Swirling flow for performance improvement of a microchannel membrane-based absorber with discrete inclined grooves

Microchannel membrane-based absorber plays a vital role in energy-efficient and highly-compact absorption cooling systems. In this study, the absorption performance of a microchannel membrane-based absorber is investigated based on a three-dimensional CFD model. The effect of the solution channel width on the absorption performance is analyzed firstly. Results show that the channel width has an insignificant impact on the heat/mass transfer behavior, however, the pressure drop increases by 16.6% with decreasing the solution channel width from 1.8 mm to 1.0 mm. To improve the absorption performance while reducing the flow resistance, three groove structures (trilateral groove, quadrilateral groove, and circle groove) with a certain inclination angle on the bottom of the solution channel are discussed. Results illustrate that the swirling solution interrupts the boundary layer at the membrane-solution interface, facilitating mixing between the diluted solution from the interface and the concentrated solution from the channel bottom, and thus the heat/mass transfer is enhanced, especially at a high solution velocity. The best-performing structure is circle groove, which reduces the solution pressure drop by 13.17% and improves the absorption rate by 0.57%. Comparisons among different channel thicknesses indicates that both the groove structure and thinner channel can improve the absorption rate, but the groove structure improves more and its pressure drop is lower. The results demonstrate that the groove structure is promising to improve the hydraulic and absorption performances of microchannel membrane-based absorbers.