8 research outputs found
Aqueous-Phase Reforming in a Microreactor: The Role of Surface Bubbles
In heterogeneous catalysis, the creation of gaseous products as bubbles in a liquid phase on the catalytic surface is associated with slip phenomena. In a microreactor, the slip length at the gasâliquid interface is in the same order of magnitude as the reactor dimensions, which can affect fluid dynamics and transport phenomena. Here, the interplay of momentum, heat and mass transfer in a microreactor, when bubbles form on the catalytic surface, was investigated using twoâdimensional simulations. The effect of bubbles on the endothermic process of aqueousâphase reforming of a glycerol solution was evaluated in terms of conversion and conversion and temperature in the reactor. Altogether, this study highlights the impact of bubbles, not only on the transport phenomena but also on the reactor performance
AqueousâPhase Reforming in a Microreactor: The Role of Surface Bubbles
In heterogeneous catalysis, the creation of gaseous products as bubbles in a liquid phase on the catalytic surface is associated with slip phenomena. In a microreactor, the slip length at the gasâliquid interface is in the same order of magnitude as the reactor dimensions, which can affect fluid dynamics and transport phenomena. Here, the interplay of momentum, heat and mass transfer in a microreactor, when bubbles form on the catalytic surface, was investigated using twoâdimensional simulations. The effect of bubbles on the endothermic process of aqueousâphase reforming of a glycerol solution was evaluated in terms of conversion and conversion and temperature in the reactor. Altogether, this study highlights the impact of bubbles, not only on the transport phenomena but also on the reactor performance
Monitoring phase transition of aqueous biomass model substrates by high-pressure and high-temperature microfluidics
AqueousâPhase Reforming (APR) is a promising hydrogen production method, where biomass is catalytically reformed under high pressure and high temperature reaction conditions. To eventually study APR, in this paper, we report a highâpressure and highâtemperature microfluidic platform that can withstand temperatures up to 200°C and pressures up to 30 bar. As a first step, we studied the phase transition of four typical APR biomass model solutions, consisting of 10 wt% of ethylene glycol, glycerol, xylose or xylitol in MilliQ water. After calibration of the setâup using pure MilliQ water, a small increase in boiling point was observed for the ethylene glycol, xylitol and xylose solutions compared to pure water. Phase transition occurred through either explosive or nucleate boiling mechanisms, which was monitored in realâtime in our microfluidic device. In case of nucleate boiling, the nucleation site could be controlled by exploiting the pressure drop along the microfluidic channel. Depending on the void fraction, various multiphase flow patterns were observed simultaneously. Altogether, this study will not only help to distinguish between bubbles resulting from a phase transition and/or APR product formation, but is also important from a heat and mass transport perspective