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ISSN Online: 2377-424X

ISBN Print: 1-56032-797-9

International Heat Transfer Conference 11
August, 23-28, 1998, Kyongju, Korea

EXPERIMENTAL INVESTIGATION OF NH3-H2O FALLING FILM ABSORPTION IN A PLATE HEAT EXCHANGER

Get access (open in a dialog) DOI: 10.1615/IHTC11.1380
pages 101-106

摘要

In this paper, experimental analysis was performed for ammonia-water falling film absorption process in a plate heat exchanger with enhanced surfaces such as offset strip fin. The objectives of this paper are to analyze combined heat and mass transfer during the ammonia-water absorption process, and to obtain heat and mass transfer coefficients (Nusselt and Sherwood numbers) as functions of an equivalent Reynolds number which was introduced to study the effect of vapor flow characteristics on the absorption rate. It was found that before absorption started, there was a rectification process at the top of the test section by the inlet subcooling effect. Near the bottom of the test section, water desorption was found by checking ammonia balance of liquid and vapor flows. Physically, this means that ammonia vapor is absorbed into the liquid flow while water liquid evaporated into the vapor flow. The heat and mass transfer coefficients increased as the inlet subcooling increased in the cases of large liquid mass flow rates. The potential concentration difference, x, eq (T v) - x,(T ,) should be minimized to have a higher rectification rate at the top and a lower water desorption rate at the bottom leading to a higher absorption rate.