Water is pumped from a large reservoir to a storage tank 30m above via a constant diameter pipe. The volumetric flow rate during pumping is 55 L/s. This is found to require 25kW of electrical power input to the motor driving the pump. The top of the storage tank is open to the atmosphere. The water density, ?=1000kg/m³, and the absolute viscosity, ?=1mPa.s. Determine: a) The overall efficiency of the pump-motor unit if all frictional losses in the pipes are neglected. b) The pressure difference between the inlet and the exit of the pump for the same case as part a). c) Frictional losses in the pipe are found to be significant. If the length of pipe between the pump and the storage tank is 130m, the pipe diameter is 20cm, and the surface roughness is 0.4mm, determine a more accurate estimate for the overall efficiency of the pump-motor unit. Minor losses can be neglected.
Added by Theodore J.
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\[ 55 \text{ L/s} = 55 \times 10^{-3} \text{ m}^3/\text{s} \] Show more…
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