Influence of pore size distribution on pool boiling heat transfer in porous artery structure

To enhance the boiling heat transfer (BHT) performance is of great significance for high heat flux heat dissipation. Through effective liquid/vapor separation mechanism, porous artery structures are proved to significantly enhance the BHT performance. However, such structures are mainly focused on adjusting the liquid/vapor distribution on the macroscale, and the engineering of liquid/vapor distribution inside the porous structure is still missing. To facilitate the vapor escape and also the liquid replenishment inside the porous structure, porous artery structures with four types of pore size distribution, i.e., mono-porous, bi-porous, gradient-aperture, and gradient aperture and bi-porous distributions, were fabricated and experimentally investigated. Experimental results show that porous artery structures with both bi-porous and gradient-aperture distributions exhibit superior heat transfer performance compared to that with mono-porous distribution due to i) reduced liquid and vapor flow resistance; ii) increased liquid replenishment via capillary suction; and iii) efficient liquid/vapor phase separation. The maximum heat flux reached up to 554 W/cm² for the optimized bi-porous distribution, which is increased by 269% compared to that on a smooth copper surface. In addition, the effects of particle size and the amount of additive PMMA on the BHT performance are investigated, and the underlying physical mechanisms are discussed.