To control the power output of an isentropic steam turbine a throttle valve is placed in the steam line leading to the turbine inlet. steam at 6 MPa and 700c is supplied to the throttle inlet.and the turbine exhaust pressure is set at 70 kPa. what is the effect on the stream exergy at the turbine inlet when the throttle valve is partially closed such that the pressure at the turbin inlet is 3 MPa.compare the second-law efficiency of this system when the valve is partially open to when it is fully open.take t=25 c