Flow of CO2–ethanol and of CO2–methanol in a non-adiabatic microfluidic T-junction at high pressures

Abstract

In this work, an experimental investigation of the single-and multiphase flows of two sets of fluids, CO 2 -ethanol and CO 2 -methanol, in a non-adiabatic microfluidic T-junction is presented. The operating conditions ranged from 7 to 18 MPa, and from 294 to 474 K. The feed mass fraction of CO 2 in the mixtures was 0.95 and 0.87, respectively. Under these operating conditions, CO 2 was either in liquid, gas or supercritical state; and the mixtures experienced a miscible single phase or a vapour-liquid equilibrium (VLE), with two separated phases. Taylor, annular and wavy were the two-phase flow regimes obtained in the VLE region. In the single phase region, the observed flows were classified into standard single-phase flows, ''pseudo'' two-phase flows and local phenomena in the T-junction. Flow regime maps were generated, based on temperature and pressure conditions. Two-phase flow void fractions and several parameters of Taylor flow were analysed. They showed a clear dependency on temperature, but were mostly insensitive to pressure. A continuous accumulation of liquid, either in the CO 2 channel or at the CO 2 -side wall after the T-junction, disturbed most of the experiments in VLE conditions by randomly generating liquid plugs. This phenomenon is analysed, and capillary and wetting effects due to local Marangoni stresses are suggested as possible causes.

Microfluidic Control Board for High-Pressure Flow, Composition, and Relative Permittivity

“…This requires one flow controlled pump for each component. By using separating containers (e.g., piston separated chambers or loops) to hold extra fluid components and a common source of pressure, flow can be driven by from only one pump (fluid setup B) 13 or a pressurized container (fluid setup C). To enable the composition to be tuned in this simplified system, an extra control element is required: a flow regulating board (FRB).…”

“…12 Microfluidic studies of CO 2 −ethanol and CO 2 − methanol flows have been presented. 13 The combination of high pressure and need for control puts extensive requirements on the equipment, 14 which increase the cost. With compressible fluids, volumetric flow metering can lead to errors due to fluid compression.…”

Fast and inexpensive method for the fabrication of transparent pressure-resistant microfluidic chips

“…Pressure-resistant microfluidic chips have become of increasing interest in recent years for flow chemistry (Benito-Lopez et al 2008;Verboom 2009;Razzaq et al 2009;Trachsel et al 2008), processes involving supercritical fluids (Benito-Lopez et al 2007;Marre et al 2012;Luther and Braeuer 2012), materials science (Marre et al 2012) and also as analysis tools (Benito-Lopez et al 2005;Keybl and Jensen 2011;Dorobantu Bodoc et al 2012;Pinho et al 2014;Macedo Portela da Silva et al 2014;Gothsch et al 2015;Blanch-Ojea et al 2012;Zhao et al 2013;Ogden et al 2014). Indeed, it is well known that operating processes at high pressure modify fluid properties, which may enable enhanced kinetics, conversion and selectivity (Verboom 2009;Benito Lopez et al 2007;Kobayashi et al 2005).…”

Fluid behavior of supercritical carbon dioxide with water in a double-Y-channel microfluidic chip

“…The microfluidics of two-phase flows where scCO 2 is one of the phases have been previously studied in a T-junction with ethanol and methanol (Blanch-Ojea et al 2012), and in annular flow with water (Marre et al 2009;Guillaument et al 2013). In the work of Blanch-Ojea et al (2012), the authors studied the effect of varying pressure and temperature in these scCO 2 -ethanol and scCO 2 -methanol systems, using a glass microfluidic chip.…”

“…In the work of Blanch-Ojea et al (2012), the authors studied the effect of varying pressure and temperature in these scCO 2 -ethanol and scCO 2 -methanol systems, using a glass microfluidic chip. In the works of Marre et al (2009) and Guillaument et al (2013), coaxially mounted silica capillaries were used to map the dripping to jetting transition regions of a scCO 2 -water system, as well as to model the influence of wall surface tension and interfacial tension between the fluids.…”