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Performance analysis of a dual-module humidity pump for efficient drying and dehumidification.

Number: 2453

Author(s) : OH J., FIX A. J., ZIVIANI D., BRAUN J. E., WARSINGER D. M.

Summary

Dehumidification and drying processes play a significant role in the energy consumption of air conditioning and the production of dry materials. Traditionally, water removal involves cooling the airstream below its dew point, requiring substantial energy for phase change and reheating. Vacuum membrane dehumidification, which utilizes vapor-selective membranes and a vacuum pump to separate water vapor without condensing it, holds great potential for energy savings. However, the energy-intensive process of vacuum pumping the permeated gases back to the ambient air hinders the system from realizing its full efficiency. To address these challenges, recent studies have proposed a dual-module humidity pump, incorporating an additional membrane module on the rejection side to keep the pressure ratio low. Despite this innovation, the sub-ambient pressure in the rejection module allows air to permeate into the system, necessitating strategic air rejection to prevent pressure buildup and diffusion barriers. In this study, the performance of a dual-module humidity pump is numerically investigated, incorporating hollow fiber membranes and synchronized operation of a water vapor compressor and vacuum pump. The geometries of hollow fiber membranes are coupled with a partial pressure-driven ε-NTU method to derive accurate water vapor transport under non-ambient conditions in both dehumidification and rejection modules. The rotational speeds of the water vapor compressor and vacuum pump are controlled to adjust the pressure ratio and find the optimal efficiency of the system. The effects of asymmetric module size and geometries are examined to maximize the vapor balance ratio. The results indicate that the synchronized motion of the vacuum pump and compressor can greatly improve system efficiency without recirculating the air for sweep operation. Also, the optimized form factor of the hollow fiber membranes is derived, providing design guidelines for future research and manufacturing processes.

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  • Original title: Performance analysis of a dual-module humidity pump for efficient drying and dehumidification.
  • Record ID : 30033115
  • Languages: English
  • Subject: Environment
  • Source: 2024 Purdue Conferences. 20th International Refrigeration and Air-Conditioning Conference at Purdue.
  • Publication date: 2024/07/17

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