IR Transceiver Irradiation Characteristics on Bubble/Slug Flow Regimes in Conventional and Minichannels

Multiphase fluid flows commonly occur in petrochemical, biotech, food, and process industries. Extraction and flow of crude oil is an example of multiphase solid, liquid, and gas flows. In this paper, the output signal characteristics of an infrared (IR) transceiver sensing system during the two-phase flows of air-water mixture inside a 2.64 mm diameter and 0.30-mm-thick glass tube is presented. An optimized distance between IR LED (transmitter) and center of the test section is predicted using COMSOL Multiphysics so that the receiver senses maximum number of photons. The experiments are done for the optimized distance to analyze bubble/slug of varying length and shapes. High-speed imaging is used for image registration of the flow regimes. A numerical model is developed with COMSOL package to understand the signal characteristics for multiple bubble/slug of varying sizes and is validated with the experimental results. Also with the developed model, a method is proposed to predict the liquid film thickness in mini/microtubes of diameters 3.42, 1.51, and 0.62 mm inner diameter and 0.60-, 1.50-, and 2.57-mm thickness, respectively. The results can be used to design IR transceiver array to measure the liquid film thickness in two-phase flow online.