Single and two-phase pressure drop in serpentine mini-channels

The pressure differential of single and two-phase flow in mini-channel serpentine geometries was investigated to determine the effects of flow patterns and radius of curvature of the serpentine on pressure drop. The friction factor for single phase flow through a straight channel was comparable to existing literature, while that in the serpentine geometry fell between conventional theory for straight channels and fully developed flow in helical coils. Extension of the single phase results to two-phase flow using a separated flow model led to the development of empirical correlations for two-phase pressure drop in the straight and serpentine configurations. Five operating regions were identified within the serpentine, each with distinct pressure drop characteristics dependent on the flow pattern and extent of bubble deformation. Two of the operating regions corresponded to bubbly and slug/unstable-annular flow, while the boundaries between the three remaining regions occurred at WeLGLC = 2.7 and 15.5; corresponding to the onset of mild cap deformation and continuous bubble breakup, respectively.

► Serpentine single phase pressure drop in between that of a straight and helical channel. ► Five operating regions identified, each with distinct pressure drop characteristics. ► Regions within plug flow regime delineated by onset of bubble deformation and breakup. ► Interplay between shear and surface force in serpentine well correlated by WeLGLC.► Separated flow model proposed for two-phase flow in serpentine channel.