System design of a novel open-air brayton cycle integrating direct air capture

The Direct Air Capture (DAC) technology is essential for achieving carbon neutrality, as it enables processes with net-negative CO₂ emissions. However, its widespread commercialization faces significant challenges due to high energy requirements. Numerous attempts have been made to address this issue through thermal integration, yet the fundamental challenge of the high cost associated with extracting large volumes of low-concentration CO₂ from ambient air remains unresolved. In this study, the integration of Open-Air Brayton Cycle (OABC) as a solution to enhance overall system utilization by simultaneously utilizing large volumes of ambient air is introduced. Various OABC coupled temperature swing adsorption based DAC system layouts are analyzed while considering different regeneration temperatures, and the results revealed the optimal configurations that significantly reduce energy cost per captured unit of CO₂ with high purity and recovery. By combining an equilibrium short-cut model for temperature swing adsorption with process simulation methodologies, this research proposes the concept of “energy cost”—a metric that represents the amount of CO₂ captured against the energy penalty incurred by integrating DAC with OABC systems. The findings demonstrate that combining DAC and OABC systems could yield high purity and recovery rates of CO₂ through strategic thermal management and advanced adsorbent usage, offering a synergistic approach to carbon capture from an energy consumption perspective.