Environmental, techno-economic and energetic performance analysis of atmospheric methane photocatalytic removal system

• Improved three-level criteria decision can effectively balance system performance . • Evaluation framework included environmental, techno-economic, and energetic criteria. • Ordered hexagonal post at 60° performed best with photocatalytic efficiency of 50.86%. • Ranking of pentagonal, triangular, and quadrilateral posts decreased sequentially. Atmospheric methane is a potent greenhouse gas that requires effective removal strategies to mitigate its environmental impact. This paper studied 48 schemes of atmospheric methane photocatalytic systems utilizing polygonal posts, assessing the effects of varying operating temperature ( T o ) and inlet volume flow rate ( Q in ) on system performance. Simulations of the velocity, temperature, and concentration fields were conducted to analyze fluid flow, heat transfer, and mass transport characteristics. A multi-level evaluation framework integrating environmental, techno-economic, and energetic criteria was developed, and the decision-making method was improved using ranking factors to identify the optimal system scheme. The results indicated that increasing T o negatively affected system performance, whereas higher Q in improved environmental and techno-economic performance but reduced energetic efficiency. Among the schemes, the ordered hexagonal posts at 60° showed the best performance under the working conditions of T o = 298 K, Q in = 1000 mL/min, P = 0.101 MPa, and an inlet CH 4 concentration = 1.86 ppm, achieving a methane purification rate of 7.78 × 10 -9 g/s, a saving to investment ratio of 1.67, and a photocatalytic efficiency of 50.86 %. This was followed by random pentagonal posts at variable angles, random triangular posts at 60°, and random quadrilateral posts at 0°. Future work will focus on multi-objective optimization to improve both system performance and economic feasibility, promoting the practical application of methane photocatalytic technology.