A novel spherical micro-absorber for dehumidification systems

In this work, a novel design concept for absorbers used in dehumidification systems is proposed to overcome the practical challenges of the conventional packed-column absorbers. In the proposed design, spherical micro-absorbers (microcapsules) that contain a liquid LiBr desiccant inside a semi-permeable polymeric membrane shell are produced by using a custom-built microfluidic technique. The produced microcapsules are capable of containing the salt during crystallization. The X-ray diffraction analysis has confirmed that the observed crystals in the microscopes images were indeed for the encapsulated (LiBr) salt. Due to the indirect contact between the liquid desiccant and the process air, problems such as solution carryover and corrosion associated with packed-column absorbers can be eliminated. The collected sorption data show that the spherical microcapsules offer a high sorption capacity of 1 gw/gdry under 80% relative humidity. The proposed microcapsules offer surface-to-volume ratios between 6,000-12,000 m(2)/m(3), which is up to two orders of magnitude higher than the conventional packed-column absorbers (200-600 m(2)/m(3)). The produced micro-absorbers can withstand a compression force up to 2 x 10(5 )their weight, elastically expanded during the absorption process without rupture, and did not show a leakage or a reduction in capacity even after an accelerated test of 200 sorption-desorption cycles.

Automated summary

The novel spherical micro-absorbers offer high sorption capacity and surface-to-volume ratios, solving issues such as solution carryover and corrosion associated with conventional absorbers.