The power extracted from the fluid by the turbine (points 1 and 2 are as shown in the figure: z1=35 m and z2=0 m). (b) The useful power delivered to the fluid by the pump (points 1 and 2 in the figure should be reversed: z1=0 m and z2=35 m).
A pump-turbine is a piece of equipment that can operate either as a pump or as a turbine, depending on the direction of the water flow. The picture on the right shows a pump-turbine system.
When it is daytime, this system is used as a turbine, taking water from the upper reservoir and discharging it into the lower reservoir, producing electricity. When it is nighttime, electricity is cheaper, and this system is used as a pump, taking water from the lower reservoir and discharging it into the higher reservoir, so that it can produce electricity again the next day when it is used as a turbine. Consider that, using the system as a turbine or pump, the water flow is 1m3/s and the pressure drop is 5 m, determine:
(a) The power extracted from the fluid by the turbine (points 1 and 2 are as shown in the figure: z1=35 m and z2=0 m).
(b) The useful power delivered to the fluid by the pump (points 1 and 2 in the figure should be reversed: z1=0 m and z2=35 m).
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