Comparative analysis and multi-criteria optimization of a supercritical recompression CO2 Brayton cycle integrated with thermoelectric modules

Abstract

Regarding the high expense of the exploiting energy from energy resources, each innovation or modification on the energy systems with the aim of enhancing the efficiency and affordability is so valuable. Along with this fact, in the present work, the effects of employing thermoelectric (TEG) unit in a recompression Brayton cycle ( $${\text{sCO}}_{2}$$ -reB/TEG) are examined. The results of thermodynamic modeling represents that adding the thermoelectric to the system in the s $${\text{CO}}_{2}$$ -reB can improve the net output power about 2.41 kW and increase the first and second law efficiency of s $${\text{CO}}_{2}$$ -reB/TEG system about 1.09% and 1.12% in comparison with s $${\text{CO}}_{2}$$ -reB system. Additionally the exergo-economic analysis for s $${\text{CO}}_{2}$$ -reB/TEG revealed that the reactor and turbine II should be considered more than other elements from exergo-economic point of view since the highest values of $$\dot{Z}_{\rm k} + \dot{C}_{\rm D,k}$$ belong to these components. After identifying the important parameters as well as evaluating system from thermodynamic and economic aspects, a multi-objective optimization is implemented on the $${\text{sCO}}_{2}$$ -reB-TEG system for determining the optimum conditions. Two optimization scenarios are defined using the results of parametric analysis. Multi-objective optimization with first scenario results in total cost rate of 1.6 $ h−1 and total exergy efficiency of 0.5 in minimum temperature, maximum temperature and compression ratio of 36.17 °C, 577.15 °C and 1.6. Furthermore, for optimization based on second scenario results in total exergy destruction cost and exergy destruction rate of 3.04 $ h−1 and 435.85 kW in 48.75 °C, 569.77 °C and 3.44 for minimum temperature, maximum temperature and compression ratio.