A steam turbine that can produce 56400 kW operates with stea

A steam turbine that can produce 56,400 kW operates with steam at inletconditions of 7,500 kPa and 400°C, and discharges as wet steam, a mixture of vaporand liquid, at 100 kPa. The total loss of enthalpy in the process is 1250 kJ/kgenthalpy

.a) (4 points) What is the temperature of the wet steam leaving the turbine?

b) (6 points) What is the mass flow rate of the steam?

c) (14 points) What is the quality of the steam leaving the turbine?

d) (6 points) After further inspection, it appears that the velocity of the fluiddecreases by 25% through the turbine. If the work generated as well thetemperature and pressures in the problem statement are still the same, will thequality of the steam increase, decrease, or stay the same (do not calculate). Be
sure to justify your answer.

Solution

Given: W_T = 56400kW, P₁ = 7500 kPa, T₁ = 400^oC, P₂ = 100 kPa, h₁ - h₂ = 1250 kJ/kg

a) From steam table, the temperature of wet steam leaving the turbine = T₂ = 99.62^oC

b) Since, W_T = m*(h₁ - h₂ )

m = 45.12 kg/s

c) From steam table, s₁ = 6.40698 kJ/kgK

s_f2 = 1.3025 kJ/kgK, s_fg2 = 6.0568 kJ/kgK

Flow of steam through turbine is isentropic process,

s₁ = s_f2 +x*s_fg2

Substituting and solving above equation, we get

x = 0.8427685

Therefore, quality of steam leaving the turbine = 84.27685%

d) As the work generated as well thetemperature and pressures in the problem statement are still the same, the quality of steam at turbine outlet will stay the same.