Question

The inlet and the outlet conditions of steam for an adiabatic steam turbine are as indicated in the notations are as usually followed.

If mass flow rate of steam through the turbine is 20 kg/s, the power output of the turbine (in MW) is

• A. 12.157
• B. 12.941
• C. 168.001
• D. 168.785

Answer 1

The correct option is A 12.157

Applying the steady flow energy equation,
$m(h_1+\frac{V_1^2}{2}+g{z}_1)+Q=m(h_2+\frac{V_1^2}{2}+g{z}_2)+W$
where Q = 0 for adiabatic flow,
$m(h_1+\frac{V_1^2}{2}+g{z}_1)=m(h_2+\frac{V_1^2}{2}+g{z}_2)+W$
On units balancing, we get
$m(h_1+\frac{V_1^2}{2000}+\frac{g{z}_1}{1000})=m(h_2+\frac{V_1^2}{2000}+\frac{g{z}_2}{1000})+W$
$20(3200\frac{(16{)}^2}{2000}+\frac{9.81\times 10}{1000})=20(2600+\frac{(100{)}^2}{2000}+\frac{9.81\times 6}{1000})+W$
$64257.96=52101.17+W$
or $W=12156.79kW$
$=12.1568MW$
$=12.157MW$