1 Determine the maximum pressure increase across a 10 hp pum

1) Determine the maximum pressure increase across a 10 hp pump if the inlet water velocity is 30 ft/s, the inlet diameter is 1” and the exit diameter is 1.5”.

2) An inventor claims to have raised the temperature of a small amount of water to 150°C by transferring heat from high pressure steam at 120°C. Is this a reasonable claim? Why or why not?

3) When two liquid streams (one hot, one cold) pass each other in a heat exchanger, which irreversibility is present? What type (internal/external/total) of irreversibility is it?

Solution

1)

W = 10 hp = 10*745.7 = 7457 watt

V_i = 30 ft/s = 30*0.3048 = 9.144 m/s

D_i = 1 ft = 0.3048 m

D_e = 1.5 ft = 0.4572 m

V_i*A_i = V_e*A_e

V_e = 4.064 m/s

P_i + V_i^2*/2 = P_e + Ve^2*/2 + (-W)

P_e - P_i = 41005.32 pascal

2)

It is not possible without external work because heat flow from high temperature to low temperature.

3)