Two-phase liquid flow in micro-/mini-channels has several thermal advantages in comparison with single-phase liquid flow, such as heat transfer rate, thermosiphon effect and isothermal heat sinks. Multiphase flows in microfluidic devices are usually used as an effective way to improve the cooling process, since phase change process can provide high heat transfer coefficient in comparison with single-phase flows. On the other hand, high surface-to-volume ratio of microheat exchangers can intensify the overall heat rejection from the system. In the current research, three models, namely (a) the formation of interior and exterior phase, (b) hydrodynamics of droplets during condensation process in a diffusive oblique fin (mini-channel) with hydrophilic walls and (c) liquid evacuation from the channel, are investigated by means of a novel perspective of pseudo-potential lattice Boltzmann model. The effects of channel slope angle on velocity profiles and outlet mass flow rate of the condensed liquid are analyzed. The results show that the slope angle plays an important role at the rate of droplet nucleation and on evacuation time. It is observed that the variation of liquid profile at the channel outlet can be neglected at angles more than 45°. Finally, it is revealed that the required time for droplets coalescence and discharging liquid from the mini-channel can be controlled by optimizing the channel angle.

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