Thermal, steady-flow, table, continuity

1. The problem statement, all variables and given/known data

Steam at 2 MPa and 208°C enters a nozzle with 20m/s. During the expansion process, its enthalpy drops to 2.86 MJ/kg because of the losses encountered.

a) Determine the exit velocity from the nozzle.
b) If the mass flow rate is 1kg/s, determine the flow area at the nozzle inlet.

2. Relevant equations

Steady-flow Energy Equation: Q-W=m{(hf-hi)+1/2(Uf^2-Ui^2)+g(Zf-Zi)},
difference between rate of heat and work=difference between rate of energy at inlet and exit

For Nozzle, heat, work, and PE can be neglected:
(hi-hf)=1/2(Uf^2-Ui^2)

Continuity equation: mi=mf=constant, mass flow rate is constant
m=ρ*A*U, ρ=density, A=flow area, U=fluid velocity

steam tables: http://ift.tt/1luT0J3

3. The attempt at a solution

a.) checking the steam tables, the enthalpy of sat. liquid is 1236kJ/kg,
(1236-2.86)=1/2(Uf^2-20*2)
Uf=53.54m/s, which is not correct. The given answer is around 400m/s.
I don’t know why ;(

I will try b) after I understand a).
Please help me with part a!

http://ift.tt/1lsOyWL

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