Question

1. Using the tables for water, determine the specific entropy at the indicated states, in kJ/kg.K. In each case, locate the state by hand on a sketch of the T-s diagram a. p-5.0 MPa, T-4000 b. p 5.0 MPa, T 100o c. p 5.0 MPa, u-1872.5 kJ/kg d. p 5.0 MPa, saturated vapor.

Answer 1

Obtain the saturated temperature of liquid at 5 MPa pressure from saturated pressure tables 263.94°C Since T>T , it is superheated state Obtain the specific entropy at 5 MPa pressure and 400°C temperature from superheated table by interpolation s-6.7690 + ( 6.5408-6.7690) × 50-40 60-40 s 6.6549 kJ/kg K Obtain the saturated temperature of liquid at 5 MPa pressure from saturated pressure tables 263.94°C Since, T,at > T ( 100°C). İt is compressed liquid phase Obtain the specific entropy at 5 MPa pressure and 100°C temperature from compressed liquid table s1.303 kJ/kg K Obtain the specific internal energy at 5 MPa pressure from saturated pressure tables 1147.8 kJ/kg u, 2597.1 kJ/kg s, 2.9202 kJ/kg K s, 5.9738 kJ/kg K Calculate the quality of steam using the following relation u-l, ї,-11 1872.5-1147.8 2597.1-1147.8 0.5 Calculate the specific entropy as follows 2.92020.5(5.9734 - 2.9202) s 4.4468 kJ/kg K

Obtain the specific entropy of saturated vapor at 5 MPa from saturated pressure table. s-s 5.9734 kJ/kg K s 5.9734 kJ/kg K T, 7" al 5 MPa