To prevent cavitation, a pump for a pumped storage power plant has to be placed at the proper elevation relative to the water level of the lower reservoir. The elevation difference between the water level of the upper and the lower reservoir is 350 m. The pump has to deliver a volume flow of 70 m?/s from the lower to the upper reservoir, at rpm = 375 rev/min. Consider a frictional pressure drop per meter elevation difference in the piping of 1 kPa in the suction pipe and 1.4kPa in the pressure pipe. Assume a water temperature of 10°C and a density of 1000 kg/m2 1) Approximate NPSHR (in m) of the pump (use Thomas number Th and specific speed).
2) At what elevation (in m) relative to the water level of the lower reservoir has the pump to be installed? (Assume lower basin water level has elevation 0 m.)
3) Draw a sketch of the arrangement and indicate the elevation differences.