Micro-Hydro Pay out Reduction Using Pump as Turbine

Abstract

Due to the depletion of fossil fuel and global environmental problems, there is a need to develop renewable energy sources. The study assessed the possibility of using a standard centrifugal pump to run as turbine in lieu of Francis turbine that is complicated, expensive, unavailable and unfeasible for small hydro application. An experiment was conducted at MSU-IIT, Iligan City, Philippines to study the characteristics of the centrifugal pump when used as turbine. The tested pump had a specific speed of 0.58, 15.55 meters head and flow rate of 0.0048 m3/s at a speed of 3450 rpm with expected efficiency of 50%. Since the available head at the test site was only 5.5 meters and flow rate of 0.0036 m3/s, the speed was calculated using its specific speed. During the experimentation, the results showed that its highest efficiency occurred at 1800 rpm which matched to the calculated speed. The results also showed that the efficiency of the pump-as-turbine approaches the efficiency of the pump in pump mode. These results are useful in the performance prediction of pumps when working as turbines. However, careful piping system analysis should also be seriously considered for any flow restriction,sudden expansion would significantly reduce the energy available for the turbine which has been observed during the experimentation. Keywords: Mechanical Engineering, standard centrifugal pump, alternative for standardturbine, experimental design, Iligan City, Philippines