Steam at 100 kPa and 150 degree C enters to an isentropic di


Steam, at 100 kPa and 150 degree C enters to an isentropic diffuser with a velocity of 500 m/s. If the exist state is 300 kPa, calculate the exist velocity of steam.

Solution

P1= 100 kPa, T1= 150oC, V1 = 500 m/s, P2 = 300 kPa, V2=?

From Steam Tables at state 1, h1= 2776.6 kJ/kg, s1= 7.6148 kJ/kgK

The process is isentropic diffusion, so the s1=s2.

From steam tables corresponding to 300 kPa and s2=s1=7.6148, the T2= 275o C and h2= 3019 kJ/kg.

V12/2 +h1 = V22/2 + h2 ==> V22//2 = V12/2 + h1 - h2 where h is in Joules

But h1 - h2 = -242.4 kJ/kg = -242400 J/kg and V12/2 =125000 only which gives negative value for V22 which is not possible.

There must be some error in the question.

 Steam, at 100 kPa and 150 degree C enters to an isentropic diffuser with a velocity of 500 m/s. If the exist state is 300 kPa, calculate the exist velocity of

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