• Energy Research

[EN]Absorption carbon capture is currently the most commercialized technology and deemed as the vital solution to balance continued use of fossil fuels and carbon emission reduction. Nevertheless, its high energy cost remains the major concern for wide-scale application. Consequently, it is of great significance to address this issue by analyzing the underlying energy conversion mechanism, answering the pivotal question “What characteristics lead to a superior absorbent?”, and developing more efficient absorbent. In this paper, an irreversible decoupling model of absorption carbon capture system, consisting of a heat engine and a chemical pump, is innovatively established. Accordingly, key performance indicators are analytically derived and the optimal operation strategies of the system are explicitly determined. Notably, the matching of two subsystems leads to a novel insight into the heat and mass transfer interaction of absorbent, according to which the simulated results and the question concerning the best absorbent are thermodynamically interpreted and addressed, respectively. Additionally, the comparisons between the calculated optimal energy conversion efficiencies with experimental and simulated results are presented and discussed. Our findings may indicate the efficient pathway for developing advanced absorbent and provide instructing information for the design and operation of practical carbon capture systems.

[EN]Low-grade thermal energy utilization plays an important role in addressing escalating energy demand and environmental challenges. However, primary low-grade thermal energy harvesting technologies are currently only capable of their own single and fixed energy conversion and transport modes, which limits their further application. To break this bottleneck, we innovatively propose an electrochemical energy converter (EEC(s)) cycle model, which consists of three isothermal processes and three open-circuit heating (or cooling) processes and operates between three heat reservoirs. Notably, the proposed EEC(s) integrates and enables flexible switching of thermal-to-electricity and thermal-to-refrigeration harvesting strategies. Moreover, the complementary roles of thermal energy and electricity are enabled to meet different levels of cooling demand. Significantly, its extraordinary thermal-to-refrigeration conversion efficiency and great potential as an alternative to conventional thermally driven refrigerators are emphasized. Specifically, when the EEC(s) operates at maximum cooling power density, a thermal-to-refrigeration conversion performance coefficient of 0.498 and a Carnot-relative efficiency of 32.3% are predicted for the given operating temperatures. Additionally, the different roles of the cell parameters in enhancing the EECs performance are specified. This work demonstrates the feasibility of integrating multiple energy conversion and transport modes into a novel electrochemical cycle configuration and provides a promising solution for efficient and comprehensive low-grade thermal energy utilizations. Natural Science Foundation of Fujian Province (Grant No. 2022J01547, No. 2023J01397, and 2023J05100) National Natural Science Foundation of China (Grant No. 12105049 and 12475034). JGA thanks financial support from NEXTGENERATION EU funds under project MIA.2021.M01.0004.E24. ACH acknowledge financial support from Ministerio de Ciencia, Innovación y Universidades of Spain under grant PID2023-147201OB-I00.