[Seminar] Adsorption-based atmospheric water harvesting using metal-organic frameworks powered by natural sunlight
Date : June 5th, 2019 (Wednesday), 13:30 ~ 14:30 p.m.
Place : E1 Seminar room (#3213)
Speaker : Hyunho Kim, Ph.D.
KIST, Center for water resources cycle
Adsorption-based atmospheric water harvesting using metal-organic frameworks powered by natural sunlight
Up to thirteen thousand trillion liters of water exist in the atmosphere at any one time. This is equivalent to about ten percent of all fresh water available on earth. However, an efficient process by which water can be captured from air, especially at low humidity levels (down to 20% relative humidity), and delivered has not been developed. Recent advances in porous adsorbents such as metal-organic frameworks (MOFs), with high sorption capacity and low regeneration temperature requirements, allow us to efficiently utilize them for the atmospheric water harvesting application. In this study, we provides a generalized framework to select the materials, design, and develop sorption-based atmospheric water systems. First, our study presents the design and demonstration of a device based on porous MOF-801 [Zr 6O4(OH)4(fumarate)6] powered by natural sunlight (solar-thermal) that captures water from the atmosphere at ambient conditions, down to 20% RH. Under these conditions, operation of competing technologies, such as dew-based atmospheric water generators (AWGs), is infeasible. Laboratory experiments and computational simulations were used to optimize the device based on this MOF to maximize water delivery capacity in arid climates. We subsequently tested an optimized device in an exceptionally arid climate with 10-40% RH and sub-zero dew points (Tempe, Arizona, United States). With a solar flux with 1.8x concentration for desorption, we demonstrated the operation of our device with a thermal efficiency (solar input to water conversion) of ~14%. Finally, we quantitatively analyzed the water quality and showed that the MOF compound was stable to water, and the metal ions and organic linkers did not leach from the framework into the harvested water. Our demonstration indicates that passive operation of sorption-based AWGs with high efficiencies (> 20%) is possible and can be operated with abundant low-grade heat sources (~100°C) under exceptionally dry climates of RH < 40%.
Dr. Hyunho Kim received his graduate degrees (S.M. in 2014 and Ph.D. in 2018) in Mechanical Engineering from the Massachusetts Institute of Technology (MIT) under supervision of Prof. Evelyn N. Wang. During his study, his research was focused on development of sorption-based energy systems including water harvesting and thermal energy storage. Dr. Kim’s work on energy and water systems received several prestigious honors and awards including Forbes 30 under 30 – Asia in 2019, Wunsch Foundation Silent Hoist and Crane Award in 2018, top 10 emerging technologies of 2017 by World Economic Forum and Scientific American. Currently, he is working as a postdoctoral researcher at Korea Institute of Science and Technology in Seoul, South Korea.
Host: 기계공학과 / 정상권 교수(3039)