Abstract Hybrid Organic Rankine Cycle (ORC) systems provide a promising pathway for improving low-grade heat recovery, especially when integrating renewable sources such as solar thermal energy and biomass. This study presents a thermodynamic analysis of a hybrid ORC employing advanced zeotropic mixtures enhanced with nanoparticles to improve heat absorption and cycle performance. Three environmentally friendly HFO-based zeotropic mixtures were evaluated in Aspen Plus, combined with TiO 2 , ZnO, and Ag nanoparticles at varying mass fractions (ϕ = 0.0001–0.1). The results indicate that temperature glide matching in the zeotropic mixtures significantly improved evaporator heat transfer and reduced irreversibility. Among the nanoparticles examined, Ag demonstrated the highest thermal enhancement, achieving an efficiency of up to 10.77% and a 12.3% increase in net power output at ϕ = 0.01. Higher nanoparticle mass fractions (ϕ = 0.1), however, resulted in reduced performance due to increased viscosity and agglomeration effects. The hybrid solar–biomass configuration provided improved thermal stability and continuous operation under fluctuating environmental conditions. Overall, the findings highlight the potential of combining zeotropic mixtures with optimally dispersed nanofluids to enhance the performance and stability of hybrid ORC systems for sustainable low-temperature power generation.
Kumi et al. (Tue,) studied this question.