Starch Particles, Energy Harvesting, and the "Goldilocks Effect"

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Science

Background:

• Conventional desiccants in energy exchangers face limitations in performance and regeneration.
• Biomass-derived materials offer sustainable alternatives for energy and environmental applications.
• Starch particles (SPs) present a novel option for desiccant coatings due to their unique properties.

Purpose of the Study:

• To investigate the water vapor adsorption-desorption properties of biomass-derived starch particles (SPs).
• To evaluate the performance of SPs as desiccant coatings in air-to-air energy exchangers.
• To compare SPs with high amylose starch (HAS) and silica gel (SG) for ventilation applications.

Main Methods:

• Characterization of starch particles (SPs), high amylose starch (HAS), and silica gel (SG) including surface area and pore width.
• Transient water vapor adsorption-desorption tests using a customized small-scale energy exchanger.
• Performance evaluation based on water swelling, water vapor uptake, and latent effectiveness.

Main Results:

• SP15 exhibited significantly higher water swelling (2 orders of magnitude) and water vapor uptake (3-6 fold) compared to HAS15 and SG13.
• The SP15-coated energy exchanger showed a 4-31% improvement in latent effectiveness over HAS15 and SG13 systems.
• Approximately 98% regeneration of SP15 was achieved under mild conditions, demonstrating superior adsorption-desorption performance.

Conclusions:

• Biomass-derived starch particles (SPs) possess unique, high-affinity water vapor adsorption properties, termed the "Goldilocks effect".
• SPs are a promising, efficient desiccant coating for air-to-air energy exchangers in ventilation systems.
• SPs hold potential as advanced materials for water and energy harvesting applications.