Answer to Question #316653 in Mechanical Engineering for Helen

Question

6. A throttling calorimeter is connected to the superheated steam line supplying steam to the auxiliary feed

pump on a ship. The line pressure measures 2.5 Mpa. The calorimeter pressure is 110 kpa and 150oC.

Determine the entropy of the steam line. PLEASE EXPALIN THE DETAILED ANSWER/SOLUTION.

ANSWER: a. 6.8 KJ/kg-oK c. 6.6 KJ/kg-oK

b. 6.2 KJ/kg-oK d. 7.5KJ/kg-oK

Answer 1

From the steam table;

Superheated steam at 110kPa,150°C we obtained;

$h_2=2775.6kJ/kg$

For saturated liquid and vapour tables;

$h_{f_1}=962.11kJ/kg$

$h_{f_g}=1841kJ/kg$

Also;

$h_1=h_2$

$h_1=h_{f_1}+xh_{fg_1}$

$x=\frac{h_1-h_{f_1}}{h_{fg_1}}$

$x=\frac{2775.6-962.11}{1841}$

$x=0.985$