Thermodynamic assessment of a DAC integrated with an open-air brayton cycle for application in the small modular reactor

This study proposes a novel sector-coupled energy system integrating an innovative small modular reactor (i-SMR), an open-air Brayton cycle (OABC), and a direct air capture (DAC) unit. The system leverages thermal and flow coupling, using regeneration heat and intake air for CO₂ capture. A dynamic adsorption model based on Golden’s string rule and thermodynamic analysis under off-design conditions quantified power loss, CO₂ purity, and capture over full cycles. Parametric optimization identified optimal performance at a mass flow of 332 kg/s and adsorption time of 7 h, minimizing capture cost while maintaining high CO₂ purity and near-saturation recovery. Under these conditions, net power loss was limited to 1.7–2.5 MWe relative to a DAC-free baseline, with total capture energy consumption below 1.4 GJ/tCO₂. These results provide the first theoretical demonstration of an i-SMR integrated OABC–DAC system, showing its potential to achieve efficient, low-penalty carbon capture through system-wide heat and flow synergies. • Small Modular Reactor based Direct Air Capture integration method proposed to reduce energy consumption. • Thermodynamic analysis is conducted to estimate energy penalty for Small Modular Reactor - Open Air Brayton Cycle – Direct Air Capture system. • Quasi-steady state modeling conducted for Direct Air Capture with integrated i-SMR.