Investigation of a microchannel heat and mass exchanger for absorption systems

Abstract

An investigation of a microchannel heat and mass exchanger for vapor absorption systems is presented. A sheet with 88 microchannels of depth 0.5 mm and width 0.76 mm is investigated via visual and thermal measurements. The flow in the microchannels is predominantly in the slug-flow regime, with distinct vapor and liquid regions. High rates of heat transfer were observed in the absorber. However, poor liquid mass transfer rates limit the performance of the microchannel absorber. The performance of the microchannel absorber is compared with that of an absorber with serpentine microscale passages containing micro-pin fins. A physics-based model for the absorption of ammonia into a dilute solution of ammonia-water in a microchannel absorber with mixing sections is developed using insights from flow visualization. The model is validated by comparing its predictions with the data. The potential of surfactants to enhance absorber performance is also investigated.