Advanced Exergy Analysis of a Supercritical CO2 Power Cycle for Waste Heat Recovery

Aiming at the issue that conventional exergy analytic methods cannot disclose which part in the total exergy destruction of components is caused by their own irreversibility and how much can be avoided by improving the components, advanced exergy analysis of a supercritical CO2power cycle for waste heat recovery is conducted to find out the cause of the exergy destruction and determine the actual improvement potential of components. Firstly, a multi-objective optimization of a recuperated layout waste heat recovery system is carried out from the aspects of thermodynamics, economy and compactness, and a thermoeconomic and exergy analyses are also performed. Then, the exergy destruction of each component is divided into four parts: endogenous avoidable, endogenous unavoidable, exogenous avoidable and exogenous unavoidable, and an advanced exergy analysis is performed. Finally, a comparison of the results of conventional and advanced exergy analyses shows the limitations of the conventional method. The results show that after optimization, the net electrical generation, LOCE and specific power heat transfer area are 6. 24 MW, 4. 48 cents/ (kW · h) and 0. 19 m2/kW, respectively. The exergy destruction rate of the recuperator is the highest, at about 37%. Due to technical limitations of key equipment, the exergy efficiency of the unavoidable cycle is reduced by about 7% compared to the ideal condition. The total exergy destruction is mainly caused by the irreversibility of the components themselves and can be reduced by about 43% by improving the efficiency of the components. The turbine has the highest endogenous avoidable exergy destruction rate under different gas turbine operating conditions. © 2024 Xi'an Jiaotong University. All rights reserved.