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

Abstract

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 mm(2) 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.

Modeling two-phase flow in a micro-model with local thermal non-equilibrium on the Darcy scale

“…By means of the given measurements, they are actually straight forward to compute from Eqs. (11). The respective lengths of the border lines need to be multiplied by the micro-model depth d and divided by the observed volume of the micro-model (V mm )…”

“…In order to accomplish this, we simulate two experimental runs of the experiment explained in Karadimitriou et al [11] with the macro-scale local thermal non-equilibrium model explained in Nuske et al [17] and given for completeness in Appendices A and B. By comparing simulation and experiment, we obtain a first-order approximation of the up-to-now unknown scaling parameter f e which was suggested in Nuske et al [17].…”

“…Karadimitriou et al [11] presented an experimental setup for the measurement of phase specific temperatures, as well as phase distribution, during invasion and equilibration processes in a transparent micro-model, made of Polydimethylsiloxane (PDMS). The described setup is a continued development of a mature measurement setup engineered at Utrecht University, Netherlands.…”

“…A parameter study was conducted and it was found that variations in f e lead to the expected and physically reasonable results. In this work, the macro-scale balance equations explained in Nuske et al [17] are employed in order to simulate the experiment described in Karadimitriou et al [11].…”

Thermal analysis of droplet flow: Numerical, analytical and experimental investigations

“…From an experimental point of view, several publications have reported original techniques to measure coupled phenomena by simultaneous thermal and optical measurements in miniaturized applications [26]. Other promising tools based on micro-electro-mechanical systems (MEMS) have been developed to control, investigate and characterize phenomena occurring in two-phase flows [27].…”