Improving Efficiency and Reducing Costs for the Supercritical C02 Design Process

Supercritical CO2 cycles have the potential to significantly improve efficiency and reduce emissions in power generation. However, the unique fluid dynamic properties of supercritical CO2 that enable these higher efficiencies also complicate the design and layout of the system, particularly its turbomachinery components. The problem stems specifically from the highly non-linear properties of CO2, which pose significant difficulties in modeling. Commercial software companies have been slow to respond to this issue, resulting in a critical unmet market need. The objective of this Phase I effort is to create a comprehensive set of computational software tools that can accurately predict the performance of compressors, pumps and turbines when operating with supercritical CO2. To reduce the scope and complexity of this effort, the specific developments needed for supercritical CO2 will be built on a foundation of existing software tool sets, already developed for turbomachinery design. Once these models have been comprehensively upgraded for the specific demands required, a complete and fully functional system for the confident design of turbomachinery components for supercritical CO2 applications will be realized. Phase I tasks include: The improvement of thermodynamic calculations for the unique demands of supercritical CO2 and its efficient application in computational fluid dynamic analysis. A comprehensive study of how to stabilize the solution process in the existing solver, with recommendations for schematic changes required in Phase II. Development of recommendations to improve turbulence models for non-linear fluid properties, such as supercritical CO2. Development of post-processing functions that can determine the need for nucleation modeling and solution reliability. Recommendations for a suitable nucleation model based on the initial results from Phase I. If this project is carried over into Phase II or Phase III, the commercial applications are extensive. The software would be applicable to many different supercritical CO2 power cycle scenarios, and it will encourage energy saving in other areas where efficient turbomachinery design with real fluid thermodynamic properties is required. Key Words: supercritical, CO2, compressor, power