A water pump increases the water pressure from 15 psia to 70 psia. Determine the power input required, in hp, to pump 1.5 ft3/s of water. Does the water temperature at the inlet have any significant effect on the required flow power?

11.52 hp

Explanation:

Givens:

p_1 = 15 pisa

p_2 = 70 pisa

V_ol=1.5 ft^3/s

Solution:

Note: m = p x V_ol (assuming in compressible flow - > p = const)

The total change in the system mechanical energy can be calculated as follows,

Δ e = (p_2 - p_1) / p

The power needed can be calculated as follows

P = W = mΔ e = p x V_ol x (p_2 - p_1) / p

= V_ol x (p_2 - p_1)

= 44 pisa. ft^3/s

= 44 x (1 btu/5.404pisa. ft^3) x (1 hp/0.7068btu/s)

= 11.52 hp