A new generation of centrifugal pumps for high conversion efficiency

Centrifugal pumps are fundamental machines in our daily life. Indeed, they can be found everywhere, for instance, in domestic, civil, industrial, and agricultural fields. In the last years, the pump market has newly gained a boost coherently with the world demographic growth. Pumps are among the main responsible for electric energy consumption, therefore even a slight efficiency improvement (+1%) can be effective in contrasting the growth of the global Greenhouse Gas Emissions (at least −570 tCO2/day in Europe). For this reason, a new generation of centrifugal pumps is here proposed. In particular, the impeller has been redesigned improving the flow guidance inside the vanes and simultaneously reducing the number of blades, with the aim to increase the blade loading, reducing manufacturing costs, and enhancing the conversion efficiency with respect to conventional configurations. Furthermore, the new impeller design respects all the geometrical constraints of the corresponding conventional configuration, allowing its retrofit with a boost of performance. To reach these goals, a 1D in-house code has been developed implementing a Harmony Search Algorithm (HSA) for the selection of the most suitable design point (H and Q), and introducing two parameters for the blade loading evaluation, namely, the blade pressure coefficient (Cp,blade), computed locally along the impeller blade walls, and the blade lift coefficient (CL), achieving an optimal vane arrangement. Starting from a baseline centrifugal pump, the novel impeller has been designed, manufactured, and finally experimentally tested. The resulting new generation of centrifugal pumps actually proves to have a higher performance (maximum efficiency at BEP +1%), a flatter efficiency curve, and a monotone bending characteristic curve, while keeping unchanged the required Net Positive Suction Head (NPSH3%).