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

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 CH₄ 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.