Investigation of boiling phenomena in microchannels using impedance spectroscopy technique correlated with videography

Inhalt:
In this work, we present a new approach for investigating boiling in microchannels with electrical sensing elements. Different electrode geometries were designed and fabricated to study volume void fraction resolution. Formerly, this phenomenon was mainly studied using high-speed video. In this work, a test device was designed and developed with transparent electrodes on top of a metal microchannel. The impedance of the multiphase flow is measured and compared with video recordings as means to verify the two-phase flow regime; this includes bubbly flow, slug flow and annular flow. It should be noted that during bubbly flow, static bubbles were simultaneously growing on the channel walls until reaching a critical size and releasing.