(289f) Estimation of Slug Length in Gas-Liquid Microreactors by Using Indirect Measurements

A more efficient reaction or extraction operation can be achieved by using the gas-liquid slug flow in microreactors, because their uniform and large gas-liquid interfaces are formed. To apply gas-liquid microreactors (GLMRs) to real production, it is necessary to develop methods for increasing their production capacity and realizing their stable long-term operation. In GLMRs, the length of a gas-liquid slug significantly affects the mixing in the slug and the mass transfer between gas and liquid phases. Therefore, the slug length is one of important control variables. The process monitoring and control method is usually based on the measurements from installed sensors. Despite developments in sensor technology, the direct installation of sensors in microchannels often disturbs the flow and generates the dead volume. Therefore, it is desirable to estimate the immeasurable state variables in microchannels by using the indirect sensors. In this research, a monitoring method that is capable of estimating the slug length from the period of measured pressure variations in the gas feed channel is developed. In addition, the amplitude of the measured pressure variations is used to estimate the gas/liquid flow rates in the GLMR without flow rate sensors. The usefulness of the developed method is demonstrated through numerical and experimental case studies on a T-shaped microreactor with gas-liquid slug flow.