A New Method for Impeller Inlet Design of Supercritical CO<sub>2</sub> Centrifugal Compressors in Brayton Cycles
Supercritical Carbon Dioxide (SCO<sub>2</sub>) is considered as a potential working fluid in next generation power and energy systems. The SCO<sub>2</sub> Brayton cycle is advantaged with higher cycle efficiency, smaller compression work, and more compact layout, as compared...
| Main Authors: | , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2020-09-01
|
| Series: | Energies |
| Subjects: | |
| Online Access: | https://www.mdpi.com/1996-1073/13/19/5049 |
| _version_ | 1797552656300900352 |
|---|---|
| author | Xiaojian Li Yijia Zhao Huadong Yao Ming Zhao Zhengxian Liu |
| author_facet | Xiaojian Li Yijia Zhao Huadong Yao Ming Zhao Zhengxian Liu |
| author_sort | Xiaojian Li |
| collection | DOAJ |
| description | Supercritical Carbon Dioxide (SCO<sub>2</sub>) is considered as a potential working fluid in next generation power and energy systems. The SCO<sub>2</sub> Brayton cycle is advantaged with higher cycle efficiency, smaller compression work, and more compact layout, as compared with traditional cycles. When the inlet total condition of the compressor approaches the critical point of the working fluid, the cycle efficiency is further enhanced. However, the flow acceleration near the impeller inducer causes the fluid to enter two-phase region, which may lead to additional aerodynamic losses and flow instability. In this study, a new impeller inlet design method is proposed to achieve a better balance among the cycle efficiency, compressor compactness, and inducer condensation. This approach couples a concept of the maximum swallowing capacity of real gas and a new principle for condensation design. Firstly, the mass flow function of real gas centrifugal compressors is analytically expressed by non-dimensional parameters. An optimal inlet flow angle is derived to achieve the maximum swallowing capacity under a certain inlet relative Mach number, which leads to the minimum energy loss and a more compact geometry for the compressor. Secondly, a new condensation design principle is developed by proposing a novel concept of the two-zone inlet total condition for SCO<sub>2</sub> compressors. In this new principle, the acceptable acceleration margin (AAM) is derived as a criterion to limit the impeller inlet condensation. The present inlet design method is validated in the design and simulation of a low-flow-coefficient compressor stage based on the real gas model. The mechanisms of flow accelerations in the impeller inducer, which form low-pressure regions and further produce condensation, are analyzed and clarified under different operating conditions. It is found that the proposed method is efficient to limit the condensation in the impeller inducer, keep the compactness of the compressor, and maintain a high cycle efficiency. |
| first_indexed | 2024-03-10T16:04:09Z |
| format | Article |
| id | doaj.art-eaa27a05ec65442f9310ffeb13a1f287 |
| institution | Directory Open Access Journal |
| issn | 1996-1073 |
| language | English |
| last_indexed | 2024-03-10T16:04:09Z |
| publishDate | 2020-09-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Energies |
| spelling | doaj.art-eaa27a05ec65442f9310ffeb13a1f2872023-11-20T15:04:04ZengMDPI AGEnergies1996-10732020-09-011319504910.3390/en13195049A New Method for Impeller Inlet Design of Supercritical CO<sub>2</sub> Centrifugal Compressors in Brayton CyclesXiaojian Li0Yijia Zhao1Huadong Yao2Ming Zhao3Zhengxian Liu4Department of Mechanics, Tianjin University, Tianjin 300350, ChinaDepartment of Mechanics, Tianjin University, Tianjin 300350, ChinaDepartment of Mechanics and Maritime Sciences, Chalmers University of Technology, 41296 Gothenburg, SwedenDepartment of Mechanics, Tianjin University, Tianjin 300350, ChinaDepartment of Mechanics, Tianjin University, Tianjin 300350, ChinaSupercritical Carbon Dioxide (SCO<sub>2</sub>) is considered as a potential working fluid in next generation power and energy systems. The SCO<sub>2</sub> Brayton cycle is advantaged with higher cycle efficiency, smaller compression work, and more compact layout, as compared with traditional cycles. When the inlet total condition of the compressor approaches the critical point of the working fluid, the cycle efficiency is further enhanced. However, the flow acceleration near the impeller inducer causes the fluid to enter two-phase region, which may lead to additional aerodynamic losses and flow instability. In this study, a new impeller inlet design method is proposed to achieve a better balance among the cycle efficiency, compressor compactness, and inducer condensation. This approach couples a concept of the maximum swallowing capacity of real gas and a new principle for condensation design. Firstly, the mass flow function of real gas centrifugal compressors is analytically expressed by non-dimensional parameters. An optimal inlet flow angle is derived to achieve the maximum swallowing capacity under a certain inlet relative Mach number, which leads to the minimum energy loss and a more compact geometry for the compressor. Secondly, a new condensation design principle is developed by proposing a novel concept of the two-zone inlet total condition for SCO<sub>2</sub> compressors. In this new principle, the acceptable acceleration margin (AAM) is derived as a criterion to limit the impeller inlet condensation. The present inlet design method is validated in the design and simulation of a low-flow-coefficient compressor stage based on the real gas model. The mechanisms of flow accelerations in the impeller inducer, which form low-pressure regions and further produce condensation, are analyzed and clarified under different operating conditions. It is found that the proposed method is efficient to limit the condensation in the impeller inducer, keep the compactness of the compressor, and maintain a high cycle efficiency.https://www.mdpi.com/1996-1073/13/19/5049supercritical carbon dioxidecentrifugal compressorimpeller inlet designmaximum swallowing capacitycondensation |
| spellingShingle | Xiaojian Li Yijia Zhao Huadong Yao Ming Zhao Zhengxian Liu A New Method for Impeller Inlet Design of Supercritical CO<sub>2</sub> Centrifugal Compressors in Brayton Cycles Energies supercritical carbon dioxide centrifugal compressor impeller inlet design maximum swallowing capacity condensation |
| title | A New Method for Impeller Inlet Design of Supercritical CO<sub>2</sub> Centrifugal Compressors in Brayton Cycles |
| title_full | A New Method for Impeller Inlet Design of Supercritical CO<sub>2</sub> Centrifugal Compressors in Brayton Cycles |
| title_fullStr | A New Method for Impeller Inlet Design of Supercritical CO<sub>2</sub> Centrifugal Compressors in Brayton Cycles |
| title_full_unstemmed | A New Method for Impeller Inlet Design of Supercritical CO<sub>2</sub> Centrifugal Compressors in Brayton Cycles |
| title_short | A New Method for Impeller Inlet Design of Supercritical CO<sub>2</sub> Centrifugal Compressors in Brayton Cycles |
| title_sort | new method for impeller inlet design of supercritical co sub 2 sub centrifugal compressors in brayton cycles |
| topic | supercritical carbon dioxide centrifugal compressor impeller inlet design maximum swallowing capacity condensation |
| url | https://www.mdpi.com/1996-1073/13/19/5049 |
| work_keys_str_mv | AT xiaojianli anewmethodforimpellerinletdesignofsupercriticalcosub2subcentrifugalcompressorsinbraytoncycles AT yijiazhao anewmethodforimpellerinletdesignofsupercriticalcosub2subcentrifugalcompressorsinbraytoncycles AT huadongyao anewmethodforimpellerinletdesignofsupercriticalcosub2subcentrifugalcompressorsinbraytoncycles AT mingzhao anewmethodforimpellerinletdesignofsupercriticalcosub2subcentrifugalcompressorsinbraytoncycles AT zhengxianliu anewmethodforimpellerinletdesignofsupercriticalcosub2subcentrifugalcompressorsinbraytoncycles AT xiaojianli newmethodforimpellerinletdesignofsupercriticalcosub2subcentrifugalcompressorsinbraytoncycles AT yijiazhao newmethodforimpellerinletdesignofsupercriticalcosub2subcentrifugalcompressorsinbraytoncycles AT huadongyao newmethodforimpellerinletdesignofsupercriticalcosub2subcentrifugalcompressorsinbraytoncycles AT mingzhao newmethodforimpellerinletdesignofsupercriticalcosub2subcentrifugalcompressorsinbraytoncycles AT zhengxianliu newmethodforimpellerinletdesignofsupercriticalcosub2subcentrifugalcompressorsinbraytoncycles |