Analysis and evaluation of the performance and utilization of regenerative flow pump as turbine (PAT) in Pico-hydropower plants

In this paper, a novel PAT system was analyzed and evaluated for utilization at very low specific speeds. Thus, a regenerative pump was employed due to the simplicity, compact size, stable features, low manufacturing costs, and very low specific speed. A theoretical analysis was developed based on the momentum exchange theory to predict the performance characteristics of the regenerative pump in reverse operation. Also, a 3D numerical simulation was implemented to study the performance of the pump in reverse mode. The numerical simulations were validated with experimental data of the pump. Results revealed that except for very low flow rates the presented model provides an acceptable prediction of the PAT performance. Results showed that at BEP, efficiency has decreased by about 20%. The head ratio and discharge ratio was obtained a bout 3.5 and 3.6, respectively. According to the results of entropy generation method, the impeller blades showed the most potential for energy losses. It was concluded that regenerative pump could be easily run as a low specific speed hydraulic turbine or a pressure reducing valve due to the cheapness, reliability and availability. •The performance of the regenerative flow pump in reverse operation was investigated using a 3D numerical simulation.•A theoretical analysis is developed based on the momentum exchange theory for the regenerative pump as turbine.•The entropy generation method is implemented for energy loss evaluation in the regenerative pump as turbine.•The impeller blades show the most potential for energy losses.•Regenerative pump could be easily run as a very low specific speed hydraulic turbine or a pressure reducing valve.