Compact bubble absorber design and analysis

A study of tubular bubble absorption in a NH₃-H₂O solution and its application to the generator-absorber heater exchange absorption cycle (GAX) was performed. Design conditions for a compact bubble absorber, which included GAX load, NH₃ vapor to be absorbed, and coolant energy quality for GAX purposes, and geometric constraints for a 1-ton refrigeration unit were determined. The performance of a first generation absorber design was determined experimentally. A second generation absorber was then designed, based on first generation experimental results. The second generation design employed judiciously chosen techniques for both heat and mass transfer enhancement. Heat transfer augmentation was achieved by repeated roughness, internal spacers, and increased thermal conductivity metal for absorber construction. Mass transfer augmentation was achieved through internal static mixers, variable cross-section flow areas, and numerous vapor injector designs. Performance of this second generation absorber was analyzed and possible directions for further improvement discussed.