Preliminary Design and Model Assessment of a Supercritical CO2 Compressor

Abstract

Abstract:The compressor is a key component in the supercritical carbon dioxide (SCO 2 ) Brayton cycle. In this paper, the authors designed a series of supercritical CO 2 compressors with different parameters. These compressors are designed for 100 MWe, 10 MWe and 1 MWe scale power systems, respectively. For the 100 MWe SCO 2 Brayton cycle, an axial compressor has been designed by the Smith chart to test whether an axial compressor is suitable for the SCO 2 Brayton cycle. Using a specific speed and a specific diameter, the remaining two compressors were designed as centrifugal compressors with different pressure ratios to examine whether models used for air in the past are applicable to SCO 2 . All compressors were generated and analyzed with internal MATLAB programs coupled with the NIST REFPROP database. Finally, the design results are all checked by numerical simulations due to the lack of reliable experimental data. Research has found that in order to meet the de Haller stall criterion, axial compressors require a considerable number of stages, which introduces many additional problems. Thus, a centrifugal compressor is more suitable for the SCO 2 Brayton cycle, even for a 100 MWe scale system. For the performance prediction model of a centrifugal compressor, the stall predictions are compared with steady numerical calculation, which indicates that past stall criteria may also be suitable for SCO 2 compressors, but more validations are needed. However, the accuracy of original loss models is found to be inadequate, particularly for lower flow and higher pressure ratio cases. Deviations may be attributed to the underestimation of clearance loss according to the result of steady simulation. A modified model is adopted which can improve the precision to a certain extent, but more general and reasonable loss models are needed to improve design accuracy in the future.

Определение Положения Границы Области Устойчивой Работы Осевого Многоступенчатого Компрессора При Выполнении Расчетных Исследований

“…Данный подход к определению границы успешно использован в работе [4], однако, в работе [5] отмечается, что данный критерий имеет существенные ограничения по режиму работы компрессора.…”

Theoretical Analysis of Isentropic Exponent Effects on the Internal Flow of Supercritical CO2 Centrifugal Compressors

“…As one of the compression devices, the centrifugal compressor has the advantages of high single-stage pressure ratio, ow stability, compactness, cheapness, etc. Our previous research showed that the centrifugal compressor is the most suitable type of compression component in a 1-100 MWe supercritical CO 2 Brayton cycle power generation system [12,13]. A literature survey reported by [14,15] revealed that most of the existing supercritical CO 2 experimental rigs adopted the centrifugal type as the compression component.…”

A New Method for Impeller Inlet Design of Supercritical CO2 Centrifugal Compressors in Brayton Cycles

“…The above analysis shows that the impeller inlet aerodynamic and geometrical parameters are coupled and interacted. In recent years, some preliminary design methods for SCO 2 compressors were developed by integrating the real gas model and the mean-line methods of air compressors [18,20]. However, those methods usually paid more attention to explore the impeller outlet parameters of SCO 2 compressors [19,21], and they cannot well cope with the interactions among impeller inlet parameters.…”