Performance of supercritical carbon dioxide (sCO2) centrifugal compressors in the Brayton cycle considering non-equilibrium condensation and exergy efficiency
Performance of supercritical carbon dioxide (sCO2) centrifugal compressors in the Brayton cycle considering non-equilibrium condensation and exergy efficiency
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DOI：
10.1016/j.enconman.2023.117849
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发表时间：
2024-01
影响因子：
10.4
通讯作者：
Hongbing Ding;Yu-Wei Dong;Yu Zhang;C. Wen;Yan Yang
中科院分区：
文献类型：
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作者：
Hongbing Ding;Yu-Wei Dong;Yu Zhang;C. Wen;Yan Yang
以超临界二氧化碳（sCO 2）离心压缩机为核心的布雷顿循环因其高效节能而受到广泛关注。因此，对sCO 2离心压缩机内部流场特性的深入研究变得尤为重要。在本研究中，我们开发了一个数学模型，以评估跨音速流中的非平衡冷凝的sCO 2压缩机的性能。结果表明，该模型能够较好地预测sCO 2的相变，为该研究的性能分析提供了可靠的工具。此外，通过引入三次样条曲线外推方法，该模型可以处理亚稳态下CO2的复杂热力学性质。在此基础上，分析了不同进口温度和转速对压气机流场特性和性能的影响。进一步发现，随着入口温度的升高，冷凝强度受到抑制，冷凝位置向后移动。在50%叶展处，液相分数从306 K时的5.15%下降到325 K时的1.32%。最后，从能量的角度对压缩机的火用损失和火用效率进行了定量分析。结果表明，进口温度变化时，湿蒸汽模型下的火用效率有很大差异。随着转速的降低，（火用）效率降低。在20,000 rpm时，效率达到81.35%，比10,000 rpm时提高了51.02%。
The Brayton cycle, with supercritical carbon dioxide (sCO2) centrifugal compressors at its core, has received widespread attention for its high efficiency and energy savings. Therefore, the in-depth exploration of the internal flow field behaviour of sCO2centrifugal compressors becomes especially critical. In the present study, we develop a mathematical model to evaluate the performance of a sCO2compressor considering non-equilibrium condensation in transonic flows. It is validated that the model can well predict the sCO2phase change and is a reliable vehicle for the performance analysis in this study. Further, by incorporating the cubic spline curve extrapolation method, the model can handle the complex thermodynamic properties of CO2under a metastable state. Then, this study presents a series of analyses for the effects under different conditions, such as different inlet temperatures and rotational speeds, on the flow field characteristics and performance of the compressor. It’s further found that with an increase in inlet temperature, the condensation intensity is suppressed and the condensation position moves backwards. At the 50% blade span, the liquid phase fraction decreases from 5.15% at 306 K to 1.32% at 325 K. Finally, from an energy perspective, this study implements a quantitative analysis of the exergy destruction and exergy efficiency of the compressor. The results show that the exergy efficiency under the wet steam model is quite different when the inlet temperature changes. With the decrease of rotating speeds, the exergy efficiency will decrease. The exergy efficiency reaches 81.35% at 20,000 rpm, which is 51.02% higher than that at 10,000 rpm.