Analysis of the Thermodynamic Potential of Supercritical Carbon Dioxide Cycles: A Systematic Approach

Abstract

After the renewed interest in supercritical carbon dioxide cycles, a large number of cycle layouts have been proposed in literature. These works, which are essentially theoretical, consider different operating conditions and modeling assumptions, and thus, the results are not comparable. There are also works that aim to provide a fair comparison between different cycles in order to assess which one is most efficient. These analyses are very interesting but, usually, they combine thermodynamic and technical restrictions, which make it difficult to draw solid and general conclusions with regard to which the cycle of choice in the future should be. With this background, the present work provides a systematic thermodynamic analysis of 12 supercritical carbon dioxide cycles under similar working conditions, with and without technical restriction in terms of pressure and/or temperature. This yields very interesting conclusions regarding the most interesting cycles in the literature. Also, useful recommendations are extracted from the parametric analysis with respect to the directions that must be followed when searching for more efficient cycles. The analysis is based on efficiency and specific work diagrams with respect to pressure ratio and turbine inlet temperature in order to enhance its applicability to plant designs driven by fuel economy and/or footprint.