Simultaneous thermal and optical imaging of two-phase flow in a micro-model

In the study of non-equilibrium heat transfer in multiphase flow in porous media, parameters and
constitutive relations, like heat transfer coefficients between phases, are unknown. In order to study the
temperature development of a relatively hot invading immiscible non-wetting fluid and, ultimately,
approximate heat transfer coefficients, a transparent micro-model is used as an artificial porous medium.
In the last few decades, micro-models have become popular experimental tools for two-phase flow
studies. In this work, the design of an innovative, elongated, PDMS (polydimethylsiloxane) micro-model
with dimensions of 14.4 × 39 mm2 and a constant depth of 100 microns is described. A novel setup for
simultaneous thermal and optical imaging of flow through the micro-model is presented. This is the first
time that a closed flow cell like a micro-model is used in simultaneous thermal and optical flow imaging.
The micro-model is visualized by a novel setup that allowed us to monitor and record the distribution of
fluids throughout the length of the micro-model continuously and also record the thermal signature of
the fluids. Dynamic drainage and imbibition experiments were conducted in order to obtain information
about the heat exchange between the phases. In this paper the setup as well as analysis and qualitative
results are presented.