Experimental Performance Evaluation of a Pump-as-Turbine System With Experimental Validation, BEP Identification, and Uncertainty

Abstract

The paper includes an extensive experimental investigation of a Pump-as-Turbine (PAT) system under controlled laboratory conditions with rigorous calibration and validation of comuncertainty. A test facility was established as a completely equipped closed loop test facility to test the hydraulic head, discharge, rotational speed, electrical output and the efficiency. Three rotational speed conditions were also applied to have the performance characteristics with nominal heads of 8 m, 10 m, and 12 m. (H–Q)  curves verified the anticipated inverse hydraulic performance whereas the efficiency (η–Q) characteristics demonstrated different Best Efficiency Points (BEPs). Low, medium, and high speeds had peaked efficiencies of 0.67, 0.75 and 0.80 at discharges of 0.054 m³ /s, 0.057 m³ /s and 0.060 m³ /s respectively. The electrical output rose up to 2.6 kW at low speed to almost 5.9 kW at high speed in line with turbomachinery affinity laws. Time-series monitoring was used to provide stability in data acquisition in the steady-state, and uncertainty propagation with the KlineClintock method reported a total efficiency uncertainty within a variation of ±3%. The findings prove that the experimental system derived can offer a credible and physically consistent data of PAT performance that can be optimized and used in micro-hydropower.