Highly Effective Multi-String Water Vapor Capturing System (Dehumidifier)

Tech ID: 30266 / UC Case 2019-332-0


UCLA researchers in the Department of Mechanical and Aerospace Engineering have developed a multi-string dehumidifier for humidification-dehumidification desalination systems.


Fresh water scarcity has motivated the development of compact and economic vapor condensation methods for distributed water treatment and harvesting. One desalination and water treatment approach is ambient-pressure humidification-dehumidification (HDH), which imitates the natural rain cycle by creating humidified air and then condensing water vapor to produce distilled water. While this technique is very tolerant to high salinity and can produce high-quality (distilled) water, its low thermal energy efficiency, particularly during dehumidification, remains a critical technical challenge. Conventional approaches to condensation rely on cooled, densely packed solid surfaces in contact with a gas stream. However, the solid surface areas per volume one can achieve are limited by weight, cost, and/or manufacturability. Thus, there remains a need for compact, low-cost, and highly-effective dehumidifiers.


UCLA researchers have developed a light, cost-effective and highly efficient multi-string dehumidifier for thermal desalination and water vapor capture systems. The multi-string dehumidifier can achieve high condensation rates, and has a large area to volume ratio, which ensures high transfer rate within a finite volume. The resulting increase in the spatial bead density delivers mass transfer coefficients and hence condensation rates per volume almost 4 times higher than the best reported values. Moreover, the parallel and continuous gas flow paths in the multi-string dehumidifier result in a significant reduction in gas pressure and hence power consumption. The dehumidifier is also cost effective and light, since the main component is cotton string. This invention can also be applied to any industries seeking lower capital or operational expenditure water vapor capturing systems.


  • Water vapor capture systems (water treatment and harvesting) 
  • Thermal desalination


  • Light, cost-effective materials used 
  • Condensation rates almost 4 times higher than best reported values 
  • Significant reduction in power consumption

Related Materials

  • Zeng, Z., Sadeghpour, A. and Ju, Y.S., 2019. A highly effective multi-string humidifier with a low gas stream pressure drop for desalination. Desalination, 449, pp.92-100.

Patent Status

Patent Pending


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  • Ju, Yongho

Other Information


Direct-contact, multi-string humidifier, thin film flows, low pressure drop, ambient-pressure humidification-dehumidification (HDH), traveling liquid beads, mass transfer

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