Question

A saturated liquid–vapor mixture of water, in a pipe line at 1.5 MPa is throttled to 100 kPa and 150°C. Determine (a) the quality of the mixture (b) the entropy change during the throttling process.

Answer 1

State 1: Saturated liquid avaper mixture of water at pi= 1.5 MPa state 2 ad P=100 kpa, T2=150°c Solution: A Throthing as an esenthalfic process eie. COMIAN- enthalpy process. he zh ie h2=h, o from steam table, at P2 = 100 kPa Tsat - 99-62 > Tsat 2 state 2 is in superheated stake. from superheated steam table af P2 = 100 kpa Ta = 150°c h = 2776.4 kJ /kg $= 7.6133 Jingok Now at P = 1.5 MPa hf=844.87 KT lkg hfy = 1947-3 kohta Sf = 2-3150 kJ/kg ffy = 4.2198 kJ/kg k a hi = hz hf fahify = 27.96.4 . 844-87+ **. 1947.3 = 2776.4

:|* = 0.99 0.99 € Entropy change (52 ~S1) Non, - Siz Srotasfg = 2.3150 f 0.99 x 42198 si = 6.4926 to " AS = s-si = 7.6133 ~ 6.4926 As = 1.1206 KJ Tagok