Investigation of a serpentine micro-pin fin heat and mass exchanger for absorption systems

An investigation of a heat and mass exchanger with micro-pin fins in serpentine passages for vapor absorption systems is presented. A serpentine micro-pin fin absorber sheet with a pin fin diameter of 350 µm and height of 406 µm is used. Visualization of the two-phase mixture flowing through the micro-feature component, and an investigation of the heat and mass transfer mechanisms over a range of temperatures, pressures, concentrations and flow rates are conducted. A model for the absorption of ammonia into a dilute ammonia-water solution in the geometry is developed based on insights from flow visualization results, and validated by comparing its predictions with heat transfer measurements. A computational fluid dynamics study of flow through the serpentine micro-pin fin passages is also used for additional insights. Liquid-phase mass transfer resistance is found to be the bottleneck to improved rates of vapor absorption in these absorbers.