Thermal assessment and optimization of process fluids in transcritical organic and transcritical CO2 Rankine cycle for waste energy recuperating system

Abstract

• Thermodynamic modeling of basic TORC and CTRC is conducted. • Evaluation of optimum operating conditions for the working fluids. • Energy and exergy analysis performed with optimized input parameters. As natural resources are depleting gradually, scientists are inclining toward the quest for an alternate source of energy and searching for efficient ways to mitigate wastage of energy. The potential of the organic Rankine cycle (ORC) in the application of recovering energy from medium and low-temperature heat sources has been explored by researchers for a long time. Over the years numerous optimizations and modifications have appeared to extract usable power from sources that are fundamentally discharging waste energy to the environment. In this study, a thermodynamic model of basic transcritical Organic Rankine Cycle (TORC) and carbon dioxide-based transcritical Rankine cycle are modeled using a validated MATLAB code, scrutinizing the optimum condition of eleven working fluids. This study prioritizes environment-friendly working fluids and the fluids with lower ODP and GWP indices have been selected for experimentation. These working fluids have been tested setting optimized input parameters and a comparative study of working fluids has been done using exergy destruction distribution. According to the second law analysis, at low turbine inlet temperature, R32 works better than other process fluids. Whereas, at higher temperatures, carbon dioxide delivers better performance compared to other working fluids.