Thermo-economic design, optimization, and evaluation of a novel zeotropic ORC with mixture composition adjustment during operation

•A novel zeotropic ORC with composition adjustment during operation is proposed.•LSC is used for heat transfer enhancement and composition tuning simultaneously.•Thermo-economic analysis and optimization of two ORCs are conducted and compared.•The effectiveness and superiority of the proposed ORC are verified.•A mixture composition regulation strategy is proposed and validated. Organic Rankine cycle (ORC) is a proposing technology that converting low temperature (usually lower than 200 °C) thermal energy into power. Mostly, the ORC is operated under off-design conditions and the operation performance is deteriorated remarkably from that achieved under rated condition. In the present study, a novel composition-adjustable zeotropic ORC is proposed. A liquid separation condenser-based unit, coupling the heat transfer intensification and mixture composition tuning, is conceptually designed, and integrated into the zeotropic ORC. A regulation strategy for working fluid composition is developed. A thermo-economic evaluation and optimization model and a mixture composition adjustment model are formulated to investigate the superiority of the proposed ORC. A sequential method and genetic algorithm (GA) are applied to conduct the thermodynamic optimization, component design, and thermo-economic optimization of the proposed ORC. A case study is conducted to validate the thermo-economic superiority of the proposed composition adjustable ORC driven by geothermal energy. Results show that the proposed ORC features 0.52% higher annual average net power output, 2.20% higher annual average thermal efficiency, and 21.43% lower average electricity production cost than conventional ORC. The fluid composition-regulating system can achieve the target composition within acceptable time.