Question

At the inlet of a steam turbine the following information are given: p=1000 kPa, T=500 deg-C, u = 3124.3 kJ/kg, v = 0.35411, V=20 m/s, z=10 m, and mdot=10 kg/s.

determine the inlet area.

Determine the flow work at the inlet in MW

Determine the rate of transport of flow energy (Jdot).

If you neglect ke and pe in the expression for j, how would the answer in part c change? in percentage

Answer 1

For an inlet steam turbine, we have

pressure, p = 1000 kPa

temperature, T = 500 ⁰C

kinetic energy, U = 3124.3 kJ/kg

velocity of the turbine, v = 20 m/s

mass flow rate, = 10 kg/sec

(a) The inlet area will be given as ::

using an equation, A = V / v                                                                     { eq.1 }

where, V = specific Volume of Superheated Steam = 0.35411 m³/kg             (from table)

inserting the values in above eq.

A = (0.35411 m³/kg) (10 kg/sec) / (20 m/s)

A = 0.17705 m²

(b) the flow work at the inlet in MW which will be given as ::

_u = [h_in + K.E_in] { eq.2 }

where, h_in = specific enthalpy of superheated steam = 3479 kJ/kg                    (from table)

inserting the values in eq.2,

_u = (10 kg/sec) [(3479 kJ/kg) + (3124.3 kJ/kg)]

_u = (10 kg/sec) [(6603.3 kJ/kg)]

_u = (66033 kJ/s) (1 MW s /1000 kJ)

_u = 66.03 MW