Transient Mass Transfer in Parallel Passage Dehumidifiers With and Without Solid Side Resistance

Desiccant dehumidifiers have been used in industrial and commercial processes to provide air of lower relative humidity than can be achieved readily with vapor compression equipment. Parallel passage rotary wheel regenerators with silica gel on the passage walls are used as dehumidifiers for air-conditioning applications. This study presents an investigation of transient mass transfer in a parallel passage dehumidifier with a thin layer of silica gel on the passage walls. A two-film resistance model was used to approximate the overall transfer resistance between the process air and the solid desiccant. Isothermal transient mass transfer experiments using parallel passages with silica gel coated walls were conducted and analyzed. It was found that the two-film model agrees with the experimental results within the experimental accuracy. Although only silica gel was used in this study, the results may be extended to other solid desiccants.