Experimental assessment of the impact of number of stages on vertical axis multi-stage centrifugal PATs

The pursuit of Best Management Practices (BMPs) for pressurized water systems has intensified interest in Pumps As Turbines (PATs), given that PAT use enables coupling of pressure regulation with small-scale hydropower generation. Installing PATs instead of micro-turbines provides for several advantages, such as cheaper procurement and maintenance costs, and importantly, the ability to select the most reliable model from among a wide variety of devices available in the market. Nevertheless, the current state of knowledge regarding PAT performance leaves out critical aspects that remain to be adequately addressed, especially for some models, such as centrifugal vertical axis multi-stage pumps running in reverse mode, despite such devices having attractive features that offer particularly advantageous benefits when high head in the system is exploitable.