Thermodynamic Design and Comparative Analysis of Rankine, ORC and Kalina Cycles for Low-Cost, Meso-Scale Power Generation Systems

Thermodynamic and thermoeconometric aspects of a 12.5kW residential solar-thermal power generating system are presented in this paper. The design of a meso-scale power system greatly differs from centralized power generation and as a result, this system is limited to maximum pressure of 4 MPa and maximum temperature below 500°C. The cycles under consideration are the Rankine cycle, the Organic Rankine cycle (ORC) with toluene, R123, and ethylbenzene as working fluids, and the Kalina cycle. Cycle comparisons are based off of a steady-state first law analysis of the systems under consideration. These systems are characterized to determine the system with the highest efficiency and minimum collection area. The solution that best fits a solar-thermal power system limited to 2 MPa is an ethylbenzene ORC. If the pressure is limited to 4 MPa, then the toluene ORC shows good potential.