EAGER: Superporous Electroactive Hydrogels for Self-cooling Closed Loop

University Of Arizona, Tucson AZ

Investigators

Abstract

This EArly-concept Grant for Exploratory Research (EAGER) project pursues research to investigate high-moisture sorbent materials with self-cooling and water recuperating properties for energy efficient building integrated cooling systems. In hot arid climates, evaporative cooling is an effective building conditioning method yielding up to 75 percent energy conservation in comparison to conventional compression cooling. However, evaporative cooling consumes and rejects massive quantities of water, which is becoming an increasingly valuable resource in arid regions. The concept for a more sustainable building cooling process will be regulated using electrically actuated polymers behaving as a moisture pump. After rapidly capturing moisture from air and upon reaching saturation, the water condensate can be extracted from the material with low energy techniques. Hydrogels can be used to improve reductions in building energy and water consumption for both hot-arid and hot-humid climate conditions. The research will determine the energy and water conserving properties of rechargeable hydrogels for building cool-down applications. Superporous hydrogels are composed of low crosslink monomer ratios, resulting in porous hydrophilic crosslinked structures, which enable them a high swelling rate regardless of the macroscopic sample size. The configuration of polyacrylate hydrogels can be dramatically altered upon a modest electric field change, where the contraction is the result of repulsion of dissociated carboxyl groups, which is mediated by the migration of hydrogen ions. The porous scaffold of these hydrogels also has the added benefit of promoting the electroactive response by reducing the Youngs modulus of the gels and enhancing the deswelling process. The hypothesis is that, in an airborne environment, the hydrophilic superporous structure will allow for high water content and fast rate of sorption while the electroactive chemistry will allow for induced water condensate release upon electrode charge. Numerical heat, air, and mass transfer for the superporous electroactive hydrogel will be analyzed by inputting material properties, such as porosity and thermal conductivity, from empirical characterization tests to inform the theory relevant to the sorption and condensate release processes.