Exergoeconomic assessment and parametric study of combined recompression supercritical carbon dioxide Brayton – Organic Rankine cycle with integrated LiBr/H2O absorption refrigeration cycle and thermoelectric generator modules

Abstract

The integration of innovative systems as an effective waste-heat recovery strategy for the utilization of low-temperature heat sources is receiving increased attention as an alternative sustainable approach towards reducing fossil fuel combustion and emission pollution. Heat sink devices are identified as the primary sources of waste-heat, hence, the effective utilization of the waste-heat through systems integration are exploited. In this study, exergetic and exergoeconomic based parametric analysis is performed on combined recompression supercritical carbon dioxide Brayton - organic Rankine cycle with integrated LiBr/H₂O absorption refrigeration cycle and thermoelectric generator units. The proposed system aims to maximize low-grade waste heat conversion to electricity through sustainable system integration. Thermodynamic and exergoeconomic analysis was performed for both the base- and enhanced-systems, and parametric investigation carried out to predict the effect of temperature, pressure and mass flow rate variation on system's performance parameters. Results obtained indicate that the enhanced-system has a net power output of +48.58 % higher than the base-system, with 1.3 %, 11.9 %, and 14.7 % contributed by the thermoelectric generators (TEGI, TEGII, and TEGIII, respectively). Similarly, the enhanced-system reveals +22.55 % and +28.19 % better first- and second-law efficiencies than the base-system. The heat exchanger, absorption refrigeration cycle generator and solution heat exchanger are the major components with the highest value of exergy destruction with 15.23 %, 12.99 %, and 11.97 % contribution to the total exergy destroyed in the system. Therefore, the same components are considered priority for system improvement efforts as suggested by the values of improvement potential, fuel depletion ratio, Irreversibility and ${\dot{Z}}_k+{\dot{C}}_D$.