Optimization of Organic Rankine Cycles for Waste Heat Recovery From Aluminum Production Plants

Frontiers in Energy Research

Elsido, Cristina¹  Castelli, Alessandro Francesco² 

[1]Department of Energy and Process Engineering, The Norwegian University of Science and Technology (NTNU), Norway

[2]Department of Energy, Politecnico di Milano, Italy

关键词: Organic Rankine cycle (ORC);    waste heat recovery;    optimization;    heat integration;    Zeotropic mixture;    Working fluid;   

DOI  :  10.3389/fenrg.2019.00044

学科分类：能源（综合）

来源: Frontiers

【 摘 要 】

This paper presents the optimization of ORCs for recovering waste heat from a hypothetical aluminum production plant to be installed in Norway. The case study is particularly interesting because it features two hot streams at different temperatures (the pot exhaust gases and the cell wall cooling air) which make available about 16 MWth below 250 °C. First, a recently proposed cycle optimization approach is adopted to identify the most promising working fluid and optimize the cycle variables (pressures, temperatures, mass flow rates) for the maximum energy performance. The analysis includes both pure fluids, including recently synthesized refrigerants, and binary zeotropic mixtures assessing in total 102 working fluids. The best pure fluid in terms of exergy efficiency turn out to be HFE-347mcc (which can achieve a target exergy efficiency of 85.28%), followed by neopentane, butane and R114. HFO-1336mzz appears to be one of the most promising non-flammable alternatives with low GWP. The mixture leading to the highest exergy efficiency is isobutane-isopentane, which can increase the net electrical power output by up to 3.3% compared to pure fluids. The systematic techno-economic optimization, repeated for two different electricity prices, shows that RE347mcc is the best option in both low and high electricity prices. The cost of the cycle using HFO-1336mzz is penalized by the larger evaporation heat (negatively influencing the heat integration) and the smaller regenerator.

【 授权许可】

CC BY