, Vol. 107, 253903.


We demonstrate capillary fed porous copper structures capable of dissipating over 1200W/cm2 in boiling with water as the working fluid.  Demonstrated superheats for this structure are dramatically lower than those previously reported at these high heat fluxes and are extremely insensitive to heat input.  We shgow superheats of less than 10K at maximum dissipation and varyinbg less than 5K over input heat ranges of 100W/cm2.  Fabrication of the porous copper layers using electrodeposition around a sacrificial template allows fine control of both microstructure and bulk geometry, producing structures less than 40 microns thick with active region lateral dimensions of 2mm x 0.3mm.  The active region is volumetrically Joule heated by passing an electric current through the porous copper bulk material.  We analyze the heat transfer performance of the structures and suggest a strong influenbce of pore size on superheat.  We compare performance of the current structure to existing wick structures.