Life Cycle Assessment Introduced by Using Nanorefrigerant of Organic Rankine Cycle System for Waste Heat Recovery

Abstract

The use of nanorefrigerants in Organic Rankine Cycle (ORC) units is believed to affect the cycle environment performance, but backed with very few relevant studies. For this purpose, a life cycle assessment (LCA) has been performed for the ORC system using nanorefrigerant, the material and energy input, characteristic indicators and comprehensive index of environmental impact, total energy consumption and energy payback time (BPBT) of the whole life cycle of ORC system using Al2O3/R141b nanorefrigerant were calculated. Total environmental comprehensive indexes reveal that ECER-135 index decrease by 1.5% after adding 0.2% Al2O3 nanoparticles to R141b. Based on the contribution analysis and sensitivity analysis, it can be found out ORC system manufacturing is of the most critical stage, where, the ECER-135 index of ORC component production is the greatest, followed by the preparation process of R141b, transportation phase, and that of Al2O3 nanoparticles preparation is small. The retirement phase which has good environmental benefits affects the result significantly by recycling important materials. Meanwhile, the main cause and relevant suggestion for improvement were traced respectively. Finally, the environmental impacts of various power generations were compared, and results show that the power route is of obvious advantage. Among the renewable energy, ORC system using Al2O3/R141b nanorefrigerant with minimal environmental impact is only 0.67% of coal-fired power generation. The environmental impact of current work is about 14.34% of other nations’ PV results.