ISSN Online: 2377-424X
ISBN Print: 978-1-56700-421-2
International Heat Transfer Conference 15
Geometric Structure of Segmented Flow Networks
摘要
Segmented flows consist of two immiscible fluids which travel along a channel in a segmented arrangement due
to an imposed pressure difference. In this paper, the geometric structure of segmented flow networks is
examined and fundamental design rules are established for two-phase flow without phase change. These rules
provide a basis for mini- and microfluidic architectures that minimize flow resistance for a global system. The
focus of the theoretical analysis is on T-shaped constructs which are frequently used to transport slugs/bubbles to
multiple sites. When the global pressure difference is dominated by the single phase flow, i.e. approaching
infinitely long slugs, geometric ratios for the T-shaped construct follow the well-established Murray’s rule.
However, when the global pressure difference is dominated by the presence of a second phase, the geometric
ratios follow alternative rules. Using the constructal method, these rules are shown to evenly distribute flow
resistance over the area occupied by the T-shaped construct. A simplified surface energy analysis has also been
conducted to estimate the work requirements during transport of a bubble from the primary to the daughter
channels of the network before breakup occurs. This work input becomes important as the ratio of the external to
internal lengthscale of the flow network decreases and a critical criterion has been outlined by considering the
channel and junction pressure scales. The design guidelines presented are useful for the optimization of
microscale chemical processes and heat exchanger technologies involving two-phase flows.