Proposal and performance assessment of a combined system based on a supercritical carbon dioxide power cycle integrated with a double-effect absorption power cycle

Abstract

The supercritical carbon dioxide Brayton cycle is a promising energy conversion approach to provide high efficiency for a wide range of applications, and it is considered to be more potent and appropriate alternative to the conventional steam Rankine cycle for the power generation. To take advantage of the attractive physical and transport properties near the critical point of the carbon dioxide, a large amount of heat is released to the heat sink before the carbon dioxide entering the compressor. In this study, a novel double-effect absorption power cycle is proposed to reuse the waste heat from the supercritical carbon dioxide power cycle for further improving the overall performance. Six decision variables are selected to perform the parametric analysis for determining the effect of these decision parameters on the performance of the proposed system, and the further parametric optimizations, exergy analysis and the comparative study are conducted for the proposed system and other carbon dioxide based system to reveal the superiority in overall performance for the proposed system. The results indicate that the major exergy destruction occurs in the heat source and the heat sink of the single supercritical carbon dioxide system. The exergy destruction in the heat sink can be effectively reduced by 16.23% by integrating the supercritical carbon dioxide system with absorption power cycle, and it can be further reduced by 3.87% by replacing absorption power cycle with the proposed double-effect absorption power cycle. In addition, compared with the single supercritical carbon dioxide system and the combined system integrating supercritical carbon dioxide power cycle with absorption power cycle, the exergy efficiency improvement of 10.94% and 3.00% and the reduction in the total product unit cost by 7.97% and 2.66% can be obtained by the proposed system, respectively.