Steam at 3.45 MPa, 260oC enters a well-insulated valve operating at steady state with a mass flow rate of 0.05 kg/s through a 2.54 cm diameter pipe. The steam expands to 1.40 MPa with no significant change in elevation. The expansion is not necessarily a throttling process.
(a) Determine the exit velocity and the exit temperature, if the ratio of inlet to exit pipe diameters, d1/d2, is 0.25.
(b) Explore and discuss the effects of area change as the steam expands by plotting:
The exit velocity
The exit temperature
The exit specific enthalpy
for d1/d2 ranging from 0.25 to 5. Use the plots to discuss the assumptions that are normally made for a throttling process.