Deriaz pump-turbine for pumped hydro energy storage and micro applications

Abstract

The growing importance of the efficiency and operational range of pumped hydro energy storage (PHES) installations, especially for variable load operations, calls for the use of more efficient turbomachinery designs. Deriaz turbomachines are promising candidates, since, among other advantages, they can operate as reversible pump-turbines with high hydraulic efficiency over a wide range of operational loads. Deriaz pump-turbines are largely absent from the literature and this paper gives an overview of their design, application and performance features. Particular attention is given to the hydraulic characteristics and design of a downsized model (6-21 kW) suitable for micro-scale PHES applications. This paper provides a practical and easily-built method to implement a micro Deriaz pump-turbine runner which gives a good outline for design at high yield (about 90%). The analysis is supported by extensive numerical simulations for different working conditions and validated by experimental data. The results confirm the superior characteristics of Deriaz pump-turbines and validate the design process, which is described here for the first time.

Innovative Projects and Technology Implementation in the Hydropower Sector

“…The maximum efficiency is around 90%, and it can be kept constant from 30 to 120% of the design flow rate. The Deriaz turbine is able to work in pumping mode [34]. Kuromatagawa II power station adopted a vertical shaft Deriaz pump-turbine in 1963 to deal with a large head variation and to attain high efficiency at part load.…”

Numerical investigation on the volute cutwater for pumps running in turbine mode

“…7), in respect of the maximum level of orthogonality (average skewness > 75 ∘ ), average expansion ratio (ER < 5), acceptable ER at viscous layer (ER 1:2) and average aspect ratio (AR 5). The final mesh is considered acceptable when the generated outputs do not show great sensitivity to local or global grid refinements [49,55]. The convergence criterion is set at 10 ¡4 and, until the converged values for efficiency and torque exceed the range of 0.04% from the solution obtained with a finer mesh, the number of the grid points are further increased.…”

Untitled

“…It has a vertical axis, and adjustable runner blades. The most recent review on the Deriaz turbine is presented in Morabito [17]. The DT has a lower specific speed than a Kaplan turbine, and it works more efficiently at partial loads and at higher available head than a Kaplan turbine, like Francis turbines.…”