An experimental study of absorption of ammonia into a constrained thin film of ammonia-water solution is presented. A large aspect ratio microchannel with one of its walls formed by a porous material is used to constrain the thickness of the liquid film. An exit visualization section was used to confirm absorption of ammonia gas within the microchannel. Experiments were performed at a pressure of 1 bar and a fixed inlet temperature of the weak solution, for weak solution flow rates from 10 to 30 g/min, inlet mass concentrations from 0 to 15 percent, and gas flow rates between 1 and 3 g/min. Results indicate that the overall heat transfer coefficient changes little for lower inlet weak solution concentrations and for lower gas flow rates, but increases noticeably for a higher solution and gas flow rate. The solution side log-mean temperature distribution increases with an increase in inlet solution concentration. Absorber exit visualization revealed the presence of periodic ammonia bubbles, occurring in varying sizes and periods, indicating that improvements to the current design are necessary to ensure complete absorption within the microchannel.

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