Parametric analysis and comprehensive multi-criteria evaluation of double-stage organic Rankine cycle

Abstract

Double-stage organic Rankine cycle (DORC) is a more effective mechanism of circulation for recovering heat released from industrial wastewater. It is crucial to determine the optimum operating circumstances for the DORC system, and its effectiveness cannot be effectively assessed by applying a single objective evaluation approach. The AHP-entropy analysis method is utilized to establish a three-level assessment system, taking into account several indicators, in order to execute a thorough study of the DORC system. Eight organic fluids, including R113, R124, R1233zd(E), etc, are chosen as the working mediums of the DORC system. The results demonstrate that the heat source temperature exists maximum value that match the working fluids under the impact of the pinch point temperature difference and the critical temperature of the working medium. When the evaporation pressure increases, the whole system performance improves, according to the AHP-entropy analysis of the operating state that corresponds to the single goal optimum value. When the critical temperature of the working medium is approximately 50 °C above the hot water temperature for a given heat source, the system performs more effectively. Additionally, when the heat source temperature is close to the critical temperature of the eight organic fluids, the DORC system operates more effectively.