NAU Vacuum Moisture Swing Capstone

VACUUM MOISTURE SWING

The goal of this project is to design and build a direct air capture device that utilizes a vacuum moisture swing process to separate CO2 from ambient air. This process utilizes common sorbent materials to bind to CO2 as air passes through them, and then it leverages a process in which moisture unbinds the CO2 from the sorbents. The intent is to have a scalable design which will be practical and energy-efficient for large-scale deployment near high CO2 areas such as factories.

The project has two primary goals: The first goal is to design and build a lab-scale device which will perform the vacuum moisture swing direct air capture process. The device will be designed to run the full direct air capture cycle, with most aspects automated. The second goal will be to optimize sorbent structures using both ANSYS fluent and the direct air capture device built. Upon recent communication with our project advisor, sorbent structure optimization may be limited to the extensive design process of the physical system.

The device will run through a five step cycle: adsorption, evacuation, desorption, final evacuation, and pressurization. During adsorption, ambient air will be pulled through the sorbent bed. The sorbent bed will then be isolated from atmosphere and a vacuum pump will draw down to complete evacuation. A water reservoir will then be exposed, causing the water to vaporize and unbind the CO2 from the sorbents in the desorption stage. The water reservoir will then be isolated and a final draw-down of the sorbent chamber will complete the final evacuation. Finally the sorbent bed will be exposed to ambient pressure, which will pressurize the system. The system can then repeat the cycles.

The new designs of the structured sorbent beds are intended to provide a lower resistance to flow, thereby decreasing the power requirement to run the cycle. A primary intent of this project is as a proof-of-concept that a vacuum moisture swing process can be a viable option for removing CO2 from air in large-scale, real-world applications.

At this time, all engineering calculations have been performed and all components have been specified. Final parts are being ordered at this time. Once majority of components have arrived the assembly process will begin. In the meantime the PLC software will be tested, further ANSYS simulations will be performed and sorbent printing compositions will be tested. Once the system has been assembled, we will prioritize wiring and coding to get the system ready for sorbent structure testing.