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Ecological cumulative exergy consumption analysis of organic Rankine cycle for waste heat power generation

Wang, Shukun, Liu, Chao, Liu, Lang, Xu, Xiaoxiao, Zhang, Cheng
Journal of cleaner production 2019 v.218 pp. 543-554
algorithms, capital, coal, ecosystems, electricity, energy conservation, environmental impact, environmental protection, exergy, heat, hydrofluoric acid, life cycle assessment, models, power generation, power plants, sustainable development
Effective energy saving and environmental protection are the global topics. Organic Rankine cycle (ORC) that efficiently converts the waste heat into electricity has drawn widespread attention. The sustainability assessment of ORC can explicitly reveal its contribution to mitigating the ecosystem degradation. Meanwhile, the ecological cumulative exergy consumption (ECEC) analysis is generally used to evaluate the sustainability of industrial activities. Therefore, we established the ORC-ECEC model based on the ecological life cycle assessment involving three fundamental aspects, the resource consumption, economic capital and the environmental impact. Particle swarm optimization algorithm was adopted to optimize the system parameters. The working fluid, R134a, is used in ORC to illustrate the features of proposed framework and conduct the comparison with coal-fired power generation system. Further, systems using working fluids of different hydrogen fluoride olefins (HFOs) are selected to investigate the effect of working fluid on ORC sustainability. The results showed that the economic capital exhibited the largest ECEC during the life-time of ORC, followed by environmental impact and resource consumption. The ECEC of system using R134a was about 1.89E+10 sej/kWh, which was much smaller than that of coal-fired power plant, 1.41E+12 sej/kWh. In addition, the ECEC analysis of systems using different HFOs indicated that ORC using R1336mzz as working fluid was significantly superior compared to systems using other working fluids from the point of view of the sustainable development.