Techno-economic performance of the 2-propanol/1-butanol zeotropic mixture and 2-propanol/water azeotropic mixture as a working fluid in Organic Rankine Cycles

The techno-economic performance of the novel 2-propanol/1-butanol zeotropic mixture and 2-propanol/water azeotropic mixture as a working fluid in Organic Rankine Cycles (ORC) for waste heat recovery applications is analyzed. The ORC with two different architectures is modeled in the Aspen Plus V.10 environment for heat recovery from hot gases at 250 and 350 °C with atmospheric and sub-atmospheric condensation scenarios. The effects of different heat source/sink conditions on the performance of zeotropic mixture are studied in detail to show under which condition the zeotropic mixtures may result in higher efficiencies. The propanol/butanol mixtures (P/B) rich in propanol and propanol/water mixtures (P/W) with composition near the azeotropic point can result in 15–75% higher overall efficiencies compared to toluene and MM. However, cyclopentane shows higher efficiencies than these mixtures when atmospheric condensation is considered. According to the economic assessment, the 55%P/45%W and 75%P/25%B mixtures lead to superior results for the atmospheric condensation scenario compared to other fluids. Also, it was found that only under a tailored boundary condition, the zeotropic mixture can perform superiorly compared to the most efficient component in the mixture.