Abstract:

A numerical investigation is performed to study the flow and heat transfer characteristics in a microchannel with droplet reentrant cavities, which have different angles with equal diameter section. The thermal enhancement factor (η? and augmentation entropy generation number (N_{s, a}) are used to evaluate the comprehensive performance of the microchannel. The numerical results indicate that the pressure drop of microchannel with droplet reentrant cavities reduced zigzag along the flow direction. Compared with the rectangular microchannel, the droplet reentrant cavities have less effect on the pressure drop. WhenRe is small, the effect of droplet reentrant cavities on heat transfer increases little and even less than rectangular. However, whenRe>300, as the angle between export tangent of reentrant cavity and equal diameter section decreases, the heat transfer performance gradually increases. The analysis of entropy generation show that the irreversible loss caused by heat transfer increases with the Reynolds number, but the irreversible loss caused by flow friction decreases, and heat transfer entropy generation is the major component of the total entropy generation. The irreversible loss of microchannel with droplet reentrant cavities is smaller than the rectangular channel and the smaller of angle with equal diameter section, the less of the irreversible loss.

Key words: droplet reentrant cavities, entropy generation analysis, heat transfer, numerical simulation, microchannel