ERI: Simultaneous Interactions between Gases, Liquids, and Adsorbents in Adsorbent-Coated Microchannels

Combustion of fossil fuels dominates the global energy infrastructure, leading to significant CO2 emissions and, in turn, environmental concerns that are intensifying yearly. Capturing this CO2 using most state-of-the-art separation technologies requires electricity, compromising their carbon footprint. Meanwhile, 67% of the primary energy is wasted in the atmosphere as heat. This award is uniquely placed at the intersection of these two problems and focuses on developing a waste heat-driven adsorption-based CO2 separation technique. This concept uses thin and porous adsorbent layers fabricated on microchannel walls, which offer excellent heat and mass transfer attributes, resulting in rapid adsorption of CO2 from the feed stream. This project will comprehensively evaluate how hot liquid water can effectively remove the adsorbed CO2 through direct contact, which has not been employed previously. Successful implementation of such a shared channel approach will increase the specific CO2 capture capacity by up to two orders of magnitude. This technology can provide inexpensive, scalable, location-independent, and compact solutions for post-combustion CO2 capture. This research will also enrich the thermal-fluids courses, generate new paradigms for senior design projects, and attract participation in STEM outreach events. Temperature swing adsorption-based (TSA) carbon dioxide (CO2) separation processes, which involve an alternating flow of gases and liquids in adsorbent-coated microchannels, have been shown to yield superior and environmentally friendly performance compared with existing processes.The proposed cyclic process begins by sending the feed gas mixture through adsorbent-coated microchannels, which results in carbon dioxide adsorption. Subsequently, hot water flows through the same channels, regenerates the adsorbent, desorbs the carbon dioxide, and removes the desorbed CO2 from the channel. This stage is followed by cooling and purging of liquid in preparation for the next cycle. Here, the regeneration stage involves a complex and poorly studied set of transport phenomena involving multiphase interactions between hot liquid water, solid adsorbent, and adsorbed, dissolved and gaseous CO2. The scientific objective of this award is to develop a fundamental understanding of these multiphase interactions through experiments and modeling to demonstrate effective CO2 separation using this technology. Experiments involving high-speed flow visualization and first-principle-based computational models will determine the intermediate variables in these transport phenomena, and the end effects of the multiphase interactions in the models will be validated with those in the experiments. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.