Abstract Polymer‐based membrane technology holds immense promise for CO 2 separation. However, it faces persistent challenges, including the high CO 2 pressure‐induced plasticization and permeability‐selectivity trade‐offs, which significantly hinder the development of polymeric membranes. To tackle this issue, we synthesized a novel polyimide 6FDA‐DAT:DABA(6FDD) containing triptycene and carboxylic groups. Upon de‐carboxylation induced cross‐linking, the membrane demonstrated a simultaneous enhancement of gas permeability and selectivity. Specifically, compared to the uncross‐linked 6FDD, the 400°C‐24 h cross‐linked membrane exhibited a remarkable increase in CO 2 permeability by 177% (93.1 Barrer) and a significant rise in CO 2 /CH 4 selectivity by 47% (57.5), reaching the CO 2 /CH 4 upper bound. More importantly, the cross‐linked membrane displayed vastly improved CO 2 plasticization resistance, withstanding up to 42 bar of CO 2 feed pressure. The design of decarboxylated cross‐linked membranes in this work paves the way for creating high‐performing and plasticization‐resistant membranes with potential applications in high‐pressure CO 2 separations.
Highway traffic increasingly extends to the mountainous area, requiring highway tunnels to be longer. Highway tunnel construction is risky and challenging, especially in the high ground temperature area of Western China. In this study, the Nige Tunnel of Yunnan Honghe Jian(ge) Yuan highway is the research object. By conducting numerous field temperature tests, geological surveys, water quality experiments, and other processes, the causes of high temperatures in the ground have been analyzed. The results show that the hot liquid or vapor from the earth's crust deep area carries various chemical materials, passing through various channels (faults and fissures) to the superficial area and forms the geothermal of the tunnel. The thermal anomaly bodies in the deep crust move upward through faults Fn1 and Fn2. Some heat sources are exposed to the surface and form hot springs, and others are distributed through secondary channels after being transmitted to the shallow part of the crust. Among them, the entrance section of the Nige Tunnel is limestone, and the groundwater infiltrating the fracture channel is mixed in the conduction process, resulting in the overall low water temperature, and the rock wall temperature is lower than the water body temperature. The exit section of the Nige Tunnel is granite, the heat source is mainly conducted through structural fractures or rock mass, resulting in high rock temperature at the exit. By analyzing the causes of high ground temperature, this study provides a theoretical basis for developing the tunnel scheme.
This study presents a novel cooling-power-desalination combined cycle for recovering shipboard diesel exhaust heat, integrating a freezing desalination sub-cycle to regulate the ship’s cooling-load fluctuations. The combined cycle employs ammonia–water as the working fluid and efficiently utilizes excess cooling capacity to pretreat reverse osmosis desalination. By adjusting the mass flow rate of the working fluid in both the air conditioning refrigeration cycle and the freezing desalination sub-cycle, the combined cycle can dynamically meet the cooling-load demand under different working conditions and navigation areas. To analyze the cycle’s performance, a mathematical model is established for energy and exergy analysis, and key parameters including net output work, comprehensive efficiency, and heat exchanger area are optimized using the MOPSO algorithm. The results indicate that the system achieves optimal performance when the generator temperature reaches 249.95 °C, the sea water temperature is 22.29 °C, and 42% ammonia–water is used as the working fluid. Additionally, an economic analysis of frozen seawater desalination as RO seawater desalination pretreatment reveals a substantial cost reduction of 22.69%, showcasing the advantageous features of this proposed cycle. The research in this paper is helpful for waste energy recovery and sustainable development.
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