Freezing in microchannels can be exploited for flow control in microfluidic applications where the use of traditional valve mechanisms is impractical. For liquid flow in a subcooled channel, freezing may initiate in dendritic, annular, or mixed modes of ice formation, depending on operational and geometric parameters. While these different modes have been observed anecdotally, the literature lacks a comprehensive parametric understanding of the ice formation behavior and the resulting time taken to block off flow in a channel. An experimental study is performed to visualize ice formation in water flowing through a subcooled circular microchannel (500 μm inner diameter) that is installed in a vacuum-insulatable, temperature-controlled test cell. The glass microchannel wall and transparent windows in the test cell and vacuum chamber allow for high-speed, high-magnification visualization of the freezing behavior. At flow rates of 0.5 ml/min, 1.0 ml/min, and 2.0 ml/min, dendritic and annular modes of ice formation are observed; the growth characteristics are presented as a function of the water flow rate.

This content is only available via PDF.
You do not currently have access to this content.