A combined dual-stage waste heat recovery system integrated to an internal combustion engine is studied. The system
consists of high-temperature steam Rankine cycle (SRC) and a low-temperature organic Rankine cycle (ORC), both combined to
recover the waste heat of the engine exhaust gases and engine coolant. In the ORC, organic working fluids R245fa, R600 and
R601a are selected for analysis and sub-critical cycle adopted.
For the comparative study of the selected working fluids, energy and exergy analysis are conducted based on the engine data,
pre-set parameters and mathematic model with net-output power, utilization rate, thermal efficiency and exergy efficiency as the
objective functions for optimization
