Segmented two-phase flow networks for fluid and heat transport

The design of real systems incorporating multiphase flows remains a significant challenge for applications including biofluidics and heat exchanger technologies. Segmented two-phase flow without phase change is common to both applications, for the purpose of transporting biological samples from one site to many and for enhancing heat transport over conventional single phase flow. This paper theoretically examines flow networks that can efficiently transport a segmented gas-liquid flow over an area. In the first part, fundamental design rules have been determined using the constructal method to minimise flow resistance of elemental bifurcations. It was determined that the geometric diameter ratio follows an alternative to the established Murray's law when the global pressure difference is dominated by the gas bubble phase. Using the findings for an elemental bifurcation, the second part investigates both single scale and multiple scale hierarchical configurations for combined fluid and heat transport. The multiple scale tree-shaped design can be advantageous in the controlled transport of segmented phases over an area and for low thermal resistance and pumping power requirements compared to a single scale serpentine channel layout. However, an increase in number of bifurcation levels of the hierarchical structure must be accompanied by an increase in the entrance branch slug length to maintain a segmented flow throughout the network. The method and results from this study can be used to reduce the design space in high fidelity investigations of mini- and microscale segmented flows for fluid and heat transport purposes.