An innovative concept for the design and modification of low-specific-speed centrifugal pump impellers with above-average efficiency and head.

Centrifugal Pumps with New Impellers Offering Above-Average Efficiency

Centrifugal pumps are among the most widely used machines globally, found in everything from household dishwashers to nuclear power plants. Today, it is difficult to imagine any industrial facility, process plant, or manufacturing line operating without them. It is estimated that 15% of all electricity generated worldwide is consumed by pumps. Can pumps be improved to boost their efficiency and thereby reduce energy consumption? The project titled "Innovative Concept for the Design and Modification of Low-Specific-Speed Centrifugal Pump Impellers with Above-Average Efficiency and Head" addresses this exact question. The research is led by Janusz Skrzypacz, D.Sc. Eng., University Professor at the Department of Energy Conversion Engineering, Faculty of Mechanical and Power Engineering, Wrocław University of Science and Technology. The initiative is executed under the Proof of Concept action, funded by the European Funds for a Modern Economy 2021–2027 (FENG) program and implemented by the Foundation for Polish Science (FNP).

In today's world, it is hard to find a machine without a pump. Even a standard automobile contains at least four pumps (one for fuel supply, a second for coolant circulation, a third for windshield washers, and a fourth for engine lubrication), whose combined power consumption can account for up to 5% of the total power generated by the engine. In thermal power plants, driving the pumps necessary to maintain the power generation process consumes between 2% and up to 10% of the station's total output. Consequently, researchers continually strive to refine centrifugal pump designs, and Prof. Janusz Skrzypacz's work is part of this ongoing effort.

"The project that my team and I are carrying out is based on creating shallow dimples on the front and rear shroud surfaces of a low-specific-speed centrifugal pump impeller. This design aims to reduce disk friction losses and increase fluid circulation, thereby raising the pump's head. The concept has been submitted for patent protection. As part of the Proof of Concept project, studies will be conducted to analyze flow phenomena in these new impellers, evaluate the impact of dimple geometry on pump performance, optimize dimple shapes and spatial distribution on the impeller surfaces, and define the application boundaries of this solution. Based on these findings, we will formulate design guidelines for such impellers," says Prof. Janusz Skrzypacz.

Preliminary research verifying the concept has already confirmed its high potential. A major advantage of this approach is its versatility: it can be applied both to the design of new impellers and, to a certain extent, to retrofitting existing constructions.

"The patent developed with my colleagues can be applied to low-specific-speed pumps, which are characterized by relatively low discharge flow rates and relatively high heads. Typical application areas include lubrication system pumps, fire pumps, central heating circulators, and similar equipment," explains Prof. Skrzypacz.

Janusz Skrzypacz, D.Sc. Eng., has worked at Wrocław University of Science and Technology for 25 years, focusing on hydraulic turbomachinery. He is the author or co-author of numerous scientific publications in domestic and international journals, a speaker at industry events, and a member of advisory boards. Throughout his career, he has participated in many joint academic-industrial projects, such as modernizing large mixed-flow pumps, upgrading large multiphase pumps, designing and implementing an LNG propulsion system for the Samsø Ferry, and designing the cryogenic system for the European Spallation Source (ESS) accelerator in Lund, Sweden. However, he remains most fascinated by issues related to the design and operation of centrifugal pumps, particularly those operating in the ultra-low specific speed range.