Thermo-economic performance comparison and advanced analysis using orthogonal experiment for organic Rankine cycle

Abstract

To improve the thermo-economic performance of organic Rankine cycle (ORC) systems, a multi-level analysis method is proposed in this study. In the first level, the optimal configuration is determined based on the thermo-economic optimization. The exergy efficiency and electricity production cost are selected as the objective functions of optimization for three ORC configurations, including simple ORC, TORC (two-stage ORC), and DORC (dual-loop ORC). In the second level, the real potential of performance improvement for the optimal configuration is revealed through advanced exergy analysis method. Finally, the order of operating parameters to different performance indicators of the optimal configuration is determined by orthogonal experiment method. The results show that the TORC system exhibits better thermo-economic performance. Although the low-temperature condenser in the TORC system has the highest exergy destruction, the LTT (low-temperature turbine) contributes the largest avoidable-endogenous exergy destruction. Thus, the LTT has the greatest potential for technical improvement. The condensation temperature and pinch point temperature difference in the low-temperature evaporator are the primary factors for the thermodynamic and economic performance of the TORC system, respectively. While the evaporation temperature of the high-temperature evaporator has the greatest effect on the potential of technical improvement for the LTT.