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Thermal design and CFD analysis of the radial inflow turbine for a CO 2 ‐based mixture transcritical Rankine cycle
Author(s) -
Xia Jiaxi,
Zhou Kehan,
Wang Jiangfeng,
Lou Juwei,
Zhao Pan,
Dai Yiping
Publication year - 2020
Publication title -
international journal of energy research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.808
H-Index - 95
eISSN - 1099-114X
pISSN - 0363-907X
DOI - 10.1002/er.5131
Subject(s) - turbine , degree rankine , rankine cycle , nozzle , transcritical cycle , computational fluid dynamics , tip clearance , mechanics , materials science , mechanical engineering , engineering , thermodynamics , gas compressor , power (physics) , physics , refrigerant
Summary Transcritical carbon dioxide (CO 2 ) Rankine cycle has exhibited great potential in the field of low‐temperature heat utilization. But its application is restricted by the condensing issue and the safety concern due to the relatively low critical temperature and high critical pressure of CO 2 . Blending CO 2 with organic fluids for the transcritical Rankine cycle is regarded as an effective method to solve these problems. And the turbine performance has great influence on the performance of transcritical Rankine cycle. In this paper, the thermal design of the CO 2 ‐based mixture turbine is firstly carried out based on the parametric optimization of the system. Then the computational fluid dynamics (CFD) analysis is performed to examine the turbine performance and validate the reliability of thermal design. Furthermore, the effects of blade tip clearance and nozzle‐to‐rotor clearance on the turbine performance are investigated. Results show that the turbine is well designed with an isentropic efficiency of 84.54%, and the CFD simulation results basically agree with the thermal design results. The influence of leakage flow on mainstream grows significantly as the blade tip clearance increases. When the blade tip clearance is 2 mm, the relative loss of power output could achieve as large as 7.81%. Larger nozzle‐to‐rotor clearance leads to more uniform distributions of Mach number and pressure, but the flow losses also increase. The effect of trailing edge disturbance on the flow field at the nozzle outlet is almost negligible if the nozzle‐to‐rotor clearance is 6 mm or more.