Electrospun hybrid microfibers for desiccant cooling/air dehumidification

The aim of this work was to assess the efficiency and suitability of hybrid adsorbent microfibers, produced by the electrospinning technique, in open-cycle adsorption applications, such as desiccant cooling, air dehumidification/humidification and heat storage, requiring high water adsorption capacity and high stability at high relative humidity, up to 80 %. Specifically, silica gel (SG) and magnesium sulfate (MS) as adsorbents and polyacrylonitrile (PAN) as polymer carrier, were used to prepare the hybrid microfibers at different concentrations of adsorbents and tested under isothermal conditions (50 °C) with relative humidity increasing from 0 % to 90 %. Characterization included morphological, structural, and thermal analyses, as well as measurement of ad/desorption isotherms and cyclic hydrothermal stability. The adsorption performances of the SG microfibers were comparable to that of the pure adsorbent: the microfibers with 50 w% silica gel showed a water absorption of 26.1 w% at 80 % relative humidity and T = 50 °C, which was in agreement with the content of SG. Under the same conditions, PAN microfibers with 50 w% MS achieved a water absorption of 42.7 w%. The dispersion of MS crystals in the microfibers improved the stability of the salt to hydration, allowing for a significant enhancement in the adsorption performance of magnesium sulfate.