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过程工程学报 ›› 2019, Vol. 19 ›› Issue (2): 246-253.DOI: 10.12034/j.issn.1009-606X.218179

• 流动与传递 • 上一篇    下一篇

有机工质向心透平变工况特性的数值模拟与极差分析

张振康1， 曾凡云2， 王志奇1*， 夏小霞1， 贺 妮1， 胡艳华1， 张建平1   

  1. 1. 湘潭大学机械工程学院，湖南 湘潭 411005 2. 楚天科技股份有限公司，湖南 长沙 410600
  • 收稿日期:2018-04-04 修回日期:2018-06-29 出版日期:2019-04-22 发布日期:2019-04-18
  • 通讯作者: 张振康 1129398320@qq.com
  • 基金资助:
    国家自然科学基金项目;湖南省自然科学基金

Numerical simulation and range analysis of off-design performance for a radial-inflow turbine

Zhenkang ZHANG1, Fanyun ZENG2, Zhiqi WANG1*, Xiaoxia XIA1, Ni HE1, Yanhua HU1, Jianping ZHANG1   

  1. 1. Institute of Mechanical Engineering, Xiangtan University, Xiangtan, Hunan 411005, China 2. Truking Technology Limited, Changsha, Hunan 410600, China
  • Received:2018-04-04 Revised:2018-06-29 Online:2019-04-22 Published:2019-04-18

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摘要： 以R245fa为工质设计向心透平，采用CFD方法对向心透平性能进行全流域三维模拟研究，考察了入口温度、转子转速和膨胀比(进出口压力比)对向心透平工况特性的影响，对主要影响因素进行极差分析。结果表明，向心透平工作转速为设计转速的80%~100%时，输出功率和等熵效率波动较小，工作转速高于设计值时透平性能迅速下降。随入口温度升高，透平输出功率与等熵效率增大；随膨胀比增大，透平输出功率线性增加。透平存在最佳膨胀比使等熵效率最大，且实际运行压比大于最佳膨胀比时，透平等熵效率变化较小。出口压力对向心透平输出功率影响最大，温度的影响最小；转子转速对等熵效率影响最大，入口压力的影响最小。

关键词: 向心透平, 变工况特性, 数值模拟, 极差分析

Abstract: The radial-inflow turbine is a key component determining the performance of organic Rankine cycle (ORC) systems. Its isentropic efficiency and power output are mainly influenced by the working fluid and operation conditions. Although R245fa is a suitable working fluid for ORC systems, there is limited research concerning full structure numerical simulation and off-design analysis for the radial-inflow turbine using R245fa. In this work, a radial-inflow turbine using R245fa was designed by one dimensional design method and a three dimensional model including volute, stator and rotor was established. According to the developed model, a numerical simulation was carried out using CFD (computational fluid dynamics) method. The effects of inlet temperature, rotor speed and expansion ratio on turbine power and isentropic efficiency were analyzed. Additionally, the range analysis about main factors which influenced the radial-inflow turbine performance was conducted. The results showed that turbine power and isentropic efficiency changed slightly when rotor speed ranged from 80% to 100% of designed value. However, turbine performance decreased rapidly if rotor speed was larger than the designed value. Turbine power and isentropic efficiency increased with the increment of turbine inlet temperature. With the increase of pressure ratio (ratio of inlet pressure to outlet pressure), turbine power increases linearly and there was an optimal pressure ratio for the radial turbine to achieve the highest isentropic efficiency. Under nominal condition, the optimal pressure ratio was 3.23 which was slightly lower than the designed value. Besides, there was a little variation for isentropic efficiency when pressure ratio was larger than that of optimal value. Based on the range analysis, sensitivity of different factors influencing the turbine performance was evaluated. For the turbine output power, the sequence of the factors were listed as: outlet pressure, inlet pressure, rotor speed and inlet temperature. It meaned that turbine power was seriously influenced by outlet pressure and inlet pressure. As for the isentropic efficiency, the rotor speed had the largest impact, followed by the turbine outlet pressure, and the inlet pressure contributed the least.

Key words: radial-inflow turbine, off-design performance, numerical simulation, range analysis