Diseño de pico-turbinas hidráulicas axiales para la recuperación de energía en redes de distribución de agua

Abstract

Energy consumed by the water industry is not negligible and improvements on energy efficiency in water distribution networks are still needed. This research work aimed to provide a new approach to design tailored torpedo shaped in-pipe axial pico-hydraulic turbines for the recovery of energy in water distribution networks. To improve over works found on the literature and bibliography ideal flow bi-dimensional cascade theory with Weinel isolated airfoil to cascade correlations were used as compromise between accuracy and simplicity. From it, a dimensionless design chart was built. A novel flow-to-head factor was chosen as main dimensionless factor to simplify stator analysis allowing for more compact chart. Simple straight untwisted blades with arc of circles profiles were imposed to simplify manufacturing. From five usual input design parameters, choosing the value of three, and letting two of them to vary allowed the trace of the space of all optimal designs. From this space, a turbine or family of turbines can be obtained. Representative comercial and open source software for CFD workflow was explored and tested. Shortcomings were found for CAD and quality mesh- ing for tested open source software. A mesh parametric study for numerical validation and uncertainty characterization with a hybrid software’s license approach was made. Open source Salome platform v9, comercial Ansys TurboGrid v17 and open source library OpenFOAM v8 were used for meshing and simulation. The maximum discretization uncertainty found for the selected mesh was about 2 %. Developed meshing and simulation criteria were satisfactory and used for the follow-up designs. A comparative study was made to test the method. A design example and a design following a method from the bibliography were carried over and simulated on the same conditions as a experimentally tested turbine found in the literature. The design example showed better performance curves on the maximum efficiency plateu giving a maximum hydraulic efficiency of 63 %. A design algorithm and selection criteria for electric components were developed from the analysis of dimensionless hydraulic-electric coupled system to charge batteries using energy recovered from the water distribution net- works. These were applied to an industrial case for the recovery of energy on the water network of the city of Murcia. A pico-hydraulic turbine was designed and electric components of the system were simultaneously selected for optimal operation in coupled state. Simulations were carried over and dimensionless curves and operational maps were made, showing that the coupled system met the requirements of the industrial case. The developed non-dimensional approach proved to be useful to design efficient tailored simple pico-hydraulic turbines with optimal hydraulic-electric coupled systems for energy recovery in distribution water networks, relaying on one dimensionless design chart