| Abstract | Pump as Turbine (PAT) is one of the ways to reduce the equipment cost in micro hydropower projects and is one attractive alternative to conventional hydraulic turbine. However, the drawback of PAT is lacking of flow controlling device, which causes rapidly dropping performance when PAT operate at off-design point. Thus, the new concept by using the flow regulating device namely, spear valve, nozzle and deflector will be proposed in this study. The objective in this research is to optimize the pump working as turbine in Impulse mode by using the flow controlling device. To optimize Impulse PAT, the geometries of a Centrifugal pump have to be known. However, the pump vendors are reluctant to supply or give typical geometries of their pump. In order to achieve this study, there are two main processes as follow: pump selection and Impulse PAT optimization. The pump’s geometries derived from pump calculation based on their given geometries and characteristic curves. These calculated geometries will be used to be the input parameter to optimize the Impulse PAT. In the optimization procedure, there are two options to inject the water in different direction. In other words, when the water jet velocity is lower than rotational speed, the first option will be applied in spite of second option. The result from optimizing Impulse PAT shows that the second option namely, when velocity of water jet is higher than rotational speed is solely adapted in pump operating as Impulse turbine. Moreover, the result shows that the maximum efficiency of Impulse PAT is occurred when the rotational speed of Impulse PAT performs nearly half of water jet velocity. |