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Evaporation-based solar thermal distillation is a promising approach for purifying high-salinity water, but the liquid-vapor phase transition inherent to this process makes it intrinsically energy intensive. Here we show that the exchange of heat between the distilled and input water can fulfill a resonance condition, resulting in dramatic increases in fresh water production. Large gains (500%) in distilled water are accomplished by coupling nanophotonics-enabled solar membrane distillation with dynamic thermal recovery, achieved by controlling input flow rates as a function of incident light intensity. The resonance condition, achieved for the circulating heat flux between the distillate and feed, allows the system to behave in an entirely new way, as a desalination oscillator. The resonant oscillator concept introduced here is universal and can be applied to other systems such as thermal energy storage or solar-powered chemical reactors.
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Specific energy analysis of using fertilizer-based liquid desiccants to dehumidify indoor plant environments
Controlling humidity in indoor plant environments is crucial to plant growth, but traditional dehumidification methods can be energy intensive. In this study, we evaluate the energy efficiency of a novel dehumidification concept that uses cold concentrated fertilizer solution as a liquid desiccant agent. This closes the water cycle by recovering water vapor for plant fertigation, and eliminates the need for energy-intensive desiccant regeneration. A theoretical transport model is used to conduct a parametric analysis of the specific energy performance of the system in response to desiccant temperature and other operating conditions. Specific energy of dehumidification is defined here as the ratio of the cooling load to the water vapor removal. Minimum specific energy results between 0.16-0.24 Wh/g are achieved at liquid desiccant temperatures between 7-14 °C. These results compare very favorably with other dehumidification technologies on the market, and satisfy new energy efficiency standards for indoor plant cultivation. The vapor flux associated with the minimum specific energy ranged from 1.2-1.6 g/m2/h. Controlling liquid desiccant temperature is shown to be critical to achieving high dehumidification rates at optimal specific energies. These encouraging results suggest that future research and development along this track can contribute to energy efficient greenhouse cultivation for sustainable food production.
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- Award ID(s):
- 2301488
- PAR ID:
- 10525536
- Publisher / Repository:
- Elsevier
- Date Published:
- Journal Name:
- Applied Thermal Engineering
- Volume:
- 238
- Issue:
- C
- ISSN:
- 1359-4311
- Page Range / eLocation ID:
- 121849
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1016/j.applthermaleng.2023.121849
