Water at 20 bar, 400°c enters a turbine operating at steady state and exits at 1.5 bar. stray heat transfer and kinetic and potential energy effects are negligible. a hard-to-read data sheet indicates that the quality at the turbine exit is 98%. can this quality value be correct? if no, explain. if yes, determine the power developed by the turbine, in kj per kg of water flowing.

quality value is not 98%

Explanation:

given data

inlet pressure p1 = 20 bar

outlet pressure p2 = 1.5 bar

temperature t1 = 400°C

solution

as assume here assume isentropic process so equation that states stray heat transfer is negligible so Q = 0  and S1 = S2

S1 = Sf2 + x Sfg2   ........................1

here x is quantity of steam and we get all other value by steam table

so at pressure 20 bar and 400°C and at pressure 1.5 bar

S1 = 7.127 kJ/kg K and Sf2 = 1.4336 kJ/kg K

and Sfg2 = 5.7898 kJ/kg K

so put all value in equation 1 we get x that is

x =

x = 0.9833

x = 98.33 %

so here we can say quality value is not 98%