AN INVESTIGATION OF REVERSING AXIAL TURBOMACHINERY FOR THERMAL ENERGY STORAGE APPLICATION

摘要

This paper investigates the feasibility of reversing axial turbomachinery for a thermal energy storage application. Under the proposed concept, the direction of flow and spool rotation is reversed when changing from electrical generation to heat pump mode, and the axial turbomachinery components function as either a compressor or turbine depending on the energy storage system's mode of operation. Such reversing pump-turbines are widely used in pumped hydro installations but have not been employed for compressible flow applications to our knowledge to date. The preliminary aerodynamic design approach for the reversing blade geometry is described, followed by a CFD-based evaluation of turbomachinery performance for the case of a 50MW thermal storage plant. The demand for high efficiency in both modes leads to an unconventional design with a large number of stages for a given pressure ratio. A statorless counter-rotating architecture is utilized for efficiency considerations, and to reduce the overall number of turbomachinery components. Initial CFD results indicate that the reversing axial turbomachinery is capable of achieving high efficiency in both modes of operation, and of satisfying the performance goals of the thermal energy storage application.