Fluids selection of an organic Rankine cycle integrated to a parabolic trough solar power plant for waste heat recovery

This study addresses challenges in conventional CSP plants, notably high-temperature steam generation and energy loss during condensation, prompting the exploration of Waste Heat Recovery (WHR) solutions. Among these, Organic Rankine Cycles (ORCs) stand out for their efficiency at low temperatures, yet literature lacks focus on their integration into CSP plants and fluid selection. This research fills this gap by investigating the performance of ORC-based WHR systems in parabolic trough solar power plants, aiming to optimize energy recovery efficiency through systematic analysis of various organic fluids. The obtained results reveal that the plant utilizing R143a achieves exceptional performance, generating over 249 GWh annually with a capacity factor close to 57%, attributed to the ORC’s remarkable efficiency surpassing 12.7%. Conversely, the plant employing pentane exhibits the lowest performance metrics due to its dry nature, recording only 241.3 GWh of generated power, an 18.41% global efficiency, and a 55.08% capacity factor. CSP plants with WHR systems, such as the one using R134a, outperform stand-alone plants, enhancing dispatch capacity by nearly 9% for both annual power generation and capacity factor, despite a decline in solar contribution caused by elevated condensing pressure.