Question

5.0kg/s cyclohexane is pumped from a height of 2.5m to a height of 15m. Before the pump inlet, the cyclohexane is motionless inside of a holding tank. The diameter of the pipe at the exit point is 2.5 cm. The density of cyclohexane is 779 kg/m3 . Calculate the pump power required in watts and hp. Assume negligible friction. Hint: you will have to include the effect of the outlet velocity ​​

Answer 1

5.0 Kg/s = 18 m³/h

height = (15 m - 2.5 m) = 12.5 m

P_h(kW) = q ρ g h / (3.6 10⁶)            

where

P_h(kW) = hydraulic power (kW)

q = flow capacity (m³/h)

ρ = density of fluid (kg/m³)

g = gravity (9.81 m/s²)

h = differential head (m)

The hydraulic Horse Power can be calculated as:

P_h(hp) = P_h(kW) / 0.746   

where

P_h(hp) = hydraulic horsepower (hp)

P_h(KW) = [18 m³/h x 779 kg/m³ x 9.81 m/s² x 12.5 m] / (3.6 x10⁶)

P_h(KW) = 0.4776 KW = 477.6 W

P_h(hp) = P_h(kW) / 0.746 = (0.4776 KW / 0.746) = 0.64 hp