Performance Analysis of an Integrated Supercritical CO2 Recompression/Absorption Refrigeration/Kalina Cycle Driven by Medium-Temperature Waste Heat

A novel power and cooling cogeneration system which combines a supercritical CO2 recompression cycle (SCRC), an ammonia-water absorption refrigeration cycle (AARC) and a Kalina cycle (KC) is proposed and investigated for the recovery of medium-temperature waste heat. The system is based on energy cascade utilization, and the waste heat can be fully converted through the simultaneous operation of the three sub-cycles. A steady-state mathematical model is built for further performance study of the proposed system. When the exhaust temperature is 505 degrees C, it is shown that under designed conditions the thermal efficiency and exergy efficiency reach 30.74% and 61.55%, respectively. The exergy analysis results show that the main exergy destruction is concentrated in the heat recovery vapor generator (HRVG). Parametric study shows that the compressor inlet pressure, the SCRC pressure ratio, the main compressor and the turbine I inlet temperature, and the AARC generator pressure have significant effects on thermodynamic and economic performance of the combined system. The findings in this study could provide guidance for system design to achieve an efficient utilization of medium-temperature waste heat (e.g., exhaust heat from gas turbine, high-temperature fuel cells and internal combustion engine).

Automated summary

A novel power and cooling cogeneration system combining a supercritical CO2 recompression cycle, an ammonia-water absorption refrigeration cycle, and a Kalina cycle has been proposed for efficiently recovering medium-temperature waste heat. A steady-state mathematical model is built to analyze the system's performance. Parametric study reveals significant effects of compressor inlet pressure, SCRC pressure ratio, main compressor and turbine I inlet temperature, and AARC generator pressure on the system's thermodynamic and economic performance.