Question

10. A supercritical power generates steam at 25 Mpa and 560􀔨. The condenser pressure is 7 kpa. Determine the exit quality of steam if it expands through a turbine in this power plant.

Answer:

a. 45.66% c. 56.66%

b. 68.45% d. 74.26%

Answer 1

Solution;

From steam tables;

At 250Mpa and 560°C;

$s_2=6.1615$

At 7kPa ;

$s_g=0.5965$

$s_{fg}=7.494$

Assuming isentropic expansion;

$s_2=s_1=s_f+xs_{fg}$

$9.5255=0.651+7.494x$

$x=\frac{6.1615-0.5965}{7.494}=0.74263$

Answer=74.26%