Using expanding channel array to form separated vapor-liquid paths instead of capillary force to realize liquid replenishment and voluntary forced convection has been proved that it can improve the pool boiling heat transfer performance substantially. In present work, we have applied several kinds of porous media onto the expanding channel heating surface, in order to block the vapor column moving upwards, facilitate horizontal movements and supply adequate fresh liquid. Afterwards, a series of experiments have been carried out to investigate the effects of the heating surface orientation on the pool boiling performance and it can be obtained that even under the condition of a large range of orientation angles, through forcing the bubbles generated by boiling escape from the horizontal direction and allowing fresh liquid to be replenished from the porous media. Then, in order to understand and verify this mechanism from the perspective of bubble dynamics, a large series of numerical investigations is also carried out to try to realize the proposed vapor escaping and liquid replenishment mechanism, focusing on the effects of wettability, porous media characteristics and other conditions. Based on the numerical results, we also began to consider explaining the mechanism of spontaneous bubble movement in expanding channel from a more microscopic point of view, focusing on the single bubble dynamics. We have proposed a series kind of visualization methods based on optical principles to capture the thin liquid film and measure its real size, verifying the relationship between the bubble dynamics of typical slug flow in expanding channel with wettability and surface tension.